Biological Systems

IF SOMETHING CHANGES THE BODY WILL ATTEMPT TO COMPENSATE AND CORRECT THAT CHANGE

control and integration of other body systems

adaptive capabilities- homeostasis

part of neuron containing nucleus, soma

part of neuron that sends impulse towards synapse

parts of neuron that receive impulse

bipolar neuron- have only one dendrite

part of neuron that has highest concentration of voltage-gated Na+ channels

part of neuron that insulates, decreasing surface area to be depolarized and increasing speed of conduction

part of neuron that receives impulse and releases neurotransmitters

part of neuron between myelin sheaths that concentrate the ion channels

polarized to -70mV, where the interior of cell is negatively charged

maintained by two things:
1. Na+/K+ pumps- pump 3 Na+ out, 2 K+ in
2. K+ leak channels- allows K+ to leak out

a neural impulse, a brief electrical charge that travels down an axon

voltage-gated Na+ channels- when membrane potential changes, they open to allow Na+ to flow into cell

they only open at threshold potential of -50 mV
bringing the cell to about +35 mV

voltage-gated Na+ channels inactivate after opening

voltage-gated K+ channels open slowly in response to depolarization, allowing K+ to flow out of cell

this brings cell to -90 mV, which slowly returns to -70mV

Schwann cells and oligodendrocytes wrap axons with myelin, leaving spaces for nodes of Ranvier

forces action potential to jump from node to node, speeding up conduction

absolute refractory period- Na+ channels are inactivated when cells are too positive, K+ channels open, near Na+ equilibrium potential

relative refractory period- Na+ channels switch from inactivated to closed (deinactivated) when cells are too negative, K+ channels close as well, near K+ equilibrium potential

gap junction between two cells, bidirectional flow of impulse, rare but important in cardiac muscle cells

steps:
1. depolarization opens voltage-gated Ca2+ channels
2. Ca2+ influx causes exocytosis of neurotransmitters in secretory vesicles
3. neurotransmitters open ligand-gated Na+ channels on motor endplate
4. Na+ influx triggers action potential

neuromuscular junction- acetylcholine is neurotransmitter

other NTs are GABA, serotonin, dopamine, norepinephrine

1. receptor determines effect, not NT
2. neurons make only one type of NT, can respond to many

action potential is an "all or nothing" response, with the only regulated step being whether the action potential will fire

excitatory postsynaptic potential- depolarize the next neuron, increases chance of action potential firing
inhibitory postsynaptic potential- polarize the next neuron, decreases chance of action potential firing

spatial summation- effect from MULTIPLE presynaptic cells is enough EPSP to fire off postsynaptic cell
temporal summation- SINGLE presynaptic cell, if EPSP are fast enough to fire off postsynaptic cell

tetanus- too many signals building up, blocks inhibitory neurons from releasing neurotransmitters

guide neuron development, regulate neurotransmitters

immune system of CNS

produce and circulate cerebrospinal fluid

one of the 4 glial cells/central neuroglia of the CNS; specialized type of epithelial cells

found lining the inner surface of the ventricles of the brain and the central canal of the spinal cord

afferent neurons- sensory neurons, to CNS

efferent neurons- motor/effector neurons, from CNS

interneurons- connects afferent and efferent neurons

monosympatic reflex arc- sensory neuron directly connects to motor neuron in the spinal cord

reciprocal inhibition- to contract and reflex muscle pairs

supraspinal circuit- involves input from the brain or brainstem to process a stimuli, unlike most reflex arcs

hindbrain- medulla, pons, cerebellum
midbrain- Reticular activating system (RAS)
forebrain- diencephalon, telencephalon (cerebral cortex)

controls heartbeat and breathing

coordinating movement and balance

coordinating and smoothing out movement

arousal (wakefulness) and awareness

relay point for all sensory information

maintain homeostasis, basic needs, controls endocrine system through pituitary gland, hormones affect mood

primitive reflexes and basic behaviors like walking

white matter- myelinated axons, highways
1. tract (brain)
2. tract/column (outer spinal cord)
3. nerve (PNS)

grey matter- unmyelinated bodies, cities
1. nucleus (deep brain)
2. cortex (brain surface)
3. horn (inner spinal cord)
4. ganglion (PNS)

think grey is more dense than white

connects cerebral hemispheres

voluntary motor control

emotion, fear

encoding to LTM

left hemisphere:
1. connected to right side of body
2. interprets right side of visual field
3. language processing (on dominant hemisphere)


right hemisphere
1. connected left side of body
2. interprets left side of visual field
3. visuospatial skills
4. emotional processing
5. music perception

processes visual information

contains somatosensory cortex, integrates sensory information, processes touch and taste

auditory cortex, sound, emotional associations, memories

higher-level processing, conscious decision making, executive functions

can be called cortices

CNS- brain and spinal cord

PNS- nerves and sensory structures

categories of PNS

somatic- voluntary control of skeletal muscle, signaled by acetylcholine, single neuron coming from CNS

autonomic- involuntary control of glands and smooth muscle (heart, stomach, bladder), signaled by acetylcholine from CNS, can excite or inhibit

categories of autonomic NS

parasympathetic- "rest and digest," decreased heart rate, respiratory rate, blood pressure, increased digestive and excretory functions

acetylcholine signal from CNS, then acetylcholine to effectors
long presynaptic neuron, short postsynaptic neuron

PARA LONG PRE

vasoconstriction- cut off blood to certain organs
vasodilation- increase blood to certain organs
happens in both systems to shift blood between GI and muscles and brain

categories of autonomic NS

sympathetic- "fight or flight," increased HR/RR/BP, pupil dilation, decreased digestion, stimulation of adrenal medulla to release epinephrine

increased brain activity, increased glucose metabolism

4Fs = flight, fight, fright, fornicate

acetylcholine signal from CNS, then norepinephrine to effectors
short presynaptic neuron, long postsynaptic neuron

increased BP does not imply vasoconstriction

vasoconstriction- cut off blood to certain organs
vasodilation- increase blood to certain organs
happens in both systems to shift blood between GI and muscles and brain

cranial nerves- carry info to/from brain stem

spinal nerves- carry info to/from spinal cord

vagus nerve- cranial nerve, part of parasympathetic NS that decreases HR and increases GI activity

collections of somas of the sensory neurons in the spinal cord

protective sheath of brain and spinal cord

mechanoreceptors- detect mechanical movement

chemoreceptors- detect chemicals, gustation and olfaction

nociceptors- detect pain

thermoreceptors- detect changes in temperature

photoreceptors- detect EM waves, rods and cones

proprioceptors- detect body position, kinesthetic sense, muscle spindle, (Golgi tendon organs, joint capsule receptors)

spine contains a gate that blocks/allows pain signals

gustation- taste buds have taste hairs, transmitted to the gustatory cortex

olfaction- smells detected by receptors in nasopharynx, transmitted directly to olfactory bulbs in the olfactory cortex

pinna
auditory canal

eardrum
ossicles (malleus, incus, stapes)

oval window
cochlea (perilymph, endolymph)
organ of Corti (basilar membrane, tectorial membrane, cilia with mechanoreceptors)
semicircular canals, utricle, and saccule

round window
Eustachian tube

pitch- place theory describes how regions of basilar membrane that vibrate determine pitch

loudness- amplitude, generates more action potentials

transmitted to auditory cortex in temporal lobe

semicircular canals (fluid shifts inside to detect balance), utricle and saccule (cilia detect acceleration), transmit to pons and cerebellum

conjunctiva- mucous membrane
sclera- thick outer coat, whites

cornea
pupil
iris
lens

retina
fovea centralis
optic disk
optic nerve

anterior chamber
posterior chamber
vitreous chamber

rods and cones
bipolar cells
ganglion cells (optic nerve)

photoreceptors are rods (best at detecting low light) and cones (best at detecting color)
opsins are proteins on photoreceptors

cones are concentrated in the fovea, cones have pigments that absorb green, red, blue, intensity of each color determines the final color perceived

photoreceptors are default on (bipolar and ganglion cells turn on/off)

retinal bound to opsins convert to all-trans on absorbing a photon, triggers polarization of cell by blocking Na+ channels
that stops release of glutamate to bipolar cells

ganglion cells transmit to through optic nerve
*optical chasm* divides the signal so left visual field goes to right brain, right visual field goes to left brain,
first hits lateral geniculate nucleus in thalamus, then goes to respective occipital lobes

signal intensity is determined by how many action potentials are sent

left visual field hits right side of retina, goes to right hemisphere

right visual field hits left side of retina, goes to left hemisphere

color- trichromatic theory

form- parvocellular cells are neurons that detect shapes and boundaries

motion- magnocellular cells are neurons that detect motion

emmetropia- normal vision
myopia- nearsightedness, needs concave lens
hyperopia- farsightedness, needs convex lens

sits on top of the kidneys

adrenal medulla- releases *epinephrine*, sympathetic NS

adrenal cortex- releases *aldosterone and cortisol* (both steroid hormones), stress

produce hormones

sent directly to blood

next to capillaries, no ducts

produce sweat, tears, mucus, earwax, saliva, stomach acid, bile, semen, breast milk, enzymes

sent onto a body surface or cavity

all have ducts except for mucus

peptide- made from amino acids, bind with cell surface receptor, which uses 2nd messenger system like *cAMP*, soluble in blood

fast and temporary!
ex: *insulin, epinephrine*

steroid- made from cholesterol, bind with intracellular receptor, which binds DNA to alter transcription, *require transport proteins to move through blood*

slow and more permanent!
ex: *aldosterone, cortisol*, ends with one/en/ol
exception: thyroid hormone is a peptide that acts like steroid

memorize hormones on pg. 317

neural- hypothalamus sends action potential to releases hormone, epinephrine released from adrenal medulla

hormonal- tropic hormones release other hormones, ACTH stimulates release of cortisol from adrenal cortex

humoral- blood component release hormone, glucose triggers release of insulin, lack of glucose triggers release of glucagon

will attempt to compensate for insufficiencies

anterior pituitary- adrenohypophysis, controlled indirectly by hypothalamus with tropic hormones, makes and secretes FLAT PEG:
1. FSH, LH for testosterone/estrogen
2. ACTH for adrenal cortex (cortisol, aldosterone)
3. TSH for thyroid gland, stimulate metabolism
4. Prolactin for milk
5. Endorphins
6. Growth hormone, stimulate growth

capillary cells, hormone making cells, uses portal veins

posterior pituitary- neurohypophysis, composed of neurons from hypothalamus that directly release hormones, stores and releases oxytocin and ADH (vasopressin)

neuroendocrine cells- neurons that release hormones, action potential travels down cell

flow of blood through tissue

ischemia- inadequate blood flow

hypoxia- inadequate O2 supply

away from heart, high pressure

muscular, elastic walls that regulate flow

arterioles- small arteries just before capillaries

towards the heart, low pressure

muscles and organs that squish against the vessels, valves ensure unidirectional since veins are not muscular or elastic

venules- small veins just after capillaries

varicose veins- when valves fail, venous pressure builds up

nutrient and waste exchange, walls are single cell thick

fluid pushed out due to pressure, fluid pushed back in afterwards due to osmosis

capillaries have lower pressure and lower velocity of blood flow because total cross sectional area is greater than arteries

BP drops to 0 mm Hg when it reaches vena cava

inner lining of all blood vessels, type of epithelial cells

4 functions:
1. vasoconstriction- maintain BP
2. inflammation- recruit WBCs
3. angiogenesis- form new blood vessels
4. thrombosis- control blood clotting

pulmonary circulation- flow of blood from heart to the lungs and back, right side of heart pumps it

systemic circulation- flow of blood from heart to body and back, left side of heart pumps

most blood passes through one set of capillaries before returning to the heart

hepatic portal system- heart to intestine to liver to heart, transports nutrients

hypothalamic-hypophysial portal system- heart to hypothalamus to pituitary gland to heart, transports hormones

retrieve water, WBCs, proteins from tissues and return to circulation

connected to circulatory system

*lymph nodes*- location of immune system cells, filter fluid from tissues

*spleen*- filters blood, removes old RBCs

thoracic duct- near the neck, where lymphatic system dumps fluid back into circulatory system

superior/inferior vena cava- receives deoxygenated blood from body
right atrium- waiting room
tricuspid AV valve
right ventricle- pumps deoxygenated blood to lungs
pulmonary semilunar valve
pulmonary artery- carries deoxygenated blood to lungs

pulmonary vein- carries oxygenated blood from lungs
left atrium- waiting room
bicuspid/mitral AV valve
left ventricle- pumps oxygenated blood to body
aortic semilunar valve
aortic arch- carries oxygenated blood to body

aorta branches off to supply blood to walls of heart

coronary veins carry deoxygenated blood to coronary sinus, which drains directly into right atrium

lub- AV valves close, systole begins
dup- semilunar valves close, diastole begins

systole- heart contracts, ventricles pump blood to body
systolic pressure- BP in arteries when heart contracts

diastole- heart relaxes, atria pump blood to ventricles
diastolic pressure- BP in arteries when heart relaxes

pulse pressure- difference between SP and DP

BP is directly proportional to cardiac output and peripheral resistance

cardiac output (L/min) = stroke volume (L/ beats) x heart rate (beats/min)

stroke volume is blood pumped with each systole, affected:
1. Frank-Starling mechanism- greater venous return stretches heart, so that it contracts harder (increase venous return by not peeing)
2. change activity level for stronger heart
3. change in posture (orthostatic hypotension)

functional syncytium- the individual cells work with adjacent cells for coordinated action. Rapid transmission of electrical impulses transfers between cells to trigger simultaneous contraction of the heart muscle. Electrical synapses, no chemical synapses

intercalated disks- connection between cardiac muscle cells, contain gap junctions

cardiac conduction system- atria signal is transmitted to ventricles after a delay, since they are separate systems not connected by gap junctions

voltage-gated Ca2+ channels- in addition to voltage-gated Na+ channels, these stay open longer for longer depolarization, greater contraction of cardiac muscle, and less tetany (twitches)

T tubules- plasma membrane dips into cytoplasm, more surface area for Ca2+ channels, also sarcoplasmic reticulum

actin-myosin fibers- contract in response to influx of Ca2+

sinoatrial (SA) node- pacemaker of the heart

Phase 4- unstable resting potential, Na+ leak channels slowly depolarize cell until threshold potential for voltage-gated Ca+ channels

Phase 0- depolarization, influx of Ca2+ from voltage-gated Ca2+ channels

Phase 3- repolarization, closure of Ca2+ channels, K+ leak channels open and K+ flows out

Phase 0- depolarization, influx of Na+

Phase 1- initial repolarization, closure of Na+ channels, K+ leak channels open and K+ flows out

Phase 2- plateau phase, influx of Ca2+ from voltage-gated Ca2+ channels balances K+ leak

Phase 3- repolarization, closure of Ca2+ channels, K+ leak channels keep leaking

Phase 4- resting potential, closure of K+ leak channels, maintained by Na+/K+ ATPase

sinoatrial (SA) node- sends impulse to atria
internodal tract

atrioventricular (AV) node- delays impulse to ventricles

bundle of His (AV bundle)

Purkinje fibers- distributes electrical impulse starting at the apex of the heart and moving upwards to pump upwards

parasympathetic NS inhibits rapid automaticity- vagus nerve release acetylcholine to signal SA node to slow down

*vagus tone*- degree of inhibition

sympathetic NS stimulates HR- norepinephrine and epinephrine stimulate cardiac muscle cells

baroreceptors- monitor BP, high BP sends signal for vagal tone increase and sympathetic decrease

pressure gradient = cardiac output (L/min) * peripheral resistance

*adrenergic tone*- sympathetic NS controls peripheral resistance, increase BP

sympathetic NS can also preferentially perfuse certain tissues

local autoregulation- happens with coronary blood flow, certain metabolic wastes build up, automatically trigger high BP

plasma (55%): (mostly water)
1. electrolytes- Na+, K+, Cl-, Ca2+, Mg2+
2. buffers- bicarbonate, maintain pH 7.4
3. glucose
4. albumin- maintain osmotic pressure in capillaries, mobilizes proteins/lipids in serum
5. immunoglobulins- immune system
6. fibrinogen- blood clotting
7. lipoproteins- transport lipids
8. waste- urea (breakdown of amino acids), bilirubin (breakdown of heme)

hematocrit (45%)-include red blood cells

leukocytes (1%)- white blood cells

blood forms 3 layers when centrifuged

most things in blood came from bone marrow stem cells

erythropoietin- hormone made in kidney, stimulates red blood cell production in red bone marrow

RBCs are made in red bone marrow, stored and destroyed in spleen

fun facts:
1. has no organelles, no DNA
2. rely on glycolysis for ATP synthesis
3. contains hemoglobin to transport O2, also CO2
4. biconcave shape has large surface area for gas exchange

incorrect A/B/Rh antigen in blood causes clumping and destruction of RBCs

sensitization- Rh- patient must be exposed to Rh+ blood first to develop antigen, then future exposure to Rh+ blood will cause transfusion reaction

hemolytic disease of the newborn:
1. Rh- mother delivers Rh+ child, becoming sensitized to Rh+
2. future Rh+ babies at risk since Rh antibodies can cross placental barrier to destroy baby's RBCs
3. injecting mother with anti-Rh during first child can prevent sensitization

AB+ blood has all 3 antigens, universal recipient
O- has no antigens, universal donor

body's ability to prevent bleeding, uses platelets

platelets- thrombocytes, produced in the bone marrow, cell fragments that do not have nuclei

platelet plug- platelets aggregate at site of damage

fibrin- protein that holds the platelet plug together

thrombin- converts fibrinogen to fibrin

thrombus- blood clot

hemophilia- defect in a clotting protein, excessive bleeding

hemoglobin- 4 identical subunits with a heme (Fe in middle to bind O2) in each, carried on RBCs and are not in plasma!

cooperativity- when one subunit goes from tense to relaxed and binds O2, the other subunits become relaxed as well and thus have higher affinity for O2

Hill coefficient- 1 is no cooperativity, 4 is perfect cooperativity

4 factors decrease hemoglobin affinity for O2:
1. low O2 environment- cooperativity
2. low pH- Bohr effect
3. high CO2 environment
4. high temperature

% saturation = hemes with O2/total hemes

O2-hemoglobin dissociation curve show cooperativity

fetal Hb has higher affinity

during physical activity, muscles do not get enough oxygen

1. anaerobic glycolysis- produce more ATP without oxygen, lactic acid is a byproduct

2. fast twitch fibers (white)- less mitochondria, use anaerobic glycolysis unlike slow twitch fibers (red)

3. creatine phosphate- supplemental energy reserve that produces more ATP, creatine is a byproduct

4. myoglobin- O2 is taken from hemoglobin and stored in myoglobin (higher O2 affinity) in muscles, can be accessed if more oxygen is needed

5. Bohr effect- oxygen saturation curve shifts down because of increased CO2/H+, allows more O2 to be dumped from hemoglobin at muscles

6. increased RR/HR- increase oxygenation

7. vasodilation- increase oxygenation

CO2 + H2O <-> H2CO3 (carbonic acid) <-> HCO3- (bicarbonate) + H+

this reaction occurs within RBCs, HCO3- exits RBC by exchanging with Cl-

3 ways that CO2 is transported:
1. carbonic anhydrase- enzyme in RBCs that catalyzes rxn
2. attached to hemoglobin (not in O2 position)
3. more water soluble than O2, so in plasma

things that must be exchanged in capillaries:
1. nutrients- amino acids and glucose
2. waste- liver removes wastes and secretes bile
3. lymphocytes- WBCs to attack invaders in tissue
4. water- albumin maintains oncotic pressure to keep water in blood vessels
5. inflammation- WBCs and water flow out of blood vessels to cause edema

nutrient exchange:
1. hepatic portal vein- carries amino acids and glucose from digestive tract to liver
2.chylomicrons- lipoproteins that store fat, enter lacteals in lymphatic system, taken up by liver, converted, carries fat to adipocytes for storage

general protection against invaders:
1. skin
2. lysozyme- enzyme in tears/saliva/ blood that kills bacteria
3. stomach acidity
4. macrophages and neutrophils
5. complement system- blood proteins that nonspecifically bind to foreign cells, signal for destruction

specific protection by antibodies (immunoglobulins), produced by B cells

antibody structure:
1. light and heavy chains joined by disulfide bonds
2. constant region- classes include IgG, IgA, IgM, IgD, IgE
3. variable region- specific antigen binding

antibody function:
1. epitope- small binding site on antigen
2. hapten- small molecule that is only recognized after bound to large carrier protein
3. can directly inactivate antigen, induce phagocytosis, or activate complement system

antibodies generated in one species will get recognized as a foreign substance in a different species

B cell development:
1. lymphocytes in humoral immunity derived from bone marrow stem cells
2. antibody proteins assembled by recombination to create different B cells, allows for clonal selection
3. antigen binding triggers differentiation to plasma cell or memory cell
4. plasma cells- actively secrete antibody protein into plasma
5. memory cells- become dormant, waiting for same antigen to reappear then becomes activated

primary immune response- just plasma cells on first exposure to antigen

secondary immune response- memory cells respond quickly, vaccination

T-cell development:
1. lymphocytes in cell-mediated immunity, T helpers and T killers
2. T cells are produced in bone marrow, but mature in *thymus gland*
3. T helpers (CD4)- activates B cells and T killer cells, communicates with hormones (lymphokines, interleukins), host of HIV
4. T killers (CD8)- destroy abnormal hosts cells (virus infected, cancer, foreign grafts)

MHC I- every cell has them, displays foreign protein on surface of cell to be *detected by T killers*

MHC II- only on antigen-presenting cells (macrophages and B cells), displays foreign protein after chopping it up to be *detected by T helpers*

T cell activation only occurs when T cell binds to both antigen and MHC molecule

white blood cells

3 types:
1. lymphocytes- B cells, T cells, NK cells
2. neutrophils- phagocytosis, most common
3. monocytes- phagocytosis, move to tissue through blood to become macrophages

innate/natural- general immune response, monocytes, neutrophils, NK cells

adaptive immunity- antigen specific response, B cells (humoral), T cells (cell-mediated)

humoral/cell-mediated are actually parts of both systems (innate and adaptive)

an individual does not produce his or her own antibodies, but rather receives them directly from another source, such as mother to infant through breast milk

bone marrow- synthesis of all cells in blood
lymph nodes

spleen- filters blood, destroys old RBCs

thymus gland- T cell maturation

tonsils and appendix- catch pathogens, not necessary

tolerance- immune system ignores normal cells

B cells are selected in bone marrow, T cells in thymus gland

autoimmunity- those that attack normal cells become anergic (unresponsive) or undergo apoptosis

liver- breaks down hydrophobic large waste products, secretes bile, synthesizes urea from free ammonia (toxic)

colon- large intestine reabsorbs water and ions from feces

skin- produces sweat, contains water, ions, and urea

kidneys- keeps everything at optimum levels

filtration- pressurized blood passed over filter, water and small molecules pass into renal tubule to form filtrate

selective reabsorption- glucose, water, proteins are put back in blood

secretion- more waste is added to the filtrate

concentration- more reabsorption of water, makes concentrated urine

renal artery
kidney
ureter
urinary bladder
internal/external sphincter
urethra

cortex
medulla
collecting ducts
papilla
calyx
renal pelvis

1. afferent arteriole
2. glomerulus
3. efferent arteriole- includes cells and proteins
4. Bowman's capsule

5. proximal convoluted tubule- water and solute reabsorption

6. loop of Henle- countercurrent multiplier, descending limb reabsorbs water, ascending limb reabsorbs ions to medulla, allows for better water reabsorption in collecting duct

7. distal convoluted tubule- more regulated reabsorption, secretion of toxins into urine

8. collecting duct- secretion of toxins into urine

9. calyces

peritubular capillaries- reabsorption via active transport, drain back to renal vein

vasa recta- countercurrent to loop of Henle, brings reabsorbed water back to blood

uses passive flow due to pressure difference

filters blood into Bowman's capsule

cortical portion- first

medullary portion- second

antidiuretic hormone (*ADH*)- increase water reabsorption in distal tubule and collecting duct, increases BP

*aldosterone*- increase Na+ reabsorption in distal tubule and collecting duct, increases plasma osmolarity, increases water retention, increases BP

*renin-angiotensin* system:
macula densa/juxtaglomerular cells- have baroreceptors to sense BP
renin- when BP drops, JG cells secrete renin to blood, converts angiotensinogen (made in liver) into angiotensin I
angiotensin-converting enzyme (ACE)- converts angiotensin I to angiotensin II
*angiotensin II*-vasoconstrictor (fast), also stimulates release of *aldosterone* (slow) to increase BP

ANP- from heart, vasodilator, inhibits renin release, inhibits aldosterone release

when pH is too high, HCO3- is excreted

when pH is too low, H+ is excreted

carbonic anhydrase converts CO2 to H2CO3

usually reabsorb bicarbonate and excrete H+

hyperventilation also raises pH

gastrointestinal (GI) tract extending from mouth to anus

made of smooth muscle

peristalsis- moving bolus of food down GI tract:
1. longitudinal layer- propel bolus forward
2. circular layer- prevents backflow

1. mastication- chewing with incisors, cuspids, molars
2. saliva- salivary amylase which hydrolyzes starch to disaccharides, lingual lipase which digests fat, lysozyme which attack bacterial cell walls
3. bolus- ball of digested food

1. pharynx- throat, has openings to trachea and esophagus
2. epiglottis- cartilage flap to cover up trachea
3. upper esophageal sphincter- muscular ring at top
4. lower esophageal sphincter- muscular ring near stomach

1. acidity- *gastric pH is 2* due to HCl secretion by parietal cells, functions: destroys microorganisms, acid-catalyzed hydrolysis of proteins, converts pepsinogen to pepsin, can also denature important proteins like antibodies!
2. *pepsin*- pepsinogen (zymogen) is secreted by chief cells and converted to pepsin, catalyzes proteolysis
3. motility- churns food, creates chyme (food + secretions)
4. pyloric sphincter- regulates food entering duodenum, cholecystokinin is hormone that signals to close it
5. *gastrin*- G cells secrete this hormone that stimulate acid and pepsin secretion, histamine binds to parietal cells to stimulate acid secretion

1. villi- multicellular projections that make up *brush border*
2. hepatic portal vein- villi have capillaries that connect
3. lacteals- lymphatic vessels to absorb fat
4. Peyer's patches- lymphocytes to monitor for pathogens
5. 3 segments: *duodenum, jejunum, ileum* (Don’t Jiggle It)

1. *pancreatic duct*- brings exocrine secretions (digestive enzymes) from pancreas
2. *common bile duct*- brings bile (waste vehicle, digest fat) from gallbladder
3. sphincter of Oddi- bile and pancreatic ducts empty here
4. duodenal enzymes- enterokinase (creates trypsin), brush border enzymes (hydrolyze disaccs/dipeps to monos)
5. duodenal hormones- cholecystokinin (to digest fat), secretin (to increase pH from stomach since duodenal pH must be neutral), enterogastrone (to stop stomach emptying)

1. ileocecal valve- separate small intestine from large
2. function: absorb water and minerals, form feces
3. segments: *cecum, appendix, rectum, anal sphincter*
4. colonic bacteria- supply vitamin K, outcompete dangerous bacteria for space

branch of autonomic NS, independent of para/sympathetic

controls everything in GI tract, pancreas, and gall bladder

2 networks:
1. myenteric plexus- controls gut motility
2. submucosal plexus- controls blood flow, enzyme secretion, ion exchange

exocrine secretions:
1. acini- sacs of epithelial cells that secrete products into GI
2. goblet cells- secrete mucus
3. gastric glands- secrete acid in stomach
4. pancreatic acinar cells- pancreas

endocrine secretions:
1. go to capillaries, do not empty into ducts
2. islets of Langerhans- pancreas, produce insulin, glucagon

pancreas:
endocrine (produce insulin, glucagon) and exocrine role (releases digestive enzymes, *zymogen* form needs to be activated)

liver:
1. produce bile (digest fat in small intestine)
2. hepatic portal vein- liver monitors blood from stomach, ex: if glucose is low, liver is only organ than can break down glycogen
3. urea- ammonia is created during amino acid breakdown, liver converts to urea
4. lipid metabolism- chylomicrons broken down are brought by lymphatic system to liver, liver makes lipoproteins with remnants, makes *cholesterol*
5. produces plasma proteins- albumin, fibrinogens, clotting factors
6. detoxification- smooth ER has enzymes to break down drugs

gallbladder:
bile is stored and concentrated here; gallstones: incorrect ingredients in bile

lowering glucose (hyperglycemia won't kill you):
1. insulin

raising glucose (hypoglycemia will kill you):
1. glucagon- peptide from pancreas
2. epinephrine- aa-derivative from adrenal medulla
3. cortisol- steroid from adrenal cortex

ghrelin- gastric cells secrete to stimulate appetite
peptide YY- jejunum secretes to reduce appetite
leptin- adipose tissues secretes to reduce appetite

excess fat-soluble vitamins are stored in adipose tissue:
1. A- visual pigment
2. D- stimulates Ca2+ absorption in gut
3. E- prevent oxidation of unsaturated fat
4. K- formation of blood clotting factors

ADEK fat soluble

too much fat would sequester vitamins, causing deficiency

excess water-soluble vitamins are excreted in urine:
1. C- collagen formation
2. biotin- CO2 transport
3. B’s- *FAD/NAD*, also thiamine for decarboxylation enzyme!

BC water soluble

3 types:
1. skeletal (striated) muscle- voluntary muscle, striated
2. cardiac muscle- heart, striated
3. smooth muscle- walls of all hollow organs, smooth

tendons- collagen, connective tissue

origin- point that muscle attaches to bone that stays still
insertion- point that muscle attaches to bone that moves

antagonistic- muscles moving in opposite directions
synergistic- muscles moving in same directions

movement:
1. flexing- reduce angle
2. extending- increase angle
3. abducting- move away from body midline
4. adducting- move towards body midline

fascicles- bundles of muscle tissue

myofibers- single muscle cell formed from fusion of cells

multinucleate syncytia- fusion of cells, controlled by 1 nerve

sarcolemma- cell membrane with a layer of collagen and polysaccharides to help connect with tendons

myofibrils- organelles inside muscle cell that contracts, made of actin and myosin

sarcomere- segments of myofibrils connected end-to-end

thin filaments (I-band) - actin is on both ends of sarcomere
thick filaments (A-band) - myosin is in middle of sarcomere

Z line- thin filaments from each sarcomere connect

H-band - thick filament segment not overlapping with thin

myosin- ATP powered motor protein, head attached to actin via a cross bridge, tail attached to thick filament

steps:
1. myosin has ADP and P bound
2. power stroke- head moves to low energy conformation, pulls actin toward center of sarcomere, releases ADP
3. ATP binds, actin is released by myosin head
4. ATP hydrolysis occurs, reset the myosin head back

fun facts:
1. ATP is used to reset myosin, not during power stroke
2. rigor mortis- no ATP means myosin cannot release actin
3. myosin head groups operate asynchronously

contractile cycle will occur spontaneously, but in myofiber contraction only occurs after Ca2+ influx

tropomyosin- fibrous protein that winds around actin, blocking myosin binding sites

troponin- globular protein on tropomyosin that binds Ca2+ and moves tropomyosin away from myosin binding sites

synapse between axon terminus and a myofiber, acetylcholine is the neurotransmitter

steps:
1. presynaptic membrane has voltage-gated Ca2+ channels, Ca2+ influx triggers release of vesicles of acetylcholine
2. postsynaptic membrane is called motor end plate, has ligand-gated Na+ channels (acetylcholine receptors)
3. end plate potential (EPP)- depolarization of myofiber
4. miniature EPP (MEPP)- EPP by a single ACh vesicle
5. *acetylcholinesterase*- hydrolyzes acetylcholine to stop

steps:
1. when EPP reaches threshold, voltage-gated Na+ channels open, causing Na+ influx and depolarization
2. transverse tubules (T-tubules)- invaginations of cell membrane into cytoplasm to depolarize interior as well
3. sarcoplasmic reticulum (SR)- net organelle of smooth ER that wraps around each myofibril, active transporters brings Ca2+ from sarcoplasm (myofiber cytoplasm) into SR
4. SR has mechanical/voltage/???-gated Ca2+ channels that further allow Ca2+ influx into sarcoplasm
5. contractile cycle occurs
6. repolarization- Ca2+ sequestered back into SR

twitch- smallest measurable muscle contraction
tetanus- strongest possible contraction (frequency summation, not a good thing)

3 methods:
1. motor unit recruitment- activate more myofibers with each motor neuron axon

2. frequency summation- rapid contractions don't allow Ca2+ to be sequestered, can build off each other

3. length-tension relationship- muscle contracts most forcibly at an optimum length, maximum degree of overlap between thick and thin filaments without obstruction

creatine phosphate- hydrolyzed to creatine to generate ATP to provide myofiber a fast energy source, since it's faster than TCA/ glycolysis

myoglobin- takes oxygen from hemoglobin, provides a quick oxygen reserve for muscles

check the oxygen debt card for more

type I slow twitch fiber (red oxidative)- slow, low force, good capillary network with lots of myoglobin

type IIA fast twitch fiber - medium everything

type IIB fast twitch fiber (white)- explosive force, fatigue quickly, very few mitochondria, anaerobic glycolysis

differences from skeletal muscle (1-4):
1. functional syncytium- not multinucleate syncytium, since only has 1 nucleus per cell, but has intercalated disks (gap junctions) that connect all cells to send action potentials

2. voltage-gated Ca2+ channels- on plasma membrane in addition to being on SR, they trigger contraction and propogate action potential during depolarization

3. plateau phase- due to voltage-gated Ca2+ channels, longer contraction for better heart pumping and to prevent disorganized impulses

4. SA node- not motor neurons, stimulate contraction

differences from skeletal muscle:
1. functional syncytium- not multinucleate syncytium, since only has 1 nucleus per cell, but has gap junctions that connect all cells to send action potentials

2. smaller- so they do not have T-tubules

3. no sarcomeres- thick/thin filaments are in cytoplasm

4. calmodulin regulation- binds Ca2+, activates MLCK which phosphorylates myosin to activate it, no troponin!

5. voltage-gated Ca2+ channels- much more reliant on these than the SR ones

6. no voltage-gated Na+ channels- so slower than skeletal but faster than cardiac

7. slow waves- constantly changing resting potential, parasympathetic NS primes smooth muscle cells to push waves past threshold and release *spike potential*, acetylcholine from parasympathetic NS increases waves, norepinephrine from sympathetic NS decreases waves

8. autonomic motor neurons- not somatic like skeletal

*fibroblasts*- adipocytes (fat cells), chondrocytes (cartilage cells), osteocytes (bone cells) are all derived from fibroblasts, which secrete collagen, a fibrous protein

elastin- another fibrous protein, stretchy

extracellular matrix- most of connective tissue is just ECM, which has collagen, elastin, fibronectin, integrin, a lot of water, *proteoglycans* (ground substance, just carbohydrates attached to proteins)

loose connective tissue- adipose and areolar tissue

dense connective tissue- tendons, cartilage, bone (lots of collagen)

collagen- fibrous protein in ICM

hydroxyapatite- calcium phosphate crystals that form around collagen framework to give bones strength

spongy bone:
spicules (trabeculae)- spikes of bone
bone marrow

compact bone:
osteon (Haversian system)- basic unit, has a central canal (Haversian canal) with blood, lymph vessels, and nerves

lamellae- concentric rings of bone around central canal

canaliculi- tiny channels branching from central canal

lacunae- lakes that canaliculi connect to with one osteocyte

osteocytes- bone cell, contact each other with long processes that have gap junctions, exchange nutrients/waste

perforating canals (Volkmann's canals)- connect different osteons, have blood, lymph, nerves as well

axial- skull, spinal cord, rib cage

appendicular- limbs and pelvis

flat bones- organ protection, hematopoiesis, compact shell with spongy core with red marrow (hematopoiesis), activity responds to erythropoietin

long bones- support and movement, compact:

diaphysis (main shaft)- compact with yellow marrow (fat), inactive

epiphysis (flared end)- compact shell with spongy core with normal marrow

avascular- no blood vessels, receives nutrition and immune proection from surrounding fluid

chondrocytes- secrete cartilage

hyaline cartilage- strong but flexible, larynx and trachea are reinforced by it, joints that have it call it articular cartilage

elastic cartilage- more flexible since it contains elastin, ear and epiglottis have it

fibrous cartilage- very rigid, intervertebral disks

3 types:
1. synarthroses- immovable joints, two bones fused together, skull is example
2. amphiarthroses- slightly movable joints, vertebral joints are an example
3. diarthroses- freely movable joints, ball and sockets are an example

other terms:
1. ligaments- connect bone to other bones, dense connective tissue
2. tendons- connect bone to muscles, dense connective tissue
3. synovial fluid- lubricate joints, kept within synovial capsule
4. articular cartilage- smoothes bone contact with each other
5. arthritis- joint inflammation, damages articular cartilage

endochondral ossification- hyaline cartilage is produced and replaced by bone, most bone growth does this

intramembranous ossification- bone growth from mesenchyme (embryonic tissue), only flat bones do this

epiphyseal plate (growth plate)- during childhood, hyaline cartilage is produced by chondrocytes between diaphysis and epiphysis, growth hormones promote ossification, which brings fuse together the diaphysis and epiphyses at 18

osteoblasts- synthesizes bone around it, eventually becomes osteocytes and retires to its lacuna

osteoclasts- destroy bone by dissolving hydroxyapatite crystals, macrophage

increased ratio of osteoclast/osteoblast activity liberates Ca2+ and phosphate into bloodstream

*parathyroid hormone* (PTH) and *calcitriol*- increase osteoclast activity and increase reabsorption of Ca2+ and phosphate in kidneys

*calcitonin*- inhibits osteoclast activity and decreases reabsorption of Ca2+ in kidneys

conduction zone- part of respiratory system that participates in ventilation (moving air in and out)

respiratory zone- part of respiratory system that participates in respiration (exchange of CO2 and O2)

pH regulation- hyperventilation causes respiratory alkalosis, hypoventilation causes respiratory acidosis

thermoregulation- evaporative water loss as water vapor absorbs heat, countercurrent exchange with nasal passages to conserve water and heat

disease protection- mucociliary escalator and alveolar macrophages

nose- warming, humidifying, filtering air with hair and mucus

nasal cavity- open space with olfactory receptors

pharynx- throat

larynx- epiglottis to seal the trachea, vocal cords to produce sound, passage is made of cartilage

trachea- passage is made of cartilage

bronchi- trachea branches to two primary bronchi, which keep branching to smaller bronchioles (walls are smooth muscle)

terminal bronchioles- smallest and final branches, walls are smooth muscle

respiratory bronchiole- walls are smooth muscle, has a few alveoli scattered in its walls

alveolar duct- made entirely of alveoli

alveoli- tiny sacs with single cell walls, capillaries surround them

epithelial cells- column shaped cells that line the entire respiratory tract

goblet cells- epithelial cells that secrete mucus

mucociliary escalator- epithelial cells in upper respiratory tract have cilia that sweep mucus towards pharynx, to be coughed out or swallowed (stomach acidity destroys pathogens)

squamous epithelial cells- flat cells in alveoli, no mucus here so alveolar macrophages engulf pathogens

surfactant- surface tension of water would cause alveoli to collapse, so this soapy substance reduces the tension

inspiration- moving air into lungs, diaphragm contraction
expiration- passive, elastic recoil

parietal pleura- lines inside of chest cavity
visceral pleura- lines surface of lungs

pleural space- the space in between, has negative pressure to keep lungs open, also some fluid to hold surfaces together with surface tension

diaphragm- dome contracts downward to force lungs and chest cavity to expand

intercostal muscles- muscles between ribs pulls ribs upward to further expand chest cavity

forced expiration- usually passive, but can be forced by contraction of abdominal muscles to press upward on diaphragm

spirometry- measurement of volume of air in lungs during ventilation, uses a spirometer

tidal volume (TV)- amount of air inspired during normal, relaxed breathing.

inspiratory reserve volume (IRV)- additional air that can be forcibly inhaled after the inspiration of a normal tidal volume.

expiratory reserve volume (ERV)- additional air that can be forcibly exhaled after the expiration of a normal tidal volume.

residual volume (RV)- amount of air still remaining in the lungs after the expiratory reserve volume is exhaled.

vital capacity (VC)- total amount of air that can be expired after fully inhaling (VC = TV + IRV + ERV). The value varies according to age and body size.

total lung capacity (TLC)- maximum amount of air that can fill the lungs (TLC = VC + RV).

inspiratory capacity (IC)- maximum amount of air that can be inspired (IC = TV + IRV).

functional residual capacity (FRC)- amount of air remaining in the lungs after a normal expiration (FRC = RV + ERV).

pulmonary capillaries- alveolar capillaries, branch from pulmonary artery to bring deoxygenated blood to lungs

RBCs pass through capillaries single file to maximize surface area exposed and increase gas exchange

pulmonary edema- usually pulmonary veins can dilate, but too high of pressure will force blood into lung tissue, lymphatic system carries fluid out of lungs

respiratory membrane- alveolar epithelium, interstitial liquid, capillary endothelium

atmospheric gas- 80% N2, 20% O2, some H2O, CO2, etc.

atmospheric pressure- 760 torr, so partial pressure of O2 is 150 tor

amount of gas that dissolves into liquid depends on partial pressure of gas and solubility of gas in liquid

[O2] = P_O2 * S_O2
concentration of dissolved oxygen = partial pressure of oxygen times solubility of oxygen in liquid

gases become less soluble as temperature increases (goldfish gulp for air when water is too warm)

difference in partial pressures between alveolar air and blood drives exchange of gas

medulla- contains respiratory control center

trigger increased ventilation rate:
1. increased P_CO2
2. decreased P_O2
3. decreased pH

peripheral chemoreceptors- monitor blood for pH, P_CO2, P_O2

central chemoreceptors- monitor cerebrospinal fluid for pH, P_CO2, P_O2

irritant receptors- trigger coughing, bronchoconstriction

stretch receptors- trigger inhibit inspiration

outmost layer of skin

layers of squamous epithelial cells

stratum basale- deepest part that replenishes upper layers with mitosis

keratin- as the cells die, they become filled with keratin, which is tough and hydrophobic and makes skin waterproof

melanin- melanocytes produce melanin, which is a brown pigment that helps absorb UV to prevent damage

middle layer of skin

embedded in connective tissue, has blood vessels

sensory receptors- touch, pressure, pain, temperature

sudoriferous glands- sweat glands, loss of heat by evaporation, signalled by aldosterone, sweat has water, ions, and urea

sebaceous glands- oil glands

ceruminous glands- wax glands, only in ear

hair follicles- hair is made of dead epithelial cells

subcutaneous tissue

protective, insulating layer of adipose tissue

homeotherms- body temperature kept constant

chemical thermogenesis- bears have brown adipose tissue that has a lot of mitochondria, uncouples ETC to generate heat instead of ATP, humans cannot do this

stay warm:
1. muscle contraction- shivering, moving
2. skin insulation- subcutaneous tissue
3. cutaneous vasoconstriction- cut off blood to skin, activated by sympathetic NS (pale when frightened)

cool down:
1. sweating
2. cutaneous vasodilation

epithelial tissue- line the surface of all organs, *epithelial cells divide the most and spend the least time in G0*

muscle tissue- muscles

connective tissue- ECM, between tissues and underneath epithelial tissue, fibroblasts become adipocytes, chondrocytes, osteocytes

nervous tissue- nervous system, *neurons are always in G0*

1. testes- produce sperm, produce testosterone
2. scrotum- regulates temperature, keeps testes cool
3. epididymis- sperm hang out here to develop their flagella and more mitochondria
4. Vas deferens- sperm travels, within the spermatic cord
5. seminal vesicles- add slightly basic fluid to sperm to form semen, remove acidity
6. prostate gland, bulbourethral gland- make more fluid
7. urethra- semen travels
8. penis- penetrate vagina

sperm is produced by the Sertoli cells of the *seminiferous tubules*
1. diploid germ cells become haploid gametes through meiosis
2. undergo more replications, makes mutations more likely on Y chromosome (since it's inherited through sperm)

sperm swims and fuses with the egg to become zygote
1. *acrosome*- contains hydrolytic enzymes to penetrate ovum
2. *bindin*- surface proteins that attaches to receptors on zona pellucida

testosterone is produced by Leydig cells in testes, stimulates spermatogenesis, later causes secondary sex characteristics to develop during puberty

androgen- male hormones
LH and FSH stimulate testosterone secretion

para does arousal and erection
sympa does orgasm

arousal, orgasm, resolution (takes longer in females)

all embryos possess Wolffian ducts (which become male genitalia) and Mullerian ducts (which become female genitalia)

testes produce Mullerian inhibiting factor (MIF)

analogous structure:
1. testis and ovaries
2. penis and clitoris

1. ovaries- produce ovum
2. uterus- carries embryo, cervix is entrance, endometrium is lining that is shed each month for menstrual bleeding, myometrium is smooth muscle
3. vagina- penis enters
4. breasts- lactation

primary oocytes are frozen in prophase I, hormones stimulate completion of first meiotic division

unequal division to become secondary oocyte and small polar body

second meiotic division occurs when sperm arrives, unequal division to large ovum and another polar body

ova and sperm have haploid genome size

follicle- a collection of granulosa cells around the ova that support its development and secrete estrogen

granulosa cells become zona pellucida- protective layer

Graafian (mature) follicle- one follicle matures during ovulation, releases ovum into fallopian tube

corona radiata- protective layer still on egg

corpus luteum- follicle stuff left over, secretes estrogen and progesterone

ovarian cycle:
1. follicular phase- follicle matures and secretes estrogen
2. ovulatory phase- secondary oocyte released from ovary
3. luteal phase- corpus luteum forms, secretes estrogen and progesterone

uterine cycle:
1. menstruation- corpus luteum degenerates, estrogen and progesterone stops, endometrial lining bleeds out
2. proliferative phase- estrogen from follicle produces new endometrium
3. secretory phase- estrogen and progesterone from corpus luteum increase development of endometrium

menopause- menstrual cycle stops at 50-60

birth control- keep estrogen and progesterone high so menstruation and ovulation does not happen

pregnancy- when embryo implants, placenta develops and secretes hCG which replaces LH, so corpus luteum does not degenerate and estrogen and progesterone stay high

*hCG* is used to test for pregnancy

acrosome and bindin

Ca2+ influx causes egg activation

polyspermy:
1. fast block- depolarization of ovum plasma membrane by Ca2+ influx
2. slow block- cortical reaction to harden zona pellucida and increase space between zona pellucida and plasma membrane

egg provides all the cellular parts of the zygote, including mitochondrial inheritance

ectoderm- forms skin, facial things, mouth and butt, and nervous system

endoderm- forms epithelial lining inside body (GI, urinary, respiratory, endocrine, auditory)

mesoderm- muscle, bone, kidneys, heart

cleavage- zygote produces *morula*, a solid ball of 16 undifferentiated cells.

blastulation- blastocyst forms, consists of:
1. trophoblast- outer cell layer of blastocyst
2. blastocoele- fluid-filled central region in the blastocyst
3. inner cell mass (ICM)- inside of blastocyst, will eventually give rise to the fetus

implantation- blastocyst burrows into endometrium, starts taking nutrients from endometrium, placenta develops 3 months later

inner cell mass also becomes amnion (amniotic fluid), yolk sac (RBC synthesis), allantois (forms umbilical cord)

gastrulation- single-layered blastula becomes the three-layered gastrula, the three germ layers

neurulation- ectoderm differentiates into neural plate, folds into neural tube, which becomes CNS

MBGN

increased demand for oxygen, GFR, nutrients

oxytocin- causes uterine contraction

parturition- birth

prolactin- released by suckling (anterior pituitary), oxytocin (posterior pituitary) also necessary for milk let-down

estrogen and progesterone together cause the endometrium to thicken
estrogen later regulates uterine cycle and development of secondary sexual characteristics

estrogen inhibits bone resorption
estrogens- female hormones

in females, triggers follicle development, estrogen production by granulosa cells and corpus luteum

in males, stimulates Sertoli cells with sperm development

in females, cells inactivated one X chromosome to become Barr body, creating two populations of cells

so only 50% of cells will have an X-linked trait in females

smaller, contains less genes

development
migration
communication

differentiation- totipotent, pluripotent, multipotent cells
dedifferentiation- cancer, induced pluripotent stem cells

gene regulation
apoptosis
regenerative capacity
senescence and aging

XY is male
XX is female

mitochondrial linked traits