Digestion

The goal of this organ system is to break down our food (catabolism) to obtain the molecules and nutrients we need.

large intestine

Voluntary control of eating and swallowing. Mechanical digestion of food by chewing and mixing with saliva, which contains lubricants and enzymes that start starch digestion

Movement of food by peristalsis from the mouth to the stomach

Churning and mixing with secreted water and acid which kills foregin bacteria and other pathogens in food, plus initial stages of protein digestion

Final stages of digestion of lipids, carbs, proteins, and nucleic acids, neutralizing stomach acid, plus absorption of nutrients

Secretion of lipase, amylase, and protease

Liver - secretion of surfactants in bile to break up lipid droplets

Gall Bladder - Storage and regulated release of bile

Reabsorption of water, further digestion (especially of carbs by symbiotic bacteria), plus formation and storage of feces

Temporary storage of feces and control of defecation

Exocrine: secretes substances into a ductal system

Endocrine: secretes substances (usually hormones) directly into the bloodstream

Exocrine glands secrete specific components like enzymes through ducts.

salivary glands and pancrease; starch; maltose

The goal of this organ system is to break down our food (catabolism) to obtain the molecules and nutrients we need.

pancreas; protein; dipeptides

pancreas; lipids; glycerol and fatty acids

both

1', 4' glycosidic linkages

1,4 and 1,6 glycosidic linkages

amylopectin

monosaccharaides by other enzymes in the small intestine

transported into the cells of the small intestine and into the bloodstream

mucus cells, parietal cells, cheif cells, G (Gastrin) cells

goblet cells

secrete a protective mucous layer that protects the lining from the enzymes and acidic (low) pH; can be damaged by H. pylori bacteria, leading to open sores or ulcers (leaving acids and enzymes to eat away at the exposed epithelial layer)

Secrete acid that kills ingested bacteria; acidic pH converts pepsinogen into active pepsin

secrete inactive pepsinogen; inactive so that it ensures that chief cells themselves are not digested

gastrin cells

Secrete the hormone gastrin -- this stimulates parietal and chief cells to secrete enzymes and acid

nervous and hormonal

the sight, taste, smell, or even thought of food stimulates the medulla oblongata (in the brain) and the vagus nerve sends signals to the stomach. This stimulates the gastric pit cells to begin secreting the appropriate components for digestive juices in the stomach.

Once food has been consumed, if peptides are detected in stomach contents or stretch receptors detect distention, impulses are sent to the brain. The brain then responds via the vagus nerve again, this time to endocrine cells in the duodenum and the parts of the stomach near the duodenum, signalling them to secrete the hormone gastrin.

stimulates the secretion of acid and pepsinogen.

inhibit gastric secretion if the pH in the stomach falls too low.

secretin and somatostatin

mix of acidic juices and consumed food in the stomach

the duodenum releases more hormones. These are secretin and cholecystokinin (CCK) which stimulate the pancreas and liver.

help neutralize the low pH of the chyme.

emulsify lipids

caused by acidic stomach contents entering the esophagus.

ppi (proton pump inhibitor)

H+

lower

outer covering of small intestin

squeeze
to move food forward.

constrict
to prevent backward flow.

contain blood and lymph vessel

responsible for nutrient absorbtion

serosa, lontiduinal muscle fibers, circular muscle fibers, submucosa, mucosa

serosa, longtidutidinal muscle fiber, cirucular muscle fiber, submuscossa, mucosa, lumen

projections of the mucosa

These increase the surface area of the mucosa, meaning absorption of nutrients can be maximized.

This increases the surface area to volume ratio -- more entry points for nutrients and a shorter distance to travel once they have been absorbed.

epithelial cells

One layer of cells -- this is advantageous to speed up absorption and travel of nutrients to the blood or lymph systems. These systems will take them to the areas of the body where they are needed.

capilaries

small blood vessels with walls only one cell layer thick. deliver materials like oxygen to small intestine, but alos transport nutrients away from the small intestine to rest of body

the epithelial cells that make up each villi have tiny finger like pojections themselves called microvilli

more surface area

mitochondria

1) Size of molecules -- larger molecules will need an integral protein or a vesicle to cross the membrane
2) Polarity of molecule -- polar molecules have a harder time crossing the phospholipid bilayer
3) Charge -- molecules with a full positive or negative charge will be unable to cross the phospholipid bilayer without an integral protein

processes, stores, alters, and detoxifies these substances before passing them back to the blood and ultimately the heart to be pumped around the body.

converted to glycogen and stored in the liver until it is needed. This is a great way for the body to stock up on reserve energy!

consist of a layer of phospholipids, protein, and cholesterol. This allows the hydrophobic lipids to travel more easily in the watery fluids of our body.

lacteal

accommodate the large size of the chylomicrons.

body cells not liver

HDLS or LDLs and returned to the bloodstream,

converted to bile salts

ncredibly strong structure due to hydrogen bonding between sheets of polysaccharides. This means that it is not digested/absorbed, but it adds bulk to the material passing through the large intestine, helping to draw in water and speed the transport through this portion of the digestive tract.

bacterium Vibrio cholerae. The V. cholerae infects the large intestine and leads to diarrhea and vomiting.

ehydration, and sometimes IV fluids.
acess to clean water

a chemical in food that is used by the body

carbohydrate, protein, fat, vitamin, mineral, water (6)

Any nutrients that cannot be made by the body must be included in the diet,

Non-essential nutrients can be made by the body or multiple molecules can serve the same purpose.

9

omega-3 and omega-6, 2

fish, eggs, diary

citrus, bell peppers, strawberries, tomatoes, brocoli

fish, dairy, egg yolk,

fairy, cheese, yogurt, squash

seaweed, fish, eggs, beef liver

proteins

ribosomes

Lacking essential amino acids can lead to deficiencies of blood plasma proteins. This lowers the amount of solute in the blood and can therefore lead to fluid retention in tissues (edema) which causes swelling.

Vitamin C is water soluble, meaning that any excess is lost in urine rather than stored for future use. This means we must constantly consume Vitamin C.
Vitamin C is essential as an antioxidant and in the creation of collagen (structural protein).

fat soluble and so can be stored in the body.
essential for allowing the body to absorb calcium

It can be acquired through diet or through sunlight/UV Rays striking the skin.

name of the pigment in human skin and eyes. Melanin helps protect skin tissue from the highly energetic rays of the sun.

more sun energy is needed for vitamin d

at the equator

Bone pain or achiness, loss of bone density, osteoporosis (degeneration of bone tissue), fractures and broken bones

softening of bones which can cause bone pain, increased fractures, diffficulty walking and stunted growth. rickets is a type of skeletal deformity in children.

a mineral ssential for the thyroid gland and the production of the hormone thyroxin.

dangerous for pregnant people and fetal development. Low iodine can also lead to goiters.

a disorder in which a mutation in a gene that codes for an enzyme involved in the conversion of phenylalanine to tyrosine (both amino acids) is not functional. In individuals with PKU, build up of phenylalanine can lead to reduced head and brain development of babies and young children and seizures, learning difficulties, and hyperactivity in older patients. Individuals with PKU must have a diet low in phenylalanine and potentially take tyrosine supplements to avoid the consequences of this non-functional enzyme.

a severe lack of intake of nutrients. When this occurs, the body begins to break down its own tissue.

With continued lack of intake of nutrients, the body will first access glycogen storage. When this is depleted, the body will then turn to lipid sources of energy. If these become depleted, the body turns to its last resort energy source: breaking down protein for energy, even from its own muscle! Amino acids are sent to the liver to be converted to glucose.

psychiatric illness that causes voluntary starvation and loss of body mass. The lack of consumed nutrients leads to tissue breakdown in the body, leading to muscle weakness, hair loss, skin dryness, low blood pressure, and decreased cardiac muscle mass.

a combination of therapies and tissue can be restored with increased consumption of nutrients.

salivary glands, pancreas, stomach, small intestive glands

chanells

anlylase, pepsin, trypsin, lupase

salivary glands and pancreas

stomach

pancreas

pancrease

pepsin and trypsin

starch

protein

protein

lipid

maltose

dipeptides

dipeptides

glycerol and fatty acids