lecture 2 * biology and cognition *

1. oxigen (O)
2. hydrogen (H)
3. carbon : fats are made of carbon (C)
4. nitrogen (N)
5. calcium (Ca)
6. phosphor ( P)
7. potassium (K)
8. sulfur (S)
9. sodium (Na)
10. chloride (Cl)
11. magnesium (Mg)

what is an ionic bond ? plus attracts minus

sodium attacts chloride in order to make table salt

electrostatic force

adding on electrons forms molecules

glucose ( sugar ) C6H12O6
amino acids: extra nitrogen atom (carbon chains with an amino hanging to it )
protein
peptides (short protein chains)
lipids (fats) : long carbon chains
phospholipids

carbon chains connected by an extra phosphate group

composed of the head with two tails

tails are strings of carbon, fatty **hydrophobic**

head is made of carbon but there is a phosphate **hydrophilic**

when the phospholipids are in contact with water they will turn into configuration:

tails oriented to each other = cell membrane

head towards water

1. dendrites
2. soma
3. axons
4. terminal buttons

dendrites: receive signals from other cells

integrates the signal received

* exotatory
* inhibitory

sends signals and branch out

covered with fatty lairs that speed up process

give the information to the next neuron

pores for mRNA transport

production, storage and transport proteins

post office for packing (neurotransmitter)

power plant (ATP: Adenosine Triphosphate)

waste processing

road system for transportation neurotransmitter through axon

1. cell nucleus
2. enfoplasmatic reticulum
3. golgi apparatus
4. mitochondria
5. lyosomes
6. microtubuli

synthesization of protein in order to copy the gene code

copies of gene → outside the cell → ribosomes → copy → leave nucleus

RM messenger

anterograde transport from the cell body (soma) to terminal buttons

kinesin

retrograde transport from terminal buttons to soma

dyenin

1. microglia
2. macroglia
3. schwann cells

immunologic defense removal dead cells

1. astrocites

1. oligocides

structure and solidity (glia=glue) isolate synaptic clefts feeding neurons with glucose

myelin sheath in *CNS*

myelin sheath in *PNS*

oligocides

schwann cells

1. diffusion
2. electrostatics

due to random motion, particles will move from regions with high concentration to regions with low concentrations

* positively charged particles repel each other
* negatively charged particles repeal each other
* oppositely charge particles attract

what ion specific channels are there?

Na +
K+
CL negative
A negative

NA + and Cl negative

difussion

Na+ driven inward

both diffusion and electrostatic forces

Cl is retained

electrostatic force

many K+ and A

cannot pass

due to its negativity the inside is overall negative

retained

electrostatic membrane force, as positivity leaves the cell is even more negative

constantly pump our form inside to outside

for every 3Na+ one K+

active 24 / 7

axon generates an action potential only if the resting potential crosses a threshold

from _70 millivolts to _60 millivolts

only if treshold is crossed

1. depolarisation
2. repolarisation
3. hyperpolarisation

more Na+ channels are opened , Na+ flows into the cell, cell inside becomes less negative *depolarisation*

K+ channels open, K+ flows out the cell, will counteract the electrical effect of Na+ inlow

1. Na+ channels close refractory period Na+ inflow is halted

K+ keeps flowing put, cell inside returns to negative *repolarization*

1. Following the massive outflow of K+ the membrane temporarily has an extra negative charge *hyperpolarisation*

the first action potential triggers a domino effect all other neurons to fire

1. relatively slow : new action potentials are generated in neighbouring regions
2. energy consuming : resting potential needs to be recovered across the whole axon by means of the Na+ and K+ pumps

**myelin** passive conduction

synaptic potential propagates with attenuation

much facter but the signal decays strongly with the distance

saltatory conduction

axon covered with pisces of myelin that prevent the generation of action potential

nodes of Ranvier

faster and energy efficint