nervous system

Question 1

what is a multipolar neuone

Answer 1

1 axon, many dendrites

Question 2

What are the different glial cells in the CNS? and one in the PNS

Answer 2

Astrocyte - growth support

Oligodendrocyte - myelin forming cell, wraps around axons

Microglia - immune function in brain

Ependymal cells - specialised epithelial cells, secrets cerebral spinal fluid.

IN the PN: Schwann cells - myelin forming cell and growth forming and immune role.

Question 3

What is gray matte?

Answer 3

Cell bodies of neurones reside in gray matter.

Gray matter is on the inside of the spinal cord (but outside the brain)

Question 4

What is white matter?

Answer 4

Myelinated axons exist.
The myelinated phenotype from the oligodendricytes provide lipid covering, a rich white colour

White matter is on the outside of the spinal cord (inside of the braiN)

Question 5

The 4 brain divisions

Answer 5

Cerebrum

Diencephalon (middle of brain, above brain stem)

Brain stem

Cerebellum (behind brain stem)

Question 6

The different lobes

Answer 6

Frontal lobe

Parietal lobe

Temporal lobe

Occipital lobe

Question 7

What are sulci and gyri?

Answer 7

Allow “more substance in a closed space.”

Allows the tissue to fold in on itself on the brain.

Sulci - infoldings of the cerebral hemispheres that form “valleys” between the gyri. (The valleys between the mountains)

Gyri - The ridges of the infolded cerebral cortex (it’s the tissue itself, the mountain)

Question 8

What is the functions of the different brain divisions; Frontal lobe, parietal, Occipital, Temporal

Answer 8

Frontal lobe - motor function

Parietal lobe - somatosensory cortex.

Occipital lobe - vision

Temporal - auditory

Question 9

What are two areas in the diencephalon that are important and what do they do

Answer 9

Thalamus - major relay station for sensory information coming into the cortex from below (e.g spinal cord and brain stem) - it’s a gate for how many information is coming into the somatosensory cortex. Olfaction doesn’t go through here

Hypothalamus - Autonomic control center - works with endocrine system, helps body sit in homeostasis

Question 10

What does the brain stem do and what are the three important components?

Answer 10

Less evolved species have a brain stem because it’s the most primitive area of the brain.

Attaches spinal cord to cerebellum and cerebrum.

1. mid brain - eye movement
2. pons - major relay area between cerebellum and cerebrum
3. Medulla oblongata - control center for involuntary function (houses vital center e.g blood pressure, and non-vital centers e.g sneezing)

Cerebellum - balance and coordination

Question 11

What are the different areas of the spinal cord? and what re they associated with?

Answer 11

Cervical area - neck

thoracic area - chest cavity

lumbar

sarcral area

Question 12

What protects the CNS? ; bone, meninges

Answer 12

Bone: skull protecting brain, vetrebal column protecting spinal cord

Meninges: cellular layers that surround the tissue, they come in 3 different layer.

1. Dura: outer. Tough structural layer, attaches tissue to bone
2. Arachnoid: Close to dura, web-like appearance.
3. Pia: deepest layer, external layer of brain and spinal cord.

Question 13

What is the subarachnoid space?

Answer 13

Because of the arachnoid web like appearance, there’s a lot of space between it.

This space contains fluid (CSF)

Question 14

What does the CSF do?

Answer 14

Protective layer. Cell-free fluid

Question 15

What does the BBB (blood brain barrier) do?

Answer 15

A barrier composed of endothelial cells and astrocytes.

Prevents free diffusion into the brain by large molecules (>500 daltons MW)

E.g O2, CO2, lipid soluble molecules (hormones can enter

Question 16

What is an action potential?

Answer 16

A brief change in electrical potential across the cell’s membrane involving the movement of ions across the membrane in response to stimulation.

Question 17

What is the resting membrane potential of a neurone?

Answer 17

Where the cell sits when it’s not excited.

-70mV (need to know it’s negative).

mV used to characterize membrane potential.

Question 18

What ions are greater on the outside of the axon than the inside?

Answer 18

Na+ and Cl -

This diagram is on ON

Question 19

What is the active process that help maintain the RMP?

Answer 19

Sodium potassium ATPASS
active because it requires ATP,

Able to pull 3Na+ out, and 2K+ in.

This is used in CV system.

Question 20

What are Na+ and K+ mainly responsible for in terms of action potential?

Answer 20

Na+ movement is largely responsible for an action potential (e.g an increase in intracellular Na+ produces an action potential)

K+ is mainly responsible for resting membrane potential

Question 21

Movement of only a few ions are required to generate the AP because the cell’s lipid membrane is…

Answer 21

a capacitor which STORES electrical charge.

Question 22

What properties of a neuron allow for rapid conduction of signals?

Answer 22

1. positive feedback
3. Myelination (fatty substance), increases ratio of outwardsResistance/InwardsResistance, helps to insulate even further where the AP’s occur on the axons. Increased resistance = faster action potential

Question 23

What are nodes of randvier?

Answer 23

Little gaps between the myelin.

At each node there are a huge abundance of voltage gated sodium channels.

There’s a high level of insulation and so an action potential happens at a node and then it jumps to the other node

The AP travels in a “saltatory conduction” manner

Question 24

Example of an unmyelinated axon

Answer 24

Pain fibres.
Sensory fibres

AP travels in a “continuous conduction” manner, it’s much slower than saltatory.

Question 25

How are signals transmitted at the synapse (synaptic transmission)?

Answer 25

1. impulse arrives at axon terminal; aggregate vesicles towards cleft.
2. The neurotransmitters fuse with the end of presynaptic membrane to release the contents into synaptic cleft.
3. The neurotransmitter is recognised by receptor on the PSN. to initiate a signal in the next cell.
4. Neurotransmitter is inactivated by an enzyme so it doesn’t continually occupy the receptors also avoids constant stimulation of the PSN.

Question 26

Why does synaptic transmission depend on Ca2+?

Answer 26

Needs to be in presynaptic neuron.

The calcium being present allows for fusion of the vesicles with the membrane.

This happens because the AP depolarises the axon terminal and opens voltage gated Ca++ channels, triggering fusion of the NT containing vesicles with the plasma membrane

Question 27

What happens at the PSN after it recieves NT?

Answer 27

Excitatory - induces AP -

Inhibitory - Stop AP - won’t have any effect on Na+ channels - stopping ability for threshold

Question 28

What are EPSPs, EPSCs, IPSPs, IPSCs?

Answer 28

EPSP (excitatory postsynaptic potential) - makes AP more likely to occur in PSN - depolarizes cell (makes it more positive) - summative effect of ISPS and EPSP’s - e.g Glutamate

EPSC (excitatory postsynaptic current)

IPSP - Makes AP less likely to occur in PSN - Hyperpolarise cell making it more negative - K+ moves out and Cl- move into cell - e.g GABA

IPSC

Question 29

The Nernst equation (predicting equilibrium potential)

Answer 29

E = (RT/zf) *loge ([K+]out/[K+]in)
Diagram in ON

where Z = valence of the ion
f = faraday constant(electrical charge of one mole of univalent ion)
T = in kelvin

AT 37degrees celsius EmV = 61.5 *Log10([K+]out/[K+]in)

Question 30

What’s the goldman equation (resting membrane potential)

Answer 30

It’s in ON

Question 31

What does the Na+/K+ ATPase pump do in the cell?

Answer 31

Because K+ is driven out the cell by its electrochemical gradient whereas Na+ is being in.

SO the pump takes sodium out of the cell so the sodium can move down its concentration gradient.

3:2 (3 Na out, 2 K in)

Question 32

What does Ouabian do to the Na+/K+ATPase and resting membrane potential?

Answer 32

as ouabian goes up, the resting membrane potential goes up too.

Ouabian inhibits the Na+/K+ ATPase. This is how it destroys the resting membrane potential

Question 33

What does afferent and efferent mean?

Answer 33

Afferent = carrying info into the CNS. (AGAYO = come)

Efferent - away from CNS