Nervous Coordination

Question 1

What are the differences between the nervous and endocrine system

Answer 1

Nervous system is very specific, short lasting and fast compared to slow, wide spread and long lasting

Nervous system uses electrical impulses produced via neurones

Endocrine uses hormones in blood plasma produced by Glands

Nervous system is temporary and reversabke

Endocrine can be permanent and Irreversible

Question 2

How are neurones adapted to function

Answer 2

Highly specialised

Carry nerve impulses rapidly

Question 3

What are the main features of a neuron

Answer 3

Cell body
Axon
Schwann cells
Nodes of ranvier
Dendrons
Dendrites
Synaptic knobs

Question 4

Describe the cell body

Answer 4

Main part of cell

Contains all organelles of normal cell
Large RER

Question 5

Describe Dendrons and Dendrites

Answer 5

Dendrons are extensions of cell body

Dendrites are sub divisions of Dendrons

Carry impulses towards body

Question 6

Describe the Axon

Answer 6

Long extension from cell body carrying impulses away from cell body

Question 7

Describe Schwann cells

Answer 7

Cells that wrap around the axon

Myelin in cell membrane create myelin sheath

Electrical insulation and phagocytosis to remove cell debry

Question 8

Describe Nodes of ranvier

Answer 8

Gaps along axon where there is no myelin sheath

Question 9

Describe the structure of a motor neurone

Answer 9

Long axon

Many Dendrites

Question 10

Describe the structure of a sensory neuron

Answer 10

One dendron and axon with cell body in the middle

Question 11

Describe the structure of an intermediate neurone

Answer 11

Many short Dendrons and one short axon

Many Dendrites

Question 12

How is resting potential established in a neurone

Answer 12

The sodium potassium pump actively transports 3 na+ out and 2K+ in.

All Na+ voltage gated channels are closed and some K+ voltage gated channels are open.

Some K+ Diffuse out (hyperpolarisation) and then back in

Until equilibrium so membrane is polarised

Question 13

How is an action potential propagated

Answer 13

Stimulus exceeds threshold producing AP

Some Na+ voltage gated channels open causing Na+ to diffuse in down electrochemical gradient increasing potential inside axon

This causes more Na+ channels to open further down, positive feedback.

More Na+ enter so more positive

Question 14

How is the membrane repolarised

Answer 14

Na+ voltage gated channels close preventing Na+ entering. Pump removes them

K+ voltage gated channels open allowing K+ to diffuse out down electrochemical gradient.

Positive feedback causes more K+ channels to open so more K+ leave (hyperpolarisation)

K+ Diffuse back in

K+ close so equilibrium is reached so membrane is polarised

Question 15

Describe the all or nothing principle

Answer 15

If generator potential exceeds threshold then AP generated

Is threshold not exceeded nothing happens

Question 16

How to magnitudes of stimuli differ

Answer 16

Frequency of AP (size is the same)

Different neurones have different thresholds

Question 17

What factors affect the speed of an ap

Answer 17

Temp
Myelination
Diameter of axon

Question 18

Describe how Myelination affects the speed of an ap

Answer 18

Myelination acts as an electrical insulator as ions can’t diffuse across lipids

Saltatory conduction occurs so less membrane surface is need to be de polarised = faster as less diffusion occurs

Question 19

Describe how temp affects the speed of an ap

Answer 19

Higher temp means ions have more kinetic energy so more faster = faster diffusion = faster conduction of AP

Increased rate of Respiration = Increased ATP production = more pumping of ions so repolarised quicker

Question 20

Describe how axon diameter affects the speed of an ap

Answer 20

Larger diameter = smaller sa:vol

Less leakage of ions = ap and resting potential easier to maintain

Question 21

Describe and explain the subcellular structure of a Synaptic knob

Answer 21

Many mitochondria and SER to produce neurotransmitter

Question 22

What is the name for a synapse that uses acetylcholine

Answer 22

Cholinergic synapse

Question 23

Describe the transmission of an ap using acetyl choline

Answer 23

Ap reaches synatipc knob causing ca2+ channels to open

Ca2+ diffuses in via facilitated diffusion

Causes vesicles containing acetylcholine diffuse towards and fuse with presynaptic membrane (exocytosis)

Acetylcholine diffuses across Synaptic cleft and binds to receptors on sodium channels on postsynatic membrane causing them to open

Na+ Diffuse into post Synaptic neurone causing de polarisation

Question 24

How is the synapse reset for a new ap

Answer 24

Ca2+ actively Transported out of Synaptic knob

Acetylcholinesterase releases and Hydrolyses acetylcholine into acetyl and choline

Diffuse across Synaptic cleft and into synatipc knob

Reformed at SER

Question 25

Why is summation necessary

Answer 25

Prevents overstimulation of nervous system

Effects of stimulus is magnified

Synapses act as barriers

Question 26

What are the two types of summation

Answer 26

Temporal and spatial

Question 27

Describe temporal summation

Answer 27

One neurone releases many bursts of neurotransmitter in a short amount of Time

Question 28

Describe spatial summation

Answer 28

More than one neurone releases low concentration of neurotransmitter which together lead to a high conc of neurotransmitter

Question 29

What are the types of Synapses

Answer 29

Excitatory and inhibitory

Question 30

Describe what an inhibitory synapse is

Answer 30

A synapse that makes an ap less likely on the postsynatic membrane

Question 31

Describe what an excitatory synapse is

Answer 31

A synapse that makes an ap more likely

Question 32

How do inhibitory Synapses work

Answer 32

Produced neurotransmitters that either open K+ channels or Cl- channels

Cause K+ to diffuse out and Cl- in

Inside becomes less positive making it harder for membrane to be de polarised

Counteracts Na+ diffusing in