3.8 Nervous System

Question 1

Functions of nervous system

Answer 1

1. Detects changes
2. Processes the information
3. Initiates responses

Question 2

2 parts of the nervous system

Answer 2

CNS
PNS

Question 3

6 steps of the nervous system mechanism

Answer 3

Stimulus
Receptor
CNS
Effector
Response
Feedback

Question 4

7 parts of the spinal cord

Answer 4

Sensory (contains cell body)
Relay
Motor
Dorsal root ganglian
Ventral root
Grey matter
White matter

Question 5

8 parts of a motor neurone

Answer 5

Dendrite
Nucleus
Cell body
Axon
Myelin sheath
Node of ranvier
Schwann Cell
Axon terminal

Question 6

Resting Potential

Answer 6

Sodium/Potasium pumps actively transports 3 Na+ out and 2 K+ in
Potasium also diffuse out
Sodium channels closed
Inside axon more negative
-70mV
Polarised

Question 7

Action Potential

Answer 7

The rapid raise and fall of the electrical potential across a nerve cell membrane as impulse passes
Na+ channels open (Na+ diffuses in)
Mambrane becomes more permeable
+40mV
Depolarised

Question 8

Why does impulse travell one way

Answer 8

Refractory period behind every impulse
Every nerve has synaps at the end

Question 9

Repolarisation

Answer 9

Na+ channels close
K+ channels open
K+ diffuse out of axon
Becomes more negative than resting potential
Hyperpolarised
Refractory period

Question 10

All or nothing principle

Answer 10

the size of the impulse is independant of the size of the stimulus

Question 11

3 things that affects the speed of conduction

Answer 11

1. Myelination
2. Axon diameter
3. Temperature

Question 12

What if axon has no myelin

Answer 12

No saltitory conduction
Impulse cant jump from node to node

Myelin is a good eletrical insulator

Question 13

Synaps functions

Answer 13

Transmit info between neurones
Transmit info in one direction only
Acts as a junction
Protects form over stimulation

Question 14

2 types of synaps

Answer 14

Eletrical - impulse jump
Chemical - too big for impulse to jump - neurotransmitter is needed

Question 15

How does impulse cross a synaps

Answer 15

1. impulse arives
2. Ca2+ diffuses into presynaptic knob
3. Vesicles fuse to presynaptic membrane and relese neurotransmitter (acetylecholine) by excotyosis
4. acetylecholine diffuse and attaches to 2 receptor sites
5. Protein channels open Na+ diffuses into post synaptic membrane - Depolarised
6. Acetylsecholinesterase breaks down acetylecholine and diffuses back into presynaptic membrane as chloride and ethanoic acid

Question 16

Effects of drugs

Answer 16

Alters brain behaviour
increase alertness
Plesant - euphoria

Question 17

Excitatory

Answer 17

• Drugs increase action potential
• Mimic neurotransmitter
• Inhibit breakdown of neurotransmitter
• Block uptake back into presynaptic knob
• Increase number of receptors on post synaptic membrane

Question 18

Inhibitory

Answer 18

• Decrease action potentials in post synaptic membrane
• Prevents exocytosis
• Binds with receptors on post synaptic membrane and blocks it
• Provents Ca2+ entry

Question 19

Function of:

Cell body

Answer 19

Contains nucleus and cytoplasm

Question 20

Function of:

Cytoplasm

Answer 20

Granular; contains many ribosomes

Question 21

Function of:

Nucleus

Answer 21

Holds DNA

Question 22

Function of:

Nissl granules

Answer 22

Synthesise neeurotransmitter

Question 23

Function of:

Dendrite

Answer 23

Carries impulse towards cell body

Question 24

Function of:

Axon

Answer 24

Carries impulse away from cell body

Question 25

Function of:

Schwaan cells

Answer 25

Wrap around axon synthesise myelin

Question 26

Function of:

Myelin Sheath

Answer 26

Electrical insulator

Question 27

Function of:

Node of ranvier

Answer 27

Gaps in myelin sheath

Question 28

Function of:

Axon terminal

Answer 28

Transmits impulse to adjacent neurone