Coordination And Control Animals

Question 1

Central Nervous System

Answer 1

brain and spinal cord

integrating activity of NS in coordinating the functioning of all parts o body

Question 2

Peripheral Nervous System

Answer 2

Cranial Nerves and Spinal Nerves

connect receptors to CNS and CNS to effectors

Question 3

Neurone

Answer 3

functional unit of nervous system

Question 4

Nerve

Answer 4

bundle of neurones

Question 5

Structure of Neurones

Answer 5

Centron - contains nucleus and other organelles - number of cytoplasmic extensions

Dendrons - transmit impulses to the cell body

Axons - transmit impulses away from cell body - terminate in synaptic bulbs

Question 6

Types of Neurone

Answer 6

Sensory
Motor
Connector

Question 7

What is the Myelin Sheath

Answer 7

many layers of cell membrane of Schwann cells- wrap themselves around axon

Question 8

Gaps in Myelin Sheath

Answer 8

Nodes of Ranvier

Question 9

Resting Potential

Answer 9

-70mV
Inside neurone negative w/respect to outside

Large excess of Na+ ions on outside - large potential difference

Question 10

Action Potential

Answer 10

Neurone stimulated - allows Na+ to diffuse in - changes potential difference - less -ve inside

If threshold reached in PD ions surge in and neurone depolarised - positive on inside
+40mV

Question 11

What is Threshold Value

Answer 11

-55mV
critical potential difference

Question 12

All or Nothing Rule

Answer 12

Action potential does not vary in size and wither occurs or does not

Question 13

Refractory Period

Answer 13

Following action potential - membrane repolarises and recovers its resting potential

membrane unexcitable during this time

Question 14

Impulse Propagation

Answer 14

Depolarisation of one part membrane sets up local circuits with the areas either side of it

+ ion attracted to neighbour - regions - flow in both directions

Question 15

2 Sides of Impulse Propogation

Answer 15

One side repolarising - in refractory period

Other side - excitable - local circuit triggers depolarisation and formation of an action potential

Question 16

What is an Impulse

Answer 16

transmission or propagation of depolarisations or action potentials along the neurone membrane

Question 17

Impulse in Myelinated Neurones

Answer 17

Local circuits cannot be set up in parts insulated

Action potential jumps from one node of Ranvier to the next - greatly increases speed

Saltatory Conduction

Question 18

What can speed up impulse transmission in non-myelinated axons

Answer 18

Large diameter - large surface over which ions might be moved

Formation of action potentials occurs more rapidly

Question 19

What do Synaptic Vesicles contain

Answer 19

Neurotransmitter chemical

Question 20

Gap between Synaptic Bulbs

Answer 20

Synaptic Cleft

Question 21

Neurone membrane before and after cleft

Answer 21

Before: pre-synaptic membrane
After: post-synaptic membrane

Question 22

What is the name of the whole structure of Synaptic bulbs together

Answer 22

Synapse

Question 23

Sequence of Synaptic Transmission

Answer 23

•impulse arrives bulb - memb becomes permeable to Ca ions

•Ca ions stimulate mvmnt vesicles towards Pre-Synaptic

•Vesicles fuse w/ Pre and release NT molecules - Acetylcholine ACh - exocytosis into cleft

•ACh diffusion across cleft to Post

•NT attach specific receptors on Post

•Causes (Na+) ion channels open - PD Post is altered (depolarised)

•ACh hydrolysed by acetylcholinesterase - bd prod choline & ethanoic acid released into cleft

•Allows resting pot be re-established

•BD prod diffuse across cleft and reabsorbed into bulb - resynthesised into NT - ATP from mitochondria

Question 25

Motor Neurone Synapse W/ Skeletal Muscle Fibre

Answer 25

Neuromuscular Junction

Question 26

Noradrenaline

Answer 26

Neurotransmitter in bulbs of sympathetic nervous system - fight or flight response Cause Na+ channels open - depolarisation Post-Synaptic Membrane create EPSP

Question 27

EPSP

Answer 27

Excitatory Post-Synaptic Potentials make membrane less negatively charged - more likely reach threshold

Question 28

GABA

Answer 28

Gamma-aminobutyric Acid In brain Cl- ion channels open - Post is **hyperpolarised** so IPSP develop

Question 29

IPSP

Answer 29

Inhibitory Post-Synaptic Potentials memb more - charged less likely to reach threshold to trigger AP stop worrying thoughts- cpntrol anxiety

Question 30

Advantages Synapses

Answer 30

•ensure transmission one direction only (nt only from pre) •protect effectors from overstimulation (echasut supply nt) •allow actions to be controlled through inhibition and stimulaton •integrate activity of different neurones synapsing with a single Post-Synaptic Neurone