Nervous Coordination

Question 1

Summarise nervous communication

Answer 1

• Fast
• Short lived
• Localised

Question 2

What does the CNS consist of

Answer 2

Brain + Spinal Chord

Question 3

What does the peripheral nervous system consist of

Answer 3

Somatic and Autonomic

Question 4

What does the somatic consist of

Answer 4

Conscious control

Question 5

What does the autonomic consist of

Answer 5

Unconscious activity such as homeostasis

Question 6

Summarise a receptor

Answer 6

• Specialised cell designed to detect a stimulus
• Specific as will only detect one stimulus
• Cell or protein
• Transform stimulus into electrical nerve impulse

Question 7

How is resting potential maintained?

Answer 7

• Sodium potassium pump using ATP to transport 3 Sodium OUT and 2 potassium IN
• Voltage gated sodium channel closed
• Potassium ion channel open so diffuses out by electrochemical gradient but no equilibrium due to diffusion and the positive outside charge

Question 8

What is a generator potential

Answer 8

A weak stimulus where some NA+ channels open and NA+ diffuses in, reaching the threshold potential

Question 9

Summarise an action potential

Answer 9

• Resting potential at first
• Generator potential
• Threshold reached
• Na+ in until 40mv, (depolarisation) and then potassium gates open
• Potassium diffuse out (hyper polarisation) when membrane potential more negative than resting potential due to slow closing of K+ channels
• Refractory period at the end and prevents new AP occurring, and that they are discrete (non-overlapping and separate) and unidirectional

Question 10

Summarise the all or nothing law of action potentials

Answer 10

• If a generator potential reaches threshold, AP occurs
• Action potentials same size
• Strong stimulus generates more AP (frequency increased)

Question 11

Why does myelination increase speed of an AP

Answer 11

• Schwann Cells that make myelin are an electrical insulator

- Impermeable to the movement of ions in and out

Question 12

Summarise saltatory conduction

Answer 12

• Neurone myelinated
• Lots of Na+ and L+ in nodes of Ranvier
• Depolarisation can only occur in nodes
• AP jumps between nodes in a process called saltatory conduction

Question 13

Define salutary conduction

Answer 13

When an action potential jumps between nodes of ranvier, so speeds up transmission of nerve impulse due to cytoplasm conducting enough charge to depolarise next node

Question 14

How does temperature effect AP speed

Answer 14

More kinetic energy so faster speeds up to 40C

Question 15

How does the diameter of an axon affect speed aP

Answer 15

Greater diameter = faster AP

due to greater SA for ion movement and so less resistance

Question 16

Define synapse

Answer 16

Junction between neurones whereby chemical transmission occurs

Question 17

Define cholinergic synapse

Answer 17

One the uses acetylcholine

Question 18

Summarise synaptic transmission at a cholinergic synapse

Answer 18

• AP arrives at presynaptic knob
• Voltage gated Ca2+ ions open and diffuse in
• Cause vesicles to move towards membrane
• Fuse and release acetylcholine by exocytosis
• Diffuse across synaptic cleft and bind with receptors
• Binding causes Na+ channels to open causing further AP if threshold reached
• Acetylcholinesterase breaks down acetylcholine to stop response

Question 19

How are synapses unidirectional?

Answer 19

• Receptor on post synapse and neurotransmitter released from pre synapse from high to low conc.

Question 20

What is synaptic divergence?

Answer 20

• When neurones join many neurones

- AP spreads to other parts of body

Question 21

What is synaptic convergance?

Answer 21

• When many neurones join a single neurone amplifying the signal

Question 22

Summarise spatial summation

Answer 22

• When neurotransmitters from multiple neurones combine to trigger an AP
• Weak stimulus creates only a few AP

Question 23

Summarise temporal summation

Answer 23

• Single AP does not always trigger an AP in next neurone

- Strong stimulus causes more frequent AP so more neurotransmitter increasing chance of next AP

Question 24

Define neuromuscular junction

Answer 24

Synapse between motor neurone and muscle fibre

Question 25

Summarise what occurs at a neuromuscular junction

Answer 25

• Neurotransmitter released
• binds to receptors
• AP travels along sarcolema
• Then travels down traverse tubules which meet the sarcoplasmic reticulum
• Ca2+ ions released

Question 26

Differences between neuromuscular junction and synapse

Answer 26

• Muscular junction has more receptors so AP more likely
• Acetylcholinesterase found in pits
• Receptors called nicotinic cholinergic receptors

Question 27

Why are muscles in antagonistic pairs

Answer 27

Muscles only pull, they cannot push

Question 28

Define ligament and tendon

Answer 28

Ligaments attach bone to bone and tendons attach bone to muscle

Question 29

Summarise skeletal muscle

Answer 29

• Lots of mitochondria
• Muscle fibres
• Multinucleate (many nuclei)
• Myofibrils containing myofilaments of actin and myosin

Question 30

A band
I band
H band
M Line
Z Line

Answer 30

A = Myosin
I = Inbetween Myosin
H = Inbetween actin
M = Middle
Z =. End

Question 31

Summarise a sarcomere when relaxed

Answer 31

• Actin myosin binding site blocked by tropomyosin

- Prevents actin myosin cross bridge forming

Question 32

Summarise a sarcomere when contracted

Answer 32

• Ca2+ released
• Tropomyosin moves
• Allows actin myosin cross bridge to be formed

Question 33

Role of Ca2+ and ATP in muscle contraction

Answer 33

Move tropomyosin
Stimulate ATPase

ATP change shape of myosin head (bend myosin head) causing power stroke
Active transport of Ca2+ into sarcoplasmic reticulum
Detaches myosin head from actin

Question 34

How is ATP made for muscle contraction

Answer 34

• Phosphocreatine binds with ADP to produce ATP

Question 35

Summarise fast twitch muscle fibres

Answer 35

• Contract and relax quickly
• High force of contraction
• Fatigue quickly
• Respire anaerobically so few mitochondria, little blood supply and less myoglobin
• High intensity and short duration

Question 36

Summarise slow twitch muscle fibres

Answer 36

• Contract and relax slowly
• Low force of contraction
• Resistance to fatigue
• Respire aerobically so lots of mitochondria, good blood supply, myoglobin
• Little anaerobic respiration
• Low intensity and long duration