B13

Question 1

Transducer

Answer 1

Sensory receptor converts stimulus into a nerve impulse (generator potential).

Question 2

Resting Potential

Answer 2

-70 mV. Polarised.
3 Na+ out/2K+ in (AT).
Inside of axon negative relative to the outside.

Question 3

Action Potential

Answer 3

+40 mV. Depolarised.
Stimulus open Na+ channels, Na+ in, cause more to open.
At +40, close, open K+ channels, K+ diffuse out (hyperpolarisation). K+ close. Pump restores RP.

Question 4

Propagation of AP

Answer 4

Stimulation causes depolarisation, which causes the depolarisation of the next region (Na+ attracted by -ve charge ahead).
Cont. and area behind returns to RP.

Question 5

Saltatory Conduction

Answer 5

Myelinated faster as AP jumps to the nodes of Ranvier. Faster, more energy efficient (reduces amount of ATP needed for repolarisation).

Question 6

All-or-nothing Principle

Answer 6

AP always same size.
Stronger stim = inc. freq. AP.
Stim needs to reach threshold value to trigger depolarisation.
Measure freq. with oscilloscope.

Question 7

Excitatory Neurotransmitter

Answer 7

Depolarisation of postsynaptic.
Acetylcholine.

Question 8

Inhibitory Neurotransmitter

Answer 8

Hyperpolarisation of postsynaptic.
Prevents AP being triggered.
GABA.

Question 9

Spatial summation

Answer 9

Multiple presynaptic connect to 1 postsynaptic. Cause neurotransmitter levels to build, reaching threshold, trigger AP.

Question 10

Temporal summation

Answer 10

Single presynaptic releases several times over a short period. Builds up in synapse until AP triggered.

Question 11

Role of synapses

Answer 11

Ensure impulses unidirectional.
Transmit from 1 neurone to multiple.

Question 12

Central Nervous System (CNS)

Answer 12

Brain and spinal cord. Relay neurones.

Question 13

Peripheral Nervous System (PNS)

Answer 13

All the neurones that connect CNS to rest of body. Sensory and motor neurones.

Question 14

Somatic Nervous System (part of PNS)

Answer 14

Conscious control. Input from sense organs, output to skeletal muscles.

Question 15

Autonomic Nervous System (part of PNS)

Answer 15

Works constantly, subconscious control. e.g. heart beat or digestion.

Question 16

Sympathetic Motor System (part of Autonomic NS)

Answer 16

Flight or fight responses. Neurotransmitter = noradrenaline.

Question 17

Parasympathetic Motor System (part of Autonomic NS)

Answer 17

Relaxing responses. Neurotransmitter = acetylcholine.

Question 18

Cerebrum

Answer 18

Controls voluntary actions e.g. learning, personality and conscious thought.

Question 19

Cerebellum

Answer 19

Controls unconscious functions e.g. posture, balance, non-voluntary movement.

Question 20

Medulla Oblongata

Answer 20

Used in autonomic control e.g. heart and breathing rate.

Question 21

Hypothalamus

Answer 21

Regulatory centre for temp. and water balance.

Question 22

Pituitary Gland

Answer 22

Stores and releases hormones that regulate many body functions.

Question 23

Reflex Arc

Answer 23

Receptor - detect stim and create AP in sensory.
Sensory - carry impulse to spinal cord.
Relay - connect sensory to motor within spinal cord or brain.
Motor - carry impulse to effector.
Effector - carry out appropriate response.

Question 24

Knee-jerk Reflex

Answer 24

Spinal reflex (brain not involved). Tap patella (stim), initiate arc (causes leg to kick).

Question 25

Blinking Reflex

Answer 25

Cranial reflex (spine not involved). Involuntary, cornea stim. Keep cornea from damage from foreign objects. Also due to loud noise or bright light.

Question 26

Reflexes inc. survival chance by...

Answer 26

Being involuntary. Not having to be learnt. Extremely fast. Everyday actions (staying upright/digestion).

Question 27

Skeletal Muscle

Answer 27

Make up bulk of body muscle tissue. Responsible for movement e.g. biceps/triceps.

Question 28

Cardiac Muscle

Answer 28

Only in the heart. Myogenic (contract without nervous stim, causing regular rhythmed heart beat).

Question 29

Involuntary Muscles (aka Smooth Muscle).

Answer 29

Walls of hollow organs e.g. stomach/bladder and wall of blood vessels and digestive tract (move food along gut).

Question 30

Structure/Function: Skeletal Muscles.

Answer 30

Striated. Conscious. Regularly arranged so muscle contracts in one direction. Rapid & short contraction.

Question 31

Structure/Function: Cardiac Muscles.

Answer 31

Striated. Involuntary. Cells branch/interconnect, result in simultaneous contraction. Intermediate contraction.

Question 32

Structure/Function: Smooth Muscles.

Answer 32

Non-striated. Involuntary. Non regular arrangement (diff cells contract in diff directions). Slow & long lasting contraction.