Communication And Nervous System

Question 1

Name 4 physiological responses

Name 3 behavioural reponses

Answer 1

Physiological: 
erector pili muscles control hair 
sweating 
shivering 
vasoconstriction/dilation 

Behavioural:
Huddling
Basking
Moving in large groups

Question 2

Sensory receptors act as transducers.

Define transducer

Answer 2

Converts one form of energy into another

Question 3

Name a mechanoreceptor
Outline how it works
(5 steps)

Answer 3

Pacinian corpuscle

1) stimuli causes lamellae to deform
2) deforms stretch mediated sodium ion channels
3) influx of Na+
4) generator threshold potential reached (depolarisation)
5) action potential triggered

Question 4

What is the resting potential?

Answer 4

-70mV

Question 5

How is the sodium ion electrochemical gradient formed?

▪▪▪

Answer 5

Sodium-potassium ion pumps move 3 Na+ out of neurone in and 2 K+ in

More Na+ on the outside

Membrane not permeable to Na+ but it is permeable to K+ so it moves back out

Question 6

Outline the action potential

5 steps

Answer 6

Stimulus causes Na+ channels to open

Influx of Na+ causes voltage gated Na+ channels to open at neurone potential -55mV(positive feedback, depolarisation)

Neurone potential reaches +30mV so voltage-gated Na+ channels close and voltage-gated K+ channels open causing outflux of K+(repolarisation, negative feedback)

Hyperpolarisation as there is a slight delay of ion channel closing

Resting potential restored by sodium-potassium ion pump

Question 7

Define synaptic divergence

Define synaptic convergence

Answer 7

Divergence = one neurone connects to many

Convergence = many neurones connect to one

Question 8

Define spatial summation

Answer 8

When 2 or more neurones converge and release small amounts of neurotransmitter together which leads to action potential

Question 9

Define temporal summation

Answer 9

When one neurone is repeatedly stimulated which builds up neurotransmitter causing action potential

Question 10

Outline how synapses work

7 steps

Answer 10

Action potential arrives at presynaptic terminal

Voltage gated Ca2+ ion channels open

Influx of Ca2+ cause vesicles containing neurotransmitter to bind to neurone membrane and release ACh via exocytosis

ACh travels in synaptic cleft and binds to choline thic receptors in post synaptic memebrane

Na+ ion channels open

Influx of Na+ depolarise and trigger action potential

AChE breaks down neurotransmitter

Question 11

Outline hormone cell signalling

What binds to receptors in CSM?
What is activated?
What is formed?
What occurs after?

Answer 11

Hormone binds to receptors on CSM

Activates adenylyl cyclase

This catalyses formation of cAMP

cAMP activates cascade of reactions

Question 12

What does the cortex produce?

Give 2 examples

What do they cause?
▪▪▪

Answer 12

Steroid hormones

Cortisol and Aldosterone

Increase blood pressure and volume (more Na+ uptake at kidney)
Gluconeogenisis
Suppress immune system

Question 13

What does the medulla secrete?
Give 2 examples
What do these cause?
▪▪▪

Answer 13

Catecholamine hormones

Adrenaline and Nor-adrenline

Gylcogenolysis
Increased breathing and heart rate
More blood supplied to vital organs, vasodilation

Question 14

Where are alpha cells?
What does it secrete?
What does it cause?
▪▪▪

Answer 14

Pancreas

Glucagon

Glycogenolysis
Gluconeogenesis
Reduces respiration of glucose in cells

Question 15

Where are beta cells?
What does it secrete?
What does it cause?
▪▪▪

Answer 15

Pancreas

Insulin

Glycogenesis
Increased cell glucose uptake
Increases respiration of glucose in cellls

Question 16

How is insulin secreted?

6 steps

Answer 16

1) Glucose enters Beta cell
2) Increased ATP production
3) Causes K+ ion channels to close
4) Depolarisation of cell
5) Voltage gated Ca2+ ion channels open
6) Influx of Ca2+ cause vesicles containing insulin to release it via exocytosis

Question 17

What detects temperature change?

Answer 17

Thermoreceptors (sends signals to hypothalamus)