Nervous System And Hormones

Question 1

Differences between nerves and hormones

Answer 1

Nerves are faster and shorter lived than hormones which don’t act quickly and have lasting effects on the body

They are both involved in sensing and responding to changes in the environment (stimuli)

Question 2

Receptors

Answer 2

Receives/detects the stimulus (pressure sensors in the skin)

Question 3

Co-ordinator

Answer 3

Determines the response (the brain and spinal cord)

Question 4

Effector

Answer 4

Carries out the response (biceps muscles)

Question 5

Advanced receptor

Answer 5

The eye is an example of an advanced receptor

- it contains a number of cells types that a fe sensitive to light

Question 6

Aqueous and vitreous humour

Answer 6

Aqueous: front of eye
Vitreous: back of eye
Both are needed to provide support to the eyeball and also allows light to pass through the eye to the retina

Question 7

The iris

Answer 7

It is the coloured part of the eye
It consists of two types of muscles:
-radial muscle (spokes on a wheel)
-circular muscle (form rings around pupil)

Question 8

Risk to the eye in bright light

Answer 8

Bright light can damage the cells of the retina leading to blindness

Question 9

Risk to the eye in dim light

Answer 9

Dim light can result in not enough light reaching to form an image

Question 10

Action of iris muscle in bright light

Answer 10

Circular: contract
Radial: relax

Question 11

Action of iris muscle in dim light

Answer 11

Circular: relax
Radial: contract

Question 12

Effect on pupil diameter in bright light and in dim light

Answer 12

Bright light: decreased

Dim light: increased

Question 13

Amount of light entering the eye in bright light and in dim light

Answer 13

Bright light: decreased

Dim light: increased

Question 14

Adaptations to nerve cells (neurone) to carry out electrical impulses through nervous system

Answer 14

Long length: to carry impulses long distances
Insulting sheath: to allow rapid transmission of impulses
Branching ends: to receive or pass impulses from/to many other nerve cells

Question 15

What are synapses

Answer 15

These are tiny gaps between nerve cells

For impulses to pass from one cell to the next a transmitter chemical must diffuse across the synapse at a high enough concentration to trigger an impulse in the next cell

Question 16

What happens when an impulse reaches a synapse (8 steps)

Answer 16

1. ) The impulse reaches the synaptic bulb (the end of the neurone)
2. ) Vesicles containing the transmitter move towards the cell membrane at the synapse
3. ) Vesicles release release their neurotransmitter into the gap between the two cells
4. ) Neurotransmitter diffuses across the gap
5. ) The neurotransmitter reaches the membrane of the next cell
6. ) When enough neurotransmitter reaches the membrane of the next cell an impulse will occur (threshold)
7. ) The impulse travels along to the next cell
8. ) The used neurotransmitter is broken down by an enzyme

Question 17

Voluntary actions

Answer 17

We have conscious control over these

Question 18

Reflex actions

Answer 18

We are not conscious of these actions
These tend to be much faster than voluntary actions as they use a special pathway of nerves called reflex arc that does away with ‘thinking time’
The rapid nature means they can be used as protection

Question 19

What are hormones

Answer 19

Hormones a re chemicals produced by special glands in the body that can travel through the blood to target organs in order to produce temporary changes in the way cells function

Question 20

How is blood glucose levels controlled

Answer 20

The key hormone is insulin.

Although needed for respiration Hugh glucose levels can result in damage to cells

Question 21

How does insulin decrease blood glucose

Answer 21

When a meal rich in carbs is ingested blood glucose levels rise and the pancreas releases insulin.
Insulin decreases blood glucose by:
-increasing rate of respiration in liver and muscle
-converts glucose to glycogen for storage in liver and muscles

Question 22

What is glucagon?

Answer 22

Release from the pancreas
It is involved in increasing blood glucose levels during exercise or when glucose levels falls

Glucagon acts on the cells of the liver causing the time o convert glycogen back to glucose

Question 23

Negative feedback

Answer 23

This mechanism is used by insulin to control blood glucose levels.
It inseparable that changes are reversed and returned back to the set
level