Unit 5 - homeostasis and response

Question 1

What is homeostasis

Answer 1

Regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes

Question 2

What do the automatic control systems in the body involve

Answer 2

Either nervous system or hormones

Question 3

Features of an automatic control system

Answer 3

Receptor cells, coordination centre, effector

Question 4

Function of receptor cells

Answer 4

Detect changes in the environment either internal (concentration of glucose in the blood) or external (temperature of the skin)

Question 5

What is a stimulus

Answer 5

A change to the environment

Question 6

Example of a coordination centre

Answer 6

Brain, spinal cord or pancreas

Question 7

Function of the coordination centre

Answer 7

Receives and processes information from the receptors

Question 8

What is an effector

Answer 8

A muscle or a gland

Question 9

Function of the effector

Answer 9

Carry out the response (restore the optimum level), either a muscle contract or a hormone is secreted from a gland

Question 10

2 parts of the nervous system

Answer 10

-The central nervous system (brain and spinal cord)
-other nerves running to and from the central nervous system

Question 11

What is a neurone

Answer 11

A nerve cell= carry electrical impulses when stimulated

Question 12

Process of when you touch a hot object

Answer 12

1. The stimulus is detected by a receptor (in this case the stimulus is heat and the receptor is the skin)
2. Electrical impulses pass from a receptor along a sensory neurone to the central nervous system
3. At the synapse of the sensory neurone a chemical is released
4. This chemical now diffuses across to a relay neurone in the CNS where it triggers an electrical impulse
5. The impulse now passes across the relay neurone and reaches another synapse
6. Once again a chemical is released which triggers and electrical impulse in a motor neurone
7. The impulse moves down the motor neurone to an effector (muscle )
8. The muscle now contracts and pulls the hand away from the heat this is the response

Question 13

Characteristics of reflexes

Answer 13

No decision making by conscious part of brain
Automatic
Rapid

Question 14

What are the 3 different neurones

Answer 14

Sensory neurones
Relay neurones
Motor neurones

Question 15

Function of sensory neurones

Answer 15

carry electrical signals - nerve impulses - towards the central nervous system (spinal cord and brain). The signal starts in a receptor which detects a change.

Question 16

Function of a relay neurones

Answer 16

carry nerve impulses within the central nervous system

Question 17

Function of motor neurones

Answer 17

carry nerve impulses away from the central nervous system. The neurone ends in either a muscle or gland, which are effectors.

Question 18

Function of cerebral cortex

Answer 18

Language , memory and consciousness

Question 19

Function of the cerebellum

Answer 19

Controls our balance and coordination of our movements

Question 20

Function of the medulla

Answer 20

Controls our breathing and heart rate

Question 21

Why is studying the brain difficult

Answer 21

-brain is protected by the skull so it is very tricky to access
-the structures of the brain are complex so it’s difficult to work out which part of the brain carries out specific functions
-brain is extremely delicate and easy to damage

Question 22

3 ways scientists use to investigate the brain

Answer 22

-look at patients who have suffered brain damage by looking at where damage has taken place they can try work out that part of the brains function
- electrically stimulate different parts of the brain and look at effects on person behaviour
-use MRI scanning to look at which part of the brain are most active during different activities

Question 23

What type of organ is the eye

Answer 23

A sense organ (contain receptors sensitive to both light intensity and colour of light)

Question 24

Function of the cornea

Answer 24

Is to start the focusing of the light rays
It is transparent so allows light through

Question 25

What is the iris

Answer 25

The coloured part of the eye in the pupil, controls the size of the pupil

Question 26

Function of the lens

Answer 26

Focus the light rays onto the back of the eye
It can change its shape allowing us to focus on distant or near objects (this is called accommodation)

Question 27

Function of the retina

Answer 27

Contain receptor cells for light
These receptor cells allow us to detect light intensity and light colour
They then send the impulses down the optic nerve to the brain

Question 28

What is the sclera and function

Answer 28

The white part of the eye, this tough outer structure protects the eye

Question 29

Function of ciliary muscle and suspensory ligaments

Answer 29

Allow us to focus on distant or near objects

Question 30

What happens to your pupil when you enter a dark room

Answer 30

Amount of light entering eye is low
This drop in light intensity is sensed by light receptors in the retina
These send electrical impulses to the brain
The brain then sends impulses to specific muscles in the iris
These muscles contract causing the pupil to become larger