2. Homeostasis pt1

Question 1

Define homeostasis

Answer 1

Homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal & external changes
(Maintains optimum conditions for enzyme action and all cell functions)

Question 2

What do we control and why in our internal environment?

Answer 2

• Temperature (for correct enzyme activity)
• blood glucose concentration (for constant energy supply)
• water levels (to control osmosis and chemical reactions)

Question 3

What are the 3 components of an effective control system and what do they do?

Answer 3

1. Receptors, to detect the change in conditions
2. Coordination’s centres, to process the information
3. Effectors, to bring about the correct response

Question 4

What’s the change in the environment called?

Answer 4

Stimulus

Question 5

What do we call the specialised nerve endings that detect the stimuli?

Answer 5

Receptors

And when grouped together form a sense organ

Question 6

List 7 of your receptors

Answer 6

• eyes
• nose
• ears
• tongue
• skin
• muscles
• joints

Question 7

Describe the type of receptor your eye has?

Answer 7

Receptors for light

Question 8

Describe the type of receptor your nose has?

Answer 8

Receptors for chemicals forming smell

Question 9

Describe the type of receptor your ears has?

Answer 9

For sound and detecting changes in position (balance)

Question 10

Describe the type of receptor your tongue has?

Answer 10

Receptors for chemicals forming taste

Question 11

Describe the type of receptor your skin has?

Answer 11

Receptors for touch, pressure, pain and temperature

Question 12

Describe the type of receptor your muscles and joints have?

Answer 12

Receptors for changes in position

Question 13

What is the name of the specialised cells in the nervous system?

Answer 13

Neurones (which work in groups called nerves)

Question 14

What does the nervous system do?

Answer 14

It enables the body to respond to changes in the environment to trigger the appropriate response

Question 15

Describe how a response in coordinated through the neurones

Answer 15

1. Once the receptor detects the stimulus, it sends a nerve impulse along a sensory neurones
2. This cell takes the impulse towards the central nervous system
3. The CNS can then coordinate an effective response

Question 16

What’s the central nervous system made up of?

Answer 16

The brain and spinal cord

Question 17

How would the neurones respond to the change?

Answer 17

4. Once the brain/spinal cord has determined an appropriate response, it sends another nerve impulse out along a motor neurone
5. This takes the impulse to an effector organ, which carries out the response
6. This organ can either be a muscle, that contracts/relaxes or a gland that’s triggered to secrete hormones as part of the endocrine system

Question 18

Name all 5 of the main parts of coordinating a response

Answer 18

1. Receptor
2. Sensory neurone
3. Coordinator (CNS)
4. Motor neurone
5. Effector

Question 19

Define a reflex

Answer 19

A reflex is a fast, automatic response that occurs without conscious thought
They control basic body functions such as breathing and digestion and help you avoid harm or danger

Question 20

Explain how a reflex occurs

Answer 20

• The sequence of events is the same as other responses but only 1 neurone is use in the CNS instead of hundreds
• this is called a relay neurone, which connects the sensory neurone to the motor neurone through the spinal cord (sometimes in the unconscious part of the brain)

Question 21

Explain the purpose of the reflex arc

Answer 21

• As it bypasses the brain it reduces the time between the stimulus and response
• This minimises damage caused by stressful stimulus
• the reflex arc will send another impulse to the conscious brain so you’re aware, but only after the reflex action has happened

Question 22

What’s the junction between each neurone called?

Answer 22

Synapse

Question 23

Explain how synapses work

Answer 23

• 2 neurones aren’t connected, so to transmit a nerve impulse, the neurone realises a chemical into the gap
• the chemical diffuses across the gap
• binds the receptors on the next neurone

Question 24

Explain the brain

Answer 24

The brain controls complex behaviour. It’s made up of billions of interconnected neurones that receive sensory inputs from your receptors (sensory neurones deliver impulses), and then coordinate the appropriate response through the effectors (motor neurones deliver impulses)
And it has different regions that carry out different functions

Question 25

What are 5 parts of the brain?

Answer 25

• cerebral cortex
• cerebellum
• medulla
• pituitary gland
• hypothalamus

Question 26

What does the cerebral cortex do?

Answer 26

Conscious
Intelligence
Memory
Language

Question 27

What does the cerebellum do?

Answer 27

Coordinating muscles

Balance

Question 28

What does the medulla do?

Answer 28

Unconscious activities

Eg. Heartbeat, breathing, digestion

Question 29

What does the pituitary gland do?

Answer 29

Secrets hormones

Question 30

What does the hypothalamus do?

Answer 30

Controls homeostatic functions

Eg. Temperature