Section 2 - Cells and control - CNS, synapse, reflexes, the brain and the spinal cord

Question 1

What is the nervous system made up of?

Answer 1

Neurones which go to all parts of body

Question 2

What are receptors and what do they do?

Answer 2

Groups of cells that can detect a change in your environment (a stimulus)

Question 3

What is sent along neurones to send information?

Answer 3

A nervous (electrical) impulse

Question 4

Nervous system order for response?

Answer 4

Stimulus => receptor => sensory neurone => CNS => motor neurone => effector => response

Question 5

Difference between ‘dendrites + dendrons’ and ‘axons’?

Answer 5

Dendrites and dendrons carry nerve impulses towards cell body.
Axons carry nerve impulses away from cell body

Question 6

Why are some axons surrounded by myelin sheath?

Answer 6

It acts as an electrical insulator so speeds up electrical impulse

Question 7

Structure and function in sensory neurone?

Answer 7

• One long dendron carries nerve impulses from receptor cells to cell body, which is located in middle of neurone.
• One short axon carries nerve impulses from cell body to CNS

Question 8

Structure and function in motor neurone?

Answer 8

• Many short dendrites carry nerve impulses from CNS to cell body.
• One long axon carries nerve impulses from cell body to effector cells

Question 9

Structure and function in relay neurone?

Answer 9

• Many short dendrites carry nerve impulses from sensory neurone to cell boy.
• An axon carries nerve impulses from cell body to motor neurones

Question 10

What is a synapse?

Answer 10

Connection between two neurones

Question 11

How are nerve signals transferred between two neurones?

Answer 11

Nerve signal transferred by chemicals called neurotransmitters, which diffuse across gap. They then set off a new electrical signal in next neurone

Question 12

What do reflexes do and what is a reflex arc?

Answer 12

Reflexes prevent injury or protect eye and a reflex arc is the passage of information in a reflex

Question 13

How do reflexes happen? order, 2

Answer 13

• Stimulus detected by receptors, impulses sent along a sensory neurone to a relay neurone in CNS. Synapse occurs between neurones
• Synapse occurs again between relay and motor neurones. Impulse then travels along motor neurone to effector, where response happens.

Question 14

How do reflexes protect the eye against very bright light?

Answer 14

Light receptors in eye detect bright light and send message along sensory neurone to brain. Message then travels along relay neurone to motor neurone which tells circular muscles in iris to contract, making pupil smaller

Question 15

2 things is CNS made up of? What are both of these made up of each?

Answer 15

Spinal cord - long column of neurones running from base of brain to spine, branching off at several places down cord and connecting with other body parts
Brain - made up of billions of interconnected neurones

Question 16

3 parts of brain?

Answer 16

Cerebrum, cerebellum and medulla oblongata

Question 17

Function of cerebrum in brain?

Answer 17

Largest part of brain, divided into two halves called cerebral hemispheres (left/right). Right controls muscles on left side of body and vice versa. Different parts of cerebrum responsible for different things

Question 18

Function of cerebellum in brain?

Answer 18

Responsible for muscle coordination and balance

Question 19

Function of medulla oblongata in brain?

Answer 19

Controls unconscious activities like breathing and heart rate

Question 20

What does a CT scanner use and show?

Answer 20

Uses X-rays to produce image of main structures of brain, but doesn’t show functions of them.

Question 21

How can a CT scanner be used to work out if a patient has lost some function of the brain?

Answer 21

If patient has lost some function and CT scan shows diseased or damaged brain structure, function of that part of brain can be worked out

Question 22

What does a PET scanner use and show?

Answer 22

Uses radioactive chemicals to show which parts of brain are active or inactive when person is inside scanner and sees both structure and function

Question 23

3 ways in which it is difficult to treat the CNS?

Answer 23

• hard to repair damage to CNS and nervous tissue
• hard to access some areas
• treatment for problems in CNS may lead to permanent damage