Reflexes

Question 1

What is a reflect arc?

Answer 1

A reflex arc is a neural pathway that causes an involuntary and immediate reaction to a stimulus, typically designed for protection.

Question 2

Example of a reflex arc?

Answer 2

when you touch a sharp object, a reflex arc is responsible for the rapid withdrawal of your hand, preventing injury.

Question 3

Reflex arcs: composed of

Answer 3

• 3 types of neurone
• Not controlled by brain
• Unconsciously controlled by spinal cord

Question 4

Stages of reflex arc?

Answer 4

1. Stimulus
2. Receptor
3. Sensory neurone
4. Relay neurone (intermediate neurone)
5. Motor neurone
6. Effector
7. Response

Question 5

Stimulus:

Answer 5

This triggers the reflex, such as heat from a hot object.

Question 6

Receptor:

Answer 6

These are specialised cells, like temperature receptors in the skin, that detect the stimulus and generate nerve impulses.

Question 7

Sensory neurone:

Answer 7

This transmits the nerve impulses to relay neurones.

Question 8

Relay neurone (intermediate neurone)

Answer 8

Usually located in the spinal cord or more rarely in the brain, these connect sensory neurones to motor neurones.

Question 9

Motor neurone:

Answer 9

This transfers nerve impulses from the relay neurones to effectors

Question 10

Effector:

Answer 10

This is the muscle or gland that receives the signal and carries out a response, like muscles in the arm receiving a signal to contract.

Question 11

Response:

Answer 11

This is the final action taken, such as quickly moving the hand away from the hot object.

Question 12

Spinal reflexes:

Answer 12

• Just involve spinal cord
• Not brain

Question 13

Cranial reflexes:

Answer 13

• Just involve brain
• Not spinal cord

Question 14

Withdrawal reflexes:

Answer 14

This is a spinal reflex that removes the hand rapidly from a sharp or hot object.

Question 15

The knee-jerk (patellar) reflex:

Answer 15

This is a spinal reflex that causes the leg to kick when it is tapped just below the kneecap and helps maintain posture and balance.

Question 16

Blinking reflex:

Answer 16

This is a cranial reflex that triggers involuntary blinking of the eyelids when the cornea is stimulated, or in response to loud sounds or bright light.

Question 17

Importance of reflex arcs:

Answer 17

• Inherent speed and lack of involvement from the brain in the decision-making process are essential for preventing excessive injuries.

Question 18

Key features of reflex arcs:

Answer 18

• Involuntary - They allow the brain to concentrate on complex processes.
• Rapid - They ensure a swift response.
• Protective - They safeguard the body from potential injuries.
• Innate - They are intrinsic mechanisms present from birth, eliminating the need for learning.