B7. Co-ordination and response

Question 1

the human nervous system is consisted of

Answer 1

1. central nervous system(CNS): brain/spinal cord

2. peripheral nervous sytem: nerve cells

Question 2

describe pupil reflex

Answer 2

dim light:
radial muscles contract → pupil dilate

bright light:
circular muscles contract → pupil contract

Question 3

what is involuntary action

Answer 3

• doesnt involve thought/brain
• cannot control the activities.
• respond quickly to avoid danger
• rapid response

Question 4

what is voluntary action

Answer 4

• conscious thought
• respond with the benefit of experience
• slow response, as the cerebrum needs to “think” before an action
• same stimulus produce various responses.

Question 5

describe a reflex action

Answer 5

• fast, automatic responses to a stimulus.

1. receptor detects a stimulus
2. sensory neurone sends impulse to relay neurone
3. motor neurone sends impulse to effector
4. effector produces a response

Question 6

Define a hormone

Answer 6

chemical substance,
produced by a gland,
carried by the blood,
alters activity of 1/+ specific target organs 
and is destroyedby the liver

Question 7

State the role of the hormone adrenaline

Answer 7

secreted by adrenal gland, prepare for rapid activities in ‘fight or flight’ situation

↑breathing rate - ↑uptake of O2/excretion of CO2
↑heart rate - more blood is pumped in muscles, provide glucose/O2
↑concentration of glucose
↑widen of pupils(dilate) - more light enter eye

*for respiration which release energy

Question 8

negative feedback

Answer 8

control system responds when conditions change from the ideal or set point and returns conditions to this set point.