chapter 9 - homeostasis & hormonal control

Question 1

define homeostasis

Answer 1

homeostasis is the maintenance of a constant internal environment

Question 2

homeostasis is a ________________ process

Answer 2

self-regulating

Question 3

examples of homeostasis in humans (4)

Answer 3

• regulating blood plasma water potential
• regulating body temperature
• regulating blood glucose concentration
• carbon dioxide concentration

Question 4

homeostasis ensures that____________________________________.

Answer 4

the conditions of the blood and tissue fluid in terms of (e.g.) body temperature and water potential are kept within the range

Question 5

changes in body temperature may result in _________________

Answer 5

enzyme denaturation

Question 6

drastic changes in water potential will affect ______________.

Answer 6

the cells

Question 7

what could happen if the blood glucose concentration rises above the norm?

Answer 7

it could cause serious health problems e.g. damaging blood vessels

Question 8

what is negative feedback?

Answer 8

negative feedback is a sequence of events that restores body conditions back to normal. it does so by bringing about an opposite effect to reverse the change that is detected.

Question 9

for negative feedback to take place, there must be……. (6)

Answer 9

1. a normal / set point that needs to be maintained
2. a stimulus – change in the internal environment
3. a receptor – that can detect the stimulus and send signals to the control centre
4. control centre – part of the body (usually the brain) that receives and processes information from the receptor and determines the response by the effector
5. effector – an organ or cell that responds to a stimulus, bringing about an effect
6. a corrective mechanism – processes which bring about the reverse effect of the stimulus
   **enzyme is involved in corrective mechanisms

Question 10

what is a hormone?

Answer 10

it is a chemical substance produced in minute quantities by an endocrine gland. It is transported in the bloodstream to target organs where it exerts its effects and is transported to the liver to be destroyed/broken down.

Question 11

what is an endocrine gland?

Answer 11

a DUCTLESS gland that secretes hormones directly into the bloodstream

Question 12

why is fluctuating blood sugar levels harmful to health?

Answer 12

high blood sugar:
- toxic to cells
- proteins in cells get destroyed
- long-term high blood sugar will cause damage to blood capillaries, nerves and organs

low blood sugar:
- brain and vital organs cannot function optimally