Homeostasis- responding to changes in the environment

Question 1

Define Homeostasis

Answer 1

The maintenance of an organisms internal environment within set limits

Question 2

Explain enzyme activity

Answer 2

-Operate best over a specific range of conditions
-By maintaining pH and body temp, all enzyme-linked reactions are efficient

Question 3

Explain cell size

Answer 3

-Will change if water potential in blood, effects the amount of water in tissue fluid and cells
-Could cause swelling and bursting

Question 4

What is negative feedback?

Answer 4

Initiates corrective mechanisms whenever the internal environment deviates from its normal levels.

Question 5

What is an example of negative feedback and explain?

Answer 5

Thermoregulation:

Normal body temp -> Body temp increase -> corrective mechanism (e.g. sweating) -> normal body temp

Question 6

What is positive feedback?

Answer 6

Deviation from normal conditions is amplified, so further deviation.

e.g. normal -> level increase -> positive feedback -> further increase

e.g. oxytocin

Question 7

What is Osmoregulation?

Answer 7

Controls water potential of blood

Question 8

What is the outer and inner area of the kidney called?

Answer 8

Outer-cortex
Inner- Medulla

Question 9

What do we need kidneys for?

Answer 9

-filter blood
-re-absorb glucose
-re-absorb dissolves ions
-re-absorb water
-releases urea, excess salts, excess water as urine

Question 10

How does waste get extracted from blood?

Answer 10

1. Blood enters kidney through renal artery which branches into tiny vessels called the afferent arterioles, and enters the Bowman’s Capsule
2. The capillaries leaving the Bowman’s capsule merge to form the efferent arteriole. These have a smaller diameter than the afferent, resulting in a build up of hydrostatic pressure.
3. Build up of pressure causes water, glucose, and mineral ions to be squeezed out of the capillary to form the globmerular filtrate.
4. Blood cells and large proteins are too large to pass into the nephron and will stay in the blood.

Question 11

Explain using a negative feedback loop how normal water potential of blood is maintained

Answer 11

Conserve water:

Normal. -> decrease in WP -> change detected by osmoreceptors in hypothalmus -> Hypothalamus signals pitiutary gland to release more ADH -> ADH increases permeability of collecting ducts. -> urine. -> normal

Expel water:

same as above but releases less ADH