Physiology 2: Homeostasis

Question 1

Define homeotasis + examples

Answer 1

Any self-regulating process by which bio systems maintain stability whilst adjusting to variable environmental conditions e.g temp, sugar, O2, pH

Question 2

Describe the steady state maintained in homeotasis

Answer 2

Internal environ is able but NOT static
Dynamic equilibrium
Continuous change occurs but relatively uniform conditions prevail

Question 3

Give an example of negative feedback

Answer 3

Blood glucose levels

Question 4

Give 2 examples of positive feedback

Answer 4

Birth in mammals
Blood clotting

Question 5

Give an example of homeostasis varying within individuals

Answer 5

Hummingbirds → state of torpor at night/ cold weather (normally 38-40oc, falls to 18-20oc)
OR
Eastern Pygmy possum → Torpor behaviour / longer deeper hibernation (up 1 a year)

Question 6

Give an example of homeostasis varying among species

Answer 6

Different species have different body temp norms e.g duckbilled platypus 32oc whereas emperor penguins 39oc
OR
Naked mole rats → live underground = no need to self regulate body temp

Question 7

Describe the role of the doping drug EPO

Answer 7

Erythropoietin (naturally occuring)
→ stimulates bone marrow to produce more red blood cells
= help to counteract a fall in O2 levels (more RBs = more haem centres available = more O2 around the body)

Question 8

How is EPO used?

Answer 8

Injected in synthetic form
Causes increase in O2 supply by 7-10%

Question 9

How can athletes naturally gain the benefits that doping using EPO gives?

Answer 9

By training at high altitudes to stimulate the homeostatic system e.g Colombian cyclists

Question 10

What are the side effects of EPO?

Answer 10

Blood thickens
Heart has to work harder
Increased risk of heart attack/ stroke

Question 11

Describe the role of the doping drug Meldonium

Answer 11

→ stimulates nitric oxide production = increases vasodilation = increase in flow of O2