Homeostasis

Question 1

4 mechanisms for heat exchange in homeostasis

Answer 1

-conduction : transfer of heat from skin to chair
- convection : transfer of heat to air surrounding the skin eg fan
- radiation : is the transfer of heat via infrared waves
-evaporation : transfer of heat by evaporation of water eg sweating

Question 2

What are pyrogens

Answer 2

Bacterial or viral infections change the set point to a higher level, resulting in a fever

Question 3

What are the benefits of a higher temperature

Answer 3

Inhibits bacterial growth
Speeds up metabolic reaction
Increases delivery of wbc to site of infection

Question 4

Increase in blood pressure

Answer 4

• baroreceptors in wall of carotid sinus and aortic arch detect increase in BP
  -brain receives an input and signals blood vessel and heart
  -arterioles dilate and HR decreases leading to decrease in BP

Question 5

Role of vasopressin in the control of blood pressure

Answer 5

Vasoconstriction which leads to increased arterial pressure
Renal fluid absorption which leads to increased blood volume which leads to increased arterial pressure

Question 6

Ways to help restore blood pressure

Answer 6

-stimulation of ADH -secretion to release blood volume
-baroreceptors reflex to increase cardiac output and total peripheral resistance

Question 7

Effects of angiotensin 2

Answer 7

Adrenal cortex - secretes aldosterone
Hypothalamus - secretes ADH and acts on the thirst centre in the brain
Smooth muscle cells arteries to constrict

Question 8

Pathway of control of circulating cortisol concentrations

Answer 8

Set point- hypothalamus - release CRH - anterior pituitary gland release ACTH- binds to receptors on adrenal cortex - cortisol released

Question 9

What does renin convert

Answer 9

Angiotensionigen into angiotensin

Question 10

Pathway of circulating sex steriod hormones

Answer 10

Set point - hypothalamus detects - release GnRH- anterior pituitary gland - release LH/FSH- bind to gonads - sex steroid ( oestrogen , testosterone)

Question 11

When there is an increase in blood sugar

Answer 11

• beta cells of the pancreas will sense an increase in blood sugar and will secrete insulin
  This will cause adipose tissue , muscle, liver to take up and store glucose
  So blood sugar drops

Question 12

When our blood sugar levels fall

Answer 12

• alpha cells secrete glucagon
  Glucagon stimulates Gluconeogenesis through glycogenolysis and glucose release from liver which increases blood sugar

Question 13

Positive feedback of haemostasis

Answer 13

• break in blood vessel
  -clotting occurs as platelets adhere to site and release chemicals
• releases chemicals attract more platelets
  -clotting proceeds until break is sealed by new close