Homeostasis

Question 1

What is a challenge?

Answer 1

A challenge produces a change in body status

Question 2

What are the components of a feedback system?

Answer 2

Regulated factor (set point, operating range, “error signal)

Detector/sensor (afferent path)

Comparator/control centre – determines set point of variable, compares and maintains variable at set point
Intrinsic: local – cell or tissue autoregulates
Extrinsic: endocrine system, nervous system

Effector – returns variable to set point (efferent path)

Response

Question 3

What needs to be controlled?

Answer 3

Circulating concentrations of chemical substances

Ions e.g. Na+, Ca2+
Nutrients e.g. blood glucose concentration
Hormones

Physical entity

Blood pressure
Core temperature

Question 4

What can change the set point?

Answer 4

Things like diseases or infection.

Question 5

What are pyrogens?

Answer 5

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

Question 6

Benefits of higher temperature?

Answer 6

• inhibits bacterial growth
• speeds up metabolic reactions
• increases delivery of white blood cells to infection sites

Question 7

How is temperature increased?

Answer 7

• Blood flow shifted to the core to conserve heat
• Increased muscle activity (shivering)
• Chills stop when high temp is reached

Question 8

What happens during the course of a typical febrile attack?

Answer 8

The actual body temperature lags behind the rapid shift in set point and though regulation is maintained during the fever, it is less precise.

Question 9

What is vasopressin?

Answer 9

Causes vasoconstriction