Week 1 - homeostasis

Question 1

What is homeostasis

Answer 1

The condition of equilibrium in the body’s internal environment

Question 2

What do homeostatic mechanisms do

Answer 2

They keep a regulated variable in the internal environment within a range of values compatible with life

Question 3

How is the regulated variable linked with the brain

Answer 3

The regulated variable has sensors or receptors that send afferent signals to the brain to keep the regulated variable within a limited range via physiological mechanisms

Question 4

Homeostatic feedback loop

Answer 4

Regulated variable –> sensor –> control centre –> effector –> back to regulated variable

Also set point –> control centre

Question 5

Tight control of a variable

Answer 5

At any given time a variable will be very close to a predicted value

Question 6

Looser control of a variable

Answer 6

A variable may fluctuate daily, but mechanisms that eventually return the variable to normal levels make sure that homeostasis exists over a longer period of time

Question 7

What happens when room temperature (the set point) decreases

Answer 7

Body temperature (the regulated variable) decreases, and all the blood rushes to the core

Question 8

Why might the set point reset at a higher body temperature

Answer 8

During a fever, the body wants to kill off any bugs

Question 9

Gain of a regulated variable

How is it calculated

Answer 9

The precision by which a control system can prevent deviation from homeostasis

Amount of correction needed / Amount of abnormality after correction

Question 10

Negative feedback

Answer 10

Acts to reduce an effect. When a change occurs in a system negative feedback opposes that change, and restores the controlled variable back to its usual value e.g. regulation of body temperature

Question 11

Positive feedback

Answer 11

Acts to increase an effect. That is, when a change occurs in a system, that change becomes amplified

Question 12

Feedforward loops

Answer 12

Physiological responses in anticipation of a change in a variable
e.g. heart rate increasing prior to running a race

Question 13

Reflex response

Answer 13

Requires knowledge from a control centre and a circuitry that connects the receptor and the effector

Question 14

Local response

Answer 14

They allow individual parts of the body to self regulate their responses to certain conditions