Homeostasis

Question 1

What is homeostasis?

Answer 1

Ability to maintain a relatively constant internal environment

Question 2

Name 3 components of the internal environment that are regulated.

Answer 2

• temperature
• volume
• composition

Question 3

Homeostasis requires…

Answer 3

organ systems integration

Question 4

Disruption of homeostasis is …

Answer 4

the basis for disease and death

Question 5

How does fever alter set point?

Answer 5

• rise in core body temperature
• accompanies infection
• White blood cells induce fever by chemical secretion
• Body temperature set point increases
• Fever enhances immune responses

Question 6

Name another process that alters set point.

Answer 6

exercise

Question 7

What is negative feedback?

Answer 7

• If a regulated variable decreases, the system responds to make it increase, and vice versa
• Self-correcting

Question 8

Define regulated variable.

Answer 8

that aspect which is maintained

Question 9

Give examples of regulated variables.

Answer 9

• blood glucose
• blood pH
• plasma ion concentrations
• hormones

Question 10

Define set point.

Answer 10

expected value of a regulated variable

Question 11

Define error signal.

Answer 11

Difference between the value of the set point and the value of the regulated variable

Question 12

Name 4 structures enabling homeostasis.

Answer 12

• receptors
• integrating centres
• effectors
• signals

Question 13

What do receptors do? Give examples.

Answer 13

• sensors that detect stimuli
• thermoreceptors
• chemoreceptors
• baroreceptors

Question 14

What do integrating centres do? Give examples.

Answer 14

• sets up a appropriate response
• medulla oblongata
• hypothalamus (ie. temperature)

Question 15

What do effectors do? Give examples.

Answer 15

• responsible for body responses
• muscles (smooth, striated, cardiac)
• glands

Question 16

What do signals do? Give examples.

Answer 16

• Allow components to communicate
• Input signal is from a receptor to an integrating centre
• Output signal is from an integrating center to an effector
• Signals are chemical messages or are sent via neurons

Question 17

Describe a negative feedback loop.

Answer 17

• set point (normal blood glucose)
• change in regulated variable (increased blood glucose)
• integrating centre (beta cells of pancreas): increased signals to effectors
• effectors (cells throughout the body): response/decreased blood glucose
• negative feedback
• change in regulated variable (increased blood glucose)
• set point (normal blood glucose)