Chap 11: Homeostasis

Question 1

Define homeostasis

Answer 1

Homeostasis is maintenance of a relatively constant internal environment within a narrow range in an organism even when external environment changes significantly

Question 2

What are some of the principles of homeostasis ? (4)

Answer 2

Stimulus is a change for normal conditions in internal environment
Receptors detect stimulus
Corrective mechanism brings abt reverse effect of stimulus
Feedback signals to the receptors that conditions has been restored to normal

Question 3

3 main parts of the human skin

Answer 3

Epidermis
Dermis
Subcutaneous ( fatty tissue )

Question 4

What are the 3 layers of the epidermis

Answer 4

Cornified
Granular
Malpighian

Question 5

What is the cornified layer made up of ?

Answer 5

Dead dry cells with keratin deposits

Question 6

Function of the cornified layer (3)

Answer 6

A) prevent uncontrolled water loss by evaporation
B) protective layer which prevents mechanical injury
C) prevents entry of microorganism into body

Question 7

What is the granular layer made up of ?

Answer 7

Living cells which slowly move upwards, eventually drying and dying to form the cornified layer

Question 8

What is the malpighian layer made up of ?

Answer 8

Consists of actively dividing cells that contain melanin

Question 9

Difference between sweat and sebaceous glands (2)

Answer 9

Sebaceous glands secrete sebum while sweat glands secrete sweat
Sebaceous glands are much larger than sweat glands

Question 10

Describe vasodilation

Answer 10

Arterioles in skin dilate
Shunt vessel constricts
More blood flows to the surface of the skin
Greater heat loss

Question 11

How does sweat cool you down

Answer 11

When sweat evaporates, it removes latent heat of vaporisation which cools the person down

Question 12

What is shivering

Answer 12

Reflex contraction of muscles which generates heat, increasing the body’s temp