Integumentary System

Question 1

What are the functions of the skin?

Answer 1

Protection from mechanical/chemical injury, microorganisms, UV, dehydration
Thermoregulation and sensory information
Vitamin D synthesis
Storage of fat and water

Question 2

Wha is keratin?

Answer 2

A fibrous structural protein found in epidermis, hair, nails feather etc

Question 3

Where is keratin synthesised?

Answer 3

Keratinocytes

Question 4

What are the 2 types of keratin? What are their properties? Give an example

Answer 4

Soft keratin- elastic e.g. skin

Hard keratin - contains more sulfur, less elastic and more resistant to degradation e.g. nails/hoof

Question 5

What are the two types of glands found in the dermis of the skin?

Answer 5

Sebaceous - secrete sebum (oil)

Sweat glands

Question 6

What is sebum composed of?

Answer 6

Lipids and dead epithelial cells

Question 7

What is the function of sebum?

Answer 7

Oil hairs, slow water loss, spread sweat, lubricate skin, inhibit bacterial growth. Goats use for territorial marking and attraction

Question 8

How is sebum released onto the skin?

Answer 8

During pilorection (hair stands up)
Squeezes muscles in the dermis
Releases sebum onto hair

Question 9

What regulates the secretion of sebum?

Answer 9

Steroid hormones

Activated in puberty

Question 10

What are the two types of sweat glands and what is the difference between them?

Answer 10

Apocrine - found in domestic species. Oilier, sympathetic adrenergic receptors
Ecrine - found in primates. Less oiler, sympathetic cholinergic receptors. Watery NaCl
Both contain myoepithelial cells

Question 11

Which species have few sweat glands? How do they compensate for reaching their higher critical temperature?

Answer 11

Cats
Dogs
Pigs
Panting - water loss from nasal turbines. Wallowing

Question 12

Preputial glands are found in pigs. What are they?

Answer 12

Glands on the foreskin

Initiates mating by releasing scent

Question 13

What are infraorbital pouches and interdigital glands found in sheep?

Answer 13

Speicalised glands used for territorial marking

Question 14

What are the function of anal glands? (Tail glands also found in cats/dogs for territory marking)

Answer 14

Release fatty secretion during defaecation

Territorial (similar to skunk)

Question 15

What is melanin? How is it formed?

Answer 15

Pigment found in skin

Oxidation of tyrosine

Question 16

What is an albino?

Answer 16

Someone with no melanin in skin

Question 17

What is the function of melanin?

Answer 17

Cammoflauge, communication, absorption of UV to prevent cells

Question 18

Where is melanin produced?

Answer 18

Melanocytes - in vesicles

In basal layer of epidermis

Question 19

How does melanin pigment hair and skin?

Answer 19

Vesicles move from melanocytes to keritinocytes

Keritinocytes reach skin surface

Question 20

What are the two types of pigment (melanin)?

Answer 20

Eumelanins (black/brown)

Pheomelanins (yellow/red)

Question 21

Melanin is synthesised in melanocytes. What stimulates and regulates this?

Answer 21

UV light

Melanocyte stimulating hormones in the pituitary gland

Question 22

What happens if no MSH is produced?

Answer 22

Eumelanin is produced

Question 23

What are sources of vitamin D?

Answer 23

Sunlight
Fish
Egg yolk
Colostrum

Question 24

What is the equation of vitamin D synthesis?

Answer 24

7-DHC —> Cholecalciferol (D3)

By UV light

Question 25

Why are animals with a thick coat more at risk of developing rickets?

Answer 25

Thick coat blocks UV, prevents vitamin D synthesis

Question 26

What do nociceptors in the skin detect?

Answer 26

Intense pain (often harmful)

Question 27

What is a graded potential?

Answer 27

A change in the size of a potential, not all or nothing

Question 28

What are the 4 sensory cells found in the skin? (From top- bottom, note deeper cells have better blood supply)

Answer 28

Merkel cells
Meissner corpuscle
Ruffini corpuscle
Pacinian corpuslce

Question 29

How do slow tonic receptors fire when activated and throughout the duration of a stimulus?

Answer 29

Rapidly when activated

Slow fire during stimulus

Question 30

How do fast phasic receptors fire if the strength of a stimulus is constant?

Answer 30

Fire once, stop firing

Question 31

Where are cold and warm receptors found?

Answer 31

Cold receptors in epidermis

Warm receptors in dermis

Question 32

Where is thermoregulation controlled?

Answer 32

Hypothalamus

Question 33

When subject to extreme temperatures, which other receptors are stimulated?

Answer 33

Pain receptors

Question 34

What are pyrogens?

Answer 34

A chemical produced by bacteria which causes fever

Question 35

Why do we get fevers? Why do we shiver?

Answer 35

Pyrogens cause the temperature ‘set point’ of hypothalamus to increase
Thermoregulatory centre interprets the normal body temperature as cold, so causes shivering

Question 36

Which nervous system causes piloerection?

Answer 36

Sympathetic NS

Question 37

There are 2 methods of thermogenesis. Non-shivering and shivering. What is shivering?

Answer 37

Antagonistic muscles contract simultaneously

Question 38

What is non-shivering thermogenesis?

Answer 38

Increasing the basal metabolic rate - higher secretions from thyroid, oxidation of fatty acids in brown adipose tissue

Question 39

What is brown fat used for? In which animals is it found in?

Answer 39

Burn energy for heat (lots of mitochondria)

neonates, hibernators and small amount in adult

Question 40

What is the dermis (corium) composed of?

Answer 40

Tough connective tissue
Cells
Glands
Vessels and nerves

Question 41

The subcutaneous layer (hyperdermis) is not part of the skin. What is it composed of?

Answer 41

Fat

Connective Tissue