Integumentary System Flashcards

1
Q

What are the functions of the skin?

A

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

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2
Q

Wha is keratin?

A

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

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3
Q

Where is keratin synthesised?

A

Keratinocytes

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4
Q

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

A

Soft keratin- elastic e.g. skin

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

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5
Q

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

A

Sebaceous - secrete sebum (oil)

Sweat glands

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6
Q

What is sebum composed of?

A

Lipids and dead epithelial cells

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7
Q

What is the function of sebum?

A

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

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8
Q

How is sebum released onto the skin?

A

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

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9
Q

What regulates the secretion of sebum?

A

Steroid hormones

Activated in puberty

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10
Q

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

A

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

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11
Q

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

A

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

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12
Q

Preputial glands are found in pigs. What are they?

A

Glands on the foreskin

Initiates mating by releasing scent

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13
Q

What are infraorbital pouches and interdigital glands found in sheep?

A

Speicalised glands used for territorial marking

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14
Q

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

A

Release fatty secretion during defaecation

Territorial (similar to skunk)

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15
Q

What is melanin? How is it formed?

A

Pigment found in skin

Oxidation of tyrosine

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16
Q

What is an albino?

A

Someone with no melanin in skin

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17
Q

What is the function of melanin?

A

Cammoflauge, communication, absorption of UV to prevent cells

18
Q

Where is melanin produced?

A

Melanocytes - in vesicles

In basal layer of epidermis

19
Q

How does melanin pigment hair and skin?

A

Vesicles move from melanocytes to keritinocytes

Keritinocytes reach skin surface

20
Q

What are the two types of pigment (melanin)?

A

Eumelanins (black/brown)

Pheomelanins (yellow/red)

21
Q

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

A

UV light

Melanocyte stimulating hormones in the pituitary gland

22
Q

What happens if no MSH is produced?

A

Eumelanin is produced

23
Q

What are sources of vitamin D?

A

Sunlight
Fish
Egg yolk
Colostrum

24
Q

What is the equation of vitamin D synthesis?

A

7-DHC —> Cholecalciferol (D3)

By UV light

25
Why are animals with a thick coat more at risk of developing rickets?
Thick coat blocks UV, prevents vitamin D synthesis
26
What do nociceptors in the skin detect?
Intense pain (often harmful)
27
What is a graded potential?
A change in the size of a potential, not all or nothing
28
What are the 4 sensory cells found in the skin? (From top- bottom, note deeper cells have better blood supply)
Merkel cells Meissner corpuscle Ruffini corpuscle Pacinian corpuslce
29
How do slow tonic receptors fire when activated and throughout the duration of a stimulus?
Rapidly when activated | Slow fire during stimulus
30
How do fast phasic receptors fire if the strength of a stimulus is constant?
Fire once, stop firing
31
Where are cold and warm receptors found?
Cold receptors in epidermis | Warm receptors in dermis
32
Where is thermoregulation controlled?
Hypothalamus
33
When subject to extreme temperatures, which other receptors are stimulated?
Pain receptors
34
What are pyrogens?
A chemical produced by bacteria which causes fever
35
Why do we get fevers? Why do we shiver?
Pyrogens cause the temperature ‘set point’ of hypothalamus to increase Thermoregulatory centre interprets the normal body temperature as cold, so causes shivering
36
Which nervous system causes piloerection?
Sympathetic NS
37
There are 2 methods of thermogenesis. Non-shivering and shivering. What is shivering?
Antagonistic muscles contract simultaneously
38
What is non-shivering thermogenesis?
Increasing the basal metabolic rate - higher secretions from thyroid, oxidation of fatty acids in brown adipose tissue
39
What is brown fat used for? In which animals is it found in?
Burn energy for heat (lots of mitochondria) | neonates, hibernators and small amount in adult
40
What is the dermis (corium) composed of?
Tough connective tissue Cells Glands Vessels and nerves
41
The subcutaneous layer (hyperdermis) is not part of the skin. What is it composed of?
Fat | Connective Tissue