Integumentary System Flashcards
What are the functions of the skin?
Protection from mechanical/chemical injury, microorganisms, UV, dehydration
Thermoregulation and sensory information
Vitamin D synthesis
Storage of fat and water
Wha is keratin?
A fibrous structural protein found in epidermis, hair, nails feather etc
Where is keratin synthesised?
Keratinocytes
What are the 2 types of keratin? What are their properties? Give an example
Soft keratin- elastic e.g. skin
Hard keratin - contains more sulfur, less elastic and more resistant to degradation e.g. nails/hoof
What are the two types of glands found in the dermis of the skin?
Sebaceous - secrete sebum (oil)
Sweat glands
What is sebum composed of?
Lipids and dead epithelial cells
What is the function of sebum?
Oil hairs, slow water loss, spread sweat, lubricate skin, inhibit bacterial growth. Goats use for territorial marking and attraction
How is sebum released onto the skin?
During pilorection (hair stands up)
Squeezes muscles in the dermis
Releases sebum onto hair
What regulates the secretion of sebum?
Steroid hormones
Activated in puberty
What are the two types of sweat glands and what is the difference between them?
Apocrine - found in domestic species. Oilier, sympathetic adrenergic receptors
Ecrine - found in primates. Less oiler, sympathetic cholinergic receptors. Watery NaCl
Both contain myoepithelial cells
Which species have few sweat glands? How do they compensate for reaching their higher critical temperature?
Cats
Dogs
Pigs
Panting - water loss from nasal turbines. Wallowing
Preputial glands are found in pigs. What are they?
Glands on the foreskin
Initiates mating by releasing scent
What are infraorbital pouches and interdigital glands found in sheep?
Speicalised glands used for territorial marking
What are the function of anal glands? (Tail glands also found in cats/dogs for territory marking)
Release fatty secretion during defaecation
Territorial (similar to skunk)
What is melanin? How is it formed?
Pigment found in skin
Oxidation of tyrosine
What is an albino?
Someone with no melanin in skin
What is the function of melanin?
Cammoflauge, communication, absorption of UV to prevent cells
Where is melanin produced?
Melanocytes - in vesicles
In basal layer of epidermis
How does melanin pigment hair and skin?
Vesicles move from melanocytes to keritinocytes
Keritinocytes reach skin surface
What are the two types of pigment (melanin)?
Eumelanins (black/brown)
Pheomelanins (yellow/red)
Melanin is synthesised in melanocytes. What stimulates and regulates this?
UV light
Melanocyte stimulating hormones in the pituitary gland
What happens if no MSH is produced?
Eumelanin is produced
What are sources of vitamin D?
Sunlight
Fish
Egg yolk
Colostrum
What is the equation of vitamin D synthesis?
7-DHC —> Cholecalciferol (D3)
By UV light
Why are animals with a thick coat more at risk of developing rickets?
Thick coat blocks UV, prevents vitamin D synthesis
What do nociceptors in the skin detect?
Intense pain (often harmful)
What is a graded potential?
A change in the size of a potential, not all or nothing
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
How do slow tonic receptors fire when activated and throughout the duration of a stimulus?
Rapidly when activated
Slow fire during stimulus
How do fast phasic receptors fire if the strength of a stimulus is constant?
Fire once, stop firing
Where are cold and warm receptors found?
Cold receptors in epidermis
Warm receptors in dermis
Where is thermoregulation controlled?
Hypothalamus
When subject to extreme temperatures, which other receptors are stimulated?
Pain receptors
What are pyrogens?
A chemical produced by bacteria which causes fever
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
Which nervous system causes piloerection?
Sympathetic NS
There are 2 methods of thermogenesis. Non-shivering and shivering. What is shivering?
Antagonistic muscles contract simultaneously
What is non-shivering thermogenesis?
Increasing the basal metabolic rate - higher secretions from thyroid, oxidation of fatty acids in brown adipose tissue
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
What is the dermis (corium) composed of?
Tough connective tissue
Cells
Glands
Vessels and nerves
The subcutaneous layer (hyperdermis) is not part of the skin. What is it composed of?
Fat
Connective Tissue
