Flashcards in Integument Deck (46):
What cells of the epidermis are responsible for producing pigment and colouration?
Which layer of the epidermis are they found?
What is the main cell type in the epidermal layers?
What is the name of the muscle which causes hair to become erect?
What are the two types of sweat glands?
Apocrine and eccrine
Which type of sweat gland is found in the footpad?
What epithelium does the epidermis consist of?
Keratinised stratified squamous
What do sudoriferous glands secrete?
Which cells are present in the outer cuticle of the hair shaft?
Flat keratinised cells
Which cells are present in the cortex of the hair shaft?
Dead cell layer
What cells are present in the medulla of a hair shaft?
Cuboidal or flat cells
What do sebaceous (oil) glands secrete?
What are the functions of sebum?
Retards water loss
Inhibits growth of certain bacteria
Helps spread sweat
How do androgens affect sebum secretion?
How does oestrogen affect sebum secretion?
What are the names of the two melanin pigments?
Eumelanins (black and brown colouration)
Pheomelanins (red and yellow colouration)
Give an example of soft keratin
Give an example of hard keratin
Nails, horn, hoof
What are the three receptor types in skin?
Mechanoreceptors (touch and pressure)
Nociceptors (intense stimuli-pain_
Which nervous system controls blood flow to the skin?
What is the difference between panting and sweating, in terms of what is lost from the body?
Sweating - loss of water and NaCl
Panting - loss of water
What does the epidermis originate from?
What does the dermis originate from?
Thickness of skin refers to relative thickness of which layer?
What are the 5 layers of the epidermis?
What processes occur in the epidermis?
Continuous proliferation of keratinocytes in basal layer
Migration, differentiation and keratinisation of keratinocytes
Squamous cells sloughed off at surface
How does the epidermis receive blood supply?
Nourished by diffusion from blood vessels in dermis
How does the dermis receive blood supply?
Contains blood vessels, lymphatic vessels, nerves, arteriovenous anastomoses
What is contained in the hypodermis?
Loose and irregular connective tissue
Large deposits of fat
What are the functions of hairs?
What epithelium covers the hair bulb?
Describe the cyclic activity of a hair
Telogen-hair is displaced distally and new hair matrix begins to form
Anagen-new hair matrix is established, renewed growth
Which specialised glands are present in pigs?
Preputial-opening of foreskin
Sexual attraction, initiates mating behaviour in sows
Which specialised glands are present in sheep?
Infraorbital pouch-territorial marking
Interdigital glands-produces a fatty secretion, marking of footprints to signal to others in flock
Which specialised glands are present in dogs?
Anal glands-release a fatty secretion during defaection, territorial marking
Tail gland-oval patch on dorsal tail, territorial marking, skin has sparser hair
How does melanin protect against sun damage?
Melanin is able to absorb UV radiation, protecting cells from UVB radiation damage
Where is MSH secreted?
If MSH receptors are not stimulated, what colour pigments are produced?
Melanin pigments are a derivative of which amino acid?
What causes the epidermis to be impermeable to water?
Stratum corneum and granular cell layer
Sebaceous gland secretion contributes to water resistance
Keratinocytes contain insoluble keratin and synthesise lipids
What makes hard keratin harder than soft keratin?
Contains more sulfar, less elastic, resistant to degradation
What is photosensitivity?
Abnormal reaction to sunlight due to accumulation of photosensitive compounds below the skin
Which are the two types of tonic, slow-adapting sensory cells?
Merkel cell and Ruffini corpuscle
Both located near skin's surface, sensitive to touch, pressure and duration
Which are the two types of phasic, fast-adapting sensory cells?
Meissner corpuscle-phasic receptor sensitive to fine touch, concentrated in hairless skin
Pacinian corpuscle-pressure-sensitive phasic receptor deep below skin in subcutaneous tissue
How do tonic receptors differ from phasic receptors?
Tonic receptors are slowly adapting, but respond for the duration of a stimulus. Fire rapidly when first activated then become slower. eg baroreceptors.
Phasic receptors are fast adapting. They rapidly adapt to a constant stimulus then turn off.
How does the brain locate and detect intensity of a stimulus?
Frequency of action potentials
Number of receptors stimulated
Different receptors have different thresholds