Integumentary System Flashcards
What are the functions of skin?
Protection Regulation Excretion Perception Storage
What does the skin provide protection from?
Mechanical damage Chemical damage Bacterial damage Thermal damage UV radiation Desiccation
How does skin protect from Desiccation?
(pathogen invasion)
keratinised layer becomes thickened where necessary
How does skin protect from Ionising radiation?
Menalin produced by melanocytes (in the epidermis) which penetrates surrounding cells and absorbs UV light
How does skin protect from Predation?
Hair and skin pigment acts as camouflage
hair or fur is raised in aggression
claws nails and horns to attack
What is the function of the integumentary system?
Food Storage- accumulation of subcutaneous fat
Production of Vitamin D which is important for bone formation, neuromuscular function and cell regeneration
What is skin colour determined by?
Melanin- yellow brown of black
Carotene- orange pigment from veg
Haemoglobin- red colouring from RBC’S
What are the layers of skin
Epidermis- stratified squamous epithelium that withstands wear and tear
Dermis- thicker than epidermis
Hypodermis- anchors skin to organs
What is the Epidermis made up of?
Stratum Corneum- outermost layer (tough and dry with old and dead cells)
Stratum Basale- innermost layer which forms the germinal layer and is in constant mitotic division. The cells move towards the surface and may produce keratin
What is the Dermis made up of?
Fibrous protein network- contains collagen and elastin
Blood vessels- nourish and heat transfer
Sensory nerve endings- touch, pressure and temperature changes
Lymphatics
Bone-may form in the dermis
What are the layers of the Dermis?
Papillary layer 1/5 of dermis- connective tissue and elastic fibres with projections called dermal papillae (pain receptors- nociceptors)
Reticular layer 4/5 of dermis- dense and irregular connective tissue, collagen and elastin. Contains blood vessels, glands, nerve receptors and adipose tissue
What is the Hypodermis?
layer of loose connective tissue that separates dermis from organs.
allows skin movement without tearing
contains adipose tissue for storage, padding and acts as a thermal insulator.
What are the four mechanoreceptors that are sensitive to external stimuli?
1.Meissner’s corpuscles (light touch)
encapsulated nerve endings encased by
stacked flattened discs just below epidermis
▪ esp. on fingertips, lips, nose, forehead (humans)
▪ least on soles of feet
2. Pacinian corpuscles (vibration and pressure)
Onion-like capsule located deep in the skin
3. Ruffini corpuscle (temperature, stretch, movement)
Branched fibres inside a cylindrical capsule
4. Merkel nerve endings (pressure and form)
Disc-shaped receptor near the border of epidermis and dermis
How does the skin regulate temperature?
homeotherms
cooling by the exocrine sudoriferous (sweat glands)
deep epidermal in-folding into the dermis
open to outer surface or into fair follicles
found over entire body surface
increase heat loss by vasodilation and relaxation of Arrector pili muscles
reduce heat loss by vasoconstriction and contraction of arrestor pili (also insulating fat and insulating fur)
What is the skin gland, Sudoriferous glands?
sweat gland mainly h2o k and NaCl horses sweat readily (latherin) pigs don't sweat secretions may contain pheromones
What is the skin gland, Sebaceous glands?
produce oily sebum which keeps the skin water resistant
arrestor pili contractions compress glands
empty into the hair follicle
Marking glands
- sheep- infraorbital, interdigital
- goats- horn glands
- pigs- carpal glands
What are the three types of skin glands ?
Merocrine (Eccrine)- exocytosis to pore- concentrated to soles of feet, palms and forehead- odourless
Apocrine- larger and deeper in skin eg; eyelids, genitals etc- bud secretions via plasma membran- odorous
Holocrine- sebaceous or sudoriferous glands- duct to pore- cell dies- odorous-
parallel to hair follicle before the muscle
What are the characteristics of hair?
grows from follicles
angle adjusted by contraction of arrestor muscles- thermoregulatorary function- used during fight or flight- 90 degrees
can be seasonal shedding which is triggered by photoperiod changes
What are the three main types of hairs?
Guard hairs- smooth outer coat
Wool hairs- undercoat- fine and curly- contains lanolin oils- produced commercially by sheep etc
Tactile hairs (vibrissae) (whiskers)- long and stiff which are common on the face, around the lips, eyes with special innervations used as probes.
What are skin modifications?
hoof, claws, nails horns and antlers feathers scales dermal bone perception organs
