week 1 sem 2 Flashcards
What is the Integumentary system?
skin/ cutaneaous membrane
largest body organ (7% of a total body weight)
Epidermis
made of layers of closely packed epithelial cells filled with keratin.
functions= protection/ vit D absorbtion
Dermis functions and characteristics
made of dense, irregular connective tissue containing blood vessels, hair
follicles, sweat glands, and other structures.
contains sensory neurons
functions = protection , thermoregulation sensation, excretion
Hypodermis,
below the dermis is mainly loose
connective and fatty tissues.
functions= thermoregulation, connection to muscles, blood resevoir
Epidermal cells
90% of epidermal cells are keratinocytes; arranged in 4-5 layers/strata.
* Produce keratin (tough, protective protein) and lamellar granules (water-proofing and
preventing microbe entry)
* Melanocytes produce pigments: melanin and carotene.
* Transfer melanin to keratinocytes.
* Protection of nuclear DNA from UV light damage.
* Langerhans cells detect pathogens and activate an immune response.
* Merkel cells (in basal layer) detect sensations of touch.
epidermis classification
keratinised, stratified, squamous epithelium.
thick skin
Thick skin found on
soles of feet, palms
and fingers has 5 layers not 4
* Contains stratum
lucidum + thicker
stratum granulosum
and corneum.
Dermis cells
- Fibroblasts: connective tissue building cells.
- Macrophages: phagocytes.
- Adipose cells: storage of lipids and lipid-soluble vitamins.
integrementary system functions
- regulate body temp
- storage
- Detects cutaneous sensations via sensory receptors
- Protects body from external environment
- Synthesis of Vitamin D3
- Excretes and absorbs substances
Describe the functions of accessory structures of the skin- hhair
Protect from UV damage
Important as sensory receptors
Describe the functions of accessory structures of the skin- sweat glands
Apocrine- Secrete sweat into hair follicles; odour since bacteria use it for nutrition.
Merocrine- Cools skin surface to reduce body temperature; excrete water, electrolytes and some drug metabolites; dilutes harmful chemicals on skin; discourages microbial growth by flushing off skin or via dermcidin.
Describe the functions of accessory structures of the skin- nails
Protects exposed/distal tips of digits.
Helps digit withstand distortion/counter pressure when subjected to mechanical stress.
Allows manipulation and grip of small objects.
Allows scratching and grooming of the body.
Describe the functions of accessory structures of the skin- Sebaceous glands
Inhibits bacterial growth; lubricates and protects keratin of the hair shaft.
Describe the functions of accessory structures of the skin- skin colour
Melanocytes increase pigment production in response to sun exposure, but too slowly to prevent sunburn
Describe the functions of accessory structures of the skin- hameoglobin
Skin is easily observed and can aid diagnosis of body conditions.
Discuss the functions of the main types of receptors in skin- Nociceptors
Respond to extremes of temperature, dissolved chemicals including those released by damaged cells, physical damage, infection, inflammation, ischaemia.
therefore tell the brain that damage has occurred to body cells
Discuss the functions of the main types of receptors in skin- Thermoreceptors
Free nerve endings in dermis
Very active while temperature changing but adapt quickly.
Discuss the functions of the main types of receptors in skin- Mechanoreceptors
Sensitive to stimuli which distort cell membranes
Free nerve endings sensitive to touch & pressure between epidermal cells.
Discuss the functions of the main types of receptors in skin- Epidermal mechanoreceptors
In areas of skin without hair.
Touch/compression à chemical release à activation of sensory neuron.
Extremely sensitive due to very small receptive field.
effects of aging on the integumentary system
- Epidermis thins
- Dendritic/Langerhans cell number drops to 50% of that at age 21 – increased risk of skin infection due to this macrophage cell loss.
- Vitamin D3 production drops by 75%-> increase risk of fracture
- Melanocyte activity drops – paler skin and whiter hair. Increased risk of sunburn.
- Gland secretion drops
- Blood flow to skin drops
- Dermis thins;
- Sex hormone levels drop
- Skin repairs up to 50% slower