integumentary system _______________ membrane (skin) – our largest organ accounts for _____ of...
TRANSCRIPT
Integumentary System
• _______________ membrane (skin) – our largest organ
• Accounts for _____ of body weight• Divided into two distinct layers
•__________•__________•Accessory structures
• Subcutaneous layer (_______________)
Functions Of The Integument
• _____________ and insulates deeper organs
• _____________ body from abrasion, trauma, chemicals, pathogens, temperature extremes and UV rays
• ___________ and ___________
• Contains ____________________associated with nerve endings
• Synthesis and storage of nutrients (______________)
Integumentary Structures
• Components of the Integumentary System
Figure 5-1
Skin Structures
The Epidermis- Four Main Cell Types • _____________ - found in
basal layer, manufacture and secrete pigment
• ______________ - basal layer, attached to sensory nerve endings
• _______________ – Arise from deepest layer of epidermis to stratum spinosum• Produce __________ – a tough
fibrous protein• Produce _____________ and
__________• Keratinocytes are dead at skin's
surface• __________________ - stratum
spinosum, part of immune system macrophage-like
The Epidermis• Stratified squamous epithelium
• Several distinct cell layers• ________________—five layers on palms and soles• ________________—four layers on rest of body
Layers of The Epidermis
• Stratum ____________• Most
_______________ layer
• Dead, flattened (squamous) cells
• Abundant keratin - __________ (cornified) tough, water-resistant protein
• Protects skin against abrasion and penetration
• Stratum ___________ (clear layer)• Occurs only in thick
skin – palms and soles
• Composed of a few rows of flat, dead keratinocytes
Layers of The Epidermis• Stratum ___________ (grainy
layer)• Consists of keratinocytes
• Tonofilaments• Keratohyaline granules
– help form keratin• Lamellated granules –
contain a waterproofing glycolipid
• Stratum ___________ (spiny layer)• “Spiny” appearance caused
by artifacts of histological preparation
• Contains thick bundles of intermediate filaments (tonofilaments)
• Resist ____________• Contain protein
_____________ • Contains _____________
Langerhans cells
Layers of the Epidermis
• Stratum ___________• __________ layer of
epidermis• Attached to underlying
dermis• _____________ actively
divide• __________– associated
with sensory nerve ending• __________ – secrete the
pigment melanin
Epidermal Cells and Layers of the Epidermis
Figure 5.3
Sources of Skin Color
• Melanocytes• Make ________from tyrosine• Melanin provides _____
protection• Gives ____________ to
brown-black color
• Carotene• Contributes
_________________• Provided from _____ (carrots
and tomatoes)
• Hemoglobin - blood pigment• Caucasian skin contains
little ___________• Allows __________ color
of blood to show through
Dermis• _____________ major layer of the skin• Provides mechanical strength, ___________, and
protection for underlying tissues• ___________________and contains a variety of
sensory receptors that provide information about the external environment
• Two layers• ________________– includes dermal papillae• ______________- deeper layer – 80% of thickness of
dermis
• _________________- creases on palms
Layers of the Dermis• Papillary layer
• Underlies epidermis• Named for dermal papillae• Aerolar __________________• Supports, nourishes epidermis• Provides sensory nerves,
lymphatics, and ____________
• Reticular layer• Tough, dense, fibrous layer• Dense __________________• Collagen fibers - limit ________• Elastic fibers - provide __________• Blends into papillary layer (above)• Blends into _______________ layer
(below)
Dermal Components• Epidermal accessory
organs
• Cells of connective ________________
• Communication with other organ systems• _______________• ______________• _____________
• Sensation• Control of blood flow
and secretion
Subcutaneous Layer - Hypodermis• Composed ____________________________________________
• ______________ skin position• Loosely attached to dermis• Loosely attached to muscle
• Contains _________________cells• Provides ________________• ______________ underlying organs
• Safely receives hypodermic needles
Hair
• ___________ strands of dead keratinized cells produced by hair follicles
• Contains hard ___________ which is tougher and more durable than soft keratin of the skin
• Chief parts of a hair• ___________ – imbedded
in the skin• ____________ – projects
above skin's surface
Hair
• Hair Shaft organized into three concentric layers• ___________ – central core • __________ – surrounds medulla• ___________ – outermost layer
• Pigmented by melanocytes at the base of the hair
Cross Section of a Hair
Figure 5.7a, b
Hair Follicle• ____________extending
from the epidermal surface into the dermis
• Deep end is expanded forming _____________
• __________ - nipple-shaped indentation with blood vessels and nerves
• _________ - germinal layer of cells (actively dividing cells) right above the papilla
• A knot of _____________ (a root hair plexus) wraps around each hair bulb
• _______________stimulates these endings, hence our hairs act as sensitive touch receptors
• ____________muscle - bundle of smooth muscle contracts to make hair stand erect
Longitudinal Section of Follicle
Figure 5.7c, d
Hair Follicles
Hair Function and Distribution• Functions of hair include:
• Helping to maintain _____________
• Alerting the body _________________on the skin
• Guarding the scalp against ____________, heat loss, and sunlight
• Hair is distributed over the entire skin surface except• __________,__________,________
• Nipples and portions of the external genitalia
Sebaceous Glands (oil glands)• Occur over entire body - Except palms and soles• Simple ____________________
• _______________ secretion – entire cell breaks up to form secretion• Secretes an oily substance called _________• Most are associated with a _____________
• Functions of sebum• Softens and lubricates hair and skin• ___________________• ___________________
Sweat (Sudoriferous) Glands
• Two types:• __________________
• Most abundant sweat gland• “True sweat”
• 99% water with some salts• Contains traces of
metabolic wastes ~ 2% urea
• Role in _________________
• Widely present in skin (up to 500/cm2)
• ______________• Odorous secretion • Absent before ___________• Present in axillary, areolar,
anal and genital areas
Eccrine (Merocrine) Gland
Figure 5.10b
Nails• _____________ modification of epidermis made of hard
keratin• Parts of the nail
• Free edge• Body - dense mass of _______________• Root• Nail folds• _____________– cuticle
Skin Injury and Repair
Four Stages in Skin Healing• ______________
• Blood flow increases• Phagocytes attracted
• ______________• Cell division and
migration• ___________ formation
Bleeding occurs at the site of injury immediately after the injury, and mast cells in the region trigger an inflammatory response.
Epidermis
Dermis
After several hours, a scab has formed and cells of the stratum germinativum are migrating along the edges of the wound. Phagocytic cells are removing debris, and more of these cells are arriving with the enhanced circulationin the area. Clotting around the edgesof the affected area partially isolatesthe region.
Sweat gland
Scab
Macrophagesand
fibroblasts
Migratoryepithelialcells
Granulationtissue
Skin Injury and Repair
One week after the injury, the scab has been undermined by epidermal cells migrating over the meshwork produced by fibroblast activity. Phagocytic activity around the site has almost ended, and the fibrin clot is disintegrating.
Fibroblasts
After several weeks, the scab has been shed, and the epidermis is complete. A shallow depression marks the injury site, but fibroblasts in the dermis continue to create scar tissue that will gradually elevate the overlying epidermis.
Scartissue
Skin Injury and Repair
Skin Injury and Repair
Table 5-1
Aging of the Skin
• Major Age-Related Changes•_____ and infection increase• Immune cells ___________•Sun protection diminishes•Skin becomes dry, ________•Hair thins, ________•Sagging, _________ occur•Heat loss ___________•Repair ________
Effects of UV Radiation• Beneficial effect - activates synthesis of
vitamin D3
• Harmful effects• ___________• Wrinkles, ___________• ___________________• ___________________
Types and Growth of Hair
_________ hairs•Body hairs of women and children
_________ hairs•Hair of scalp•Axillary and pubic area (at puberty)
_______________________•Due to aging•Male pattern baldness
Burns
Classified by severity•_______________– only upper epidermis
is damaged•_______________– upper part of dermis is
also damaged• _____________ appear• Skin heals with little scarring
•___________________• Consume ______________ of skin• Burned area appears white, red, or
_______________
Estimating Burns Using the Rule of Nines
Figure 5.11a
Skin Cancer
_______________________•Least malignant and ________________
_______________________•Arises from ________________ of stratum
spinosum
________________•A cancer of _________________ •The most dangerous type of skin cancer
Skin Cancer
Squamous cell carcinoma
Figure 5.12Melanoma
Squamous cell carcinoma
Basal cell carcinoma
The Skin Throughout Life
______________•Develops from embryonic ectoderm
________________•Develop from mesoderm
_________________•Develop from neural crest cells
The Skin Throughout Life
Fetal skin•Well formed after the ________________•At 5-6 months
• The fetus is covered with __________ (downy hairs)
•Fetal sebaceous glands produce ___________________
The Skin Throughout Life
Middle to old age•Skin thins and becomes _____________•Shows ____________ effects of
environmental damage•Skin ______________ become more
common