the integumentary system anatomy & physiology chapter 4
TRANSCRIPT
The Integumentary System
Anatomy & PhysiologyChapter 4
Classification of Body Membranes
Epithelial Connective Tissue
1. cutaneous membranes
◦ skin
2. mucous membranes◦ covers body cavities
that open to exterior◦ mucosa
3. serous membranes◦ serosa◦ covers ventral
cavities & organs in them
◦ visceral & parietal peritoneum
1. synovial membrane
◦ no epithelial cells◦ made of areolar CT◦ line capsules
surrounding synovial joints, tendon sheaths & bursae
Includes:◦ Skin◦ Nails◦ Hair◦ Sweat & Oil Glands
Integumentary System
Functions: protection body temperature homeostasis excretion of urea& uric acid part of vitamin D synthesis
Integumentary System
of deep tissues from mechanical damage◦ physical barrier by keratin (toughens skin)◦ contains pressure receptors: send sensory
message to CNS; heat & cold receptors CNS
from chemical damage◦ skin is relatively impermeable (keratin)◦ contains pain receptors CNS
from bacterial invasion◦ skin secretions are acidic so inhibit bacterial
growth; phagocytes in skin ingest invaders from UV radiation
◦ melanin made by melanocytes in skin protects nuclei
Protection
dessication◦ keratin & other substances provide
waterproofing body temperature homeostasis
◦ when body overheated blood flow to skin increases & some heat radiates off body, sweating
◦ when body cold less blood flows to skin, more to trunk, goose bumps
Functions of Skin
excretory function: sweat contains urea, uric acid (breakdown products of proteins)
helps in synthesis of Vitamin D◦ sunlight on skin activates conversion of
pre-vitamin D vitamin D
Functions of Skin-2
Vitamin D
made of 2 kinds of tissues1. Epidermis2. Dermis
Structure of the Skin
made of stratified squamous epithelium
some keratinized, some not avascular Cells:
◦Keratinocytes majority of cells make keratin
◦Melanocytes◦Langerhans Cells Immune System
Epidermis
1. stratum basale◦ deepest layer◦ constantly undergoing cell division/ cells
pushed upward2. stratum spinosum3. stratum granulosum4. stratum lucidum (only in thick skin)
◦ clear, flatter, more keratin5. stratum corneum (cornified =
keratinized)◦ outermost layer/ 20-30 dead cells thick
Epidermal Layers
dead cells flake off steadily continually being replaced by cells gradually pushing up from the stratum basale
Stratum Corneum
pigment◦ (yellow to brown to black)
produced by melanocytes◦ most are in stratum basale
cells stimulated to make more melanin when skin exposed to sunlight◦ shields DNA from damaging effects of UV
radiationfreckles & moles: seen where melanin
concentrated in 1 spot
Melanin
causes elastic fibers to clump leathery skin
depresses immune system UV radiation damages DNA skin
cancer
Excessive Sun Exposure
a strong, stretchy envelope that helps to hold the body together◦ leather is the dermis of whatever animal it
was made from made of dense CT 2 regions:1. Papillary2. Reticular
Dermis
upper dermis dermal papillae: uneven projections
into lower epidermis that contain:1. capillaries2. pain receptors3. touch receptors:
Meissner’sCorpuscles4. in thick skin: form ridges
(fingerprints) that improve gripping ability
Dermis: Papillary Layer
deepest skin layer Contains:1. sweat & oil glands, hair follicles, blood
vessels2. Pacinian corpuscles (deep touch
receptors)3. many phagocytes4. fibers: elastic: give young skin elasticity collagen: make dermis tough&
keep skin hydrated by binding to water
Dermis: Reticular Layer
Skin plays major role in maintaining homeostasis of temperature:
Overheated:◦ Blood vessels in dermis dilate increases
blood flow to skin heat radiates off body Hypothermic:
◦ Blood vessels in skin constrict decreases blood flow to skin less heat loss thru skin
Body Temperature Homeostasis
aka bedsores due to extended restriction of normal
blood supply to skin
Decubitus Ulcers
3 pigments contribute to skin color:1. Melanin
◦ amount & kind (yellow black)
2. Carotene◦ orange – yellow pigment◦ stratum corneum & subcutaneous layers
3. Hemoglobin◦ amount O2 bound to it in RBCs in dermal
blood vessels◦ has greater affect in light skinned people
Skin Color
cyanosis: blue hue to skin; due to poorly oxygenated blood
erythema: redness, due to increased blood flow (infection, inflammation); burn, HT, blushing
pallor: paleness, due to emotions, anemia, low BP, decreased blood flow
jaundice: yellow; usually from liver disease (not clearing bilirubin)
hematomas: bruising (bleeding under skin)
Skin Color in Sickness & in Health
Glands: all are exocrine glands (secrete
product thru ducts) secrete their product to skin 2 groups:1. Sebaceous glands2. Sweat glands
Appendages of the Skin
are oil glands all over skin except palms& soles ducts mostly empty onto hair follicle
rest onto skin surface
Sebaceous Glands
sebum: product secreted by sebaceous gland◦ made of oils & fragmented cells and
antibacterials◦ function: lubricant’ keeps skin soft & keeps
hair from getting brittle◦ increase activity during puberty (reason
skin becomes oilier)
Sebaceous Glands
if ducts become blocked whitehead forms material in it oxidizes & dries blackhead
Acne: active infection of sebaceous glands, mild to severe causing permanent scarring
Seborrhea: cradle cap; overactivity of sebaceous glands pink raised lesions yellow to brown crust
Sebaceous Glands Gone Bad
SEBACEOUS GLANDS
ACNE SEBORRHEA
also known as sudoriferous glands all over skin 2 types:1. Eccrine sweat glands2. Apocrine sweat glands
Sweat Glands
all over body produce sweat
◦clear ◦pH 4 – 6 (being acidic bacteriostatic)
◦mainly water (+ NaCl, NH3, urea, uric acid, & lactic acid)
Eccrine Sweat Glands
typically sweat released from duct thru pore (different from facial “pores”; those are openings of hair follicles)
Eccrine Glands
important part of body’s heat-regulating equipment
+ nerve endings to cause sweat to be released whenever external temperature or body temperature is high
when water in sweat evaporates it cools body
important to keep body temperature w/in few degrees of 37 ◦C or it malfunctions
Eccrine Sweat Glands
mostly in axilla & genital areas ducts empty onto hair follicles secretions: fatty acids, proteins, +what is in eccrine sweat
if colonized with bacteria will have odor, otherwise odorless
begin to function during puberty (stimulated by androgens)
Apocrine Sweat Glands