6 Functions of the Integumentary System

1. protection

2. body temperature regulation

3. cutaneous sensation

4. metabolic functions

5. blood reservoir

6. excretion

Protection

keratin: dehydration and waterproofing

bacterial invasion, sudden temp. changes, UV rays, underlying tissues

Body Temp. Regulation

prevents heat loss

sweating causes blood vessels to swell

Cutaneous Sensation

receptors for different senses:

touch, pain, pressure, temp

Metabolic Functions

synthesize vitamin D

UV rays produce cholesterol

Blood Reservoir

holds 5% of body's blood supply

Excretion

water, salts, organic compounds

5 Strata of Epidermis

1. Stratum basale

2. Stratum spinosum

3. Stratum granulosum

4. Stratum lucidum

5. Stratum corneum

Stratum Basale

base layer; deepest epidermal layer

single row of cells -- mostly keratinocytes

undergoes mytosis

Stratum Spinosum

prickly layer

8-10 layers thick

keratinocytes appear as "prickle cells" (desmosomes)

occassionally contains Langerhan cells

Stratum Granulosum

3-5 layers

flat cells

accumulates 2 types of granules (made of keratin and fills up cells)

1. keratohyaline -- forms keratin in upper layer

2. lamellated -- contain waterproofing glycolipid

Stratum Lucidum

thin, translucent later above granulosum

** only visible in THICK skin**

Stratum Corneum

"horny" layer

20-30 layers thick; 3/4 thickness

protects against penetration and abrasion

all cells dead

completely filled with keratin

waterproof

Subcutaneous

a.k.a.  hypodermis or superficial fascia

tissue just deep to the skin

consists of adipose tissue -- stores fat

anchors skin to muscle but loosely enough that the skin can freely slide over structures (areolar CT)

shock absorber and insulator

Epidermis

made up of keratinized stratified squamous epithelial tissue

4-5 layers

for waterproofing and hardening

Thick skin

v.s.

Thin skin

Thick:

5 layers

palms, fingertips, soles of feet

Thin:

4 layers

everywhere else

4 Cell Types found in Epidermis

1. keratinocytes -- 80-90%; produce keratin

2. melanocytes -- spider-shaped; synthesize melanin

3. Langerhans -- phagocytes; activate immune system

4. Merkel -- sensory receptor for touch/hair; present at epidermal/dermal junction

Melanin

formed from melanocytes

pigment shield that protects NUCLEUS from UV radiation

Dermis

made of dense irregular areolar CT

heavily embedded with fibers

supplied with nerve fibers and blood vessels

contains hair follicles, oil, and sweat glands

has 2 layers: papillary and reticular

Papillary

top layer of dermis (20%)

made of areolar CT

contains blood vessels, collagen, and elastic fibers

contains dermal papillae

contains Meissner's carpuscle --> touch

epidermal ridges help with gripping & give fingerprints

Dermal Papillae

little mountains in dermis that push into epidermis

frees more nerve endings --> pain

Reticular

thick bottom layer of dermis (80% thickness)

made of dense irregular CT

3 Pigments that Contribute to Skin Color

1. melanin -- made of tyrosine; made from melanocytes; yellow --> brown; increases when you tan

2. carotene -- found in orange plant products; yellow --> orange

3. hemoglobin -- projects pinkish hue of fair skin

Vitiligo

white blotches on skin

autoimmune disorder: body attacks melanocytes

Albino

lack melanin

don't have tyrosinase

tyrosine -X-> tyrosinase -X-> melanin

inherited

Suderiferous Glands

merocrine (eccrine) sweat glands

most abundant

regulates body temp

found everywhere EXCEPT lips, nipples, and parts of external genitialia

abundant on palms, soles of feet, & forehead

duct extends to open pore at skin surface

Sweat

consists of salt & water

pH: slightly acidic

kills off some bacteria

odorless --> gets odor from bacteria

Apocrine Sweat Glands

larger than eccrine glands

ducts empty into hair follicles

found in axillary and anogenital (starts at puberty)

Specialized Sweat Glands

1. Ceruminous glands -- secrete earwax (keep water out of ear)

2. Mammary glands -- secrete milk

Sebaceous Glands

oil gland

holocrine gland

found all over body EXCEPT for palms and soles of feet

secretes sebum - an oily secretion that softens and lubricates hair and skin, slows H2O loss from skin, and kills bacteria

Basal Cell Carcinoma

least malignant; most common

affects basal cells

cancer lesions appear on sun-exposed areas of face

cured by surgical excision

doesn't metastasize

Squamous Cell Carcinoma

arises from keratinocytes of stratum spinosum

lesions: reddened, small, rounded elevation

can metastasize

surgically removed

Melanoma

most dangerous; highly metastatistic; resistant to chemo

affects melanocytes

Diff. Types of Cartilage

1. Skeletal

2. Hyaline -- most abundant

3. Elastic -- flexible

4. Fibrocartilag - resistant to stretch

4 Classifications of Bone

1. long

2. short

3. flat

4. irregular

Long Bones

longer than wider

all limbs EXCEPT patella, wrist, ankle bones, and 3 bones of phalanges

Flat Bones

thin & flat

sternum, scapula, ribs, and most skull bones

Short Bones

roughly cube shaped; width ~ length

wrist and ankle bones

*special type: sesamoid -- forms in a tendon (patella)*

Irregular Bones

have irregular shapes

vertebrae, hip bones

5 Functions of Bones

1. Support

2. Protection

3. Movement -- muscles use bones as levers

4. Mineral & growth factor storage -- minerals: Ca & P; growth factor: insulin

5. Blood cell formation -- hematopoiesis

2 Bone Textures

1. Compact -- outer layer; thickest in shaft of bone (diaphysis)

2. Spongy -- internal honeycomb; found in ends of long bone (epiphysis)

Long Bone Anatomy

1. Diaphysis (shaft)

2. Epiphysis (end)

3. Metaphysis

Diaphysis

forms long axis of bone

surrounds medullary cavity (mostly fat filled)

- filled with fat/yellow bone

marrow in adults

- filled with red marrow

in children

Epiphysis

bone ends

joint surface covered with articular cartilage (hyaline) -- cushions, absorbs stress, protects

Epiphyseal Line/Plate

occurs between shaft and end

hyaline cartilage that grows during childhood to lengthen the bone

epiphyseal line appears when growth is complete

Metaphysis

Periosteum

membrane that covers the external surface of the bone (except for joint surfaces)

outer layer (fibrous) - dense irregular ct; made of collagen fibers; takes stress from all direction

inner layer (osteogenic) - consists of bone-forming cells, osteoblasts, and bone-destroying cells, osteoclasts; increases bone width

nutrient foramen - opening that allows nerve fibers, lymphatic vessels, and blood vessels to pass thru

3 Functions of Periosteum

1. provides anchoring points for tendons & ligaments to outer layer

2. secured to underlying bone by perforating Sharpey's fibers

3. increases width of bone inner layer

Sharpey's Fibers

Endosteum

delicate connective tissue membrane that covers internal bone surfaces

"within the bone"

lines canal passages to compact bone

covers trabecular (thin, small pieces) of spongy bone

Short, Irregular, & Flat Bones

compact bone on the exterior, spongy bone on interior

spongy bone called diploe --arranged like a sandwich

Red Marrow

soft tissue

found w/in trabecular cavities of spongy bone

adult bones contain little red marrow

blood cell production: hematopoesis

most active red marrow (in adults): head of femur, humerus, sternum, & hip bone

Osteon (Haversion) system

structural unit of compact bone

interconnecting canals

Central Canal

canal in center of osteon that contains small blood vessels, lymphatics, and nerve fibers

runs the length of the bone

Perforating Canal

canals that run at right angles to the central canal

blood vessels go thru periosteum to medullary cavity

Lacuna

small space or cavity

houses osteocytes

found at junctions of lamella

Lamella

layer of bone matrix in osteon

made of calcium and phosphorus

hardened material

canaliculi

connects lacunae to central canal

filled with fluid (canals) that carry nutrients and H2O

Compact bone

v.s.

Spongy bone

Compact: hard, very well organized, resists stress in one direction

Spongy: poorly organized, resists stress in all directions, makes bones flexible and light

Both: vascular, have endosteum, lacunae, and osteocytes

Organic Components of Bone

1. cells - osteogenic, osteoblasts, osteocytes, osteoclasts)

2. osteoid (organic part of matrix) - made up of collagen which allows for flexibility and strength

Inorganic Component of Bone

Ossification

bone formation

2 Types:

1. intramembranous -- forms cranial bones and clavicle

2. endochondral -- forms all bones below the based of the skull (minus clavicle)

Fetal Skeleton

Bone Growth in Length

lengthen by growth in epiphyseal plates (made from hyaline cartilage)

Bone Growth in Width

osteoblasts secreate bone matrix while osteoclasts remove bone --> widens while it lengthens

Hormones present at Puberty

sex hormones

• testosterone (boys)
• estrogen (girls)

increase bone growth

cause degeneration of epiphyseal plate

*estrogen does this faster*

Hormones at Childhood

• growth hormone

pituitary gland

keeps cartilage and epiphyseal plate reproducing

too much GH: pituitary giant

too little GH: pituitary dwarf

past puberty, too much GH: acromegaly

• thyroid hormone

regulates GH so skeleton has normal proportions

Bone Remodeling

1. Bone deposit - uses osteoblasts

2. Bone resorption - uses osteoclasts

reasons: fracture, cast, lifestyles (exercise/coach potato, disease)

Vitamins & Minerals that affect normal bone growth

vitamins: A, C, D

minerals: Mg, Mn, P, Ca

Wolff's Law

Structural Classification of Joints

• fibrous
• cartilaginous
• synovial (joint cavity)

3 Types of Fibrous Joints

• sutures
• syndesmoses (ligaments connecting *distal end* of tibia and fibula)
• gomphoses (tooth w/ avelolar socket)

Cartilaginous Joints

• synchondroses- hyaline cartilage; immovable joint between sternum & first rib and within epiphyseal plate
• symphyses - fibrocartilage; amphiarthrosis; pubic symphysis of pelvis & intervertebral disks

Synovial Joint Structure (6)

1. articular cartilage -- hyaline; covering bone ends at movable joints to prevent rubbing; on epiphysis
   
2. articular capsule - dense irregular CT, collagen fibers; double-layered capsule that holds bones together; outer membrane: fibrous capsule
   
3. synovial cavity - spacee containing small amt. of synovial fluid
4. fibrous capsule - tough external layer made of dense irregular CT; strengthens joint
5. synovial membrane - inner layer that makes synovial fluid
6. reinforcing ligaments

Synovial Fluid

reduces friction

nourishes cells of articular cartilage

carries on phagocytosis and engulfs debris

weeping lubrication - lubricates free surfaces of cartilage

Bursae

fibrous sac lines with synovial membrane and containing synovial fluid

decreases friction

Bursitis

inflammation of a bursae

"water on the knee"

Bunions

Tendonitis

Stability of Synovial Joints

1. articular surfaces

2. ligaments

3. muscle tone (most important; holds bone in place)

Plane Joint

type of synovial joint

allows short gliding movement

nonangular movement

ex: intercarpal and intertarsal

Hinge Joints

type of synovial joint

allows flexion and extension

uniaxial movement

ex: elbow, interphalangeal joints, knee

Pivot Joints

type of synovial joint

uniaxial rotation around its own axis

ex: radioulnar joint & atlantoaxial joint

Condyloid Joint

type of synovial joint

flexion, extension, ABduction, ADduction

biaxial

radiocarpal joint (wrist)

Saddle Joint

type of synovial joint

biaxial

carpometacarpal joints of thumbs

Ball & Socket Joint

type of synovial joint

universal movement

shoulder and hip