A&P Exam 2

chapters 5-9

what does the integumentary system include

skin, hair, nails, and cutaneous glands

what tissues form the skin

epithelial and connective

what supports the integumentary system

nerves, blood vessels, and smooth muscle

what does the skin do

protects, senses, and helps regulate internal conditions

what is the epidermis

outer epithelial layer

what is the dermis

underlying connective tissue

what is the hypodermis

connective tissue beneath the skin

what is the epidermis made of

keratinized stratified squamous epithelium, has no blood vessels, and provides surface barrier

what is the dermis made of

areolar and dense irregular connective tissue, has blood vessels + nerves, and provides support + strength + nourishment

what is the hypodermis made of

areolar and adipose tissues, larger vessels + nerves, and provides anchoring, cushioning, and insulation

what are keratinocytes

produce keratin and contribute to the protective barrier

what are melanocytes

produce melanin and transfer it to nearby keratinocytes

what are dendritic cells

langerhans cells participate in immune defense

what are tactile epithelial cells

merkel cells associate with sensory neurons for touch

what is the epidermal strata

(deep to superficial)

basale → spinosum → granulosum → lucidum (think skin only) → corneum

nemonic (top to bottom) = Come Let’s Get SunBurned

what is the stratum basale

single deepest row, dividing cells replace surface cells, and melanocytes + merkel cells occur here

what is the statum spinosum

several rows of keratinocytes, desmosomes resist separation, and keratin helps strengthen the cells

what is the stratum granulosum

cells flatten and accumulate keratin-associated proteins. lipid release strengthens the water barrier

what is stratum lucidum

a clear layers of dead cells in think skin (palms of hand and soles of feet)

what is stratum coreneum

flattened, dead, keratin0filled cells resist abrasion and continually shed

how does epidermal renewal happen

basal stem cells divide and supply new keratinocytes. As they mature they lose their nuclei and organelles. surface cells shed as deeper cells replace them

what is thick skin

palms and soles, prominent stratum corneum, statum lucidum, and no hair follicles or sebaceous glands

what is thin skin

most of the body, no distinct stratum lucidum, and generally contains hair follicles and sebaceous glands

what is the papillary region of the dermis

superficial areolar connective tissue

what is the reticular regions of the dermis

deeper dense irregular connective tissue

what does collage provide

strength

what does elastic fibers provide

stretch and recoil

what is the dermal papillae

projects toward the epidermis and strengthen the interface

what is the capillary loops

helps supply the overlying epidermis

what are the epidermal ridges

surface patterns seen in fingerprints (arch, loop, whorl)

what is near the surface of cutaneous sensory structure

Merkel cell-nerve complexes - sustained light touch

meissner corpuscles - light touch and low-frequency vibration

what is in the deeper skin of cutaneous sensory structure

pacinian corpuscles - deep pressure changes and vibration

hair root plexuses - hair movement

what are the free nerve endings of cutaneous sensory structures

detect pain, temperature, itch, and other sensations

what is the hair shaft

projects above the skin

what is the hair root

lies within the follicle

what is the hair bulb

expanded base containing the matrix

what is the role of hair

to protect the scalp and eyes

how does hair detect movement

through hair root plexuses

what are arreector pili

small smooth muscles attached to follicles and contraction raises hairs and produces goose bumps

what are sebaceous glands

sebum usually enters a hair follicle. lubricates skin and hair

what are eccrine sweat glands

watery secretion reaches a surface pore. evaporation supports cooling

what are apocrine sweat glands

secretion enters a hair follicle, common on the axillae and groin, and bacteria contribute to odor

what are the ceruminous glands

modified glands in the ear canal and help form protective earwax

in the eccrine gland how is the sweat carried to the suface

through the duct

how is heat removed from the skin

through evaporation

what is the nail matrix

dividing cells that produce the nail

what is the nail hyponchium

thickened tissue beneath the free edge

what does nail growth depend on

living matrix cells

what is melanin

pigment made by melanocytes. amount, type, and distribution influence coloration

what is hemoglobin

blood in dermal vessels contributes color. blood flow and oxygenation affect appearance

what is carotene

dietary pigment that can accumulate in skin and subcutaneous fat

how does melanin protect

it absorbs some ultraviolet radiation and helps protect cellular DNA

what does mechanical protection use

keratin and strong cell connections resist abrasion

what does water balance use

extracellular lipids and the surface layers limit water loss

what does immune defense use

resident immune cells help detect threats and intact surface limits entry

what does UV protection use

melanin reduced some UV exposure to living water loss

how does temperature regulation work

when hot dermal blood flow promotes heat loss and sweat evaporation cools the skin

when cold dermal blood flow conserves heat

what do sensory receptors do

report touch, pressure, vibration, temperature, and pain

what does excretion do

is a minor skin feature

sweat removes water, salts, and small amounts of wastes

how does skin produce vitamin D

UVB initates conversion of a presursor into vitamin D3

how does liver and kidney produce vitamin D

further processing produces active hormone calcitriol

how does intestine produce vitamin D

calcitriol helps increase calcium absorption

what is a epidermal wound

damage remains within avascular epithelium. an isolated epidermal would does not bleed. surviving cells restore the surface

what is a deep wound

damage reaches vascular connective tissue. bleeding and inflammation may occur. repair may include scar formation.

how does epidermal would healing work

surviving basal cells migrate across the damaged surface

cell division supplies replacement kertinocytes

cells mature and restore the layered barrier

an injury limited to the epidermis typically heals without a dermal scar

how does deep wound healing work

1. Inflammatory phase - clotting limits blood loss, immune cells clear damaged material and microbes

2. migratory phase - epithelial cells and fibroblasts move into the area. new vessels support repair

3. proliferative phase - cell numbers and collagen increase. granulation tissue supports closure

4. maturation phase - collagen remodels and tissue strength increases over time

what is a superficial burn

epidermis only, often painful and red

what is a partial thickness burn

epidermis and part of dermis. blistering may occur

what is a full thickness burn

entire epidermis and dermis. may extend into deeper tissues. sensation may decrease centrally

how does aging change skin structure and function

epidermal renewal slows, reduce strength and recoils in elastic fibers, reduced gland actvity means dryness and altered cooling, and repairs may take longer

what are the functions of the skeletal system

support / protection, movement, mineral storage, and marrow functions

how does support and protections work

skeleton supports soft tissues and shields organs such as brain and heart

how does movement work

contracting skeletal muscles pull on hones to produce movement at joints

how does mineral storage work

bones stores calcium and phosphate and participates in mineral homeostasis

how does marrow functions work

red marrow produces blood cells and yellow marrow stores triglycerides

what are long bones

longer than wide and with a shaft + ends

what are the short bones

similar length + width. flat (thin and curved)

what are irregular bones

complex shape. sesamoid (develops within a tendon)

what is the diaphysis

shaft around the medullary cavity (body)

what is the epiphyses

expanded proximal and distal ends

what is the metaphyses

transition regions containing a growth plate or adult epiphyseal line (in between the diaphysis and epiphyses)

what is the periosteum

civers the outer bone except articular surfaces. its inner layer contains osteogenic cells

what is the endosteum

lines internal bones surfaces including the medullary cavity and trabeculae

what is the articular cartilage

hyaline cartilage at joint surfaces. it reduces friction and distributes load

where is the yellow marrow

adult long bone shaft

where is the red marrow

axial skeleton and proximal humerus + femur

what is the organic bone matrix

collagen and other organic components from osteoid. collagen resists pulling and adds flexibility

what is mineral component bone matrix

hydroxyapatite crystals, rich in calcium + phosphate, and provides hardness + resistance to compression

what are osteoprogenitor

cells divide and provide osteoblasts precursors

what are osteoblasts

secrete osteoid and support mineralization

what are osteocytes

occupy lacunae and monitor and maintain the matrix

what are osteoclasts

resorb bone using acid and enzymes

what do osteocytes do

detect mechanical conditions and help coordinate remodeling

what do osteoclasts do

remove mineral and organic matrix

what do osteoblasts do

deposit new organic matrix that subsequently mineralizes

how does collagen get damaged & what happens

heating damages the organic framework and the specimen becomes more brittle

how does mineral removal happen & what happens

acid leaches mineral salts and the remaining collagen framework becomes more flexible

what does compact bone form

dense outer cortex (especially thick in the diaphysis)

what does spongy bone form

internal trabeculae with spaces for marrow

what are central and perforating canals

central canals run through osteons. Perforating canals connect them with outer vascular routes