A&P Exam 2

Integumentary System

two or more kinds of tissues grouped together & performing specialized functions constitutes an organ

vital in maintaining homeostasis

15-20% of body mass, - 2m²

Skin

protection from drying out, foreign organism, friction w/ environment

maintain body temperature

excretion (NaCl, urea)

sensory

vitamin D production (necessary for calcium absorption by gut)

lipid soluble substances can be absorbed through skin

Corticosteroids

produced in adrenal cortex → stress response, immune, inflammation

hydrocortisone - immune suppressive drug, allergic reactions or rashes

impaired wound healing, high BP

biomarkers for psychological stress

Urishiol-Induced

poison-ivy

induced immune response, binds & changes shape of protein in cell membrane, body doesn’t recognize as self & attacks

• 15-30% people no response, 25% strong response

• stronger reactions after repeated exposure

Takes weeks to go

Thick Skin

thick on palms & soles of feet

upper back has thickest dermis

Thin skin

located everywhere except palms, soles of feet, & upper back

eyelids = thinnest

Epidermis

stratified squamous epithelium

4 distinct layers

• Stratum Basale

• Stratum Spinosum

• Stratum Granulosum

• Stratum Corneum

Stratum Basale

single layer, the stem cells, cuboidal, big nuclei → dividing cells

E) Stratum Basale

Label E

Stratum Spinosum

“prickle layer” larger cells becoming flatter, desmosomes hanging on with cell shrinkage = looks psiny

D) Stratum Spinosum

Label D

Stratum Granulosum

1-3 cell layers thick, keratin granules = stain darkly

C) Stratum Granulosum

Label C

Stratum Lucidum

a single layer of dead skin cells found only in thick skin (palms, soles of feet, upper back)

B) Stratum Lucidum

Label B

Stratum Corneum

abrupt transition, flattened, desiccated, a nucleate cells, loose organelles just keratin filaments, layer of lipids-water barrier, thickest where friction (calluses) = dead layer

A) Stratum Corneum

Label A

Psoriasis

autoimmune disease

skin divides too rapidly (3vs.30 days)

triggers = stress & medications

3% - 7.5 million Americans;

Dermis

uneven boundary helps attachment

dermal papillae meet epidermal ridges

more ridges in thick skin - more surface area

2 Layers -

• Papillary Layers - top layer

• Reticular Layer - random collagen fibers

Langers Lines = collagen & elastic fibers (follow fiber direction in surgery0

potential to form bone

Blisters

shearing force, fluid in derma-epidermal junctions

Hypodermis

adipose tissue - varies in thickness

muscle for facial muscles, more well developed in other mammals

Melanocytes

produce melanin, replicate slower

scattered among basal cells

goes to tip of processes, “injected” into skin cells

UV radiation stimulates melanin production

2 Factors of Melanocytes

Dark to protect from UV radiation

Light to synthesize Vitamin D ‘

Humans have a lot of sweat glands, less hair to deal with heat but more UV damage

Eumelanin

brownish/black

genetically determined

Pheomelanin

reddish/yellow

genetically determined

Light Skin

melanin degraded in stratum spinosum, lasts longer in darker skin, larger granules

Jaundice

yellow skin

carotenes in fat, blood vessels near skin

Cyanosis

bluish skin (slow moving blood)

Albanism

genetic mutation = less melanin = white skin

Nerve Supply of Skin

lots of sensory receptors

free nerve endings = heat/touch/cold/pain

surround hair follicles = tactile (ex. whiskers)

Lamellated Corpuscles (encapsulated nerve endings)

deep pressure, large

unmyelinated nerve w/ concentric lamellae with fluid between

Tactile Corpuscles (fine touch)

in dermal papillae - touch receptors

fingers, toes, & lips

tapered cylinders just beneath epidermis

nerve takes a spiral path, Schwann cells surround

Hair

humans are covered all over in hair, except on palms, soles, lips, nipples, & part of external reproductive organs

on average each person’s head carries about 100,000 hair follicles

each hair grows for several years, will fall out & be replaced

Hair Scent

hair carries an individual’s scent, by which he or she may be recognized → attract mates

Temperature Regulation - Hair

hair = traps air = insulator

sweat glands = cool off

hair follicles produce hair

distribution of hair influenced by sex hormones

Sweat Gland

coiled & release to surface

Sebaceous Gland

secrete sebum - fatty/cell debris, coats hair & skin surface

holocrine gland - release products by disintegrating the whole cell

directly on skin - labia minora, areola, eyelids, lips

Hair Follicle

hair/sebaceous gland canal to surface

bulb w/ dermal papilla

sheaths surround

starts at surface → moves down into skin

arrector pili muscle = goose bumps

Proteins in Hair

hair is extremely complex & sophisticated composite, where proteins are combined with lipids & minerals to form a unique structure w/ extraordinary properties

Human Follicle Cross Section

hard keratin

medulla - central part-large open cells (only in thick hair)

cortex - cuboidal cells to keratin filled

cuticle = squamous cells to outside

Human Hair Color

no biological function of human hair color

melanin found in two forms - eumelanin & phaeomelanin (mixture of both in most people’s hair)

decreased melanocyte activity = grey hair

Eccrine Sweat Glands

simple coiled glands

not associated w/ hair follicles

down growth from epidermis

secretory & duct segments

temp regulation

NaCl, urea, ammonia excreted

Apocrine Sweat Glands

coiled tubular/branched (sometimes)

large lumen

same down growth as hair = retain connections

store products in lumen, unlike eccrine

protein rich secretion, lipids - odor when bacteria digest

functional at puberty

pheromones in many mammals

Ceruminous Glands

glands of external auditor meatus = secretes ear wax

Mammary Glands

secrete milk, milk lines from axilla to groin, like sebaceous/seat = secrete lipid

number of glands = number of offspring

Nails

tightly compacted cornified epithelial cells

plates at keratinzied cells - hand keratine

nail plates resting on nail bed

nail bed = stratum basale/spinosum

nail - modified stratum corneum

pale luma - partially keratinized cells, become transparent after

Tattoos

pigment in dermis layer

phagocytes engulf pigment, epidermis flakes off, stable in upper dermis, does migrate deeper over decades → fading

Skin Repair

basal cell proliferation under injury

if all epidermis gone; hair, sweat gland cells have stem cells

3rd degree etc. → need skin graft

Healing of Wounds & Burns

inflammation is a normal response to injury or stress

blood vessels in affected tissues dilate & become more permeable → fluids leak into damage tissue

inflammed skin - reddened, swollen, warm, painful

Cuts

a shallow cut results in epidermal cells long its margin to divde more rapidly

deep cuts result sin blood vessels breaking which causes a clot to form:

• Clot & dried tissue fluid form scab

• Growth factor stimulate new tissue formation

• phagocytic cells remove dead cells & debris

• excess collagenous fibers may form scars

First Degree Burns

superficial, partial-thickness

Second Degree Burns

deep, partial thickness

Third Degree Burns

full-thickness, autograft, allograft (from another cadaver), skin substitutes

Regulation of Body Temperature (skin)

vitally important because even slight shifts can disrupt rates of metabolic reactions

skin plays a role in homeostatic mechanism that regulates body temperature

Heat Production & Loss

heat is a product of cellular metabolism

most active body cells are the heat producers: skeletal muscle cells, cardiac muscle cells, cells of certain glands such as the liver

primary means of heat loss is radiation, there is also conduction, convection, & evaporation

Hyperthermia

abnormally high body temperature

humid day = evaporation doesn’t happen, core> 106 degrees F

skin dry, weak, dizzy, nauseous , headache, rapid pulse

Hypothermia

abnormally low body temperature

shivering & coldness to confusion, lethargy

Age Changes in Skin

epidermis & hypodermis thins

melanocytes decrease

sweat/sebaceous glands = less activity

healing = 4x slower

age spots - sun damage & weakened vessels in dermis = bruise

hair = grey/white, nails = weak

Skin Cancer

most common human cancer - half Americans >65 develop at least once

Basal Cell Carcinoma (90% in US) = rarely spread

Squamous cell carcinoma - squamous cells elsewhere in body also

• Light skin & sun exposure

• Can metastasize (lower lip)

Adenocarcinoma (glands) - colon, lung

Melanoma

clusters of melanocytes

melanoma = when cells become malignant

spread in lymph nodes, to liver & lungs, brain, but STILL melanoma cells

Asymmetry, Border (ragged), Color (uneven), Diameter (>5 mm usually)

biopsy to check for cancer cells - staged as to how thick it is if spread

Skeletal System

206 bones

• 80 bones in axial skeleton

• 126 bones in appendicular

20% of body weight

Associated Connective Tissue - cartilage, tendons ligaments, discs

Bones are made up of many tissues = one tissues, cartilage, dense connective, blood & nervous tissue

Functions of Bone

maintain body shape

protect internal organs (brain, spinal cord)

system of levers for the muscle system to act upon

mineral storage = Ca²⁺ & phosphorus

Hold blood forming cells

surface feature for muscle (insertions & origins)

Long Bone Anatomy

Diaphysis - main tubular shaft of long bone, midsection

Metaphysis - wide, flared neck portion, between epiphysis & diaphysis

Epiphysis (proximal/distal) - rounded end/tip of long bone

Epiphyseal Line - remnant of epiphyseal plate, after bone longitudinal growth stops

Periosteum - covers outer surface of bone

Compact Bone - forms outer protective shell of bones

Spongy Bone - (cancellous bone) porous, makes up interior of bones

Articular Cartilage (hyaline) - covers & protects the end of bones

Medullary Cavity - hallow central space inside the diaphysis

Marrow - soft, spongy tissue found inside the center cavities of bone → produce blood cells

Nutrient Artery - main blood vessels for long bones

Periosteum

Covers outer surface of bone (except for articulations - cartilage)

outer fibrous layer

collagen fibers from ligaments + tendons go into the bone tissue at an angle

Endosteum

lines bone cavities

1 cell layer thick lining

bone stem cells line marrow cavity & trabeucle of spongy bone

Bone Marrow

red bone marrow = where blood cells are made

yellow bone marrow = fat storage

as you grow, amount of red bone marrow doesn’t increase in proportion to bone growth

• yellow marrow forms

lot of red bone marrow in sternum, pelvis

What type of tissue is bone?

Bone is a connective tissue = cells + extracellular matrix

• Matrix is mineralized → support & protection

Calcium phosphate in form of hydroxyapatite crystals

30: 70% organic/inorganic salts

without organic minerals = fragile

Osteocytes

maintain bone tissue

mature bone cells

transport nutrients & waste

extracellular matrix of bone is largely collagen & inorganic salts

• Collagen = resilience

• Inorganic salts = bone hard

Mature Bone

osteons (haversion systems) 4-20 lamellae w/ central nerve, artery, vein

osteocytes trapped in matrix, connected to each other by canaliculi (processes of osteocytes)

sometimes chain of 15

Osteon

cylinder shaped unit containing bone cells & matrix lamella that surround a central canal; havarain system

many come together to form the compact bone

osteons run longitudinally with the axis of bone, functioning as weight-bearing pillars, resisting compression

Central Canal

contains blood vessels & nerves surrounded by loose connective tissue

runs down the middle of osteons

• Blood in these vessels nourishes bone cells associated with the central canal via gap junctions between osteocytes

Perforating Canal

connects central canals to one another

contain larger blood vessels & nerves by which the smaller blood vessels & nerve fibers in central canals communicate with the surface of bone & medullary cavity

Lamellae

layers of extracellular matrix concentrically clustered around a central canal

Lacunae

small fluid-filled cavities within the bone matrix that house the osteocytes

Canaliculi

channels/tunnels that connect lucanae to each other and to blood vessels

Nutrient Foramina

blood supply to bone (very important = healing/nutrients)

Spongy Bone

rarely contains osteons

Trabeculae (braching bony plate that separates irregulater spaces within spongy bones) surrounding red bone marrow spaces

composed of osteocytes & extracellular matrix, but the bone cells do not aggregate around central canals

get nutrients from substances diffusing into the canaliculi

Immature Bone

develops in fetus

does not have organized lamella = “woven bone”

relatively more cells/area

adult: tooth sockets, remodeling

Bone Development & Growth

parts of skeletal system begin to develop during first few weeks of prenatal development

human skeleton is initially hyaline cartilage + fibrous membrane (300 bones at birth)

by 25 bone the skeleton is almost completely hardened

Osteogenic Cells

develops into osteoblasts

Osteoblast

forms bone tissue

synthesize organic components of matrix (collagen, bone matrix proteins)

hormones stimulate activity

Osteoclast

function in resorption of bone (destruction of bone matrix)

derived from WBCs = bone resorption

large, motile cells

secrete enzymes that digest matrix

Intramembranous Ossification

(between membranes) flat bones of the skull, clavicles, sternum, & some facial bones (mandible, maxillae, & zygomatic bones)

during their development (osteogenesis) membranelike layers of embryonic connective tissue appear at the sites of future bone

• Mesenchymal cells that are part of the connective tissues enlarge & differentiate into osteoblasts

• Osteoblasts form bony matrix around themselves

• Dense networks of blood vessels supply these connective tissues

• Spongy bone forms in all direction along the blood vessels

Endochondral Bones/Ossification

bone begins as hyaline cartilage

• Form models for future bones

• Most bones of skeleton

1. cuff of bone forms in mid-region - BONY COLLAR

2. cartilage cells in center swell, secrete calcium

3. calcified cartilage inhibits diffusion = kills cells

4. blood vessels grow in, bone stem cells move in

secondary center of ossification - leaves cartilage epiphyseal plate

• when that cartilage stops growing bone has reached its max length

Zone of Resting Cartilage (growth at epiphyseal plate)

first layer of cells

closet to end of epiphysis

resting cells

anchors epiphysis plate to epiphysis

Zone of Proliferating Cartilage (growth at the epiphyseal plate)

2nd layer of cells

many rows of young cells

undergoing mitosis

Zone of Hypertrophic Cartilage (growth at epiphyseal plate)

older cells left behind when new cells appear

cells enlarging and becoming calcified

Zone of Calcified Cartilage (growth at epiphyseal plate)

4th layer of skin

thin, dead cells, calcified extracellular matrix

Homeostasis of Bone Tissue

bone remodeling occurs throughout life

bone resorption - action of osteoclasts

bone deposition - action of osteoblasts

10-20% of skeleton is replaced each year

Factors Affecting Bone Development & Repair

Deficiency of Vitamin A - disrupts normal growth & remodeling of bone

Deficiency of Vitamin C - results in fragile bones

Deficiency of Vitamin - rickets, osteomalacia = weak

Insufficient Growth Hormone = dwarfism

Excessive Growth Hormone = gigantism, acromegaly

Insufficiency Thyroid Hormone = delays bone growth

Physical Stress - stimulates bone growth

Sex Hormones

promote bone formation: stimulate ossification of epiphyseal plates

Fractures

break in the bone

simple/compound (open) - infection

single: horizontal, oblique, spiral

comminuted → 2 bone fragments

Healing in Bone

1 Day = hematoma formation (fibrin mesh)

3 Days = inflammation, macrophages remove debris, periosteum & endosteum response w/ proliferation of bone stem cells

1 Week = soft callus → granulation, matrix

3-6 Weeks = callus → ossification, woven bone

8+ Weeks = remodeling → absorb/deposit, strength, lamellate

Osteoporosis

imbalance: bone resorption + bone formation

no symptoms, but increase in fractures

bone mineral density is reduced & microarchitectures deteriorates

spongy bone = more active (more surface area) - ends of long bones + vertebrae problems

• 30-35 loss begins

age = decrease in androgens, especially estrogen, smoking, malnutrition, genetics

exercise, nutrition, & hormones help

Bone Functions: Support, Movement, & Protection

gives shape to head, etc.

support body weight

protect vital organs (ex. lungs)

bones & muscles interact when move

Bone Functions: Blood Cell Formation

hematopoiesis

red bone marrow

Bone Functions: Inorganic Salt Storage

most abundant salt is calcium phosphate

others = magnesium, sodium, potassium, carbonate ions

Skeleton Organization

206 bones

actual number of bones varies person to person

Axial Skeleton

skull, hyoid bone, thoracic cage, vertebrae

Appendicular skeleton

shoulder girdle, upper limbs, pelvic girdle, lower limbs