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A&P I Exam 3 Review Slides

Lectures 9-12

Ch. 4 and Ch. 5

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Types/Functions of Epithelial Tissue

• Functions of Epithelial Tissue

– Physical protection

– Control of permeability

• Secretion, Absorption, Filtration

– Provide sensation

– Provide specialized secretions (glands)

• Types of epithelium

1. Covering and Lining Epithelium

– External Surfaces, e.g., skin, Internal surfaces

2. Glandular Epithelium

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Characteristics of Epithelial Tissue

• Specialized contacts with other cells

• Polarity (different ends of cell do different

things)

• Avascularity (no blood supply)

• Regeneration (can divide to make new

cells)

• Cellularity (lots of cells in close contact)

Remember: Epithelial tissues always have a

free surface and a basement membrane

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4

Basal Lamina

Two components:

Lamina Lucida

- glycoproteins and fine protein filaments

- Barrier for passage of substances from

underlying tissue into epithelium

Lamina Densa- bundles of coarse protein fibers

- gives basal lamina its strength

Formerly called: Basement membrane

Figure from: Martini, Fundamentals of Anatomy & Physiology, Benjamin Cummings, 2004

Lamina = thin layer

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Classification of Epithelial Tissues

• Shape

– Squamous (Thin, flat, irregular in shape)

– Cuboidal (Square or cuboidal)

– Columnar (Rectangular, tall)

• Type of layering (stratification)

– Simple (one layer)

– Stratified (two or more layers)

– Note that classification of stratified epithelium is based on the shape of the superficial, not deep, layers

Epithelial tissues are classified according to

both their:

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Characteristics of Epithelial Tissue

Specialized Contacts

Figure from: Martini,

Anatomy & Physiology,

Prentice Hall, 2001

Tight junction – forces

substances to go through

cells, rather than being able

to pass between them

Gap junction – allow rapid

passage of small

molecules/ions between

cells

Desmosome – binds cells

together firmly so they stay

connected

Hemidesmosome – binds

cells to basement

membrane

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Locations/Functions of Epithelial Tissues

NAME OF ET DESCRIPTION

STRUCTURE

LOCATION FUNCTION

SIMPLE

SQUAMOUS

a single layer of

flattened cells

linings of air sacs,

capillaries, lymph

vessels, body cavities;

covering ventral organs

Mesothelium/endothelium

diffusion, reduction

of friction

SIMPLE

CUBOIDAL

a single layer of cube-

shaped cells with

large centrally

located nuclei

linings of kidney tubules,

ducts of glands

absorption,

secretion

SIMPLE

COLUMNAR

a single layer of tall

cells with basally

located nuclei,

goblet cells, & mucrovilli

lining of intestine protection,

absorption,

secretion

PSEUDO-

STRATIFIED

COLUMNAR

a single layer of tall

cells with

scattered nuclei,

cilia, & goblet cells

lining of trachea,

lining of fallopian tube

protection, secretion

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Locations/Functions of Epithelial Tissues

NAME OF ET DESCRIPTION

STRUCTURE

LOCATION FUNCTION

STRATIFIED

SQUAMOUS

many layers of

flattened cells

keratinized =

epidermis;

non-keratinized =

lining of vagina,

anus, throat, mouth

protection

TRANSITIONAL several layers of

cells that change

shape under

pressure

lining of urinary

bladder and ureters

Distensibility (able

to stretch)

GLANDULAR simple cuboidal lining the ducts of

glands

secretion

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Review of Epithelial Tissues

• Exocrine glands have several different mechanisms of secretion

– Merocrine

• Release of product from vesicles by exocytosis – none of cell is lost

– Holocrine

• Entire cell is lost: packed with secretion and then bursts

• Ex: Unicellular = mucous gland; multicelluar = sweat gland, sebaceous gland,

mammary gland, etc.

• Glands are specialized epithelium

– Secrete on to a surface (exocrine)

– Secrete into a duct (exocrine)

– Secrete into the blood (endocrine)

Glandular epithelium is classified by:

1. Shape of secretory portion of gland

2. Branching pattern of the duct

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Membranes

Serous• line body cavities that lack

openings to outside

• reduce friction

• inner lining of thorax and

abdomen

• secrete serous fluid

• Mesothelium found in serous

membranes

Mucous• line tubes and organs

that open to outside world

• lining of mouth, nose,

throat, digestive tract, etc.

• secrete mucus

Cutaneous• covers body

• skin

A membrane is a combination of epithelium and

connective tissue that covers and protects other structures

and tissues. Technically, then, a membrane is an organ.

Synovial• surround joint cavities

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Review of Connective Tissues

NAME OF CT DESCRIPTION LOCATION FUNCTION

MESENCHYME Precursor (stem)

tissue to other CTs

Embryo gives rise to all other

CT’s

AREOLAR gel-like matrix with

fibroblasts, collagen

and elastic fibers

beneath ET (serous

membranes around

organs & lining

cavities)

diffusion, cushioning

organs

ADIPOSE closely packed

adipocytes with

nuclei pushed to one

side by fats

beneath skin, breasts,

around kidneys &

eyeballs

insulation, energy

store, protection

RETICULAR network of reticular

fibers in loose matrix

basement

membranes,

lymphatic organs

Support; forms

stroma of organs

DENSE

REGULAR

dense matrix of

collagen fibers

tendons, ligaments attachment (high

tensile strength)

DENSE

IRREGULAR

loose matrix of

collagen fibers

dermis of skin strength in several

directions

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Review of Connective TissuesNAME OF CT DESCRIPTION LOCATION FUNCTION

ELASTIC CT matrix of elastic

fibers

lung tissue, wall of

aorta

durability with

stretch

HYALINE

CARTILAGE

chondrocytes in

lacunae in

amorphous

matrix

embryonic. skeleton,

costal cart, tip of

nose, trachea,

larynx

support

FIBRO-

CARTILAGE

less firm than above intervertebral discs,

pubic symphysis

tensile strength,

shock absorber

ELASTIC

CARTILAGE

above plus elastic

fibers

external ear,

epiglottis

shape maintenance

plus flexibility

BONE concentric circles of

calcified matrix

Bones support, protection,

movement, Ca ++

storage,

hematopoiesis

BLOOD red cells, white cells

and platelets in

liquid plasma

in heart and blood

vessels

transport of nutrients,

wastes & gases

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Name of

CT

Different types of

this CT

Main types of cells

present

Main types of

fibers present

Consistency of

matrix Examples of Locations

CT Proper

1) Areolar (Loose)

2) Dense regular

3) Dense irregular

4) Adipose

5) Reticular

6) Elastic

1) Fibroblasts

2) Fibroblasts

3) Fibroblasts

4) Adipocytes

5) Fibroblasts

6) Fibroblasts

1) Collagen, Elastic

2) Collagen

3) Collagen

4) Reticular

5) Reticular

6) Elastic

Semi-liquid

1) Skin, between muscles

2) Tendons, ligaments

3) Dermis

4) Body fat areas

5) Stroma of liver, spleen

6) Lungs, airways,

arteries/heart

Cartilage 1) Hyaline

2) Fibrocartilage

3) Elastic

(All) Chondrocytes

1) Collagen (sparse)

2) Collagen (dense)

3) Elastic

All types: Semi-

solid, gelatinous;

rubbery

1) Ribs, ends of bones

2) Intervertebral disks

3) Pinna of ear, epiglottis

Bone 1) Dense

2) Spongy

(All) Osteocytes Collagen Solid

(hydroxyapatite)

1) Outer portions of bone

2) Inner portions of bone

Blood

--

1) RBCs

2) WBCs

3) Platelets (cell

fragments)

Fibrinogen (soluble) Liquid Blood vessels, heart

Lymph -- Lymphocytes Reticular (in stroma

of lymphoid organs)

Liquid Lymph vessels

Connective Tissue (CT) Summary Table

Three main components of ALL types of CT: cell, fibers, ground substance

-cyte = fully differentiated; -blast = young, actively synthesizing cell

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Connective Tissue - Major Cell Types

Fibroblasts

• fixed cell

• most common cell; always

in CT proper

• large, star-shaped

• produce fibers

• produce ground substance

Macrophages

• wandering cell

• phagocytic

• important in defense

• derived from circulating

monocytes

Mast cells are mediators of inflammation – see later…

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Connective Tissue Fibers

Collagenous fibers

• thick

• composed of collagen

• great tensile strength

• hold structures together

• abundant in dense CT

• tendons, ligaments

Elastic fibers

• bundles of

microfibrils embedded

in elastin

• fibers branch

• elasticity

• vocal cords, air

passages

Reticular fibers

• very thin collagenous

fibers

• highly branched

• form supportive

networks

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The “Ground Substance” of CT

Figures from: Alberts et al., Essential Cell Biology, Garland Press, 1998

VERY hydrophilic!

**Function: Very active in

controlling passage of

substances through this portion

of the matrix and keeping CT

hydratedGAGs = glycosaminoglycans (negatively charged

polysaccharides); a major molecule in ground

substance

glucosamine

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Tendons and Ligaments

Tendons: Connect muscle to bone

Ligaments: Connect bone to bone

Aponeuroses: Broad, fibrous sheets; usually attach muscle to muscle (or bone)

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CT Framework of the Body

Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Fascia: layers of fibrous

connective tissue covering

and separating muscle. It

connects the organs of the

dorsal and ventral cavities

with the rest of the body

Provide:

- Strength

- Stability

- Organ position

- Conduits

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Muscle – Overview

• General characteristics

– Elongated cells with special properties

– Muscle cells (myocytes) = muscle fibers

– Contractile (major property of all muscle)

– Use actin (thin) and myosin (thick) for contraction

• Three types of muscle tissue

– Cardiac (involuntary)

– Skeletal (voluntary)

– Smooth (involuntary)

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Review of Muscle TypesNAME OF

MUSCLE

TISSUE

DESCRIPTION OF

STRUCTURE

TYPE OF

CONTROL

LOCATION FUNCTION

SKELETAL

MUSCLE

long, thin fibers with

many nuclei and

striations

Voluntary attached to bones to move bones

SMOOTH

MUSCLE

spindle shaped cells with

one centrally

located nucleus,

lacking striations

Involuntary walls of visceral

hollow organs,

irises of eyes,

walls of blood vessels

to move substances

through

passageways (i.e.

food, urine, semen),

constrict blood

vessels, etc

CARDIAC

MUSCLE

a network of striated

cells with one

centrally located

nucleus attached by intercalated discs

- Intercalated disks

consist of : 1)gap

junctions and 2)

desmosomes

Involuntary heart pump blood to lungs

and body

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Nervous Tissue

• found in brain, spinal cord, and peripheral nerves

• conduction of nerve impulses - neurons

• sensory reception

• neuroglial cells are supporting cells

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Introduction to Inflammation

Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Restoration of tissue homeostasis after injury or infections involves two processes,

in order: 1) inflammation and 2) repair

Main signs of inflammation: Redness, heat, pain, swelling, and loss of function

(Inflammation = ‘-itis’)

Histamine

Histamine

Heparin

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Functions of the Integumentary System

• Functions of the integument

– Protection (from mechanical/chemical/bacterial damage, UV radiation)

– Temperature regulation (extreme heat, extreme cold) and Fluid conservation

– Excretion

– Vitamin D production

– Sensation (touch, pressure)

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Layers of the Epidermis - Overview

Bare Skin Gets Lots of Cuts

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Thick and Thin Skin

Thin (0.07-0.12 mm)(epidermal thickness) Thick (0.8-1.4 mm)

(epidermal thickness)

Thick skin - palms of hands, soles of feet; five epidermal layers

Thin skin - everywhere else; four epidermal layers (no s. lucidum)

Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

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Cells of the Epidermis

• Epidermis of the skin is classified as a keratinized stratified squamous epithelium

• Cells of the epidermis include

– Keratinocytes (90%)

• Keratin – a tough, fibrous intracellular protein (protection)

• Lamellar granules (waterproofing, extracellular)

– Melanocytes (8%)• Produce melanin (protection from UV radiation)

– Langerhans cells (1-2%)• Migrate to skin from bone marrow

• Participate in skin’s immune response (dendritic cells)

– Merkel cells (< 1%)

• Least numerous; specialized epithelial cells

• Function in sensation of touch

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Skin Color

1. Genetic Factors

• varying amounts and

type of melanin

• varying size/number of

melanin granules

• albinos lack melanin

(but not melanocytes!)

2. Environmental Factors

• sunlight

• UV light from sunlamps

• X rays

3. Physiological Factors

• dilation of dermal blood vessels

(erythema)

• constriction of dermal blood

vessels (less pink, pale = pallor)

• level of oxygenation of blood

* normal = pink (fair-skinned)

* low = bluish (cyanosis)

• carotene -> Vit A (yellow)

• jaundice (yellow)

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Skin Color and Melanin

Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004

Melanocytes produce melanin

- tyrosine melanin

- UV radiation up-regulates production of

melanin

- Dark-skinned individuals have

* same number, higher activity of melanocytes

* more pigmented layers of epidermis

Dark-skinned Fair-skinned

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Keratin and Vitamin D

• Keratin (tough, fibrous intracellular protein)

– Protection

– Water resistance

• Vitamin D3 (“sunshine vitamin”)

– After UV irradiation epidermal cells in s. spinosum and

s. basale convert a cholesterol-related steroid to Vit D3

(cholecalciferol)

– Vit D3 – absorption of calcium and phosphorus by

small intestine

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Two Layers of the Dermis

1. Papillary layer (near epiderm.)

- areolar connective tissue (CT)

- capillaries and sensory neurons

- dermal papillae

- fingerprints (with epi. ridges)

2. Reticular layer

- dense, irregular CT

- collagen fiber bundles extend

upward and downward

- also contains elastic fibers and

cells of CT proper

- accessory organs of

integumentary system (from epi.)

Figure adapted from: Martini, Anatomy & Physiology, Prentice Hall, 2001

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Subcutaneous Layer

- Stabilization of dermis

- Areolar and adipose tissue

- Male/female hormones

Also called ‘hypodermis’.

This is the superficial fascia.

- Insulation (retains heat)

Basal lamina

- Reservoir of blood

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Hair (pilo-)

• epidermal cells

• tube-like depression

• extends into dermis

• hair root (in dermis)

• hair shaft (outer 1/3)

• hair papilla (growth area)

• hair follicle (surrounds hair

root)

• melanin

• arrector pili muscle

(from epidermis)

Basal lamina

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Hair Follicles

Figure adapted from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Some hair color

Three types of hair:

1. Lanugo – long,

blond, fine (fetal,

anorexia nervosa)

2. Vellus – short, blond

(children)

3. Terminal – course,

pigmented (adults)

Most hair color

(Protection)

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Sebaceous (Oil) Glands

• multicellular, holocrine glands

• absent on palms and soles

• usually associated with hair

follicles

• secrete sebum, a waxy, oily

material

• inhibits growth of bacteria

• lubricates and protects keratin

of hair shaft, and conditions skin Sebaceous follicles – not

associated with hair.

Discharge directly on to

skin. On face, back, chest,

nipples and male sex

organs.

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Sweat Glands (Multicelluar)

• apocrine (merocrine secr.)

glands

- associated with hair follicles

- thick, odorous secretion

• ceruminous glands

• mammary glands

• also called sudoriferous glands

• eccrine (merocrine secr.) glands

- most numerous

- palms, soles, forehead, neck,

back

- directly on to surface

- watery secretion

- for thermoregulation

Specialized (apocrine secretion)

Sweating with visible wetness = diaphoresis

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Nails

Figure from: Saladin,

Anatomy & Physiology,

McGraw Hill, 2007

Be able to identify these structures by labeling this diagramHyponychium

(Perionychium)

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Regulation of Body TemperatureHyperthermia – Abnormally high

body temperature

May be caused by

- environment (heat, humidity)

- illness (fever [>=37.20C], pyrexia)

- anesthesia (malignant h.)

Corrected by loss of heat mainly by

radiation (dilation of blood vessels),

evaporation (sweating)

Heat exhaustion (prostration)

- Fatigue

- Dizziness

- Headache

- Muscle cramps

- Nausea

- May lead to heat stroke

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Regulation of Body Temperature

Hypothermia – Abnormally

low body temperature (at

least 20C below normal body

temp)

May be caused by:

- exposure to cold (primary)

- illness (secondary)

- surgical induction (clinical)

Cardiac arrest is likely if

temperature falls below 28oC

(82oF)

Corrected by mechanisms to

retain body heat (see * left)

**

Healing of Cuts

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Tissue repair can occur by either:

1) regeneration – healing with tissue that was originally present

2) fibrosis – healing with ‘scar’ tissue

Figure From: Marieb

& Hoehn, Human

Anatomy & Physiology,

9th ed., Pearson

1. Bleeding/clotting

2. Scab formation

3. Epidermal cell migration and

collagen production

4. Shedding of scab;

covering of wound

with epithelium