-Covers exposed surfaces, lines internal passageways and forms glands

ex: lining of digestive tract organs and other hollow organs, also skin surface.

Fills internal spaces, provides structural support for other tissues, transports materials within the body and stores energy reserves.

ex: bones, tendons, fat and other soft padding tissue

Carries information from one part of the body to another in the form of electrical impulses.

ex: Brain, spinal cord, nerves

1) Covering and lining epithelium: forms the outer layer of the skin, lines urogenital, digestive, and respiratory systems, covers walls and organs of the ventral body cavity.

 2) Glandular epithelium: fashions the glands of the body.

- Polarity: Cells are bound together tightly

- Specialized contacts: Exposed surface and base

- Supported by connective tissues: Attached to underlying tissues by the base membrane

- Avascular: Lack blood vessels

- High Rate of cell division b/c cells are damaged or lost frequently

-Provides physical protection from abrasion, dehydration, and destruction

-Controls permeability and can be altered based on stimuli- absorption and filtration

-Provide sensation because they have large sensory nerve supply

-Produce secretions in gland cells

Fingerlike extensions of the plasma membrane of epithelial cells found on the apical surface where absorption and secretion take place. 

Increases the surface area of these cells so that filtration and reabsorption happen at a higher rate.

1) CAM's: Transmembrane proteins called cell adhesion molecules that help epithelial cells (and other types of cells) attach to one another.

2) Tight junctions

3) Gap junctions

4) Desmosomes

Adhesion belt that attaches to the microfilaments of two cells joining them toghether; attachement is so close that water and other solutes annot pass between the cells.

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CAM's and proteoglycans link between two cells; resistatn to stretching, twisting, and bending.

(Desmos=ligament; soma=body)

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Contains two parts:

1) Clear Layer: closer to epithelium and restricts movement of proteins and large molecules from underlying connective tissue into epithelium.

2) Dense Layer: closer to the connective tissues which provides strong connection onto the underlying connective tissue

Highly regenerative! Stimulated by loss of apical-basal polairty and lateral contacts. If a cell breaks off, it divides so that it can replace that part. 

Supplied with nerve tissue!

Since it is avascular, it recieves nourishment through diffusion from underlying tissues.

First name indicates the number of cell layers

Simple epithelia: one layer

Stratified epithelia: two or more layers. Classified by shape of cells in APICAL LAYER.

Second name indicates the shape of the cells

Squamos: flattened and scalelike; nucleus flat

Cuboidal: boxlike; nucleus round

Columnar: tall, column shape; nucleus elongated

[image]

1) Absorption

2) Secretion

3) Filtration

4) Very thin

ex: Gas exchange in lungs, also filtratio and secretion

Allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae.

Used where rapid diffusion is necessary!

Nonciliated type: lines most of the digestive tract (stomach to rectum), gallbladder, and excretory ducts to some glands

Ciliated type: lines small bronchi, uterine tubes, and some of the regions of the uterus.

Nonciliated type: male sperm-carrying duts and ducts of large glands

Ciliated type: lines the trachea and most of the upper respiratory tract

Two or more cell layers, regenerate from below- basal cells divide, cells migrate to surface.

More durable than simple epithelia

Protection is major role

-Most widespread of stratified epithelia.

-Thick membrane composed of several cell layers

-Free surface cells are squamos.

-Deep layers (basal cells) are cuboidal or columnar. Basal cells are active in mitosis and produce the cells of the more superficial layers.

Keratin type: surface cells are full of keratin and dead

Nonkeratinized type: forms the moist linings of the esophagus, mouth, and vagina

Keratinized type: forms the epidermis of the skin, a dry membrane.

What kind of cell is this? Name the parts.

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Stratified Squamos epithelium

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RARE

Found in some sweat and mammary glands

Typically two cell layers thick

Limited distribution in body

Small amounts in pharynx, male urethra, and lining some glandular ducts.

Also occurs at transition areas between two other types of epithelia

Only apical layer is columnar

Resembles both stratified squamos and stratified cuboidal

Basal cells are cuboidal or columnar

Surface cells are dome shaped or squamos-like, depending on degree of organ stretch. 

[image]

What cell is this? Name the parts.

 [image]

Transitional Epithelium

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Gland: makes secretions (aqueous fluid produced by cells).

Classified by: site of product release- endocrine or exocrine, and relative number of cells forming the gland. Ex: unicellular= goblet cells; or multicellular

-Ductless glands: secretions not released into a duct

-Secretion (by exocytosis): secrete hormones that travel through lymph or blood to their specific target organs

-Target organs respond in some characteristic way

-Secretions released onto body surfaces (skin) or into body cavities.

-More numerous than endocrine glands

-Secrete products into ducts

-Ex: mucous, sweat, oil, and salivary glands

-The only imporatnt unicellular glands are mucous cells and goblet cells

-Found in epithelial linings of intestinal and respiratory tracts

-All produce mucin: dissolves in water to form mucus, which is a slimy protective, lubricating coating.

[image]

Composed of a duct and a secretory unit

Usually surrounded by supportive, connective tissue: this tissue supplies blood and nerve fibers, and extends into and diveds glands into lobes

Classified by structure and secretion

Structure

1) Simple glands=unbranched duct

2)Compound glands=branched duct

3)Tubular cells=tubuloalveolal

Secretion

1)Merocrine (most): secrete products by exocytosis as produced

2)Holocrine: accumulate products within the rupture

Most abundant and widely distributed of primary tissues

Four main classes

1)Connective tissue proper

2)Cartilage

3)Bone

4)Blood

Binding and support

Protecting

Insulating

Storing reserve fuel

Transporting substances (only substances in blood)

Three main characterics:

1)Have mesenchyme (an embryonic tissue) as their common tissue of origin

2)Have varying degrees of vascularity (blood vessels)

3) Have extracellular matrix: there are not many cells in connective tissue, mostely nonliving extracellular matrix that separates cells. This allows this tissue to bear weight, withstand tension, and endure abuse.

1) Ground substance

2) Fibers

3) Cells

Composition and arrangement varies in different connective tissues

What type of cell is this? Name parts.

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Connective Tissue

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Subclasses:

1) Loose connective tissue: areorlar, adipose, and reticular

2)Dense connective tissue: regular, irregular, and elastic

Cells associated: fibroblasts, fibrocytes, defense cells, and adipocytes. 

Matrix: gel-like ground substance. All three fiber types are in the matrix; collegen, reticular, and elastic.

1) Six different types; vary in density and types of fibers

2) Functions as a binding tissue

3) Resists mechanical stress, particularly tension

4) Provides reservoir for water and salts

5) Nutrient (fat) storage

Subclasses:

1)Hyaline cartilage

2)Elastix cartilage

3)Fibrocartilage

Cells Associate:

1)Chondroblasts found in growing cartilage

2)Chondrocytes

Matrix: gel-like ground substance. Fibers; collagen, elastic in some

1) Resists compression because of the large amounts of water held in the matrix

2)Functions to cushion and support body structures

Subclasses:

1) Compact bone

2) Spongy bone

Cells associated:

1) Osteoblasts

2) Osteocytes

Matrix: Gel-like ground substance calcified with inorangic cells. Fibers=collagen

Hard tissue that resists both compresion and tension. 

Functions in support

Blood (subclasses, cells, and matrix)

Subclasses: see ch 17

Cells: Erythrocytes (RBC), Leukocytes (WBC), Platelets 

Matrix: Plasma.

No fibers

Blood (features)

A fluid tissue

Functions to carry O₂, CO₂, nutrient wastes and other substances (ex: hormones)

Binding and Support

Protection

Insulating

Storing reserve fuel

Transporting substances (only substances in blood)

Three types of fibers that SUPPORT

1) Collagen: stronest and most abundant type. Tough, provides high tensile strength

2) Elastic Fibers: networks of long, thin, elastic fibers that allow for stretch and recoil

3) Reticular: Short, fine, highly branched collagenous fibers (chemcially different from collagen). Branch, forming networks that offer more "give"/stretching.

1) Blast Cells

2) Fat cells

3) WBC

4) Mast Cells

5)Macrophages

Cell in Connective Tissue

- immature form is mitotically active, secretes ground substance and fibers

-Fibroblasts: in connective tissue proper

-Chondroblasts: in cartilage

-Osteoblasts: in bone

-Hematopoetic stem cells in bone marrow

-"cyte" cells= mature form, maintain matrix

Cell in Connective tissue 

Stores nutrients

White Blood Cells

Cell in connective tissue

- Neutrophils, eosinophils, lymphocytes

- Tissue response to injury

Cells in connective tissue

- Initiate local inflammatory response against foreign microorganisms they detect

cells in connective tissue

- Phagocytic cells that "eat" dead cells and microorganimsms. Function in the immune system

-A type of connective tissue proper that is classified as loose connectice tissue.

-Supports and binds other tissues: universal packing material between other tissues

-Most widely distributed

-Provides reservoir of water and salts

-Defends against infection

-Stores nutrients as fats

-Contains fibroblasts

-Loose arrangement of fibers

-large amount of ground substance: soaks up fluid when inflamed- edema

Gel-like matrix with all three fiber types

Cells: fibroblasts, macrophages, mast cells, and some WBC

-Wraps and cushions organs

-The macrophages phagocyte bacteria (fights infection!)

-Plays important role in inflammation

-Holds and conveys tissue fluid

-Widely distributed under epithelia of body

-Ex: forms lamina propria of mucous membranes

-Packages organs

-Surrounds capillaries

-White Fat:

Similar to areolar but has greater nutrient storage.

Individual cell is called adipocyte (stores nutrients)

Scanty matrix

Richly vascularized

Shock absorption, insulation, energy storage

-Brown Fat:

Use lipid fuels to heat bloodstream not to produce ATP

Also an adipocyte

-Matrix as in areolar, but very sparse 

-Closely packed adipocytes or fat cells

-Have nutrients pushed to the side by large fat droplet

-Provides reserve food fuel

-Insulates against heat loss

-Supports and protects organs

-Under skin in subcutaneous tissue

-Around kidneys and eyeballs

-Within abdoment

-In breasts

-Resembles areolar, but the fibers that are used are reticular fibers instead of collagen or elastic.

-Fibroblasts in reticular connective tissue are called reticular cells

-Supports free blood cells in lymph nodes, the spleen, and bone marrow

-Network of reticular fibers in a typical loose ground substance

-Reticular cells lie on the network

-Fibers form a soft internal skeleton (stroma) that supports other cell types including white blood cells and macrophages.

-Closely packed bundles of collagen fibers running parallel to direction of pull. 

-White structures (fibers) with great resistance to pulling

-Fibers slightly wavy so they stretch a little

-Fibroblasts manufacture fibers and ground substance

-Few cells b/c its primarily made of collagen fibers

-Poorly vascularized

-Primarily parallel collagen fibers

-A few elastic fibers

-Major cell type is fibroblast

[image]

-Attaches muslces to bones or to muscles

-Attaches bones to bones

-Withstands great tensile stress when pulling force is applied in one direction

-Tendons

-Most ligaments

-Aponeuroses 

-Same elements as regular connective, but has bundles of collagen thicker and irregularly arranged

-Resists tensions from many directions: dermis, fibrous joint capsules, fibrous coverings of some organs

-Primarily irregularly arranged collagen fibers

-Some elastic fibers

-Fibroblast is the major cell type

 [image]

-Withstands tension exerted in many directions

-Provides structural strength 

-Fibrous capsules of organs and joints

-Dermis of the skin

-Submucosa of the digestive tract

-Some ligaments very elastic: those connecting adjacent vertebrae

-Many of the larger arteries have this type of tissue in their cell walls: this makes sense because larger arteries need to expnad once blood pumps through them, and then shirnk when blood as left.

-Dense regular connective tissue containting a high proportion of elastic fibers

[image]

-Allows tissue to recoil after stretching

-Maintains pulsatile flow of blood through arteries

-Aids passive recoil of lungs following inspiration

-Walls of large arteries within certain ligaments associated with the vertebral column

-Within the walls of the bronchial tubes

-Chondroblasts (stem cells) and chondrocytes (finished cells)

-Tough yet flexible

-Lacks nerve fibers

-Up to 80% water- can rebound after compression

-Avascular: receives nutrients from membrane surrounding it

-Perichondrium: surrounds cartilage tissue and helps supply nutrients to it

-Three types of cartilage

1)Hyaline

2)Elastic

3)Fibrocartilage

-Amorphous but firm matrix

-Collagen fibers form an imperceptible network

-Chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae

[image]

-Supports and reinforces

-Serves as resilient cushion

-Resists compressive stress

-Forms most of the embryonic skeleton

-Covers the ends of the long bones in joint cavities

-Forms costal cartilages of the ribs

-Cartilages of the nose, trachea, and larynx

-Similar to hyaline cartilage, but more elastic fibers in matrix

 [image]

-Maintains the shape of a structure while allowing great flexibility

-Supports the external ear (pinna)

-Epiglottis

-Matrix similar to but less firm thant hat in hyaline cartilage

-Thick collagen fibers predominate

[image]

-Tensile strength allows it to absorb compressive shock

-Intervertebral discs

-Pubic symphysis

-Discs of knee joint

Connective tissue

- Most atypical connective tissue since it's a fluid

- RBC most common type; also WBC and platelets

- Fibers are soluble proteins that precipitate during blood clotting

-Functions in transport

-Red and white blood cells in fluid matrix

[image]

-Transport respiratory gases, nutrients, wastes, and other substances

-Contained within the blood vessels

-Hightly vascularized

-Responsible for most types of movement

-3 Types

1) Skeletal muscle tissue: voluntary

2)Cariac muscle tissue: involuntary

3)Smooth muscle tissue: walls of hollow organs other than heart; involuntary

-Long, cylindrical, multinucleated cells; obvious striations

-Voluntary movement; locomotion; manipulation of the environment; facial expression; voluntary control

-In the skeletal muscles attached to bones or occasionally to skin

[image]

-Branching, striated, generally uninucleated cells that interdigitate at specialized junctions (intercalated discs)

-As it contracts, it propels blood into circulation; involuntary

-Located at walls of the heart

[image]

-Spindle-shpaed cells with central nuclei; no striations; cells arranged closely to form scheets

-Propels substances or objects (foodstuffs, urine, a baby) along internal passageways; involuntary control

-Mostly in the cell walls of hollow organs

[image]

-Main component of nervous system

-Brain, spinal cord, nerves

-Regulates and controls body functions

-Neurons

-Neuroglia surround cells

-Have neurons, which are branching cells

-Cell proceses that may be quite long extend from the nucleus-containing cell body

-Contributing to nervous tissue are nonexitable supporting cells

[image]

-Nuerons transmit electrical signals from sensory receptors and to effectors (muscles and glands) which control their activity

-Supporting cells support and protect neurons

-Located in the brain, spinal cord, and nerves

-Composed of at leaset two primary tissue types

-Is an epithelium bound to underlying connective tissue proper

-Are simple organs?

-Three types:

1) Cutaneous membrane

2)Mucous membrane

3)Serous membrane

-Skin

-Keratinized stratified squamos epithelium (epidermis) attached to a thick layer of connective tissue (dermis)

-Dry membrane

-Mucosa indicates location, not cell composition

-All called mucosae

-Moist membranes bathed by secretions or urine

-Epithelial sheet lies over layer of connective tissue called lamina propria

-May secrete mucus

-Serosae: found in closed ventral body cavity

-Composed of a single squamos epithelium (mesothelium) resting on thin areolar connective tissue

-Parietal serosae

-Visceral serosae

-Serous fluid between layers (stops friction)

-Moist double membrane

-Pleurae, pericaridium, peritoneum

Pleurae: lungs/visceral cavity

Pericardium: heart

Peritoneum: abdominal cavity

-Necessary when barriers are penetrated 

-Cells must divide and migrate

-Occurs in two major ways

1) Regeneration: same kind of tissue replaces destroyed tissue; original function restored 

2)Fibrosis: Connective tissue replaces destroyed tissue; original function lost

Step 1 in Tissue Repair

Inflammation

-Release of inflammatory chemicals

-Dilation of blood vessels sot hat you can send white blood cells and other kinds of cells to the area

-Increase in vessel permeability

-Clotting occurs with the help of platelets

Organization restores blood supply

-The blood clot is replaced with granulation tissue

-Epithelium begins to regenerate

-Fibroblasts produce collagen fibers to bridge the gap

-Debris is phagocytized from the area

Regeneration and fibrosis

-The scab detaches

-Fibrous tisue matures; epithelium thickens and begins to resemble adjacent tissue

-Results in a fully regenerated epithlium with underlying scar tissue

Regeneration capacity in different tissues

What tissues:

Regenerate extremely well? moderaly? virually not at all?

Extremely well: epithelial, bone, areolar connective, dense irregular connective, and blood-forming tissue

Moderately: smooth muscle, dense regular connective tissue

Virtually not at all: cadiac muscle, nervous tissue of brain (except according to new research), spinal cord

Developmental Aspects

-Name the Primary Germ layers

(superficial to deep)

-What do these form?

Ectoderm- Nerve tissue arises from this

Mesoderm- muscle and connective tissue

Endoderm

-Formed in early embyonic development

-Specialize to form the four primary tissues

-Epithelial cells arise from all layers

-Normally function well through youth and middle age if adequate diet, circulation, and infrequent wounds and infections

-Epithelia thins with increasing age so more easily breached

-Tissue repair less efficient

-Bone, muscle, and nervous tissue begin to atrophy

-DNA mutations possible; increased cancer risk