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Tissues

Introduction• Cells become specialized to perform specific functions

– Tissues are: groups of similar cells that perform the same function

• Tissues differ from each other in:• 1. size, • 2. shape• 3. arrangement, • 4. function

4 TISSUE TYPESFour primary tissue types• 1. Epithelial tissue• 2. Connective tissue• 3. Muscle tissue• 4. Nervous tissue

EPITHELIAL TISSUE• Sheets of cells covering body surfaces or lining

body cavities or structures that secrete substances

• Found in:– Epidermis of skin (stratified squamous)– Lines digestive tract (stomach-rectum=simple

columnar)– Walls of blood vessels (alveoli of lungs=simple

sqaumous)– Inner lining of body cavities/organs/glands (sweat

gland and kidneys=simple cuboidal)

Epithelial Structure: # layers a. Simple epithelium

– Single cell layer– Flat, irregular shape

b. Stratified Epithelium

– Two or more cell layers

Common in high-abrasion areas

– e.g., Skin surface, mouth

Epithelial Structure: Cell ShapeCell shape• All epithelia have six sides• Cells vary in height• Three common shapes

– Squamous cells– Cuboidal cells– Columnar cells

– Shape of nucleus conforms to shape of cell

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Muscle Tissue

1. Muscle tissue is contractile tissue2.Provide us with motion, posture and heat3. Muscle cell or fiber is basic unit4. 40-50% of body weight5. 3 Types of muscle

A. skeletal muscleB.cardiac muscleC.smooth muscle

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Skeletal Muscle Tissue

A. Covers skeleton-attached to boneB. Visible light and dark banding (looks

striated) so it is called striated muscleC. Voluntary or conscious controlD.Cells are long cylinders with many nucleiE. Muscle fibers contract and relax rapidly

when stimulated

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Skeletal Muscle

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Cardiac Muscle Tissue

1. Appearance: cells are slightly striated branched cylinders with one central nuclei, cells interlace

2. Fx: attached to and communicate with each other by intercalated discs

3. Contracts involuntarily

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Cardiac Muscle

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Smooth Muscle Tissue

1. Appearance:Spindle shaped cells with a single central nuclei

2. Location: Walls of hollow organs (blood vessels, GI tract, bladder)

3. Involuntary and nonstriated

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Smooth Muscle

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Connective Tissue -7 types

1. Loose connective tissue2. Elastic connective tissue3. Adipose4. Fibrous5. Cartilage6. Bone7. Blood

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Characteristics of Connective Tissues

A. Cells far apart with a lot of intercellular material

B. Intercellular material is secreted out to produce the Matrix (fibers & substances secreted by cells

C. Matrix varies from liquid, gel to solidD. Has good nerve & blood supply except

cartilage & tendons

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Types of cells in Connective1. Fibroblasts= most numerous, star-shaped. -Produce collagenous and elastic fibers found in matrix.

2. Macrophages= less numerous– engulf bacteria & debris by phagocytosis

*NO FREE SIDE ON CONNECTIVE: IT IS SURROUNDED BY OTHER TISSUE OR ORGANS

*NO BASEMENT MEMBRANE (ONLY ON EPITHELIAL)

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Types of Fibers in Connective Tissue1. Collagenous (25% of protein in your body)

A.tough, resistant to pull, yet pliable B. formed from the protein collagenC. White in appearance, abundant in tendons

2. Elastic (composed of elastin)A.Very elasticB.Yellowish, called yellow fibrous tissueC. Abundant in vocal cords

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1. Loose connective: AkA: areolar Appearance: 1.bundles of interlacing collagen fibers

with single interlacing elastin fibers 2. Fibroblasts, macrophages,and fat cells- One of most widely distributed tissuesLocation in body: Fills spaces between organs and parts of organsFx:- connects many adjacent structures in body-

acts like “elastic glue”/- “Packing tissue”- fills spaces

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Loose Connective: Areolar• STRUCTURE:

– Mixed up mess– Contains “bit” of

everything• FXN:

– “Packing” material

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2. Elastic/Yellow Elastic Connective Tissue(Characteristics)

A. Consists mostly of elastic fibersB. Appear as short, kinky, hair-like threadsC. Few cells presentD. Has yellowish colorE. Can be stretchedF. Found: part of arterial walls, lung tissue,

and air passages

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Elastic Connective Tissue

• Black = elastic fibers,• Pink = collagen fibers• Nuclei are mostly fibroblasts

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Elastic Connective

• WrinklesLoss of elastin over

time as you age. Skin (epithelial tissue sags over it)

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3. Adipose Tissue (Fat)

A. Fat tissue- special type of loose connective in which cells are filled with fat

B. Widely distributed in bodyC. Appearance: large cells with a single

vacuole containing a droplet of fat

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Adipose tissue (Fat)• STRUCTURE:

– Flattened nuclei– Filled with dietary

fatLocation: Deeper

layer of skin, organ padding, yellow marrow

• 3 Fxn’s: Reduces heat loss, energy storage, protection of organs

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4. Fibrous (Dense) Connective Tissue: tendons, liagaments,

fasciaa. Composed largely of strong

collagenous fibers (few cells)b. Arranged in wavy parallel

bundlesc. Matrix between bundles

contain cells, rows of fibroblasts

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Fibrous connective-cont.

d. Silvery white, strong and toughe. Little elasticity (can resist tension in all

directions)f. Sparingly supplied with blood vessels

(slow to heal) fx: 1. form ligaments(bone to bone) (See knee model) 2. make up tendons (muscles to bone) 3. sheets cover muscles, whites of eyes , dermis of skin

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Tendons

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5. Cartilage

a. Network of fibers in rubbery ground substance

b. Flexible but firm. Does not contain minerals found in bone

c. There are 3 types

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Cartilage • Location of 3 types: 1.Elastic:ribs attach sternum,tip of nose/ears

• 2.Fibro: between vertebrae

• 3.Hyaline: trachea• STRUCTURE:

– “chondrocytes” scattered in groups throughout matrix

– Avascular• FX:

– Provide flexible support

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Osseous tissue (Bone)

• Good blood supply allows for fast healing from breaks/fractures

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7. Blood

-Serves as a transporting fluid- oxygen, nutrients, hormones, wastes

-*Its matrix is called: plasma*- Formed by special tissue in red marrow

Plasma is composed of: a. Erythrocytes- red blood cells b. Leukocytes- white blood cells c.Thrombocytes-cell fragments called platelets

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Blood

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Nervous Tissue-4th type of tissue

-It is sensitive to changes in surroundings.- Basic unit is the Neuron: a nucleus with long

and branching cell processes a.dendrite --- carries impulses towards the cell body

b. axon ---- carries impules away from the cell body• Location: brain, spinal cord, and nerves.

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Nerve Tissue

Quick Quiz

• 1. Give 2 of the 4 major functions of epithelial tissue.

• 2. What is the difference between simple and stratified?

• 3. Name 3 types of muscle tissue, give example of location for each

• 4. Name two differences that exist between the different types of connective tissue 36

Quick Quiz:

• 5. Name two things that all connective tissues have

• 6.Explain how the anatomy of loose connective tissue relates to its physiology

• 7. What is the cause of wrinkles besides the sun?

• 8. Why do ACL (sprains/strains) heal slower than bone breaks?

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• 9. What is the name for bone cells?

• 10. What is name for cartilage cells?

• 11. How does a neuron work?

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