Tissues

Chapter 5

Epithelial tissue

Covers organs, forms the inner lining of body cavities, lines hollow organsAnchored to connective tissue by basement membraneLacks blood vesselsCells readily divide; injuries heal quickly

Simple squamous epithelium– Single layer of thin,

flattened cells– Fit together like tiles– Nuclei are broad and thin– Site of diffusion– Line air sacs of lungs,

walls of capillaries– Easily damaged

Simple cuboidal epithelium– Single layer of cube shaped cells– Centrally located spherical nuclei– Covers ovaries, lines kidney tubules, ducts of

glands– Functions in the kidneys in secretion and

absorption– Functions in the glands in secretion of

glandular products

Simple columnar epithelium– Elongated, thick– Nuclei located near the basement membrane– Lines uterus and most organs of digestive tract– Some have microvilli– Goblet cells scattered throughout

Pseudostratified columnar epithelium– Appear layered– Cell nuclei are at two or more levels in the row

of aligned cells– Cilia– Lines passages of the respiratory system

Stratified squamous epithelium– Thick– Cells divide in deeper layers, and newer cells push

older ones farther outward where they flatten– Forms outer layer of the skin– As skin cells age, they accumulate a protein called

keratin and then harden and die– Prevents water loss and blocks substances from

entering– (not keratinzed) Lining of mouth, throat, vaginal, and

anal canal

Stratified cuboidal epithelium– Two or three layers– Form the lining of a lumen– Provides protection– Lines mammary glands, sweat glands, salivary

glands, pancreas, developing ovarian follicles and seminiferous tubules

Stratified columnar epithelium– Several layers– Superficial cells are elongated– Basal layers are cuboidal– Male urethra and vas deferens– Parts of the pharynx

Transitional epithelium– Specialized to change in response to increased

tension– Inner lining of urinary bladder, ureters, and part

of the urethra

Tissue EngineeringVideo

Homework

Review Exercises p. 111 #1-5 (omit i.)Write the questions and answers

Connective Tissues

Bind structuresProvide support and protectionServe as frameworksFill spacesStore fatProduce blood cellsProtect against infectionsHelp repair tissue damage

Major cell types– Fibroblasts

• Fixed• Star-shaped• Produce fibers by

secreting proteins into the matrix of connective tissues

• Scurvy (lack of vitamin C) interrupts fibroblasts’ ability to produce collagen

– Macrophages• Originate as white blood cells• Carry on phagocytosis

– Mast cells• Usually located near blood vessels• Release heparin, which prevents blood clotting, and

histamine, which promotes inflammation

Connective tissue fibers produced by fibroblasts– Collagenous

• Great tensile strangth• Compose ligaments and

tendons• White fibers

– Elastic• Composed of elastin• Found in vocal cords• Yellow fibers

– Reticular• Very thin collagenous

fiers• Delicate support

Loose connective tissue (areolar)– Composed of fibroblasts– Binds the skin to the underlying organs– Fills spaces between muscles

Adipose tissue (fat)– Cushions joints and some organs, such as the

kidneys– Insulates beneath the skin– Stores energy in fat molecules

Dense connective tissue– Consists of thick collagenous fibers and

network of elastic fibers– Very strong– Found in tendons, ligaments, white layer of

eyeball, and deeper skin layer

Cartilage– Provides support and

protection– Chondrocytes occupy

small chambers called lacunae

– Three types• Hyaline (nose)• Elastic (ears)• Fibrocartilage

(intervertebral disks)

Bone– Hardness due to mineral

salts and collagen– Supports and protects– Attachment for muscle– Contains red marrow (forms

blood cells)– Osteocytes concentrically

clustered around osteonic canal, form a cylinder-shaped unit called an osteon

Blood– Transports– RBCs, WBCs, platelets, plasma

Muscle Tissue

Contractilemuscle fibers lengthen and shorten

Skeletal muscle– Attached to bone– Can control by conscious effort (voluntary)– Alternating light and dark cross-markings

called striations– Each cell has many nuclei– Move the head, trunk, and limbs

Smooth muscle tissue– Cells lack striations– Shorter than skeletal muscle tissue– Spindle-shaped– Single, centrally located nucleus– Makes up walls of hollow internal organs, such

as the stomach, intestines, urinary bladder, uterus, and blood vessels

– involuntary

Cardiac muscle tissue– Only in the heart– Striated cells are joined end to end– Cells touch each other an intercalated disk– Controlled involuntarily

Nervous Tissue

Found in the brain, spinal cord, and peripheral nervesSense changes in their surroundingsIncludes neurons (nerve cells) and neuroglial cells

Types of membranes

1. Serous– Line body cavities that lack openings to the

outside – inner lining of thorax and abdomen, cover

organs within cavity– Simple squamous epithelium, loose connective

tissue– Secrete serous fluid, a lubricant

2. Mucous– Line cavities and tubes that open to the

outside of the body– Oral and nasal cavities and the tubes of the

digestive, respiratory, urinary, and reproductive systems

– Epithelium, loose connective tissue– Secrete mucus

3. Synovial– Inner linings of joint cavities between the

ends of bones– Dense connective tissue, loose connective

tissue, adipose tissue– Secrete synovial fluid, lubricant

4. Cutaneous– skin

http://www.mhhe.com/biosci/ap/holeessentials/student/olc/chap05out.html