MCB 244 Exam 2

Epithelial tissue

Sheet of closely adhering cells and one or more cells thick

What way do epithelial tissues face?

The upper surface is exposed to the environment or an internal space in the body

Where does the epithelium cover?

Body surface (skin), lines body cavities, forms external/internal linings of many organs, and constitutes most gland tissue

What are the functions of the epithelial tissue?

Protection, secretion, excertion, absorption, filtration, and sensation

What does the epithelia protect?

Deeper tissues from invasion and injury

What does epithelia secrete?

Mucus, sweat, enzymes, and hormones

What does epithelia excrete?

Removes wastes from tissues such as CO₂ or bile

What does epithelia absorb?

Chemicals and nutrients from adjacent medium,

Where does epithelia filtrate?

All substances leaving the blood go through the epithelia lining blood vessels, urinary waste goes through the kidney lining

How does epithelia have sensation?

Nerve endings that detect stimulation ranging from a touch on the skin to irritation of the stomach

Where is the basement membrane

Between an epithelium and the underlying connective tissue

What does basement membrane contain?

Collagen, glycoproteins, carbohydrate complexes, and proteins of connective tissue

What does basement membrane do?

Anchors epithelium to the connective tissue, controls exchange of materials between the epithelium and underlying tissues, and binds growth factors from below to regulate development

Basal surface

Surface of an epithelial cell facing the basement membrane

Apical surface

Uppermost surface of an epithelial cell exposed to the lumen of an organ

Laterall surface

Sidewall of a call between apical and basal surface

What class of epithelium is this?

Simple

What class of epithelium is this?

Pseudostratified columnar

What class of epithelium is this?

Stratified

What cell shape is this?

Squamous

What cell shape is this?

Cuboidal

What cell shape is this?

Columnar

What is the class and shape of this epithelia

Simple squamous

What is the class and shape of this epithelia

Simple cuboidal

What is the class and shape of this epithelia

Simple columnar

What is the class and shape of this epithelia

Pseudostratified columnar

Where can simple squamous epithelium be found?

Air sacs of lungs, kidneys/kidney tubules, heart and blood vesels, stomach membranes, and intestines

Where can simple cuboidal epithelium be found?

Liver, thyroid, mammary, salivary, bronchioles, and other glands

Where can simple columnar epithelium be found?

Stomach inner lining, intestines, gallbladder, uterus/uterine tubes, and some kidneu tubules

Where can pseudostratified columnar epithelium be found?

Respiratory tract from nasal cavity to bronchi and portions of male urethra

What is the function of simple squamous epithelium?

Allows rapid diffusion or transport of substances through membrane, secreting lubricating serous fluid

What is the function of simple cuboidal epithelium?

Absorbs, secretes, produces protective mucous coat, and moves respiratory mucus

What is the function of simple columnar epithelium?

Absorbs, secreates mucus, and moves egg/embryo in uterine tube

What is the function of pseudostratified columnar epithelium?

Secretes and propels mucus

Startified epthelia cell structure

Ranges from 2 to 20 or more layers of cells, with some restinf dierctly on others, only the deepest layer is attached to the basement membrane

What is the class and shape of this epithelia?

Keratinized stratified squamous

What is the class and shape of this epithelia>

Nonkeratinized stratified squamous

What is the class and shape of this epithelia?

Stratified cuboidal

What is the class and shape of this epithelia?

Urothelium

Where can keratinized stratified squamous epithelium be found?

Epidermis, especially the palms and soles

Where can nonkeratinized stratified squamous epithelium be found?

Tongue, oral mucosa, esophagus, anal canal, and vagina

Where can stratified cuboidal epithelium be found?

Sweat gland ducts, egg-producing vesicles of ovaries, and sperm-producing ducts of testis

Where can urothelium be found?

Urinary tract, part of kidney, ureter, bladder, and part of the urethra

What is the function of keratinized stratified squamous epithelium?

Resist abrasion and penatration by pathogenic organism and retards water loss through skin

What is the function of nonkeratinized stratified squamous epithelium?

Resists abrasion and penetration by pathogenic organisms

What is the function of stratified cuboidal epithelium?

Sweat secretion, ovarian hormone secretion, produces sperm

What is the function of urothelium?

Stretches to allow urinary tract filling and protects underlying tissues from osmotic damage by urine

Connective tissues are…

Abundant, widely distributed, and histologically variable

What do connective tissues include?

Fibrous tissue, adipose tissue, cartilage, bone, and blood

True or false: Connective tissues vary greatly in vascularity

True

What are the types of cells of fibrous connective tissue?

Fibroblasts, macrophages, leukocytes (white blood cells), plasma cells, mast cells, and adipocytes

What are fibroblasts

Large, fusiform or stellate cells with slender, wispy branches

What do fibroblasts do?

Produce the fibers and ground substance that form the matrix of the tissue

What are macrophages?

Large phagocytic cells wandering through connective tissues

What do macrophages do?

Engulf and destroy bacteria, foreign particles, and dead/dying cells of our body. Also activate immune system when they sense antigens, arise from monocytes

Antigens

Foreign matter

Monocytes

White blood cells that macrophages arise from

What are leukocytes/white blood cells?

Travel briefly in the bloodstream, crawl out through the walls of small blood vessels, and spend most of their time in the connective tissue

What are the two most common types of leukocytes?

Neutrophils and lymphocytes

What do neutrophils do?

They wander around attacking bacteria

What do lymphocytes do?

They react against bateria, toxins, and other foreign agents, often forming dense patches in the mucous membrane

Where do plasma cells come from?

Lymphocytes that turn into plasma cells when they detect foreign agents

What do plasma cells do?

They synthesize disease-fighting proteins called antibodies

Where are plasma cells found?

Lymph nodes, intestine wall, and inflamed tissue

Where are mast cells found?

Along blood vessels

What do mast cells secrete?

Heparin and histamine

What does heparin do?

Inhibit blood clotting

What does histamine do?

Increase blood flow by dilating blood vessels

Where are adipocytes found?

Small clusters in some fibrous connective tissues

Adipose tissue

Adipocyte dominated tissue in singly or small clusters in areolar tissue

What are the three types of protein fibers found in fibrous connective tissues?

Collagenous, reticular, and elastic fibers

Collagenous fibers are…

Tough, flexible, and stretch resistant

What fiber is the body’s most abundant protein, constituting to 25% of the total?

Collagen

What parts of the body are mainly made of collagen?

Tendons, ligaments, and dermis of the skin

What form and colors does collagen take in tissue section imaging?

Coarse, wavy bundles dyed pink, blue, or green

Where is less visible collagen?

Matrix of cartilage, bone, and muscles

What are reticular fibers?

Thin collagen fibers coated with glycoprotein forming spongelike framework

Where are reticular ribers found?

Spleen, lymph nodes, and part of basement membranes underlying epithelia

What are elastic fibers?

Thinner, collagenous fibers that branch and rejoin each other along their course

What protein makes up elastic fibers?

Coiled elastin coated with glycoprotein (fibrilin) to allow stretching and recoiling

Where are elastic fibers accounted for?

Skin, lungs, and arteries for spring back after being stretched

Elasticity

Tendency to recoil when tension is released

What are the two categories of fibrous connective tissue

Loose and dense

Loose connective tissue

Occupied by ground substance, dissolves out of tissue during histological fixation, leaves empty space in prepared tissue sections

What are the two kinds of loose connective tissue

Areolar and reticular

Dense connective tissue

Occupies more space than the cells and ground substance, appears closely packed in tissue sections

What are the two types of dense connective tissue

Regular and irregular

What kind of loose connective tissue is pictured

Areolar

What kind of loose connective tissue is pictured

Reticular

Where is areolar tissue mostly found

Surrounding blood vessels, nerves, esophagus, trachea, fascia between muscles, and underlying nearly all epithelia

What are the functions of areolar tissue

Loosely binds epithelia to deeper tissues, allows nerve and blood passage through other tissues, ready supply of leukocytes for immune defense, and nutrient and waste removal for overlying epithelia

Where are reticular tissues mostly found

Lymph nodes, spleen, thymus, and bone marrow

What is the function of reticular tissues

Form supportive stroma (framework) for lymphoid organs

What kind of dense connective tissue is pictured

Dense regular connective

What kind of dense connective tissue is pictured

Dense irregular connective tissue

Where are dense regular connective tissues mostly found

Tendons and ligaments

What is the function of dense regular connective tissues

Ligaments tightly bind bones together and resist stress, tendons attach muscle to bone and transfer muscular tension to bones

Where are dense irregular connective tissues mostly found

Deeper portion of dermis of skin, capsules around viscera like the liver, kidney, spleen, and around fibrous sheaths of cartilage and bones

What is the function of dense irregular connective tissues

Withstand stresses applied in unpredictable directions and imparts durability to tissues