Chapter 4: The Tissue Level of Organization

Flashcards covering the main tissue types, membranes, and their functions.

What are the four basic types of tissues in the human body?

Epithelial, Connective, Muscular, Nervous

What are cell junctions?

Points of contact between cells.

What are the general features of epithelial tissue?

Cells arranged in sheets, densely packed, attached to a basement membrane, avascular but with nerve supply, frequent mitosis.

How are covering and lining epithelia classified?

Classified according to cell shape and the number of layers.

Describe simple squamous epithelium.

Single layer of flat cells; lines CV and lymphatic system (endothelium), serous membranes (mesothelium), air sacs of lungs, kidneys, cornea, tympanic membrane; functions in filtration, diffusion, and secretion.

Describe simple cuboidal epithelium.

Single layer of cube-shaped cells; covers ovary surface, lines eye lens capsule, pigmented epithelium of retina, kidney tubules, small gland ducts; functions in secretion and absorption.

Describe nonciliated simple columnar epithelium.

Single layer of nonciliated columnlike cells with microvilli and goblet cells; lines GI tract, gland ducts, gallbladder; functions in secretion and absorption, mucus lubrication.

Describe ciliated simple columnar epithelium.

Single layer of ciliated columnlike cells with goblet cells; lines bronchioles, uterine tubes, uterus, paranasal sinuses, spinal cord's central canal, brain ventricles; cilia move mucus and oocytes.

Describe nonciliated pseudostratified columnar epithelium.

Appears multilayered, but all cells attach to the basement membrane; lines epididymis, large gland ducts, parts of the male urethra; functions in absorption and secretion.

Describe ciliated pseudostratified columnar epithelium.

Appears multilayered, all cells attached to basement membrane, contains goblet cells and cilia; lines airways of the upper respiratory tract; secretes and sweeps away mucus.

Describe stratified squamous epithelium.

Two or more layers of cells, apical layer is squamous, deeper layers are cuboidal or columnar; keratinized (skin) and nonkeratinized (wet surfaces); provides protection against abrasion, water loss, UV radiation, and foreign invasion.

Describe stratified cuboidal epithelium.

Two or more layers of cube-shaped cells; ducts of sweat glands and esophageal glands, part of the male urethra; functions in protection, limited secretion and absorption.

Describe stratified columnar epithelium.

Basal layers consist of shortened, irregular cells, apical layer has columnar cells; lines part of the urethra, large excretory ducts of some glands, small areas in the anal mucous membrane; functions in protection and secretion.

Describe urothelium (transitional epithelium).

Variable appearance, relaxed state resembles stratified cuboidal, stretched state resembles stratified squamous; lines urinary bladder, ureters, urethra; allows stretching and maintains protective lining.

What is a gland?

Single cell or mass of epithelial cells adapted for secretion.

Describe endocrine glands.

Secretions (hormones) enter interstitial fluid and then bloodstream; examples include pituitary, pineal, thyroid, parathyroid, adrenal glands, pancreas, ovaries, testes, thymus; regulate metabolic and physiological activities.

Describe exocrine glands.

Secretory products released into ducts that empty onto the surface of a covering and lining epithelium; examples include sweat, oil, earwax, salivary glands, pancreas; produce substances such as sweat, oil, earwax, saliva, or digestive enzymes.

Describe unicellular exocrine glands.

Single cells, goblet cells.

Describe multicellular exocrine glands.

Composed of many cells that form a distinctive microscopic structure or macroscopic organ; sweat glands, oil glands, salivary glands.

What are the modes of glandular secretion?

Merocrine (cell remains intact), apocrine (apical portion released), holocrine (cell destroyed as it releases its product).

What are the two basic elements of connective tissue?

Cells and extracellular matrix.

What are the fibers in the extracellular matrix of connective tissue?

Collagen, elastic, and reticular fibers.

What are the types of embryonic connective tissue?

Mesenchyme and mucous.

What are the types of mature connective tissue?

Loose, dense, cartilage, bone, and blood.

What is cartilage?

Collagenous fibers embedded in a firm matrix of chondroitin sulfates. (Cartilage is made of strong fibers (collagen) stuck inside a firm, squishy material (chondroitin sulfate) that acts like a cushion.)

Describe hyaline cartilage.

provides smooth surfaces for movement at joints, flexibility, and support; weakest type of cartilage and can be fractured.

• Most abundant cartilage in the body; at ends of long bones, anterior ends of ribs, nose, parts of the larynx, trachea, bronchi, bronchial tubes, embryonic and fetal skeleton.

Describe fibrous cartilage.

Support and joining structures together. Strength and rigidity make it the strongest type of cartilage.

• Public symphysis, intervertebral discs, menisci of the knee, portions of tendons that insert into cartilage

Describe elastic cartilage.

Provides strength and elasticity; maintains the shape of certain structures

• Lid on top of the larynx (epiglottis), part of the external ear (auricle), auditory (Eustachian) tubes.

Describe bone tissue.

Function: Support, protection, storage; houses blood-forming tissue; serves as levers that act with muscle tissue to enable movement.

• Both compact and spongy bone tissue make up the various parts of bones of the body.

Describe blood tissue.

Function: Red blood cells: transport oxygen and some carbon dioxide; White blood cells: carry on phagocytosis and mediate allergic reactions and immune system responses; Platelets: essential for clotting.

• Within blood vessels (arteries, arterioles, capillaries, venules, veins), within chambers of the heart.

What are membranes?

Flat sheets of pliable tissue that cover or line a part of the body.

What are the two types of membranes?

Epithelial (mucous, serous, cutaneous) and synovial membranes.

What does muscular tissue consistent of?

Fibers that provide motion, maintain posture, and produce heat.

What is the function of skeletal muscle tissue?

Motion, posture, heat production, protection.

What is the function of cardiac muscle tissue?

Pumps blood to all parts of body.

What is the function of smooth muscle tissue?

Motion (constriction of blood vessels and airways, propulsion of foods through gastrointestinal tract, contraction of urinary bladder and gallbladder).

What two kinds of cells does nervous tissue consists of?

Neurons and neuroglia.

What is the location of the nervous tissue?

Nervous system.

What is the function of the nervous tissue?

Exhibits sensitivity to various types of stimuli; converts stimuli into nerve impulses (action potentials); conducts nerve impulses to other neurons, muscle fibers, or glands.

What is electrical excitability?

The ability to respond to certain stimuli by producing electrical signals, such as action potentials

What is tissue repair?

Replaces worn out, damaged, or dead cells.