Anatomy & Physiology I Lab BSC 2093 L BSC1085L Dr. Jason Schwartz

Overview Human body starts with one cell Division makes millions of cells Each specialized for particular functions Some are so specialized, they can create hazards Ex. Heart cells Groups of similar cells that are similar in structure and function: tissues

Tissues Histology = The study of tissues Tissue = A collection of cells that perform related functions, and are similar in structure The Four Primary Tissue Types Epithelial Connective Muscular Nervous

Classification of Tissue 1. Epithelial Tissue- lines body cavities, hollow organs and ducts. Forms skin. 2. Connective Tissue- protects and supports the body and organs. 3. Muscle- generates physical force needed for body motion. 4. Nervous Tissue- generates nerve impulses in response to internal and external changes. With the brain, helps maintain homeostatic function.

Epithelial Tissue -- General Features Cover surfaces, line cavities and form glands. Attached to underlying connective tissue by a basement membrane Avascular---without blood vessels nutrients diffuse in from blood vessels in underlying connective tissue What does this mean for especially thick epithelia? Good nerve supply Rapid cell division; responsive to environmental stresses Named according to the shape and arrangement of cells

Special Characteristics Except for glandular, they fit closely together to form continuous sheets Always have one free surface (apical surface): exposed to body’s exterior or the cavity of an internal organ Lower surface rests on a basement membrane, structureless material secreted by cells No blood supply of their own (avascular); depend on diffusion from capillaries Regenerate themselves very easily

Types of Tissues Epithelium (covering) Connective (support) Nervous (control) Muscle (movement) All interweave to form the fabric of the body Tissues organized into organs One organ can be composed of several tissue types

Epithelial Tissue Also called epithelium Lining, covering, and glandular Forms glands Covers all free body surfaces Versatile cells Outer skin layer, and lining of body cavities Every substance entering or leaving must pass through these cells

Classification of Epithelium Two names First name is for number of cells: simple (one) or stratified (more than one) Second name describes shape: squamous (flattened), cuboidal (cube-shaped), and columnar (column-shaped) Names are combined *Stratified epithelia are named for the cells at the free surface of the membrane, not the those resting on the basement membrane

Classification of Epithelia Simple or stratified Figure 4.1a

Classification of Epithelia Squamous, cuboidal, or columnar Figure 4.1b

Simple Epithelia Most concerned with absorption, secretion, and filtration Simple Squamous epithelium Single layer resting on basement membrane Fit closely together Usually forms membranes that use diffusion: air sacs of lungs, walls of capillaries Also forms serous membranes or serosae: slick membranes lining ventral body cavity and cover organs in ventral cavity

Epithelia: Simple Squamous Figure 4.2a

Lung

Squamous Epithelium (surface view)

Simple Epithelial Tissue

Squamous Epithelium (surface view)

Simple Epithelial Tissue

Epithelia: Stratified Squamous Thick membrane composed of several layers of cells Function in protection of underlying areas subjected to abrasion Forms the external part of the skin’s epidermis (keratinized cells), and linings of the esophagus, mouth, and vagina (nonkeratinized cells)

Epithelia: Stratified Squamous Figure 4.2e

Simple Cuboidal & Squamous Epithelium Cuboidal g Squamous g

Fig. 5.9

Fig. 5.9a

Stratified Squamous Epithelium

Stratified Squamous Epithelium of the Esophagus

Simple Epithelia contd. Simple Cuboidal Epi. One layer resting on basement membrane Common in glands and ducts: salivary glands and pancreas Forms walls of the kidney tubules, and covers surface of the ovaries

Simple Cuboidal & Squamous Epithelium Cuboidal g Squamous g

Epithelia: Simple Cuboidal Single layer of cubelike cells with large, spherical central nuclei Function in secretion and absorption Present in kidney tubules, ducts and secretory portions of small glands, and ovary surface

Fig. 4.2b

Simple Cuboidal Epithelium Thyroid Gland The layered spaces are the lumens of follicles whose walls are composed of simple cuboidal epithelium.

Fig. 5.5a

Fig. 5.5b

Simple Epithelia contd. Simple Columnar Epi. One layer of tall cells Fit close together Goblet cells: produce a lubricating mucus, often seen in this type of epithelium Lines entire length of digestive tract from stomach to anus *Epithelial membranes that line body cavities open to the exterior are called mucous membranes or mucosae

Epithelia: Simple Columnar

Fig. 4.2c

Goblet Cell Figure 4.3b

Simple Columnar Epithelium Gall Bladder Simple columnar epithelium lines the gall bladder. Note the underlying connective tissue with blood vessels.

Simple Columnar Epithelium

Simple Columnar Epithelium

Simple Epithelia contd. Pseudostratified Columnar Epi. Rest on basement membrane Cells are different heights, and nuclei appear at different heights above basement Give false (pseudo) impression of stratified Mainly absorption and secretion Pseudostratified ciliated columnar epithelium Ciliated, lines most of respiratory tract Goblet cells produce mucus to trap dust and debris

Epithelia: Pseudostratified Columnar Single layer of cells with different heights; some do not reach the free surface Nuclei are seen at different layers Function in secretion and propulsion of mucus Present in the male sperm-carrying ducts (nonciliated) and trachea (ciliated)

Stratified Epithelia Two or more cell layers More durable than simple Primarily for protection Stratified Squamous Epithelium Most common stratified Usually several layers Free edge are squamous, closer to basement are cuboidal or columnar Found in “high friction” areas: esophagus, mouth, other parts of skin

Stratified Epithelia Stratified Cuboidal and Columnar Epithelia Usually just two cell layers with (at least) the surface cells being cuboidal Surface cells of stratified columnar are columnar, but its basal cells vary in size and shape Both are fairly rare Found mainly in the ducts or large glands

Stratified Epithelia Transitional Epithelium Highly modified Stratified squamous epithelium Forms lining of only a few organs: bladder, the ureters, and part of the urethra All part of the urinary system and undergo considerable stretching Basal layer are cuboidal or columnar; those at the free surface vary in appearance Stretching changes shape, cells can flatten and become squamous-like

Glandular Epithelia Gland: consists of one more cells that make and secrete a particular product Secretion: typically contains protein molecules in an aqueous fluid Noun and verb: glandular cells obtain needed materials from the blood and use them to make their secretion, which they then discharge Two types: Endocrine glands: no connection to surface (ductless), secrete hormones through diffusion Exocrine glands: retain ducts, secretions empty to surface: sweat and oil glands, liver and pancreas, internal and external

Renal Corpuscle 400X Bowman’s capsule capsular space glomerulus

Fig. 4.2g

Simple Columnar Epithelium Gall Bladder Simple columnar epithelium lines the gall bladder. Note the underlying connective tissue with blood vessels.

Simple Columnar Epithelium Gall Bladder Simple columnar epithelium lines the gall bladder. Note the underlying connective tissue with blood vessels.

Pseudostratified Columnar Ciliated Epithelium Trachea The pseudostratified columnar epithelium of the trachea is ciliated and has goblet cells.

Pseudostratified Columnar Ciliated Epithelium

Epithelia: Transitional Several cell layers, basal cells are cuboidal, surface cells are dome shaped Stretches to permit the distension of the urinary bladder Lines the urinary bladder, ureters, and part of the urethra

Transitional Epithelium (Ureter) 3 apical (free) surface

Transitional Epithelium Urinary Bladder The expandable stratified epithelium of the bladder is referred to as transitional epithelium. Note that its surface cells are large rather than flattened as in stratified squamous epithelium.

transitional epithelium of mucosa Ureter 100X transitional epithelium of mucosa lamina propria smooth muscle adventitia

* Ureter 400X lamina propria smooth muscle transitional epithelium

detrusor muscular layer Urinary Bladder 40X transitional epithelium of mucosa lamina propria submucosa detrusor muscular layer

Bladder (Empty) White line- defines height of epithelium

Bladder (Full) Orange arrow - Flattened "plump" cells White line- defines height of epithelium

Red arrow - Transitional Epithelium of Urethra