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

Anatomy & Physiology I LabBSC1085L

Dr. Jason SchwartzDr. Jason Schwartz

BSC 2093 L

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

•Histology = The study of tissues•Tissue = A collection of cells that perform related functions, and are similar in structure

•The Four Primary Tissue TypesEpithelialConnectiveMuscularNervous

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

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

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

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

Squamous Epithelium (surface view)

Simple Epithelial Tissue

Squamous Epithelium (surface view)


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

Squamous

Cuboidal

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

Squamous

Cuboidal


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 GlandThe layered spaces are the lumens of follicles whose walls are composed of simple cuboidal epithelium.

Fig. 5.5a

Fig. 5.5b


• 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 BladderSimple columnar epithelium lines the gall bladder. Note the underlying connective tissue with blood vessels.


• 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 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


• 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

Fig. 4.2g


Gall BladderSimple columnar epithelium lines the gall bladder. Note the underlying connective tissue with blood vessels.

Pseudostratified Columnar Ciliated Epithelium

TracheaThe 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)

apical (free) surface

Transitional Epithelium

Urinary BladderThe 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.

Ureter 100X

transitional epithelium of mucosa

smooth muscle

adventitia

lamina propria

* Ureter 400X

lamina propria

transitional epithelium

smooth muscle

Urinary Bladder 40X

transitional epithelium of mucosa

detrusor muscular layer

lamina propria

submucosa

Bladder (Empty)Bladder (Empty)

White line- defines height of epithelium

Bladder (Full)Bladder (Full)

Orange arrowOrange arrow - - Flattened "plump" cellsFlattened "plump" cells

White line- defines height of epithelium

Red arrowRed arrow - - Transitional Epithelium of UrethraTransitional Epithelium of Urethra

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

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