Ch 4: Tissue

• Groups of cells that are similar in structure and perform a common or related functions are called TISSUE

• The study of tissue, or histology, complements the study of gross anatomy. Together they provide the structural basis for understanding organ physiology.

TissuesTissues

• The tissues of the human body include four major types: general function

• Epithelial: covering

• Connective: support

• Muscle: movement

• Nervous: control

Types of Tissue!!

EPITHELIAL TISSUES

EPITHELIAL TISSUES

• Epithelial Tissue: is a sheet of cells that covers a body surface or lines a body cavity

• Nearly all substances received or given off by the body must pass through an epithelium layer.

EPITHELIAL TISSUES

• Epithelial Tissue lacks of blood vessels, contains little intercellular material and are continually being replaced

• They function in protection, secretion, absorption, filtration, excretion, and sensory reception.

EPITHELIAL TISSUES

• Epithelium Tissue has many characteristics that separate it from other tissue types

• ET has Polarity- which means it has an apical surface (near the top) and a basal surface (near the bottom)

• Specialized Contacts• Supported by

connective tissue.

EPITHELIAL TISSUES

• Each Epithelium Tissue is given two names.

• The first name indicates the number of cell layers present. – Simple- one layer– Stratified- more than one layer

• The second describes the shape of its cells– Squamous, cuboidal, and columnar.

• .

EPITHELIAL TISSUES

• .

Simple Squamous Epithelium

• This tissue consists of a single layer of thin, flattened cells through which substances can pass easily. So delicate they can easily be damaged.

• Common site of diffusion and osmosis. Its functions in the exchange of gases in the lungs

• Lines the air sacs of the lungs (gas exchange), forms the walls of the capillaries, lines the insides of blood vessels and lymph vessels.

• Covers the membrane that line body cavities. • EX: Cheek Cells

Simple Squamous Epithelium

Simple Squamous Epithelium

Simple Cuboidal Epithelium

• This tissue consists of a single layer of cube-shaped cells. Usually have a centrally located spherical nuclei

• It carries on secretion and absorption. Secretes glandular products.

• Covers the ovaries, lines the kidneys, tubules and ducts of certain glands like pancreas and the liver.

Simple Cuboidal Epithelium

Simple Cuboidal Epithelium

Simple Columnar Epithelium

• The tissue is composed of a single layer of elongated cells whose nuclei are usually at about the same level, near the basement membrane.

• Some have cilia some do not• Secretes and absorbs…this tissue is thick!!• This tissue lines uterus and portions of the

digestive tract like small/large intestines and stomach.

Simple Columnar Epithelium

Simple Columnar Epithelium

Simple Columnar Epithelium

Pseudostratified Columnar Epithelium

• They appear stratified but are NOT, They appear to have two or more nuclei but they each reach the basement level.

• Goblet cells scattered throughout the tissue that secret mucus, which the cilia sweep away.

• It lines tubes of the respiratory system. The mucus and cilia created by this tissue trap the dust and microorganisms that enter the airway.

Pseudostratified Columnar Epithelium

• “C” the nuclei appear at various levels giving it the stratified appearance

• “B” the cilia can easily be seen

Pseudostratified Columnar Epithelium

Pseudostratified Columnar Epithelium

Stratified Squamous Epithelium

• Named for the shape of the cells,…consists of many layers, relatively thick. Cells nearer the surface are flat where as the deeper are cuboidal and columnar.

• Tissue can contain Keratin, which is a protein that accumulates and protect the underlying tissue.

• Epidermis-outer most layer of the skin• Also lines the skin and lines the oral cavity, throat,

vagina, and anal canal.

Stratified Squamous Epithelium

• Observe that the surface cells (at B) are flattened (are squamous).

Stratified Squamous Epithelium

Stratified Cuboidal Epithelium

• This tissue is composed of two or thee layers of cube-shaped cells.

• It lines the larger ducts of the mammary glands sweat glands, salivary glands, and pancreas. Forms the lining of ovarian follicles and seminiferous tubules

• It functions in protection.

Transitional Epithelium

• This tissue is specialized to change in response to tension..

• Transition epithelium is unstretched and consists of many layers when the organs wall contract the tissue stretches and appears thinner when the organ is distended.

• Forms the lining of the urinary bladder and lines the ureters and part of the urethra.

Transitional Epithelium

Transitional Epithelium