Body Tissues A. Tissues 1. Groups of cells with similar structure and function 2. Four primary types a. Epithelial tissue (epithelium) b. Connective tissue c. Muscle tissue d. Nervous tissue

B. Epithelial Tissues. 1. Locations – Body coverings – Body linings – Glandular tissue 2. Functions – Protection – Absorption – Filtration – Secretion

3. Epithelium Characteristics a. Cells fit closely together and often form sheets b. The apical surface is the free surface of the tissue c. The lower surface of the epithelium rests on a basement membrane d. Avascular (no blood supply) e. Regenerate easily if well nourished

4. Classification of Epithelia a. Number of cell layers – Simple—one layer – Stratified—more than one layer

5. Classification by shape a. Shape of cells – Squamous flattened – Cuboidal cube-shaped – Columnar column-like

6. Simple Epithelia a. Simple squamous – Single layer of flat cells – Usually forms membranes Lines body cavities Lines lungs and capillaries

Simple Epithelia b Simple cuboidal – Single layer of cube-like cells – Common in glands and their ducts – Forms walls of kidney tubules – Covers the ovaries

Simple Epithelia c. Simple columnar – Single layer of tall cells – Often includes mucus- producing goblet cells – Lines digestive tract

Stratified Epithelia d. Stratified squamous – Cells at the apical surface are flattened – Found as a protective covering where friction is common – Locations Skin Mouth Esophagus

Stratified Epithelia e. Stratified cuboidal —two layers of cuboidal cells – Both are Rare in human body f. Stratified columnar— columnar—surface cells are columnar, cells underneath vary in size and shape

C. Connective Tissue 1. Found everywhere in the body 2. Includes the most abundant and widely distributed tissues 3. Functions – Binds body tissues together – Supports the body – Provides protection 4. Variations in blood supply – Some tissue types are well vascularized – Some have a poor blood supply or are avascular 5. Extracellular matrix – Non-living material that surrounds living cells

D. Connective Tissue Types 1. bones 2. Hyaline cartilage 3. Elastic cartilage 4. Fibrocartilage 5. Dense connective tissue (dense fibrous tissue) 6. Loose connective tissue 7. Blood (vascular tissue)

1. Bone (osseous tissue) – Composed of Bone cells in lacunae (cavities) Hard matrix of calcium salts Large numbers of collagen fibers – Used to protect and support the body

2. Hyaline cartilage – Most common type of cartilage – Composed of Abundant collagen fibers Rubbery matrix – Locations Larynx Entire fetal skeleton prior to birth

3. Elastic Cartilage – Provides elasticity – Location Supports the external ear

4. Fibrocartilage – Highly compressible – Forms cushion-like discs between vertebrae

6. Dense connective tissue (dense fibrous tissue) Tendons— attach skeletal muscle to bone Ligaments— attach bone to bone at joints Dermis—lower layers of the skin

7. Loose connective Tissue a.Areolar b.Adipose c.Reticular connective tissue-Bone Marrow

a. Areolar tissue Most widely distributed connective tissue Soft, pliable tissue like “cobwebs” Functions as a packing tissue Contains all fiber types Can soak up excess fluid (causes edema)

b. Adipose tissue Fat Cells Functions – Insulates the body – Protects some organs – Serves as a site of fuel storage

Blood (vascular tissue) – Blood cells surrounded by fluid matrix called blood plasma – Fibers are visible during clotting – Functions as the transport vehicle for materials

8. Muscle Tissue a. Function is to produce movement b. Three types – Skeletal muscle – Cardiac muscle – Smooth muscle

a. Skeletal muscle – Under voluntary control – Contracts to pull on bones or skin – Produces gross body movements or facial expressions

Characteristics of skeletal muscle cells Striated Multinucleat(more than one nucleus per cell) Long, cylindrical

b. Cardiac muscle – Under involuntary control – Found only in the heart – Function is to pump blood – Characteristics of cardiac muscle cells Cells are attached to other cardiac muscle cells at intercalated disks Striated One nucleus per cell

c. Smooth muscle – Under involuntary muscle – Found in walls of hollow organs such as stomach, uterus, and blood vessels – Characteristics of smooth muscle cells No visible striations One nucleus per cell Spindle-shaped cells

9. Nervous Tissue Composed of neurons and nerve support cells Function is to send impulses to other areas of the body – Irritability – Conductivity