Tissues Four major tissue types 1. Epithelial 2. Connective 3. Muscle 4. Nervous

1 - Epithelial Tissues General characteristics - cover organs and the body line body cavities line hollow organs avascular cells readily divide cells tightly packed function in protection, secretion, absorption, and excretion classified according to cell shape and number of cell layers

Epithelial Tissues 1. Simple squamous – single layer of flat cells substances pass easily through line air sacs line blood vessels line lymphatic vessels 2. Simple cuboidal – single layer of cube-shaped cells line kidney tubules & ducts of some glands cover ovaries

Epithelial Tissues 3. Simple columnar – single layer of elongated cells sometimes possess cilia or microvilli line uterus, stomach, intestines 4. Pseudostratified columnar – single layer of elongated cells appear striated often have cilia line respiratory passageways

Epithelial Tissues 5. Stratified squamous – many cell layers top cells are flat can accumulate keratin outer layer of skin line oral cavity, throat, vagina, and anal canal 6. Stratified cuboidal – 2-3 layers cube-shaped cells line ducts of mammary, sweat & salivary glands, and the pancreas

Epithelial Tissues 7. Stratified columnar – top layer of elongated cells cube-shaped cells in deeper layers line vas deferens, male urethra, and part of pharynx 8. Transitional – many cell layers cube-shaped and elongated cells line urinary bladder, ureters, and part of urethra

Glandular Epithelium Composed of cells that are specialized to produce and secrete substances. 1. Endocrine glands are ductless (product secreted into tissue fluid or blood) 2. Exocrine glands have ducts (product secreted into ducts) - Unicellular exocrine gland composed of one cell goblet cell (secrete mucous) - Multicellular exocrine gland composed of many cells sweat glands, salivary glands, etc.

Types of Glandular Secretions 1. Merocrine glands fluid product (exocytosis) salivary/sweat glands pancreas 2. Apocrine glands cellular product lose portions of cells mammary glands 3. Holocrine glands secretory products release whole cells sebaceous glands

2 - Connective Tissues General characteristics - most abundant tissue type many functions bind structures provide support and protection serve as frameworks fill spaces store fat produce blood cells protect against infections help repair tissue damage have a matrix (cells are farther apart than epithelial) have varying degrees of vascularity have cells that usually divide some are quite rigid (bone and cartilage), some are more flexible (adipose tissue)

Connective Tissue Major Cell Types 1. Fibroblasts fixed cell (present in stable numbers) most common cell large, star-shaped produce fibers 3. Macrophages wandering cell (appear temporarily) phagocytic important in defense 2. Mast cells fixed cell release heparin (anticoagulant) release histamine (chemical messenger, causes vasodilation)

Connective Tissue Fibers 1. Collagenous fibers thick composed of collagen great tensile strength abundant in dense CT hold structures together tendons, ligaments 3. Elastic fibers bundles of microfibrils embedded in elastin elastic vocal cords, air passages 2. Reticular fibers very thin collagenous fibers highly branched form supportive networks

Connective Tissues I- Connective tissue proper 1. loose connective tissue 2. adipose tissue 3. reticular connective tissue 4. dense connective tissue 5. elastic connective tissue II- Specialized connective tissue 6. bone 7. cartilage 8. blood

Connective Tissues 1. Loose connective tissue mainly fibroblasts fluid to gel-like matrix collagenous fibers elastic fibers bind skin to structures beneath most epithelia between muscles 2. Adipose tissue adipocytes cushions and insulates stores fats beneath skin behind eyes around kidneys and heart

Connective Tissues 3. Reticular connective tissue composed of reticular fibers supports walls of liver, spleen, lymphatic organs 4. Dense connective tissue packed with collagenous fibers elastic fibers few fibroblasts bind body parts together tendons, ligaments, dermis poor blood supply

Connective Tissues 5. Elastic connective tissue abundant in elastic fibers some collagenous fibers fibroblasts attachments between vertebrae walls of large arteries, airways, heart 6. Bone solid matrix supports and protects forms blood cells attachment for muscles skeleton osteocytes in lacunae

Connective Tissues 7. Cartilage rigid matrix chondrocytes in lacunae poor blood supply three types a. hyaline b. elastic c. fibrocartilage a. Hyaline cartilage most abundant ends of bones nose, respiratory passages embryonic skeleton b. Elastic cartilage flexible external ear, larynx c. Fibrocartilage very tough shock absorber intervertebral discs pads of knee and pelvic girdle

Connective Tissues Three types of cartilage

Connective Tissues 8. Blood fluid matrix called plasma contains red and white blood cells, as well as platelets transports/defends/ clotting throughout body in blood vessels heart

3 - Muscle Tissues General characteristics muscle cells called muscle fibers contractile three types 1. skeletal 2. smooth 3. cardiac 1. Skeletal muscle attached to bones striated voluntary 2. Smooth muscle walls of organs skin walls of blood vessels involuntary not striated 3. Cardiac muscle heart wall involuntary striated

Muscle Tissues

4 - Nervous Tissues found in brain, spinal cord, and peripheral nerves basic cells are neurons neuroglial cells are supporting cells sensory reception conduction of nerve impulses