Tissue

Groups of cells similar in structure and function

Nervous tissue: Internal communication Brain, spinal cord, and nerves Muscle tissue: Contracts to cause movement Muscles attached to Muscles of heart () Muscles of walls of hollow organs (smooth) Epithelial tissue: Forms boundaries between different environments, protects, secretes, absorbs, filters Skin surface () Lining of GI tract organs and other hollow organs Connective tissue: Bones Tendons Fat and other soft padding tissue

*Epithelial Tissue (Epithelium)  Two main types (by location):  1.  On external and internal surfaces  2.  Secretory tissue in glands

Characteristics  Cells have polarity—upper and lower surfaces  Are composed of closely packed cells  Continuous sheets held together by tight junctions and  Supported by a connective tissue reticular lamina (under the basal lamina)  Avascular but  High rate of regeneration

Classification  Ask two questions:  1. ?  1 = simple epithelium / pseudostratified  >1 = stratified epithelium  2. ?  Squamous  Cuboidal  Columnar  (If stratified, name according to upper layer of cells)

Simple Stratified Apical surface Basal surface

Squamous Cuboidal Columnar

Simple Squamous   Substances easily pass through  Lines blood vessels and lymphatic vessels  Lines (alveoli)  Function: 

Simple Cuboidal  Single layer of  Lines kidney tubules  Covers ovaries  Lines ducts of some glands  Function: 

Simple Columnar  Single layer of  May have cilia  May contain microvilli  Often have  Lines the  Function: 

Pseudostratified Columnar  Single layer of cells that  Usually contain cillia and goblet cells  Lines the

Stratified Squamous Epithelium  Many cell layers  Top cells shaped  Can accumulate  Makes up the outer skin layer (Epidermis)  Lines oral cavity (think gums), vagina, and anal canal  Function:

Transitional Epithelium  Many cell layers  Changes thickness   Lines the urinary bladder, ureters and part of urethra

*Connective tissues  3 Types:  Fibroblasts:  Large, star shaped  Fixed cells   Macrophages   Wandering cell   Mast cells  Fixed  Release heparin –  Release histamine – promotes reactions of

Major Fiber Types  Fiber  Thick with great strength  Composed of  Abundant in dense connective   Found in tendons and ligaments

Fiber Types  Fiber  Composed of  Fibers are branched and flexible  Found in

Fiber Types  fibers  Very thin collagenous fibers  Highly branched  Forms supportive network

Loose Fibrous Connective  Contains many  Fluid to gel like matrix  Collagenous and elastic fibers  Binds skin to  Found beneath most epithelia  Found

Adipose Connective  Has specialized cells called  Cushions, insulates, and stores fat  Found under the skin  Found

Connective  Compose of  Provides  Forms the framework for liver, spleen, and other lymphatic organs

Dense fibrous connective  Packed with  Has only a few  Poor blood supply  Binds body parts together  Forms tendons and ligaments  Found in

Elastic Connective  Abundant with elastic fibers  Few  Contains fibroblasts  Found as attachment between  Found in the walls of large arteries, airways and the heart

Bone Connective  Solid matrix  Cells called osteocytes  Cells found in (chambers)  Supports and protects  Provides attachment for  Produces blood cells 

Blood Connective  Fluid matrix called  Red blood cells, white blood cells and  Function:  Defends against infection  Aids in  Contained within blood vessels

*Cartilage  Rigid Matrix  (cells) in lacunae (chambers)  Poor blood supply  3 Types: 

Hyaline Cartilage Connective  Most type  Found on the  Forms part of the rib cage  Located on the tip of the nose & in resp. passages  Forms the

Elastic Cartilage Connective   Forms external ear  Found within the

Fibrocartilage Connective  Very tough  Acts as a  Forms  Pads within the knee and pelvic girdle

*Muscle Tissue  Skeletal   Attached to bones

Smooth muscle   Not  Found in the walls of internal organs & blood vessels  Located in the

Cardiac muscle   Contains intercalated discs  Found in the walls of the heart

* Nerve Tissue Cells are called Function in

*Membranes  Serous  Lines body cavities that   Contains serous fluid   Composed of epithelial and connective tissue  Inner lining of the thoracic and abdominal cavities

membranes  Mucous  Lines tubes and organs  Secretes  Composed of epithelial and connective tissue  Lines oral and nasal passageways, digestive tract, respiratory tract, urinary & Reproductive tract

membranes  Cutaneous  Covers  Composed of epithelial and connective tissue  Skin!

membranes  Synovial  May contain  Secretes  Composed of connective tissue  Inner lining of joints