Tissues and Differentiation

a group of similar, specialized cells that work together to perform a common function

A tissue that lines most body internal and external surfaces. Any substance that enters or leaves the body must cross an epithelium.

• 1. Protection
• 2. Permeability
• 3. Secretion
• 4. Sensation

ET provide protection from abrasion, dehydration, etc. It protects both internally and externally. All linings, skin, digestive track, reproductive system.

ET controls permeability and regulates the exchange between the environment and the body. Tissues can change permeability (In pregnancy, gut absorbs more calcium)

EX:Lungs are responsible for gas exchange; intestines absorb nutrients and pass the rest,

all exocrine glands are either dervied from or attached to epithelium

EX: Oil, mucus, serous fluid

To give information about the internal and external enviorment

EX: know when to go to the bathroom.

• 1. Cellularity
• 2. Avascular
• 3. Polarity
• 4. Attachement
• 5. Regeneration

ET is made of mostly cells, joined by cell junctions, usually not very thick.

lacks blood supply;uses diffusion of nutrients from underlying tissues or absorption from the environment.

There are structural and functional differences between the exposed and attached surface

basal edge attached to underlying tissue; its composed of protein fibers; 

it restricts the movement of large molecules out of the body and helps to provide strength and integrity of tissue.

Tissue is continuously replaced through rapid divisions of stem cells in the epithelium located near the basal lamina

1. Movement of fluids over and across epithelium.

2. Movement of fluids through epithemlium.

3. Protection from secretions.

• 1. Squamous
• 2. Columnar
• 3. Cubiodal
• 4. Transitional
• 5. Glands

Hair like extensions that move substances over epithelial surfaces ad help trap impurities.

Ex: moving mucus to dump it into the stomach

finger-like projections that move fluid through the epithelium and increase surface area for absorption.

We get more function with more surface area, we see folding to increase surface area to accomplish the function.

• 1. Location:
• 2. Function:
• 3. Composition:
• 4. Details:

• 1. Location: Usually serves as the outer layer of a cell.
• 2. Function: Secretion and absorption 
• 3. Composition: Single layer of cells
• 4. Details: fragile, more permeable than stratified.

• 1. Location: Also on the outer layer but could also be below a layer of simple epithelial
• 2. Function: protection
• 3. Composition: multiple layers of cells
• 4. Details:

• 1. Location: capillaries, alveoli; serous lining of ventral cavity
• 2. Function: exchange gases & nutrients (Cap); secrete slippery substance to reduce friction 
• 3. Composition: composed of thin flattened cells, like a fried egg
• 4. Details: they are exchange epithelia, for rapid exchange of materials.

• 1. Location: Depends but mostly they are on top.
• 2. Function: protection, 
• 3. Composition: composed of many layers of cells.
• 4. Details: Keratinized-found as part of the skin (water proofing protein)
• Non-Keratinized- found in the mouth, tongue, esophagus, vagina and anus.

• 1. long and straight, most common
• 2. composed of bundles of protein 
• 3. strong
• 4. Located: tendons and ligaments, in ct that surrounds the organs

thin, branching fibers

works like a mesh webbing; like a collander for cells

connective tissue, found in the spleen

branched wavy fibers

strecthy

found in connective tissue

• 1. location: within the connective tissue, stationary
• 2. function: responsible for maintaining connective tissue.
• 3. composition:protein subunit of fiber
• 4. details- build fiber

• 1. location: scattered throughout the CT
• 2. function: phagocytize pathogens, release chemotatic factors to illicit an immune response.
• 3. composition:  large cell
• 4. Details: fixed: attached to CT in certain organs, migrating: free to migrate or roam

• 1. location: mobile
• 2. function: mount an immune response and increase inflammation
• 3. composition: cells
• 4. details: response to infection or injury

• 1. location: found all over the body, most membranes, package organs, surrounds capillaries
• 2. function: wraps and cushions the organs, has macrophages which phagocyte the bacteria, plays a role in inflammation
• 3. composition: lg variety of fibers and cell, in ground substance aka gel matrix, with fibroblasts, macrophages. and mast cells.
• 4. details:

• 1. location: hypodermis, around kidneys and eyeballs, abs, breasts
• 2. function: energy reserve, insulation, supports and protects organs.
• 3. composition: fat droplets with nuclei on the side.

• 1. location: lymph nodes, bone marrow, spleen
• 2. function: reticular fibers created by reticular cells support functions cells of the organs/structures.
• 3. composition: reticular fibers in a network, looks like cherry blossoms

• 1. location: joints, dermis, digestive tract
• 2. function: withstand tension in many directions, structural strength
• 3. composition: collagen fibers are interwoven

• 1. location: tendons, most ligaments,
• 2. function: attaches muscles to bones or to muscles, withstands great tensile stress pulling force in one direction
• 3. composition: parallel collagen fibers, few elastic fibers, major cell type fibroblast

• 1. location: walls of large arteries, vertebrate column, walls of bronchial tubes
• 2. function: allows recoil of tisse, maintains pulsing of blood through artieries
• 3. composition: high proportion of elastic fibers.

dense ground substance with closed packed fibers

• 1. cartilage
• 2. bone

• 1. location: embryonic skeleton, nose
• 2. function:
• 3. composition: fine collagen fibers

• 1. location: ear, epiglotis
• 2. composition: elastic fibers make its flexible and resilient

• 1. location: inter vertebral discs, discs of knee joints
• 2. Function: provides a lot of strength, resists compresion.
• 3. composition: dense collagen fibers and little ground substance

1. location: found in a lacunae around a blood vessel that are connected to one another through extensions that run through networks.