group of similar cells and their intercellular substances that have a similar origin and function together to perform a specialized activity

Four Main Types of Tissues
-classified by their function and structure

1. Epithelial Tissue (Epithelium)---
-covers body surfaces, lines body cavities and ducts, forms glands
-2 types

A. Covering and Lining Epithelium---
-cover body surfaces and some organs
-lines body cavities, blood vessels, respiratory system and gastrointestinal tract
-makes up parts of the sense organs for smell, hearing, vision and touch
-tissue from which gametes develop

B. Glandular Epithelium--- forms the secreting portion of the gland

*both types are “stuck” on connective tissue by a substance called the Basement membrane

*epithelial tissue continuously renewing

*specialized cells have lost their ability to undergo mitosis (muscle and nerve)

2. Connective Tissue---protects and supports the body and its organs, binds organs and stores energy

3. Muscular Tissue---movement

4. Nervous Tissue---initiates, transmits and interprets nerve impulses that coordinate body activities

Named based on two components:

1. Arrangement of Layers

A) Simple Epithelium
-single layer thick
-specialized for absorption or filtration and is found in areas with minimal wear and tear

B) Stratified Epithelium
-several layers thick
-found in areas with high degree of wear and tear

C) Pseudostratified Epithelium
-single layer with appearance of being multilayered
-cells that reach the surface have cilia that move mucous and foreign particles

2. Cell Shapes

A) Squamous--flat and scale like

B) Cuboidal--cube shape

C) Columnar
-tall and cylindrical
-somewhat rectangle

D) Transitional
-combination of shapes
-found in areas of body that undergo a lot of distention

*The combined names lead to the naming of the tissues types:

Simple Squamous Epithelial

Simple Cuboidal Epithelial

Simple Columnar Epithelial

Stratified Squamous Epithelial

Stratified Cuboidal Epithelial

Stratified Columnar Epithelial

Stratified Transitional Epithelial

Pseudostratified Columnar Epithelial

1. Simple Squamous Epithelium---
-adapted for diffusion, osmosis, filtration
-lines aveolar of lungs were gases are exchanged
-kidneys for blood filtration
-inner ear and tympanic membrane
-vascular and lymphatic systems

2. Simple Cuboidal Epithelium
-secretion and absorption
-surface of ovaries
-kidneys were the function is to absorb water
-ducts and secreting units of glands

3. Simple Columnar Epithelium
-lines Gastrointestinal Tract from the cardia of the stomach to the anus
-gallbladder and excretory ducts of many glands
-protects underlying tissues

3 modifications of simple columnar epithelium in the Digestive system:

microvilli---increase surface area

goblet cells---secrete mucous that lubricates

cilia---
-found on some columnar epithelium in the upper respiratory system
-sweep mucous containing foreign particles toward the throat were they will be swallowed or eliminated

-more than 2 cell layers thick
-named for the shape of the cells on the surface

1. Stratified Squamous Epithelium
-surface layers---squamous
-bottom cells continually replicate, cells push outward, the farther away from the blood supply the cells became dehydrated and shrink and become harder
-surface cells rubbed off

A) Non-keratinized Stratified Squamous Epithelium (SSE)
-found on wet surfaces that are subject to wear and tear
-lines the mouth, esophagus, tongue and vagina

B) Keratinized SSE
-surface cells contain keratin
keratin---protein that is waterproof, resistant to friction and bacterial invasionfoun in the outer layer of skin

2. Stratified Cuboidal Epithelium
-rare and uncommon
-function to protect and secrete

3. Stratified Columnar Epithelium
-rare and uncommon
-function to protect and secrete

4. Stratified Transitional Epithelium
-allows cells to stretch without breaking apart from each other
-line hollow structures that expand from within

5. Pseudostratified Columnar Epithelium
-may contain goblet cells that secrete mucous
-line upper respiratory tract and certain parts of the male reproductive system

-secrete stuff
-cells secrete substances into ducts, onto a surface or into the blood

*secretion is an active process

1. Endocrine glands “ductless”
-ultimately secrete their products into the blood
-secretions are always hormones (ex. pituitary, thyroid and adrenal)

2. Exocrine glands
-secretions go into tubes (ducts) that empty at the surface
-secrete mucous, perspirations, oil, wax, and digestive enzymes
-3 types of exocrine glands classified by the function they perform

A) Holocrine glands

-accumulate secretory product in the cell cytoplasm. The cell dies and is discharged with the contents (ex. oil glands)

B) Merocrine glands
-form product then discharges it from the cell
-most exocrine glands are like this (ex. salivary glands)

C) Apocrine glands
-accumulate their product at the outer margin of the cell. This portion is pinched off from the rest of the cell. The cell repairs itself. (ex. sweat glands found in axillary, anal, and genital areas)

-most abundant tissue in the body

-highly vascular EXCEPT---cartilage

-cells scattered throughout with a large amount of matrix between
-intercellular matrix largely determines the tissue qualities

4 general types of connective tissue
1. Connective tissues proper
2. Cartilage
3. Osseous (bone)
4. Vascular

1. Areolar Connective Tissue---
-present around all mucous membranes and around all blood vessels and nerves
-found around some organs and the papillary region of the dermis
-consist of fibers and cells embedded in a semifluid substance (appears unorganized)

Function
-strength, elasticity and support
-may join together with adipose tissue to form the:

Subcutaneous Layer---
-this layer attaches the skin to the underlying tissues
-also connects organs to inside stuff
-also called superficial fascia

2. Adipose Tissue---
-ring shaped cells, with peripheral nuclei, that are specialized for fat storage
-present in the subcutaneous layer beneath the skin, around the kidneys, bottom of the heart, behind the eyeball, padding around joints and in the marrow of the long bones

Function
-energy storage
-insulation
-cushion

Clinical Application:
Suction Lipectomy---
removing fat cells from certain parts of your body

3. Dense Regular Connective Tissue---
-consist of predominately collagenous fibers arranges in bundles, fibroblast present in between bundles
-organized in appearance
-found in tendons, ligaments and membranes around various organs
-provides strong attachments to various structures

4. Dense Irregular Connective Tissue---
-fibers unorganized
-occurs where tension is exerted in various directions
-found in periosteum of bone, perichondrium of cartilage, fibrous capsules around certain organs

5. Elastic Connective Tissue---
-fibers are freely branching in many directions
-found in lung tissue, walls of arteries, trachea, vocal cords and ligaments between vertebrae
-provides strength to structures and allow stretching to various organs

6. Reticular Connective Tissue---
-network of interlacing fibers with thin, flat cells around the fibers
-found in the liver, spleen and lymph nodes
-forms covering of some organs and binds together smooth muscle tissue cells

-capable of enduring more stress than other tissues in the body

-contains no blood vessels or nerves, except for those found in the perichondrium
-made up of a dense collection of collagenous fibers (provide support) embedded in chondroitin sulfate matrix (provides the ability to assume original shape)

perichondrium--- covering that consist of dense irregular connective tissue

1. Hyaline Cartilage---
-appears in the body as a bluish whit shiny substance
-most abundant form of cartilage in the body
-found covering the ends of long bones, form costal cartilage, gives shape to the nose, larynx, trachea, bronchi and bronchial tubes

chondrocytes (cartilage cells)--- -found in groups within spaces of matrix spaces of matrix called lacunae

Functions
-provides flexibility and support as articular cartilage
-gives shape to organs
-reduces friction
-absorbs shock at the joints

2. Fibrocartilage---
-chondrocytes found scattered through many bundles of collagenous fibers
-found in the symphysis pubis, menisci of the knee and the intervertebral disk

Function
-rigid support
-absorption of shock

3. Elastic Cartilage---
-chondrocytes located in a threadlike network of elastic fibers
-found in the external ear and the auditory tubes

Function
-gives support and maintains shape of a structure