Administration



Tissues

We'll talk about the other stuff as we need to.

So, what are these things?

They are groups of similar cells that perform a particular function.

There are four major types

Epithelial

Connective

Muscle

Nervous

All tissues have an extracellular matrix

This is a nonliving portion of the tissue

Epithelial Tissue

Function

Protection, secretion, absorption, and excretion

Location

Cover body surfaces, cover and line internal organs, compose glands

Distinguishing characteristics

Lack blood vessels, readily divide, cells are tightly packed

One side is always exposed to an open area

Basement membrane the part of the extracellular matrix that anchors it to the connective tissue

Different types of epithelial tissues

Classified by shape and number of layers

There are nine different types

Simple squamous - Stratified cuboidal

Simple cuboidal - Stratified columnar

Simple columnar - Transitional

Psuedostratified columnar

Stratified squamous - Glandular

Simple Squamous Epithelium

Simple – composed of only one layer of cells

Squamous – thin flattened cells

They look somewhat like floor tiles and their nuclei are usually broad and thin

Since stuff pass through them pretty easily, they are usually used at site of diffusion

Alveoli in the lungs, capillaries, inside of blood vessels

Delicate, so it is easily damaged

Simple Cuboidal Epithelium

A single layer of cube shaped cells

The nuclei are typically centrally located

Lines ovary, kidneys, and the ducts of other glands such as the salivary gland, thyroid, liver, and pancreas

In the kidneys it is used to secrete and absorb, in the glands it only secretes glandular products

Simple Columnar Epithelium

A single layer of elongated cells (taller than they are wide)

Nuclei are typically located near the basement membrane

They have other things added depending on their job

Cilia to help create currents

Small processes called microvilli to absorb

Flask shaped glandular cells (goblet cells) to make mucus

Psuedostratified Columnar Epithilium

Look to be more that one layer, but are not. The appearance come from the nuclei being at different levels

Typically have cilia on the free surfaces

Line the respiratory system

Used for secretion, protection, and movement of mucus

Stratified Squamous Epithelium

Has many layers of the cells that are flattened in the upper layers

The cells divide in the deeper layers, and push the older layers outward

Make up the upper layer of the skin, the lining of the anal cavity, vagina, oral cavity, and the esophagus

Used for protection

Stratified Cuboidal Epithelium

Made of two to three cuboidal cells layers

Form the linings of lumens (openings)

More layers = more protection

Line the large ducts of the mammary glands, sweat glands, salivary glands, and pancreas

Stratified Columnar Epithelium

Once again, made of many layers

The basal layers (base layers) are cuboidal, but the upper layers elongate

Found in the male urethra, vas deferns, and the pharynx

Used for protection and secretion

Transitional Epithelium

Specialized to change in response to increased tension

Used in area that expand and deflate

Forms the inner lining of the ureters and the urinary bladder

Not only changes shape, but prevents wastes from diffusing back into the body

Glandular Epithelium

Specialized to produce and secrete substances

Into ducts – exocrine glands

Into the body fluids – endocrine glands

Three main types

Merocrine – releases secretions without loss of cytoplasm

Apocrine – losses small portions of the cell body

Holocrine – release entire cell filled with product

Connective Tissue

Binds structures together, provides, support and protection, serve as framework, fills space, stores fats, produces blood cells, fights against infections, and helps repair damaged tissues

Lots of extracellular matrix

Can be fibers or a ground substance

Can usually divide, typically have a good blood supply

Major Cell Types

Fibroblasts – large star shaped cell

Produce fibers

Macrophages – originate as white blood cells

Carry out phagocytosis

Move about and are scavengers and defenders

Mast cells – widely distributed, typically near blood vessels

Release heprin and histamine

Connective Tissue Fibers

Collagenous fibers – thick threads of collagen proteins

Grouped in long parallel bundles

Not very elastic, but great tensile strength

Really important in making ligaments and tendons which hold muscles and bones together

appears white when a lot are together therefore sometimes called White Fibers

Some more fibers

Elastic Fibers – composed of elastin proteins

Thin fibers branch forming complex networks

Stretch easily,but not a lot of tensile strength

Common in areas that are typically stretched

Ex: vocal cords

Sometimes called yellow fibers due to yellowish appearance when a number are together

Last fiber type

Reticular fibers – very thin collagenous fibers

Highly branched

Provide delicate supporting networks to many tissues

Least common of the fibers

Loose Connective Tissue

AKA areolar tissue

Delicate, thin membranes throughout the body

Mainly made of fibroblasts and a gel-like extracellular matrix that has lots of fibers

Binds skin to underlying organism fills space between muscles, lies under most layers of epithelium

Special type- Adipose tissue (fat) forms within adipocytes. Lies beneath the skin and around other organs

Cushions joints and some organs and insulates as well as stores energy in fat molecules

Dense Connective Tissue

Consists of many densely packed, thick, collagenous fibers and a fine network of elastic fibers

Strong, so can withstand pulling

Used in tendons and ligaments

Also make up the sclera (the white of the eye)

Cartilage

Rigid connective tissue

Provides support, framework, and attachment points

Provides the structural models for many bones

Lots of gel-like matrix and collagen fibers

Chondrocytes (cartilage cells) live in small chambers and nutrients must diffuse to them from a perichondrium

Bone

Most rigid connective tissue

Hardness due to storing mineral salts between the cells. This and the collagenous fibers make up the extracellular matrix

Osteosytes are located in lacunae and rings of material is laid around them

Blood

Yep, it is a connective tissue

It travels about and transports many materials to body cells and the environment

Muscular Tissue

Are able to contract (shorten) in response to a specific stimuli. This causes something to move.

Three types

Skeletal

Smooth

Cardiac

Skeletal Muscle Tissue

Found only in muscles that are attached to bones

Under voluntary control

Has long thread like cells with alternating light and dark cross-markings called striations and are multinucleated

Allows us to move the head, trunk, and limbs, as well as smile, talk, sing, chew, swallow and breath

Smooth Muscle Tissue

Called smooth because they have no striations

Are shorter than skeletal muscles and are spindle-shaped

Found in the walls of hollow internal organs

Typically involuntary

Cardiac Muscle Tissue

They are striated with a single nuclei and intercalated discs ( a special intercellular junction)

They are only found in the heart

They are involuntary also

Nervous Tissue

Found in the brain, spinal cord, and peripheral nerves

Basic cell is called a neuron

Neuroglial cells are the helper cells

They respond to changes in their environment

Used for sensory reception and conduction of nerve impulses

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download