Body tissues are divided into 4 categories: 1. Connective 2. Nerve 3. Muscle 4. Epithelial

Tissue TypesBody tissues are divided into 4

categories:1. Connective2. Nerve3. Muscle4. Epithelial

1. Connective Tissue

-Functions: Connect, support, transportation (blood), defense, and storage (fat)

-cells are surrounded by some type of non-living matrix

-classified by their structure and the type of matrix

-there are four major classes of connective tissue with subcategories

I. Fibrous, II. Bone, III. Cartilage, IV. Blood

a) Loose- the stretchable fascia between organs-like an elastic glue spread between organs

I. Fibrous (have extracellular fibers)

b) Adipose- fat storage under the skin -important for protection and insulation

c) reticular- web like fibers of the lymphatic (immune) system

- helps filter blood - contains white blood cells to destroy

dangerous invaders

d) dense- tendons and ligaments –flexible but strong

-tendon- connects muscle to bone -ligament- connects bone to bone

II. Bone bone cells are called osteocytes -osteoblast- bone building cell -osteoclast-­­ bone destroying cell

the 2 cells above work together and can reshape bone

Cross-section of long bone

Haversian system

Osteocytes

III. Cartilage chondrocytes are cartilage producing cells cartilage is avascular (no blood vessels) there are 3 subcategories of cartilage

a) hyaline cartilage- shiny and smooth, at the ends of bones (linings of joints)

chondrocytes

b) Fibrocartilage- strongest and most durable, “shock absorbers” (intervertebral discs, meniscus of the knee joint)

c) Elastic cartilage- most flexible cartilage (ears, nose, larynx)

Considered a connective tissue because it is made in the bones

Hematopoiesis- the process of blood production in the red marrow of the bones

has a liquid matrix called plasma

There are 3 main types of blood cells:1) Erythrocytes- red blood cells: carry O2 (some CO2)

2) Leukocytes- white cells: kill invaders3) Thrombocytes- responsible for blood clotting by

producing platelets

IV. Blood

2. Muscle TissuesAll are responsible for movement-May be voluntary or involuntary-May be striated or non-striated

Voluntary= may be “willed” to move

Involuntary= not controlled by thought or will

Striated= visible “stripes” on tissue

Non-striated= no visible “stripes

Striated and voluntary Cells are very long and thin with multiple

nuclei

I. Skeletal muscle

Non-striated and involuntary Cells are shorter and each with one nucleus

II. Smooth Muscle

Striated and involuntary Cells connect at dark “disks” and only one

nucleus per cell.

III. Cardiac muscle (heart)

3. Nerve Tissue

-Rapidly regulate and integrate body activities

-2 basic kinds of cells

1. neurons=conducting cells2. glial cells= support cells

Soma: main body of cell (nucleus is here) Dendrites: short thin branches that carry signal

towards the soma Axon: long thin “wire” carrying signal away from

the soma Synapse: where neurons connect to transmit

signal

Important parts of a neuron:

Schwann Cells- wrap around the axon to insulate the “wiring” to speed nerve signal transmision

One Very Important Glial Cell:

- Responsible for the fatty white matter of the nervous system

4. Epithelial Tissue-Cells are tightly packed into sheets with no “matrix” between cells

-sheets of cells attached to a “basement membrane”

-2 main types:membranousglandular

Classification is based on shapes and layers:

Membranous Epithelium

Description of Cell Shapes:Squamous -(flat and scaly)Cuboidal -(cubic)Columnar -(tall narrow column)Pseudostratified columnar -(odd columns, not

all reach the surface)

Description of Layers:Simple (one layer)Stratified (several layer of same cell type)

Simple Squamous- VERY thin. Where quick diffusion is necessary

lining of blood vessels, tiny air sacs in lungs, parts of kidney, etc.

Cross-section“flat”

Stratified Squamous- areas that receive friction

skin, mouth, esophagus

Cross-section

Cuboidal- lines many ducts and tubules

Cross-section

Columnar epithelium- may be ciliated with tiny “hairs” (cilia)

Non ciliated- lines gastrointestinal

tract

Ciliated- lines respiratory tract

Synthesizes and secretes a chemical product

Glandular Epithelium

oEndocrine gland- secrete directly to bloodstream

oExocrine gland- secrete into collecting ducts

oUnicellular gland- single cells called goblet cells that produce mucous