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reynold-parrish
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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