Human Anatomy And Physiology

Tissues

3 Primary or Embryonic Germ Layers
-formed early in embryonic development
-specialize to form the 4 major tissue typed

1. Ectoderm
-gives rise to nerve tissue

2. Mesoderm
- gives rise to Connective Tissue, Endothelium and Mesothelium

3. Endoderm
-gives rise to most mucosae

Ectoderm, Mesoderm, Endoderm gives rise to Epithelial Tissue

Tissue
- group of cells with similar structures and function surrounded by extracellular matrix

Classified according to:
1. Structure of cells
2. Function of cells
3. Composition of extracellular matrix

4 Major Types of Tissue
1. Epithelial Tissue
2. Connective Tissue
3. Muscle Tissue
4. Nerve Tissue

Epithelial Tissue
-found on surfaces as covering or lining

Classification as to shapes:
1. Squamous cells -flat
2. Cuboidal - cube shaped
3. Columnar - tall and narrow

Classification as to numbers of layers:
1. Simple - single layer
2. Stratified - many layer

Classification as to type of cells:
1. Transitional - many layers with surface cells changing in shape from rounded to flat

2. Ciliated - columnar cells with cilia on free surface

Types of Epithelial Tissue

1. Simple Squamous - one layer flat cells
2. Stratified Squamous - many layer of flat cells
3. Transitional - many layers of cells
4. Cuboidal - one layer of cube shaped cells
5. Columnar - one layer of column shaped cells
6. Ciliated - one layer of columnar cells with cilia

CONNECTIVE TISSUE
- with abundant extracellular matrix in addition to cells

Types of Connective Tissue

1. Areolar or Loose
- fibroblasts and a matrix of tissue fluid collagen and elastin fibers

2. Adipose
-adipocytes that store fat

3. Fibrous
- mostly collagen fibers with few fibroblasts

4. Elastin
- mostly elastin

5. Bone
- osteocytes in a matrix of calcium salts and collagen

6. Blood
- Plasma, RBC, WBC, Platelets

7. Cartilage
- chondrocytes in protein matrix

MUSCLE TISSUES
- specialized for contraction
- shortens when muscle cells contract

3 Types of Muscle Tissue

1. Skeletal
- large cylindrical cells with striations and nuclei each

2. Smooth (organs)
- small tapered cells with no striations and one nucleus each

3. Cardiac
- branched cells with faint striations and one nucleus each

NERVE TISSUE
- consists of nerve cells called neurons and some specialized cells
- forms brains, spinal cord and nerves
- responsible for coordinating and controlling body activities

Parts of Nerve Tissue

1. Neuron - nerve cell

A.) Cell Body

- contains the nucleus and regulates function if neuron

B.) Axon
- cellular process that carries impulses away from cell body

C.) Dendrites
- cellular process that carries towards the cell body

2. Synapse
- space between axon of one neuron and dendrite or cell body of the next neuron

3. Neurotransmitters
- chemicals released by axon

4. Neuroglia
- specialized cells in Central Nervous System

5. Schwann Cells
- specialized cells in Peripheral Nervous System