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Histology
The study of tissues
Tissue
A group of similar cells working together to perform a common function.
4 Types of Tissues Epithelial Connective Muscle Nervous
Epithelial Tissue
Covers a body surface or lines a body cavity
Characteristics of Epithelial Tissue
Composed of closely packed cells with specialized points of attachment
Have a free surface and attached to a basement membrane
Avascular but innervated
Rapid cell division Specialized to form
glands
Functions of Epithelial Tissue Protection Absorption Secretion
Filtration Excretion Sensory
Classification of Epithelial Tissue
Cell Shape:Squamous – flattened cells
Cuboidal- boxes
Columnar-tall
Cell Arrangement:Simple – single layers
Stratified – multiple layers
Examples of Epithelial Tissue
Simple Squamous Epithelium(Alveoli of lungs & linings of Blood vessels)
Simple Cuboidal Epithelium(Kidney tubules) A. Cuboidal cells
B. Nucleus of cell
Simple Columnar Epithelium(Digestive Tract)
A. Columnar cellsB. NucleusC. Cell membrane
Pseudostratified Epithelium(Trachea) A. Basement
membraneB. CiliaC. Nucleus
Stratified Squamous Epithelium(Lining of mouth)
A. Layers of epithelium
B. Surface cells
Stratified Squamous Epithelial(Human Cheek Cells)
A. NucleusB. CytoplasmC. Cell Membrane
Transitional Epithelium(Urinary bladder) A. Surface cells
B. Attached cells
Specialized for stretching
Connective Tissue
Connective Tissue
Found everywhere in the body; most abundant and widely distributed of all the tissues.
Characteristics of Connective Tissue
Cells widely separated by an extracellular matrix
Varying degrees of vascularization
Functions of Connective Tissue Binding and support Protection Insulation Transportation
Structural Elements Ground Substance
– unstructured material that fills the space between the cells
Cells Fibers
Collagen fibers Elastic fibers Reticular fibers
Examples of Connective Tissue
Areolar Connective Tissue(beneath the skin)
A. FibroblastsB. Collagen fibersC. Elastic fibers
Reticular Tissue(Spleen, liver, lymph nodes)
A. Reticular fibers
Adipose Tissue(Fat)
A. Nucleus of fat cellB. Fat droplet
Dense Fibrous Connective Tissue(Tendons)
A. FibroblastsB. Collagenous
fibers
Hyaline Cartilage(Ends of bones, trachea, larynx)
A. ChrondrocyteB. MatrixC. Lacuna
Bone A. Central Canal
B. LamellaeC. Osteocyte in
lacunaD. Canaliculi
Blood Leucocytes
(White Blood Cells)
Erythrocytes (Red Blood Cells)
Sickle Cells
Muscle Tissue
Responsible for body movements
Classification Location
Skeletal Cardiac Visceral
Appearance Smooth Striated
Action Voluntary Involuntary
Skeletal Muscle:Attached to bones for movement
AKA: Muscle fibers Long, blunt,
cylindrical Multinucleated Striated Voluntary
A. Width of cellB. Nucleus
Cardiac Muscle:Found in heart
Involuntary Mononucleate Branched StriatedA. Intercalated discsB. Nucleus
Visceral/Smooth Muscle:Found in walls of hollow organs
Involuntary Spindle-shaped Mononucleate No visible
striations
B. Nucleus
Nervous Tissue
Regulates and controls body functions
2 Major Cell Types
NeuronsGenerate and
conduct nerve impulses
Functional cells of the nervous system
Supporting CellsNonconductingSupport, protect and
insulate neurons
Neuroglia
Parts of Neuron
Cell Body Dendrite
Receives information from sensory receptors Axon
Carries impulses away from cell body to target structure
Neurons & Neuroglia A. Cell Body
B. Cell Process (axon or dendrite)
C. Neuroglia (small dark dots)
Neuromuscular Junction A. Axon
B. Motor end platesC. Skeletal cell