Histology. 4 Types of Tissues Human Body Tissues Connective MuscleNeural.
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Transcript of Histology. 4 Types of Tissues Human Body Tissues Connective MuscleNeural.
What are Epithelial Tissues?Structure• Cover internal and external surfaces• Close together• Avascular• Easily regenerated• Life span: 1-2 days
• Basement membrane: attaches epithelia to underlying connective tissue• Made of protein fibers
Functions• Protection• Permeability• Secretion• Exocrine glands
Epithelial SurfacesApical Surface• Microvilli• Increase surface area• Absorption and
secretion• Cilia• Beat to move materials
across the surface
Basolateral Surface• Attached to underlying
cells or tissues• Sides of the cell
Basolateral Surface
Apical Surface
Squamous Epithelium• Simple Squamous• Shape: thin, flat cells; 1 layer• Function: diffusion; filtration• Found: forms capillary walls;
lines air sacs in lungs
• Stratified Squamous• Shape: thin, flat cells;
multiple layers• Function: protection• Found: skin surface; lines
tongue, mouth, esophagus, & anus
Cuboidal Epithelium• Simple Cuboidal• Shape: box-shaped; 1 layer• Function: secretion;
absorption• Found: covering the surface
of ovaries; lining kidney tubules, salivary ducts, & pancreatic ducts
• Stratified Cuboidal • Shape: box-shaped; multiple
layers• Function: strengthen lumen
walls• Found: ducts of large sweat
glands, salivary glands, & pancreas
Columnar Epithelium• Simple Columnar• Shape: tall, rectangular; 1
layer• Function: absorption,
secretion, & protection• Found: lines stomach,
intestinal tract, excretion ducts, gall bladder
• Pseudostratified Columnar• Shape: single layer, irregularly
shaped (looks like multiple layers)• Function: protection,
secretion• Found: lining respiratory
passageways & auditory tubes
Transitional Epithelium
• Transitional• Shape: Numerous layers
of rounded cells• Function: withstands
stretching• Found: lines urinary
bladder and portions of ureters & urethra
What are Connective Tissues?Structure• Highly vascular• 3 Components:
1. Cells2. Protein Fibers3. Ground Substance
Functions (lots of variation!)• Support & Protect – framework• Transport materials – fluid with dissolved materials• Energy reserve – fat in adipose tissue• Defense – responds to pathogens by releasing
antibodies• Protection of organs
3 Types of Connective Tissues1. Connective Tissue Proper• Syrupy ground substance• Ex: Loose (areolar, adipose) & Dense (ligaments, tendons)
2. Fluid Connective Tissue• Cells suspended in watery ground substance with dissolved
proteins• Ex: Blood & Lymph
3. Supporting Connective Tissue• Dense ground substance• Closely packed fibers• Ex: Cartilage (hyaline, elastic, fibrocartilage) & Bone
1. Connective Tissue Proper – Cell Types
• Fibroblasts• Produce and maintain connective tissue
fibers & ground substance• Permanent• Local maintenance & repair
• Macrophages• Defense: Engulf pathogens & damaged
cells• Release chemicals to stimulate immune
response• Fixed or migrating (reinforcement)
• Adipocytes• Fat cells• Permanent• Nuclei & organelles pushed to the side
1. Connective Tissue Proper – Fiber Types
• Collagen• Long, straight, unbranched• Flexible
• Elastic• Protein – elastin• Wavy, branched, stretchy
1. Connective Tissue Proper – Loose Connective Tissue
• Areolar Tissue• Contains all cells and fibers of
connective tissue proper• Separates skin from muscles• Provides padding• Allows movement• Extensive blood supply
• Adipose Tissue• Adipose (fat) cells• Behind eyes, kidneys, heart,
abdomen, buttocks, & breasts
1. Connective Tissue Proper – Dense Connective Tissue
• Mostly collagen• Regular – collagen fibers
are parallel• Tendons – connect
skeletal muscle to bone• Ligaments – connect
bone to bone, contain elastin
2. Fluid Connective Tissue
• Blood• Plasma – watery matrix
with dissolved proteins• Red Blood Cells• White Blood Cells• Platelets
• Lymph• Interstitial fluid (water &
solutes) enters lymphatic vessels
3. Supporting ConnectiveTissue - Cartilage
• Cartilage – gel with embedded fibers• Chondrocytes – cells found in lacunae• Difficult to repair – no blood vessels• 3 Types:
1. Hyaline – closely packed fibers, tough but flexible• Connects ribs to sternum, supports trachea of respiratory tract,
covers bone surfaces in joints
2. Elastic – elastic fibers, very flexible• External flap of outer ear, epiglottis, auditory tube
3. Fibrocartilage – little ground substance, collagen fibers, durable & tough• Between vertebrae, between pubic bones, around or within some
joints
3. Supporting ConnectiveTissue - Bone
• Osseous Tissue – bone• Matrix – hard calcium & flexible collagen• Little ground substance
• Osteocytes found in lacunae• Lacunae surrounded by blood vessels• Canaliculi extend from central canal
What are Muscle Tissues?• Specialized for contraction• 3 Types:
1. Skeletal Muscle – striated, voluntary muscle• Large multinucleated cells (long &
slender)• Striations (series of bands)
2. Cardiac Muscle – striated, involuntary muscle• Smaller striated cells, one nucleus• Interconnected by intercalated discs• only found in the heart
3. Smooth Muscle – nonstriated, involuntary muscle• Small, slender cells with one nucleus• walls of blood vessels, hollow tube-
like organs
What are Neural Tissues?• Specialized for conducting electrical impulses• Neurons – communicate through electrical events• Long cell with 3 main parts
1. Cell body with nucleus2. Dendrites – branching projections that receive info3. Axon – long projections (with synaptic terminals) that relay
signals to other cells• Limited ability to repair
Tissue Injury & Repair
• Inflammation• In response to pathogens, impact, abrasion,
extreme temperatures, or chemical irritation• Mast cells release chemicals (i.e. histamine)
that dilate blood vessels to induce swelling, redness, heat, & pain
• Regeneration• Fibroblasts produce dense collagen fibers
called fibrous tissue (aka scar tissue)