Transcript Document 7156954

HISTOLOGY
•Epithelial
•Connective
•Muscle
•Nervous
EPITHELIAL TISSUE (GENERAL)
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Functions:
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Protection
Control permeability
Specialized secretions via exocrine glands
Structure:
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Covers internal and external surfaces
Cells bound closely together
Exposed surface, surface attached to connective tissue by
basement membrane
 Basement Membrane: Network of protein fibers that
forms barrier between epithelium and connective tissue
Avascular – obtain nutrients across attached surface
Continual division of stem cells
 Damaged cells are continually replaced
 Epithelial cells only survive 1-2 days
SQUAMOUS EPITHELIUM
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Simple Squamous
 Thin and flat cells, 1 Layer
 Function: diffusion & filtration
 Found: forms capillary walls,
lining air sacs of lungs, lining
body cavities
Stratified Squamous
 Thin and flat cells, More than 1
layer
 Function: protection
 Found: in places of mechanical
stress, skin surface, lining
tongue, mouth, esophagus, and
anus
CUBOIDAL EPITHELIUM
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Simple Cuboidal
 Box shaped cells, 1 layer
 Function: Secretion or absorption
 Found: covering surface of
ovaries, lining kidney tubules,
salivary ducts, and pancreatic
ducts
Stratified Cuboidal
 Box shaped cells, more than 1
layer
 Function: strengthen lumen
walls
 Found: ducts of large sweat
glands, salivary glands, and
pancreas
COLUMNAR EPITHELIAL
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Simple Columnar
 Tall, rectangular cells, 1 layer
 Function: absorption,
secretion,& protection
 Found: Lines stomach, intestinal
tract, excretion ducts, gall
bladder
Pseudostratified Columnar
 Single layer irregularly shaped
cells (looks like multiple layers)
 Function: protection, secretion
 Found: Lining respiratory
passageways, and auditory tubes
TRANSITIONAL EPITHELIAL TISSUE
 Transitional
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Numerous layers of
rounded cells
Function: Withstands
stretching
Found: Lines urinary
bladder and portions of
ureters and urethra
EXOCRINE GLANDULAR EPITHELIA
Exocrine glands: excrete secretions thru ducts onto surface
Unicellular – Goblet cells scattered among epithelial cells
 Multicellular – Secretory sheet, classified by pattern of
ducts
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ex – mucin lining stomach
Mode of Secretion:
 Merocrine: via exocytosis
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Apocrine: lose cytoplasm and secretory product
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Ex. Skin Perspiration, Mucus Glands, Saliva,
Ex. Mammary glands, Axillary Perspiration
Holocrine – cell fills with secretion then bursts and dies
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Ex. Sebaceous glands – oils from base of hair
CONNECTIVE TISSUES
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3 Components
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Specialized cells
Matrix that surrounds cells
Protein Fibers
 Ground Substance (fluid)
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Functions (vary widely)
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Support & Protect - framework
Transport materials – fluid with dissolved material
Energy reserve – fat in adipose tissue
Defense – responds to pathogens by releasing antibodies
Highly Vascular
Protect Organs
CLASSIFICATION OF CONNECTIVE TISSUES:
3 TYPES
 Connective
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Syrupy ground matrix
Ex. Loose (areolar, adipose) & Dense (tendons
& ligaments)
 Fluid
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Connective tissue
Cells suspended in watery ground substance
w/dissolved proteins
Ex. Blood & Lymph
 Supporting
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Tissue Proper
Connective Tissue
Dense ground substance
Ex. Cartilage (Hyaline, Elastic, Fibrocartilage)
and Bone
CONNECTIVE TISSUE PROPER:
CELL TYPES
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Fibroblasts
Produce and maintain connective tissue fibers
and ground substance
 Local maintenance & repair
 permanent
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Macrophages
Defense: Engulf damaged cells and pathogens
Release chemicals to stimulate immune
response
 Fixed or migrating (reinforcement)
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Adipocytes
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Permanent fat cells
Droplet of lipid pushes nucleus to side
Mast Cells
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Mobile, found near blood vessels
Have vesicles filled with chemicals to be
released after an injury or infection
CONNECTIVE TISSUE FIBERS
 Collagen
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Long, straight,
unbranched, flexible
 Elastic
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Protein – elastin
Wavy, branched,
stretchy
 Reticular
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Fibers
Thin, branching
interwoven network
GROUND SUBSTANCE
Fills spaces between cells, surrounds fibers
 Connective tissue proper – clear, colorless,
syrupy to slow movement of pathogens
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LOOSE CONNECTIVE TISSUE
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Areolar Tissue
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Contains all cells and fibers
of connective tissue proper
Separates skin from
muscles
Provides padding
Allows movement
Extensive blood supply
Adipose tissue dominated
by adipose cells
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Behind eyes, kidneys,
heart, abdomen, buttocks,
and breasts
DENSE CONNECTIVE TISSUE
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Consists of mostly collagen
fibers
Regular – collagen fibers
are parallel
 Tendons – connect
skeletal muscle to bone
 Ligaments – contain
elastin, connect bone to
bone
Irregular – meshwork of
collagen fibers
 Provides support in many
directions n (i.e. skin)
FLUID CONNECTIVE TISSUES
 Blood
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Plasma- watery matrix
w/dissolved proteins
Red blood cell (rbc)
White blood cells (wbc)
Platelets
 Lymph
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Interstitial fluid (water
and solutes) enters
lymphatic vessels
SUPPORTING CONNECTIVE TISSUE:
CARTILAGE
 Cartilage
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– gel w/embedded fibers
Chondrocytes – cells found in lacunae
No blood vessels, therefore difficult to repair
Types:
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Hyaline – tightly packed collagen fibers, tough but flexible
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Elastic – elastic fibers, resilient and flexible
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Connects ribs to sternum, supports passageways of respiratory tract,
covers bone surfaces in joints
Flap of outer ear, epiglottis, auditory tube
Fibrocartilage – mostly collagen fibers, durable and tough
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Between vertebrae, between pubic bones, around or within joints
Hyaline
Cartilage
Elastic
Cartilage
Fibrocartilage
SUPPORTING CONNECTIVE TISSUE:
BONE
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Osseous tissue: Bone
Matrix – hard calcium and flexible collagen, very
little ground substance
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Osteocytes found w/in lacunae
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Lacunae surround blood vessels
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Canaliculi extend from central (Haversian)
canal
Osseous Tissue
MEMBRANES
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Membranes - epithelia and connective tissues
combine to form 4 types of membranes:
Mucous Membranes
 Serous membranes
 Cutaneous membranes
 Synovial membranes
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MUCOUS MEMBRANES
 Mucosae
– line cavities with exterior
contact
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Digestive, respiratory, reproductive, and
urinary tracts
 Epithelial
surfaces kept moist
 Ex.
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Simple columnar epithelia of dig. tract
Stratified squamous epithelia of mouth
Transitional epithelia of urinary tract
SEROUS MEMBRANES
 Minimizes
friction when organ moves
 Line internal subdivisions of ventral body
cavity
Parietal – lines inner surface of cavity
 Visceral – lines outer surface or organs
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 Simple
epithelia supported by loose
connective tissue
Pleura – covers pleural cavity and lungs
 Peritoneum – lined abdominal cavity and
associated organs
 Pericardium – lines pericardial cavity and heart
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CUTANEOUS MEMBRANE
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Aka Skin – covers surface of body, thick, dry
Stratified squamous epithelium and underlying
dense connective tissue
SYNOVIAL MEMBRANES
Lines articulation (joint) capsule
 Loose connective tissue and incomplete layer of
epithelial tissue
 Produce synovial fluid for smooth movements
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Mucous Membrane
Serous Membrane
Cutaneous Membrane
Synovial Membrane
MUSCLE TISSUE
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Muscle tissue – interaction between myosin and actin create a contraction
Skeletal – striated voluntary muscle
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Cardiac – striated involuntary muscle
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Large, multinucleated cells (long and slender)
Incapable of dividing, but produced through stem cells
Striations (series of bands)
Only contract when stimulated by nerves
Smaller striated cells, single nucleus
Interconnected by intercalated discs
Limited ability to repair
Pacemaker cells establish a regular rate of contraction
Smooth – nonstriated involuntary muscle
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Walls of blood vessels, hollow tube=like organs
Small, slender cells w/ one nucleus
Actin and myosin are scattered so no striations
Can be repaired
Can contract on own or by nervous system
Skeletal Muscle
Cardiac Muscle
Smooth Muscle
NEURAL TISSUE
Specialized for conducting electrical impulses
 2 Types Cells:
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Long cells w/ 3main parts:
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Neurons – communicate thru electrical events
Neuralgia – physical support for neural tissue, supply
nutrients to neurons
Cell body w/ nucleus
Dendrites – branching projections that receive info
Axon – long projection (w/synaptic terminals) relays
info to other cells
Limited ability to repair
TISSUE INJURY AND REPAIR
 Inflammation
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In response to pathogens, impact, abrasion,
extreme temperatures, or chemical irritation
Mast cells release histamine and heparin that
dilate blood vessels to induce swelling,
warmth, redness and pain
 Regeneration
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Fibroblasts produce dense collagen fibers
called fibrous tissue (scar tissue)
Fibrosis is the permanent replacement of
normal tissues with fibrous tissue (i.e. heart
and muscle tissues)
TISSUES AND AGING
 Speed
and effectiveness of tissue repair
decreases with age (change of hormones
and lifestyle)
 Epithelia gets thinner, bones become
brittle, cardiac muscle fibers and neurons
cannot be replaced
 Osteoporosis – inactivity, low calcium, and
decrease in estrogen result in poor bone
strength