Tissues

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Tissues

• Function and Location
• For Epithelial, Connective, Muscular and Nervous

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Nervous tissue Internal communication Brain,
spinal cord, and nerves
Muscle tissue Contracts to cause movement
Muscles attached to bones (skeletal) Muscles of
heart (cardiac) Muscles of walls of hollow
organs (smooth)
Epithelial tissue Forms boundaries, protects,
secretes, absorbs, filters Skin surface
(epidermis) Lining of GI tract organs and other
hollow organs
Connective tissue Supports, protects, binds
Bones Tendons Fat and other soft padding
tissue
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Characteristics of All Epithelial

• Composed mainly of cells bound closely together
• A free surface exposed to the environment,
  passageway or internal chamber
• Basement membrane
• Avascular
• Regeneration
• May have villi, microvilli or cilia

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Functions of Epithelial Tissue

• Physical Protection
• Intercellular connections/gap junctions and tight
  junctions
• Control Permeability
• Provide Sensation
• Produce specialized secretions
• Exocrine secretions are discharged unto the
  surface or through duct
• i.e. sweat, milk
• Endocrine secretions are released into blood
  stream
• i.e. hormones

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Classifying Epithelial

• Classified by number of cell layers
• Simple one cell layer
• Stratified more than one layer of cells
• And Cell shape
• Squamous cells are thin and flat,
• Cuboidal small boxes, appear square, nucleus
  lies near center of cell
• Columnar column like cells with oval nuclei.
• (Shape of nucleus is similar to shape of cell.)

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Simple Squamous
C flattened cells fried egg appearance F
thin, permeable, used for filtration/absorption
by diffusion
FUNCTIONS Reduces friction controls vessel
permeability performs absorption and secretion
LOCATIONS lines heart and blood vessels,
Covers organs, portions of kidney
tubules cornea alveoil of lungs
Cytoplasm
Nucleus
Connective tissue
Lining of peritoneal cavity
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Simple Cuboidal
C one layer of cube-like cells w/ large
spherical central nuclei F secretion and
absorption L glands, ducts, portions of kidney
tubules
LOCATIONS Glands ducts portions of kidney
tubules thyroid gland
Connective tissue
FUNCTIONS Limited protection, secretion,
absorption
Nucleus
Cuboidal cells
Kidney tubule
Basement membrane
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Simple Columnar
(c) Simple columnar epithelium
C single layer of tall closely packed cells
oval nucleus may cilia and goblet cells. Goblet
cells secrete mucus. F absorption and
secretion some can hold and secrete mucus,
enzymes L digestive tract, uterine tubes, c.
ducts of kidneys
Microvilli
LOCATIONS Lining of stomach, intestine,
gallbladder, uterine tubes, and collecting ducts
of kidneys
Cytoplasm
Nucleus
Intestinal lining
Basement membrane
Loose connective tissue
FUNCTIONS Protection, secretion, absorption
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Overview of Simple Columnar
(c) Simple columnar epithelium
Description Single layer of tall cells with
round to oval nuclei some cells bear cilia
layer may contain mucus- secreting unicellular
glands (goblet cells).
Simple columnar epithelial cell
Function Absorption secretion of mucus,
enzymes, and other substances ciliated type
propels mucus (or reproductive cells) by ciliary
action.
Location Nonciliated type lines most of the
digestive tract (stomach to anal
canal), gallbladder, and excretory ducts of
some glands ciliated variety lines small
bronchi, uterine tubes, and some regions of the
uterus.
Basement membrane
Photomicrograph Simple columnar epithelium of
the stomach mucosa (860X).
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• Simple Columnar in the Digestive Tract
• Goblet Cells
• Cilia

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Pseudostratified Columnar
C One layer of cells with varying heights
nuclei seen at different levels may have goblet
cells (secrete) and have cilia F secrete mucus
primarily L lining of nasal cavity, bronchi and
trachea
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Pseudostratified from trachea
LOCATIONS Lining of nasal cavity, trachea,
and bronchi portions of male reproductive tract
Cilia
Cytoplasm
Nuclei
FUNCTIONS Protection, secretion
Basal lamina
Loose connective tissue
Trachea
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Stratified Squamous Epithelium
C free surface cells are squamous deeper
layers are cuboidal F protection against
abrasion, pathogens,chemical attack L surface
of skin, extends into every opening
FUNCTIONS Provides physical protection against
abrasion, pathogens, and chemical attack
LOCATIONS Surface of skin lining of mouth,
throat, esophagus, rectum, anus, and vagina
Squamous superficial cells
Stem cells
Basal lamina
Connective tissue
Surface of tongue
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Generally 2 layers of cube-like cellsFunction
ProtectionLocation sweat glands and other
large glands
Stratified Cuboidal
Lumen of duct
LOCATIONS Lining of some ducts (rare)
Stratified cuboidal cells
FUNCTIONS Protection, secretion, absorption
Basal lamina
Sweat gland duct
Nuclei
Connective tissue
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Transitional Epithelium
C resembles both stratified cuboidal and
stratified squamous basal cells resemble
columnar or cuboidal surface cells similar to
squamous F stretch and recoil
Description Resembles both stratified squamous
and stratified cuboidal basal cells cuboidal or
columnar surface cells dome shaped or
squamouslike, depending on degree of organ
stretch.
Transitional epithelium
Function Stretches readily and permits
distension of urinary organ by contained urine.
Basement membrane
Location Lines the ureters, urinary bladder,
and part of the urethra.
Connective tissue
Photomicrograph Transitional epithelium lining
the urinary bladder, relaxed state (360X) note
the bulbous, or rounded, appearance of the cells
at the surface these cells flatten and become
elongated when the bladder is filled with urine.
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LOCATIONS Glands ducts portions of kidney
tubules thyroid gland
Connective tissue
FUNCTIONS Limited protection, secretion,
absorption
Nucleus
Cuboidal cells
Basal lamina
Kidney tubule
LOCATIONS Lining of some ducts (rare)
Lumen of duct
FUNCTIONS Protection, secretion, absorption
Stratified cuboidal cells
Basal lamina
Nuclei
Connective tissue
Sweat gland duct
LOCATIONS Urinary bladder renal pelvis ureters
FUNCTIONS Permits expansion and recoil after
stretching
Epithelium (relaxed)
Basal lamina
Connective tissue and smooth muscle layers
EMPTY BLADDER
Epithelium (stretched)
Basal lamina
Connective tissue and smooth muscle layers
FULL BLADDER
Urinary bladder
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Glandular Epithelium
Two types Endocrine ductless secrete hormones
into extracellular space eventually enters blood
stream. Exocrine more numerous secrete
products using ducts i.e sweat, oil, mucus,
enzymes Classified by structure, mode and type of
secretion.
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Unicellular Exocrine glands

• Ductless
• Goblet cells secrete mucus directly into organ
  mucus never makes it to bloodstream

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Merocrine Glands

Secrete products by exocytosis Cells arent
changed after secretion i.e pancreas, sweat
glands, salivary glands
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Apocrine Glands
Accumulate products underneath cell surface
eventually cell pinches off Cell repairs itself
repeats process I.e. mammary glands, sweat glands
under arm pits
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Holocrine Glands
Oil gland
Accumulate product until they rupture die for
cause Secretions include product plus cell
debris i.e. sebaceous (oil) glands
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Secretory vesicle
Golgi apparatus
Nucleus
Salivary gland
Merocrine
Breaks down
Mammary gland
Golgi apparatus
Secretion
Regrowth
Apocrine
Cells burst, releasing cytoplasmic contents
Hair
Cells produce secretion, increasing in size
Sebaceous gland
Hair follicle
Cell division replaces lost cells
Stem cell
Holocrine
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Functions of Connective Tissue

• Binding, support and protection
• Insulation/Storing Energy
• Defending the body
• Transportation of substances

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Characteristics of Connective Tissue

• Common origin all arise from same embryonic
  tissue Mesenchyme (next slide)
• Degree of vascularity
• Many Specialized cells
• Composed mainly of extracellular material not
  cells
• Matrix- includes fibers and ground substance
• Ground substance fluid of tissue

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Blast immature cell Cyte mature cell Clast
cell that breaks down others. I.e. osteoclasts
break down bone
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Matrix

• Amorphous has no distinct shape or form
• Ground substance material that fills space
  between cells fluid of tissue
• 3 Types of fibers
• Collagen long, straight, thick white fiber
  strong but flexible unbranched fiber
• Elastin branched and wavy fiber that contains
  protein elastin coiled yellow fibers rubberband
  quality
• Reticular least common fine, branching fibers
  that form networks of fibers support soft tissue
  of organs.

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Connective Tissue
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Cells of Connective Tissue Proper

• Fibroblasts- produce fibers and ground substance
• Macrophages engulf bacteria and other foreign
  bodies (phagocytize)
• Mast Cells mark substances for destruction by
  secreting chemicals (histamine) that start the
  immune response
• Adipocytes (fat cells) stores fat, nucleus and
  organelles are pushed to the side.

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Fixed macrophage
Mast cell
Reticular fibers
Elastic fibers
Melanocyte
Free macrophage
Plasmocyte
Collagen fibers
Blood in vessel
Fibroblast
Free macrophage
Adipocytes (fat cells)
Mesenchymal cell
Ground substance
Lymphocyte
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Areolar
C loose matrix with all three fiber types
contains macrophages, mast cells and WBCs F
cushion organs phagocytize bacteria, (assists
when infections are present. L distributed
under epithelia packages organs
Elastic fibers
Collagen fibers
Fibroblast
macrophage
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C closely packed cells nucleus pushed off to
side by fat droplet vascular F reserve fuel
insulates supports and protects organs. L
under skin around kidneys and eyeballs in
bones, abdomen and breasts
Adipose
LOCATIONS Deep to the skin, especially at sides,
buttocks, breasts padding around eyes and kidneys
FUNCTIONS Provides padding and cushions shocks
insulates (reduces heat loss) stores energy
Adipocytes
Adipose tissue
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C network of reticular fibers in lots of
extracellular matrix composed of reticular cells
and blood cells F form a soft internal
skeleton for organs L lymph nodes bone marrow
and spleen
Reticular
Reticular fibers
Reticular tissue
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C mainly consists of parallel collagen and some
elastin fibers main cell is fibroblast. L
tendons and ligaments F Attach muscle to bone
bone to bone withstands pulling forces (wavy
fibers enable the tissue to stretch)
Dense Regular
Collagen fibers
Fibrocyte nuclei
Tendon
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Characteristics of Cartilage

• Avascular and lacks nerve fibers (diffusion thus
  cartilage is rarely thick)
• Ground substance consists of chondroitin sulfate
• Chondrocytes are the working cells
• Lacunae (small cavities) surround cells

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C matrix appears glossy (amorphous) collagen
fibers most common but not visible L tip of
nose trachea, larynx, ribs costal cartilage,
soft spot, bones of synovial joints, and nasal
septum F offers support with a little
flexibility absorbs resists compressive stress
LOCATIONS Between tips of ribs and bones of
sternum covering bone surfaces at synovial
joints supporting larynx (voice box),
trachea, and bronchi forming part of nasal septum
Chondrocytes in lacunae
FUNCTIONS Provides stiff but somewhat flexible
support reduces friction between bony surfaces
Matrix
Hyaline cartilage
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C little ground substance with lots of collagen
fibers dominating the matrix. Fibers are
interwoven which offers more strength L discs
between vertebra, pubic symphysis, knee
meniscus F shock absorber, resist compressions,
prevents bone to bone contact.
Fibrocartilage
Collagen fibers in matrix
Chondrocyte in lacuna
Fibrous cartilage
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C contains more elastin fibers making tissue
very flexible L ear, epiglottis F maintains
shape of structure but offers more flexibility
and stretch.
Elastic Cartilage
Chondrocyte in lacuna
Elastic fibers in matrix
Elastic cartilage
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C matrix similar to cartilage but contains more
collagen fibers ground substance is Ca and PO4
vascular, vessels travel thru canaliculi Lacunae
(free space) may be present F support, protect,
store Ca and PO4 forms blood cells L Bone
Bone
Canaliculi
Osteocytes in lacunae
Central canal
Matrix
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Blood
(k) Others blood
Description Red and white blood cells in a fluid
matrix (plasma), proteins are not in fiber Form
but are dissolved in plasma, Contains cell
fragments called platelets
Plasma
Neutrophil
Function Transport of respiratory gases,
nutrients, wastes, and other substances. Helps
fight off disease, blood clotting
Location Contained within blood vessels.
Red blood cells
Lymphocyte
Photomicrograph Smear of human blood (1860x)
two white blood cells (neutrophil in upper left
and lymphocyte in lower right) are seen
surrounded by red blood cells.
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Comparison of Classes of Connective Tissues (1
of 2)
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Comparison of Classes of Connective Tissues (2 of
2)
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Muscular Tissue

• Characteristics
• Contain many cells
• Contains lots of vascular tissue
• Elongated shape cells are called fibers
• Possess myofilaments, proteins that enable the
  muscle to contract.

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C long parallel cells with many nuclei banded
or striated voluntary L attach to bones of
skeleton F large movements walking, moving
extremities
Skeletal Tissue
Nuclei
Muscle fiber
Striations
Skeletal muscle
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C striated only one nuclei per cell branching
cells join at junctions called intercalated
discs involuntary F intercalated disc enable
to heart to beat as one unit. Cardiac muscle
contracts together and relaxes together. L
walls of heart
Cardiac Muscle
Nucleus
Cardiac muscle cells
Intercalated discs
Striations
Cardiac muscle
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C not striated each cell contains one nucleus
fibers appear to taper at ends not exactly
parallel involuntary F moves substances
through hollow organs L found in walls of
digestive organs, urinary tract and blood vessels
Smooth Muscle
Smooth muscle cell
Nucleus
Smooth muscle
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C contains cells called neurons and supporting
cells F neurons transmit electrical impulses
supporting cells are nonconducting cells that
support, insulate and protect neurons. L
nervous system brain, spinal cord, nerves
Nervous tissue
Nervous
Nuclei of supporting cells
Cell body of a neuron
Neuron processes
Photomicrograph Neurons (350x)
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Nuclei of neuroglia

• Maintain physical structure
• of tissues
• Repair tissue framework
• after injury
• Perform phagocytosis
• Provide nutrients to neurons
• Regulate the composition of
• the interstitial fluid
• surrounding neurons

Cell body
Axon
Dendrites
Nucleolus
Nucleus of neuron
Dendrites (contacted by other neurons)
Axon (conducts information to other cells)
Microfibrils and microtubules
Mitochondrion
Contact with other cells
Nucleolus
Nucleus
Cell body (contains nucleus and major organelles)
A representative neuron (sizes and shapes vary
widely)