Download The Tissue Level of Organization

CHAPTER 4
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Tissues are collections of cells and cell
products that perform specific, limited
functions
Histology = study of tissues
There are 4 types of tissues
1. Epithelial
2. Connective
3. Muscle
4. Neural
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Covers body surfaces, lines cavities and tubular structures
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Includes epithelia and glands
Characteristics
 Cells are tightly packed together
 Free (apical) surface exposed to environment
 Attached to underlying connective tissue (basement membrane)
 Avascular (no blood supply)
 Continually replaced at exposed surface
Physical protection (abrasion, dehydration, destruction)
Control permeability
Provide sensation
Produce specialized secretions
1.
2.
3.
4.
Exocrine= secretions are discharged onto the surface
o Milk, sweat, enzymes entering the digestive tract
 Endocrine = secretions are discharged into tissue fluid and blood
o hormones
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Cell layers
1.
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Simple epithelium: single layer of cells
Stratified epithelium: several layers of cells
Pseudostratified epithelium: appears to be stratified but is not
Cell shapes
2.
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Squamous – thin and flat
Cuboidal – cube shaped
Columnar – tall, slender rectangles
1. Simple Squamous
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Locations: Lining of the heart , blood vessels, kidney tubules,
inner lining of cornea, alveoli of lungs
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Functions: Reduce friction, controls vessel permeability,
adsorption and secretion
2. Simple Cuboidal
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Locations: Sweat glands, ducts, kidney tubules, thyroid gland
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Functions: Limited protection, absorption and secretion
3. Simple columnar
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Locations: Lining of the stomach, intestines, gall bladder,
uterine tubes, collecting ducts of kidney
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Functions: protection, absorption and secretion
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Other: : Cells are very long and often have cilia
4. Stratified Squamous
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Locations: surface of skin, lining of mouth, throat, esophagus,
rectum, anus and vagina
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Functions: Protection from abrasion, pathogens, and chemicals
5. Pseudostratified ciliated columnar
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Locations: lining of nasal cavity, trachea and bronchi and
portions of male reproductive tract
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Functions: Protection and secretion
6. Transitional
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Locations: bladder, renal pelvis, ureters
Functions: permits expansion and recoil after stretching
Practice Identifying
epithelial tissues
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Most diverse tissue of the body
Highly vascular
Never exposed to external environment
Characteristics
 Specialized cells
 Extracellular matrix (majority of tissue volume;
determines function)
▪ Solid extracellular protein fibers
▪ Fluid extracellular ground substance (amorphous gel like
substance composed of large carbohydrates and proteins)
1.
2.
3.
4.
Support and protection
Transportation of materials
Storage of energy reserves
Defense of the body
1.
Connective Tissue Proper
a) Loose (underlying skin, fat)
b) Dense (tendons and ligaments)
2.
Supporting Connective Tissues
a) Cartilage (solid rubbery matrix)
b) Bone (solid crystalline matrix)
3.
Fluid Connective Tissues
a) Blood
b) Lymph
1. Loose Connective Tissue
 More ground substance, less fibers
 Mainly composed of fibroblasts
 Locations: between other tissue and organs, beneath
skin, digestive, respiratory and urinary tracts, between
muscles, around blood vessels, nerves and joints
 Functions: cushion, support,
allows movement, defense against
pathogens
1. Loose Connective Tissue
2. Adipose Tissue
 Fibroblasts enlarge and store fat
 Very little matrix
 Locations: beneath the skin and around organs
especially at sides, buttocks, breasts, around eyes and
kidneys
 Functions: padding, shocks insulates,
stores energy
2. Adipose Tissue
3. Dense Connective Tissue
 More fibers, less ground substance
 Fibroblast matrix composed of parallel collagen fibers
 Locations: between skeletal muscles (tendons)
between bones (ligaments), covering skeletal muscles
 Functions: firm attachment; conducts pull of muscle,
reduces friction between muscles, stabilizes position of
bones, helps prevent overexpansion of organs (bladder)
3. Dense Connective Tissue
Gel-type ground substance
For shock absorption and protection
No blood vessels
Types of cartilage include
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Hyaline cartilage
Elastic cartilage
Fibrous cartilage
Hyaline Cartilage
1.
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Most common
Location: between ribs and sternum, bone joints,
trachea, bronchi and nasal septum
Function: Stiff but flexible support; Reduces friction
between bones
Elastic Cartilage
2.
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Elastic fibers in addition to collagen
Locations: external ear and epiglottis
Functions: Supportive but very flexible
Fibrous Cartilage (fibrocartilage)
3.
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Strong collagen fibers in matrix
Locations: knees, pubic bones, intervertebral discs
Functions: Limits movement, prevents bone-tobone contact, absorbs shock, reduces friction
Most rigid connective tissue
Matrix composed of hard mineral salts deposited
around collagen fibers
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Gives bone rigidity and elasticity
Bone cells (osteocytes)
Periosteum (Covers bone surfaces)
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Physical barriers
Line internal spaces of organs and tubes that
open to the outside
Line body cavities
Different types of membranes\
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Mucous
Serous
Cutaneous
Synovial
Meninges
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Mucous = protection
Line passages that have external connections
 Lining of digestive, respiratory, urinary and
reproductive tracts
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Epithelial surfaces are moist to reduce friction
and help absorption and excretion
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Line cavities not open to outside
Are thin but strong
Have fluid to reduce friction
Three serous membranes
 Pleura – lungs
 Peritoneum – abdomen
 Pericardium - heart
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Outer covering of body
Skin
Thick, waterproof and dry
Stratified keratinized squamous epithelium
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Line freely movable joint cavities
Secrete synovial fluid into joint cavity –
provides lubrication
Protects the end of bones
Lacks a true epithelium
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Specialized for contraction
Produces all body movement
Three types
 Skeletal
 Cardiac
 Smooth
1.
Skeletal Muscle
 Specialized for contraction
 Moves and stabilizes bone
 Guards entrances and exits
 Generates heat
 Protects organs
 Cells are long, cylindrical, striated and multinucleate
2.
Cardiac Muscle
 Found only in the heart
 Circulates blood
 Maintains blood pressure
 Cells are short, branched and
striated usually with a single
nucleus
3.
Smooth muscle
 Walls of hollow, contracting organs (blood vessels
digestive, respiratory, urinary and reproductive tracts)
 Moves food, urine and other secretions
 Controls diameter of respiratory passageways and blood
vessels
 Cells are short, spindle-shaped and
non-striated with a single central
nucleus
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Specialized for conducting electrical impulses
Rapidly senses internal or external environment
Processes information and controls responses
Concentrated in the central nervous system
 Brain and spinal cord
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Two kinds of neural cells
 Neurons
 Neuroglia
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A.k.a nerve cells
Perform electrical communication
Parts of a neuron
 Cell body – contains the nucleus
 Dendrites – receive incoming signals
 Axon (nerve fiber) – long thin extension of the cell body
which carries outgoing electrical signals to the effector
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Supporting cells
Repair and supply nutrients to neurons
Tissues respond to injury to maintain homeostasis
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Inflammatory response
The tissue’s first response to injury
Signs and symptoms of the inflammatory response
 Swelling, redness, heat, pain
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Can be triggered by
 Trauma (physical injury) or infection
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Fibroblasts produce dense network of
collagen fibers (scar tissue)
Most successful in…
 epithelia, connective tissues and smooth muscle
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Least successful in…
 Neural tissue, cardiac muscle
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Speed and efficiency of tissue repair decrease
with age due to
 Slower rate of energy consumption (metabolism)
 Hormonal alterations
 Reduced physical activity
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Osteoporosis – age related reduction in bone
strength of women
Tissue
ID
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