Transcript Chapter 4 Notes - Tri-City

Anatomy: Chapter 4
Epithelial Tissue
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Sheet of cells that covers a body surface or lines
a body cavity
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Forms boundaries between different environments
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Outer layers of skin, lines open cavities of
cardiovascular and respiratory systems
Epidermis of skin, bladder
Serves many functions
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Protection – skin protects from infection, injury
Absorption- digestive tract specialized
Filtration- kidneys performs all the next 3
Excretion
Secretion - glands
Sensory reception
Characteristics of Epithelium
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Cellularity
Specialized contacts
Polarity
Supported by CT
Avascular but innervated
Regeneration
Characteristics of Epithelium
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Cellularity
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Composed almost
entirely of closely
packed cells
Very little
extracellular space
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Specialized
contacts
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Fit close together
to form continuous
sheets
Bound by lateral
contacts called
tight junctions or
desmosomes
Characteristics of Epithelium
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Polarity
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Have apical or exposed
surface and basal or
attached surface
Polarity means cells
near apical surface
differ from those near
basal surface in both
structure and function
Apical – are smooth
with microvilli
Basal lamina- thin
supporting sheet for
basal surface.
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Non cellular, acts like
tape for cells.
Made of glycoproteins
Very sticky
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Supported by CT
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Rests upon CT and is
supported by CT
Just below basal lamina
is the reticular lamina
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Contains fine network
of collagen fibers that
belong to underlying
CT
Basal lamina + reticular
lamina = basement
membrane
Basement membrane
defines epithelial
boundary
Characteristics of Epithelium
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Avascular but
innervated
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Contains no blood
vessels
Supplied by nerve
fibers
Nourished by
diffusion from
blood vessels
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Regeneration
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High regeneration
capacity
Often removed by
abrasion
As long as nutrition
is adequate then
they can replace at
a high rate
Classifications of Epithelia
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Simple vs Stratified
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Simple
Stratified
Squamous vs Columnar vs Cuboidal
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Squamous
Columnar
Cuboidal
Simple Epithelia
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Simple – made of a single layer of
cells
Typically found where absorption
and filtration occurs
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Sub levels to follow
Simple Squamous Epithelia
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Single layer of flattened cells with disc shaped
central nuclei and sparse cytoplasm
Function: passage of materials by diffusion
Location: kidney, alveoli of lungs, blood vessels,
lymphatic vessels
Simple Cuboidal Epithelium
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Single layer of cubelike cells with large central nuclei
Function: secretion and absoption
Location: kidney tubules, ducts of small glands,
ovary surface
Simple Columnar Epithelium
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Single layer of tall cells with oval nuclei; some have
cilia or mucus secreting cells
Function: absoption, secretion of mucus and
enzymes
Location: nonciliated lines digestive tract,
gallbladder, and excretory system
Pseudostratified Columnar Epithelium
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Single layer of cells of differing heights, some not
reaching apical surface, nuclei seen at different
levels, may contain goblet cells or cilia
Function: secretion(mucus), ciliary action
Location: trachea and upper respiratory tract
Stratifed Epithelium
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All contain 2 or more layers of cells
Regenerate from basal cells (from
below)
Considerably more durable than
simple epithelia cells
Typically used for protection
Stratified Squamous Epithelium
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Thick membrane composed of several cell layers,
basal cells are cuboidal/columnar and
metabolically active, upper cells flattened
Function: protects from abrasion
Location: mouth, esophagus, epidermis of skin
Stratified Columnar Epithelium
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Several cell layers, base cells usually cuboidal,
superficial cells elongated and columnar
Location: rare in body, urethra and large glands
Function: protection, secretion
Transitional Epithelial Tissue
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Resembles both strat. Squamous and strat. Cuboidal.
Basal cells cuboidal or columnar; surface cells domed
Function: distention of urinary organ (helps you pee)
Location: lines ureters, bladder, and part of urethra
Assignment
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Pg. 147
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Questions 3 M.C. and 2 C. T.
Connective Tissue
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Found literally everywhere in the
body
Most abundant and widely
distributed of the primary tissues
Class of C.T.
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C.T. Proper
Cartilage
Bone
blood
Functions of C.T.
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Binding and Support
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Protection
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Bone and cartilage
Transportation
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Bone and cartilage
blood
Insulation
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Fat (adipose tissue)
Common Characteristics of C.T.
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Common origin
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Degrees of vascularity
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Arise from mesenchyme (embryonic)
Range from avascular (cartilage) to poorly
vascular (dense CT) to very vascular (tissue
that supply blood vessels)
Extracellular Matrix (ECM)
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Non-living womb
Allows CT to bear weight, withstand great
tension, and endure abuses.
Structural Elements of C.T.
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Ground Substance
Fibers
Cells
Properties of cells and composition
and arrangement of ECM vary
greatly
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Tough: tendons and ligaments
Fragile: around organs
Structural Elements of C.T.
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Ground Substance
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Unstructured material that fills space between
cells
Composed of:
 Interstitial fluid
 Cell adhesion proteins
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Act like cell glue
Proteoglycans
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Have core that GAG’s attach to
GAG = glycosaminoglycans
High GAG content = stiffer ground substance
Holds large amounts of fluid and fuction as
molecular sieve
Fibers
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Provide support
3 types
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Collage
Elastic
Reticular
Collagen strongest and most abundant
Collagen fibers
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Made of strong protein “collagen”
They are extremely strong and have
a high tensile strength
Tests have shown that collagen
fibers are stronger then steel fibers
of the same size
White in color; called “white fibers”
Elastic fibers
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Made of a very rubbery, stretchy
protein called “elastin”
These fibers can stretch and recoil
much like a rubber band
They are found in skin, lungs, and
blood vessels, where there is much
elasticity needed
Fresh fibers are yellow in color;
called “yellow fibers”
Reticular fibers
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Made of very fine collagenous
fibers
Branch extensively and form very
delicate networks
Support soft tissue of organs
Abundant where CT meets other
tissue
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Ex: basement membrane of epithelium
or capillaries
Cells
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Types
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Both immature and mature forms exist
“blast” cells are the forming cells
“cyte” cells are the mature cells
Blast cells are very mitotic and secrete
ground substance and ECM
Primary Blast Cells
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Fibroblasts
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Chondroblasts
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Form cartilage
Osteoblasts
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Form CT Proper
Form bone
Hematopoietic stem cells
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Form blood
Primary Blast Cells to “Cytes”
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After ECM and ground substance
are synthesized then the cells
assume their mature “cyte” form
These mature cells maintain the
health of the ECM, however if the
matrix is injured they can revert
back to their more active “blast”
form and repair and regenerate the
matrix
Other Types of Cells
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Connective tissue is home to many
other types of cells
Fat cells
 White blood cells
 Mast cells
 Macrophages
 Plasma cells, these produce antibodies
Mast cells and macrophages are
important to overall body defense.
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Mast Cells and Macrophages
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Mast cells are oval shaped cells that
cluster along blood vessels
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Their job is to detect foreign substances and
initiate local inflammation
 Ex: bacteria, fungi, pathogens
Macropahges are large irregular cells that
avidly phagocytize the forgeign
substances ( They eat )
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Scattered throughout loose CT, bone marrrow
and lymphatic tissue.
Types of Connective Tissue
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Embryonic CT
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Mesenchyme, first definitive layer
formed from mesoderm, embryonic
germ layer
Arises early in development and
differentiates into all forms of CT
Mucous CT
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Temporary, rare but also derived from
mesenchyme
CT Proper
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Loose CT Proper
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areolar
Adipose
reticular
Dense CT Proper
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Dense regular
Dense irregular
elastic
CT Proper - Loose
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Areolar CT
 Gel like matrix, 3 fiber types; contains
fibroblasts, macrophages, mast cells and
WBC
 Wraps and cushions organs, important in
inflammatory response, holds tissue fluid
 Location: widely distributed under
epithelia, packages organs, surrounds
capillaries; forms lamina propia of
mucous membranes
More Areolar CT
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Gelatin like ground substance
Holds liquids for all other cells
Inflammatory response:
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When area is injured, areolar CT soaks
up fluids and can cause edema
Areolar is most widely distributed CT,
essentially packing material for the
body
Loose CT Proper
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Adipose Tissue “fat”
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Very sparse matrix, closely packed
adipocytes, nucleus pushed to side by
large fat droplet
Provide reserve fuel, insulation,
supports organs
Under skin, around kidneys and
eyeballs, in abdomen, breast tissue
More Adipose Tissue
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Similar in structure to areolar but
able to store way more nutrients
90% of mass is adipocytes (fat
cells)
Highly vascular and metabolic
“Brown fat”- different form
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Consumes stores and creates heat
“White fat” – reglar adipose tissue
Loose CT Proper
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Reticular
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Network of reticular fibers in a typical
loose ground substance; reticular cells
lie on the network
Form soft internal skeleton that
supports other cells
Location: lymphoid organ (bone
marrow, spleen, lymph nodes)
Dense Regular CT
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Parallel collagen fibers, few elastin
fibers, main cell is fibroblast
Attaches muscles to bones or to
other muscles, attaches bones to
bone
Location: tendons, most ligaments
Dense irregular CT
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Irregularly arranged collagen fibers,
some elastic fibers, major cell is
fibroblast
Able to withstand tension is many
directions
Dermis of skin, fibrous capsule of
organs and joints
Cartilage
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Stands up to both tension and
compression
Qualities b/t dense CT and bone
Avascular, lacks nerve fibers
Ground substance contains large amounts
of Chondroitin and hyaluronic acid
Up to 80% water
Closely bound collagen fibers and a few
elastic fibers
Chondroblast is primary cell
More Cartilage
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Old cartilage loses its ability to
divide
Heals very slowly (Sports injuries)
3 types
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Hyaline
Elastic
fibrocartilage
Hyaline Cartilage
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Most abundant cartilage
Firm matrix, large number of
collagen fibers
“gristle”
Supports, reinforces; cushioning
properties
Embryonic skeleton, costal cartilage
More Cartilage
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Elastic
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Nearly identical to
hyaline but with
more elastin fibers
in matrix
Maintains shape
while allowing
flexibility
External ear,
epiglottis
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Fibrocartilage
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Similar to hyaline
but less firm with
larger collagen
fibers
High tensile
strength with
ability to resist
compression
Meniscus of knee,
“discs” of back
Other CT
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Bone
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Hard, calcified
matrix
Well vascularized
Osteocyte is main
cell
Supports, protects,
stores calcium,
blood cell
formation
Skeleton
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Blood
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RBC and WBC in a
fluid matrix
Transports gases,
nutrients, waste,
etc
Inside blood
vessels
Nervous Tissue
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Main component of the nervous
system (brain, spinal cord, nerves)
Regulate and control body functions
Neurons – nerve cell; highly
specialized cell that generates nerve
impulses
The Neuron
Parts of the neuron
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Soma (cell body)
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Dendrites – highly branched
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Conduct and transmit nerve impulses
Myelin sheath- white fatty substance
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Receive signals
Axon – nerve fiber
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Contains organelles, carries on cell function
Proteolipoid (mix of proteins and lipids)
Insulates and speed up nerve impulses
Axon terminal – links to dendrites to form
synapse
Neuron facts
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Extreme longevity
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They are amitotic
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They cannot replace themselves if destroyed
High metabolic rate
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Given good nutrition can live up to 100 years
Require constant supply of oxygen and glucose
to function
Very large complex cells
Muscle Tissue
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Muscle tissue is:
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Highly cellular
Well vascularized
Responsible for most movements
Made of myofilaments
3 types:
Skeletal muscle
 Cardiac muscle
 Smooth muscle
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Skeletal Muscle
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Attached to bones of skeleton
Form flesh of body and are
responsible for movement of
skeleton
Muscle fibers are often striated in
appearance. Long cylindrical
multinucleated
Fast Twitch vs Slow Twitch
Cardiac Muscle
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Found only in walls of the heart
Contractions propel blood through
circulatory system
Cells are branching, striated,
uninucleated that fit closely/tightly
together at junctions called
intercalated discs
Smooth Muscle
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No external striations
Spindle shaped with central nucleus
Found mainly in walls of hollow
organs (urinary and digestive tract)
Function is to squeeze substances
along a path by contracting and
relaxing
Muscle contractions
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Voluntary = skeletal muscle
Involuntary = smooth and cardiac
muscle
Other muscle functions:
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Maintaining posture (core,trunk)
Generating body heat
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40% of body mass
Stabilizing joints
Tissue Repair and Inflammation
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Step 1: Inflammation
Step 2: Organization, 1st phase
of tissue repair
Step 3: Regeneration
Step 1: Inflammation
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Tissue trauma causes injured cells
to release inflammatory chemicals
Capillaries dilate and become more
permeable
WBC and plasma w. antibodies flood
the wound and form a clot
Leftover stuff is phagocytized by
macropahges
Step 2: Organization
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Occurs while inflammation is going
on
Clot replaced by granuation tissue
Granulation tissue has capillaries
that bleed freely; also contains
fibroblasts that produce growth
factors that signal for repair
Macrophages again digest leftover
materials
Step 3: Regeneration
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During repair, surface epithelium
begins to regenerate
Epithelium grows under scab until it
resembles the epithelium around it
Scar tissue may be present still
The severity of the wound
determines healing time and repair
process varies across tissue types
Germ Layers
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Ectoderm
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Mesoderm
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Forms epithelial tissues
Muscle and all CT
Endoderm
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Nervous tissue
All primary tissues are developed and
major organs formed by the 2nd month