nerve activates contraction -...
TRANSCRIPT
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Histology
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Body Tissues
Cells are specialized for particular functions
Tissues
Groups of cells with similar structure and function
Extracellular Matrix
“cell glue” between cells
Histology
study of tissue
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Body Tissues
Four primary types (functional categories)
Epithelium
protection /secretion /absorption/ filtration
Connective
support & structure
Nervous
communication & control
Muscle
movement (internal & external)
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Primary Germ Layers
Endoderm
(Epithelial)
Mesoderm
(Epithelial, Muscle, Connective)
Ectoderm
(Epithelial, Nervous)
Digestive & respiratory
epithelium
Muscles Epidermis
Urethra epithelium Skeleton (bones & cartilage) Lining of mouth, anus,
nostrils
Bladder Blood Sweat & sebaceous
glands
Liver & pancreas Blood vessel epithelium Hair
Dermis Brain & spinal cord
Excretory & reproductive organs Eyes, nose, ear
epithelium
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EPITHELIAL TISSUES
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Epithelial Functions
Protection
Sensory
Secretion
Absorption
Excretion
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Epithelium Characteristics High cellularity
cells fit closely together
very little EC matrix
Contains specialized contacts
tight junctions & desmosomes
Avascular
no blood vessels within it
diffusion provides nutrients & carries waste away
lots of nerve fibers
Reinforcement & connection
Defines boundaries
cancer causes a breach in these boundaries
Regenerate easily if well nourished
Found in areas of high friction
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Classification of
Epithelium
Combination of shape & # of cells is used to name tissues
Shape of cells
Squamous – flattened
Cuboidal – cube-shaped
Columnar – column-like
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Classification of Epithelium
Number of cell layers
Simple
one layer
found in areas of transport
Stratified
more than one layer
High abrasion areas for protection
Secretory membranes
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Classification of Epithelium
• Pseudostratified • “False” layers
• Ciliated (respiratory tract)
• Non-ciliated (male urethra)
• Transitional • multiple layers of epithelial
cells, “hodge-podge”
• Found in urinary tract
• can look cuboidal until
bladder stretches, then
looks squamos
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Keratinized Epithelium
Keratin
tough waterproof material
found in upper layers of some stratified squamos
epithelium
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Non-Keratinized Epithelium
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Epithelial Membranes
Mucous membranes
Line body cavities OPEN to the exterior
Example: digestive, respiratory, urogenital
Mucus protects by trapping microorganisms, substances in
mucus will destroy them
Cutaneous Membranes
Skin
Helps waterproof & protect body
First line of defense in immune system
Serous Membranes
Lines all CLOSED body cavities
Serous fluid located between layers to reduce friction due
to organ motion
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Epithelial Membranes
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Glandular Epithelium Gland
one or more cells that secretes a particular product
Two major gland types
Endocrine gland
Ductless – secretes product directly into blood or tissue
Produces hormones
Exocrine gland
Empty through ducts to the epithelial surface
Include sweat and oil glands
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Glandular Epithelium • Apocrine
• secrete their product from intact cells
• Ex: Mammary glands
• Holocrine
• entire cells and their secretions accumulate as
the gland’s secretory product
• cells rupture
• Ex: Sebaceous (oil) glands
• Merocrine
• Most common
• accumulate their secretory product at the
apical surface of each cell, which then
separates from the remainder to form a
secretion in the lumen of the gland.
• cells then repair themselves.
• Ex: Salivary glands
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Glandular Epithelium
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Connective Tissue
Support & strengthen & provide structure
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Connective Tissue Found everywhere in the body
Includes the most abundant and widely distributed tissues
Functions
Binds body tissues together
Supports the body
Provides protection
Insulates to maintain body temperature
Transportation of other molecules
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Origin of Connective Tissue
Mesenchyme: embryonic tissue that
differentiates into all forms of CT
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Connective Tissue
Characteristics
Variations in blood supply
Some tissue types are well vascularized
Adipose – danger of hemorrhage with liposuction
Some have poor blood supply or are avascular
Blood supply is necessary for healing
brings oxygen & “spare parts”
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Extracellular Matrix Two main elements
Ground substance
proteins and polysaccharide molecules
function as a molecular sieve to diffuse nutrients & other substances
Fibers
Produced by the cells
Three types
Collagen fibers – tensile strength
Elastic fibers – stretch with recoil
Reticular fibers - support
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Connective Tissue Cells
Prefixes
Fibro
Osteo
Chondro
Hemo(cyto)
Suffixes
Blast – build the cells
Cyte – cell
Clast – breakdown the cells
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Connective Membranes
Synovial
Lines spaces between bone and joint
Secrete synovial fluid to reduce friction
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Connective Tissue Outline
Bone
Cartilage
Hyaline
Fibrocartilage
Elastic
Perichondrium
Fibrous
Areolar (Loose connective)
Adipose
Reticular
Dense fibrous
Regular
Irregular Blood
Plasma
Cells
Eryhtrocytes
Leukocytes
Thrombocytes
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Connective Tissue Types - BONE
Bone (osseous tissue)
Composed of:
Bone cells in lacunae (cavities)
Hard matrix of calcium salts
Large numbers of collagen fibers
Osteon – primary anatomical and functional unit of compact bone
Used to protect and support the body
Hematopoiesis – formation of blood cells
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Connective Tissue Types - CARTILAGE
Hyaline cartilage
Most common cartilage
Composed of:
Abundant collagen fibers
Rubbery matrix
Avascular
Found in
Entire fetal skeleton
Ventral ends of ribs
Articular surface of bones
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Fibrocartilage
Highly compressible
Strongest & most durable
forms cushion-like discs between vertebrae, pubic symphysis, meniscus
Connective Tissue Types - CARTILAGE
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Elastic cartilage
Provides elasticity, very flexible
Supports the external ear, larynx
Connective Tissue Types - CARTILAGE
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Perichondrium
Surrounds cartilage
Connective Tissue Types - CARTILAGE
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Connective Tissue Types - FIBROUS
Areolar (Loose Connective)
Most widely distributed connective tissue (surrounds blood vessels & nerves)
Soft, pliable tissue
Contains all fiber types
Can soak up excess fluid
Main function – to cushion and protect organs
Types of fibers
Collagenous - collagen
Elastic – elastin , stretchable
Reticular – very thin
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Connective Tissue Types - FIBROUS
Adipose
Matrix is an areolar tissue in which fat globules predominate
Many cells contain large lipid deposits
Functions
Insulates the body
Protects some organs
Serves as a site of fuel storage
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Adipose
Connective Tissue Types - FIBROUS
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Reticular
Delicate network of interwoven fibers
Holds together adipose tissue
Forms stroma (internal supporting network) of lymphoid organs; soft skeleton
Lymph nodes
Spleen
Bone marrow
Connective Tissue Types - FIBROUS
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Dense fibrous
Main matrix element is collagen
fibers
Cells are fibroblasts
Irregular – not parallel
dermis
Regular - parallel
Tendons – attach muscle to bone
Ligaments – attach bone to bone
Connective Tissue Types - FIBROUS
Regular
Irregular
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Connective Tissue Types - FIBROUS
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Connective Tissue Types - BLOOD
Fibers are visible during clotting
Functions as the transport vehicle for materials
55% Liquid component
plasma
45% Blood cells
Erythrocytes - RBC
Leukocytes - WBC
Thrombocytes - platelets
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Connective Tissue Outline
Bone
Cartilage
Hyaline
Fibrocartilage
Elastic
Perichondrium
Fibrous
Areolar (Loose connective)
Adipose
Reticular
Dense fibrous
Regular
Irregular Blood
Plasma
Cells
Eryhtrocytes
Leukocytes
Thrombocytes
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Muscle Tissue
Highly vascular & highly cellular
Less matrix = more flexibility
More blood flow = more ATP made
Actin & myosin – contractile myofilaments
Function is to produce movement
3 types
Skeletal
Smooth
Cardiac
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Muscle Tissue Types Skeletal muscle
Can be controlled voluntarily
Cells attach to connective tissue
Cells are striated
Cells have more than one nucleus
attached to bone
Smooth muscle
Involuntary muscle
Surrounds hollow organs
Attached to other smooth muscle cells
No visible striations
One nucleus per cell
Viscera of hollow internal organs
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Cardiac muscle
Found only in the heart
Function is to pump blood (involuntary)
Cells attached to other cardiac muscle cells at intercalated disks
Cells are striated
One nucleus per cell
Muscle Tissue Types
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Nervous Tissue
Consists of brain, spinal cord, nerves
Carry electrical signals
Neurons: generate & conduct electricity
Usually nonregenerative
Neuroglia: support neurons
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Tissue Repair
Determination of type of repair
Type of tissue damaged
Severity of the injury
Regeneration
Replacement of destroyed tissue by the same kind of cells
Fibrosis
Repair by dense fibrous connective tissue (scar tissue)
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Regeneration of Tissues
Regenerate easily
Epithelial tissue
Bone
Regenerate poorly
Skeletal muscle – replaced with connective tissue, not muscle
Cartilage
Nervous
Replaced largely with scar tissue
Cardiac muscle
Nervous tissue within the brain and spinal cord
Connective - keloids
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Steps of Tissue Repair
1. capillaries dilate – brings blood to supply clotting
factors
2. clot forms – seal off injury
3. scab forms – protect injury
4. debris is cleaned out – macrophages eat away
damaged tissue to leave room for repair
5. Organization of tissue parts – granulation occurs (a
type of intermediate tissue)
6. Macrophages digest & remove original clot
7. Surface epithelium regenerates – scab usually falls
off at this time
End result: Healed injury!
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Tissue Disease