histology. body tissues cells are specialized for particular functions tissues groups of cells...
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Histology
Body TissuesBody 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
Body TissuesBody Tissues
Four primary types (functional categories) Epithelium
protection /secretion /absorption/ filtration Connective
support & structure Nervous
communication & control Muscle
movement (internal & external)
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
EPITHELIAL TISSUES
Epithelial Functions
Protection Sensory Secretion Absorption Excretion
Epithelium Characteristics 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
Classification of
Epithelium Combination of shape & #
of cells is used to name tissues
Shape of cells
Squamous – flattened
Cuboidal – cube-shaped
Columnar – column-like
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
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
Keratinized Epithelium Keratin
tough waterproof material found in upper layers of some stratified squamos
epithelium
Non-Keratinized Epithelium
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
Epithelial Membranes
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
Glandular EpitheliumGlandular 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
Glandular Epithelium
Connective TissueSupport & strengthen & provide structure
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
Origin of Connective Tissue
Mesenchyme: embryonic tissue that differentiates into all forms of CT
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”
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
Connective Tissue Cells
Prefixes Fibro Osteo Chondro Hemo(cyto)
Suffixes Blast – build the cells Cyte – cell Clast – breakdown the cells
Connective Membranes
Synovial Lines spaces
between bone and joint
Secrete synovial fluid to reduce friction
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
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
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
Fibrocartilage Highly compressible
Strongest & most durable
forms cushion-like discs between vertebrae, pubic symphysis, meniscus
Connective Tissue Types - CARTILAGE
Elastic cartilage Provides elasticity, very flexible
Supports the external ear, larynx
Connective Tissue Types - CARTILAGE
Perichondrium Surrounds cartilage
Connective Tissue Types - CARTILAGE
Connective Tissue Types - FIBROUSConnective 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
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
Adipose
Connective Tissue Types - FIBROUS
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
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
Connective Tissue Types - FIBROUS
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
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
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
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
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
Nervous Tissue
Consists of brain, spinal cord, nerves Carry electrical signals Neurons: generate & conduct electricity
Usually nonregenerative Neuroglia: support neurons
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)
Regeneration of TissuesRegeneration 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
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!
Tissue Disease