Transcript Essentials of Human Anatomy 2

Essentials of Human Anatomy
Body Tissues
Dr Fadel Naim
Ass. Prof. Faculty of Medicine
IUG
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Tissue Level of Organization
• Group of similar cells
– common embryonic origin
– common function
• Histology
– study of tissues
4 Basic Tissues (1)
1. Epithelial Tissue
– covers surfaces because cells are in contact
– lines hollow organs, cavities and ducts
– forms glands when cells sink under the surface
2. Connective Tissue
– supports and binds structures together
– stores energy as fat
– provides immunity to disease
4 Basic Tissues (2)
3. Muscle Tissue
– cells shorten in length producing movement
4. Nerve Tissue
– cells that conduct electrical signals
– detects changes inside and outside the body
– responds with nerve impulses
Biopsy
• Removal of living tissue for microscopic
examination
• Useful for diagnosis, especially cancer
• Tissue preserved, sectioned and stained
before microscopic viewing
• A biopsy is performed after appropriate staging
studies
• Alternatives include
– fine needle aspiration (FNA)
• A simple procedure that can be done using local anesthesia.
• Most helpful in diagnosing soft tissue tumors and bony tumors with
homogenous cell types
• Obtains the least amount of material.
– core needle biopsy
• May be aided by ultrasonography, fluoroscopy, computed
tomography (CT), and magnetic resonance imaging (MRI).
• The surgeon obtains a core of tissue that measures 10 mm by 2 mm.
– open biopsy or incisional biopsy
• A surgical procedure that provides the largest amount and the best
sampling of tissue for pathologic identification.
Epithelial Tissue
• Functions
– Protection
– Sensory functions
– Secretion
– Absorption
– Excretion
Slide 8
Epithelial
Tissues
General characteristics • cover organs and the body
• line body cavities
• line hollow organs
• have a free ( apical ) surface
• have a basement membrane
• avascular
• cells readily divide
• cells tightly packed
• cells often have desmosomes
• classified according to cell shape and number of cell layers
Types of Epithelium
• Covering and lining epithelium
– epidermis of skin
– lining of blood vessels and ducts
– lining respiratory, reproductive, urinary & GI
tract
• Glandular epithelium
– secreting portion of glands
– thyroid, adrenal, and sweat glands
Classification
Cell Shapes
1. Squamous
2. Cuboidal
3. Collumnar
Arrangement
1. Simple
2. Stratified
3. Pseudostratified
Simple Epithelial Tissues
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Simple squamous
Simple cuboidal
Simple columnar
Pseudostratified columnar
Epithelial Tissues
Simple squamous –
• single layer of flat cells
• substances pass easily through
• line air sacs
• line blood vessels
• line lymphatic vessels
Simple Squamous
Epithelial Tissues
Simple cuboidal –
• single layer of cube-shaped
cells
• line kidney tubules
• cover ovaries
• line ducts of some glands
Simple Cuboidal
Epithelial Tissues
Simple columnar –
• single layer of elongated cells
• nuclei usually near the basement
membrane at same level
• sometimes possess cilia
• sometimes possess microvilli
• often have goblet cells
• line uterus, stomach, intestines
Simple Columnar Epithelium
Simple Columnar Epithelium
with cilia
Epithelial Tissues
Pseudostratified columnar –
• single layer of elongated cells
• nuclei at two or more levels
• appear striated
• often have cilia
• often have goblet cells
• line respiratory passageways
Pseudostratified Columnar
Epithelium
Stratified Epithelial Tissues
• Stratified squamous
• Stratified cuboidal
• Stratified columnar
Epithelial Tissues
Stratified squamous –
• many cell layers
• top cells are flat
• can accumulate keratin
• outer layer of skin
• line oral cavity, vagina, and
anal canal
Stratified Squamous Epithelium
Epithelial Tissues
Stratified cuboidal –
• 2-3 layers
• cube-shaped cells
• line ducts of mammary glands,
sweat glands, salivary glands,
and the pancreas
Stratified Cuboidal Epithelium
Epithelial Tissues
Stratified columnar –
• top layer of elongated cells
• cube-shaped cells in deeper
layers
• line part of male urethra and
part of pharynx
Stratified Columnar Epithelium
Epithelial Tissues
Transitional –
• many cell layers
• cube-shaped and elongated
cells
• line urinary bladder,
ureters, and part of urethra
Transitional Epithelium
Glandular Epithelium
Composed of cells that are specialized to produce and secrete
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Endocrine Glands
• Lack ducts and secrete their products
directly into the interstitial fluid and
bloodstream.
• Hormones act as chemical messengers to
influence cell activities elsewhere in the
body.
Exocrine Glands
– Usually maintain their contact with the
epithelial surface by means of a duct.
– Duct secretes materials onto the surface of
the skin or onto an epithelial surface lining an
internal passageway.
Connective Tissues
General characteristics • most abundant tissue type
• many functions
• bind structures
• provide support and protection
• serve as frameworks
• fill spaces
• store fat
• produce blood cells
• protect against infections
• help repair tissue damage
• have a extra-cellular matrix
• have varying degrees of vascularity
• have cells that usually divide
Extra-Cellular Matrix
• Cells rarely touch due to extracellular
matrix
• Matrix(fibers & ground substance secreted
by cells
• Consistency varies from liquid, gel to solid
Connective Tissue
Major Cell Types
Fibroblasts
• fixed cell
• most common cell
• large, star-shaped
• produce fibers
Mast cells
• fixed cell
• release heparin
• release histamine
Macrophages
• wandering cell
• phagocytic
• important in injury
or infection
Connective Tissue Fibers
Collagenous fibers
• thick
• composed of collagen
• great tensile strength
• abundant in dense CT
• hold structures together
• tendons, ligaments
Reticular fibers
• very thin collagenous fibers
• highly branched
• form supportive networks
Elastic fibers
• bundles of
microfibrils embedded
in elastin
• fibers branch
• elastic
• vocal cords, air
passages
Connective Tissues
Connective tissue proper
• loose connective tissue
• adipose tissue
• reticular connective tissue
• dense connective tissue
• elastic connective tissue
Specialized connective tissue
• cartilage
• bone
• blood
Connective Tissues
Loose connective tissue
• mainly fibroblasts
• fluid to gel-like matrix
• collagenous fibers
• elastic fibers
• bind skin to structures
• beneath most epithelia
• blood vessels nourish
nearby epithelial cells
• between muscles
Adipose tissue
• adipocytes
• cushions
• insulates
• store fats
• beneath skin
• behind eyeballs
• around kidneys and heart
Connective Tissues
Reticular connective tissue
• composed of reticular fibers
• supports internal organ
walls
• walls of liver, spleen,
lymphatic organs
Dense connective tissue
• packed collagenous fibers
• elastic fibers
• few fibroblasts
• bind body parts together
• tendons, ligaments, dermis
• poor blood supply
Connective Tissues
Elastic connective tissue
• abundant in elastic fibers
• some collagenous fibers
• fibroblasts
• attachments between bones
• walls of large arteries, airways, heart
Bone (Osseous Tissue)
• solid matrix
• supports
• protects
• forms blood cells
• attachment for muscles
• skeleton
• osteocytes in lacunae
Cartilage Connective Tissue
Characteristics:
– Weaker than bone
– More flexible than bone
• Cells in an abundant matrix.
• Cell Types
– Chondroblasts
– Chondrocytes in lacunae
• Avascular
3 Major Functions of Cartilage
• Supporting soft tissues.
• Providing a gliding surface at articulations
(joints)
• Providing a model for the formation of
most of the bones in the body.
Types of Cartilage
• Three types of cartilage:
– Hyaline cartilage
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Most abundant kind
Has a perichondrium (membrane)
Associated with synovial joints
Most bones first modeled in hyaline cartilage
– Fibrocartilage
• Has collagen fibers
• Intervertebral discs, pubic symphysis
– Elastic cartilage
• Has elastic fibers
• Ear, respiratory tubing
Types of Epithelial
Membranes
Mucous
Serous
• line body cavities
that do not open to
the outside
• reduce friction
• inner lining of
thorax and abdomen
• cover organs of
thorax and abdomen
• secrete serous fluid
• line tubes and organs
that open to outside world
• lining of mouth, nose,
throat, etc.
• secrete mucus
Cutaneous
•covers body
• skin
Synovial
• composed entirely of
connective tissue
• lines joints
Muscle Tissues
Skeletal muscle
General characteristics
• muscle cells called
muscle fibers
• contractile
• three types
• skeletal
• smooth
• cardiac
• attached to bones
• striated
• voluntary
Smooth muscle
• walls of organs
• skin
• walls of blood vessels
• involuntary
• not striated
Cardiac muscle
• heart wall
• involuntary
• striated
• intercalated discs
Muscle Tissues
Skeletal Muscle
Smooth Muscle
Cardiac Muscle
Nervous Tissue
• Sometimes termed neural tissue.
• Found in brain, spinal cord, and peripheral
nerves
• Consists of neurons, or nerve cells, and
glial cells that support, protect, and
provide a framework for neurons.
Neurons
• Detect stimuli, process information quickly, and
rapidly transmit electrical impulses from one
region of the body to another.
• Prominent cell body functions in control;
information processing, storage, and retrieval;
internal communication.
Neurons
• Processes extend from the nerve cell
body.
– Dendrite
– Axon
Wound Healing: Mechanisms
• Contraction - amputation
• Epithelialization - ulcer
• Connective tissue deposition laceration
Tissue Repair: Restoring
Homeostasis
• Worn-out, damaged tissue must be replaced
• Fibrosis = replacement with stromal connective
tissue cells (scar formation)
• Regeneration = replacement with original cell
types (parenchymal cells)
– some cell types can divide (liver & endothelium)
– some tissues contain stem cells that can divide
• bone marrow, epithelium of gut & skin
– some cell types can not divide & are not replaced
• muscle and nervous tissue
THE END