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What are Tissues?
- Tissues are groups of cells
- – Similar in structure
- – Characteristic in pattern
- – Specialized for the performance of specifictasks
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Histology
The study of tissues - Histo means tissue
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Epithelial tissue
- • Covers surfaces
- • Lines cavities
- • Forms glands
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Connective tissue
• Supports and forms the framework of all parts of thebody
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Muscle tissue
- • Contracts
- • Produces movement
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Nervous tissue
• Conducts nerve impulses
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What is the Function of Epithelium
- • Forms a protective covering for the body
- • Main tissue of skin’s outer layer
- • Forms membranes and ducts
- • Lines body cavities and hollow organs
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What is the structure of Epithilium
- • Tightly packed to protect underlying tissue or toform barriers
- • Repairs itself quickly
- • Can become stronger if subjected to wear & tear
- – i.e. calluses in skin
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Epithelial Cell Structure - 3 different shapes
- • Squamous - flat
- • Cuboidal - square
- • Columnar - long and narrow
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Epithelial Cell Structure - 3 Different layers
- • Simple – single layer
- • Stratified – many layers
- • Pseudostratified – staggered, so appear to be multilayered but are not
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Transitional epithelium
Capable of great expansion but returns to original size - bladder
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Special Functions of Epithelial Tissue
- 1. Produce secretions
- • Digestive juices
- • Sweat
- • Goblet Cells - epithelial cells in respiratory & digestive tract that produce mucus
- 2. Protect by trapping particles
- • Secrete mucus
- • Cilia projections trap particles
- 3. Glands – an organ specialized to produce a substance that is sent out to other parts of the body
- • Manufactures secretions from materials removed from blood
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Describe the Exocrine Gland
- • Have tubes or ducts to carry secretions away from glands
- • Effective in a limited area near the source
- • Structure
- • Single cell – goblet
- • Multiple cells
- • Simple tubular - intestine
- • Branched tubular - stomach
- • Coiled tubular - skin
- • Simple saclike - skin
- • Compound formation of tubes and sacs – mouth
- Some Examples
- • Gastrointestinal glands secrete digestive juices
- • Sebaceous glands in skin produce oil
- • Lacrimal glands produce tears
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Decsribe the Endocrine Gland
- • Ductless glands that secrete directly into the blood
- • Hormones have effects on specific target tissues
- • Structure – an extensive network of capillaries
- Examples
- • Pituitary
- • Thyroid
- • Adrenal
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Function & Structure of Connective Tissue (overview)
- Function
- • Supporting fabric of all parts of the body
- • Most extensive and widely distributed tissue of the body
- Structure
- • Matrix - large amounts of nonliving material between cells
- • Fibers – generally give matrix some structure
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Structure of Connective Tissue Classifications
- Classified according to composition of the intracellular matrix
- • Liquid connective tissue
- • Blood & lymph
- • Cells suspended in fluid matrix
- • Soft connective tissue
- • Adipose and areolar tissue
- • Cells loosely held together with semi-liquid matrix
- • Fibrous connective tissue
- • Ligaments, tendons, capsules
- • Cells held together with densely packed fibrous matrix
- • Hard connective tissue
- • Bone or cartilage
- • Cells held together with a hardened matrix that contains minerals
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Name the two Soft Connective Tissue types
2 types
- • Areolar (loose) Tissue
- • Most common type of connective tissue in the body
- • Intercellular matrix is jelly-like
- - Examples
- • Membranes around vessels & organs
- • Between muscles
- • Under skin
- • Adipose Tissue
- • Fatty tissue for storing energy and providing protective padding
- • Cells store fat
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What are Fibroblasts
cells that produce fibrous connective tissue
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Describe Fibrous Connective Tissue
- • Structure -very dense with large numbers of fibers
- • Collagen is most common fiber
- • Elastin fibers allow tissue to stretch and return to original length
- • Vocal cords
- • Arterial walls
- • Function – cover various organs
- • Capsules – very strong coverings for organs
- • Kidneys
- • All fibers arranged in same direction to allow for pulling in one direction
- • Tendons
- • Ligaments
- • Fibroblasts – cells that produce fibrous connective tissue
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Collagen
- • The Body’s Scaffolding
- • Most abundant protein in body
- • 25% of total protein
- • 19 types of collagen
- • Collagen fibers give intercellular matrix both strength and flexibility
- • Stronger than steel fibers of same size
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Hard Connective Tissue - Cartilage
- Structure
- • strong & flexible
- Function –
- • Structural material
- • Reinforcement
- • Shock absorber
- • Surface that reduces friction
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Cartilage - 3 types
- Hyaline cartilage – aka gristle
- • End of long bones
- • Tip of nose
- • Fibrocartilage – not elastic
- • Between spinal bones and pelvic bones
- • Elastic cartilage – can spring back into original shape
- • Outer ear
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Chondrocytes
cells that produce cartilage
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Hard Connective Tissue
- Bone aka osseous tissue
- • Structure - connective tissue with intercellular matrix hardened by minerals
- • Osteocytes – bone cells
- • Blood vessels, nerves in intercellular matrix
- • Bone marrow
- • Function
- • Support
- • Produce red blood cells
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Osteoblasts
cells that form bone
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Muscle Tissue
- • Function
- • Produce movement through contraction of its cells
- • Structure - cells are long thread-like fibers
- • Skeletal muscle
- • Cardiac muscle
- • Smooth muscle
- • After injury
- • repairs itself only with difficulty
- • Often replaced with scartissue
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3 Types of Muscle Tissue
- 1. Skeletal Muscle
- • Voluntary – can consciously contract skeletal muscle
- • Function - moves the body
- • Structure –
- • Very large cells
- • More than one nucleus
- • Striated (striped) pattern
- 2. Cardiac Muscle
- • Involuntary – contracts without conscious thought
- • Function – produces regular contractions, causing the heart to pump blood
- • Structure –
- • Cells are branched and interwoven
- • Membranes between cells also act to interconnect cells
- 3. Smooth Muscle
- • Involuntary
- • Function contract to produce movement of fluids or substances
- • Walls of hollow organs and vessles
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Nervous Tissue function and structure
- • Function – control and communications
- • Brain – control center of body
- • Spinal Cord – information superhighway
- • Nerves – direct communication between brain and body
- • Structure
- • Neuron – nerve cell
- • Neuroglia – support cell
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Neurons
- Nerve cell
- • Cell Body – transmits nerve impulses
- • Dendrite – branched tail that receives impulses for cell body
- • Axon – single tail that sends impulses away from cell body
- • Can be several feet long
- • Myelin – coating that Insulates axon
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Neuroglia
- nerve support cell
- • Protect nerves from harmful substances
- • Remove foreign material & debris
- • Form the myelin insulation
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Membranes function ans structure
- Function
- • Coverings
- • Dividers
- • Linings
- • To Anchor
- Structure
- • Epithelial membranes - layered
- • Serous membranes
- • Mucous membranes
- • Cutaneous membranes - skin
- • Connective tissue membranes
- • Synovial membranes
- • Meninges
- • Superficial fascia
- • Deep fascia
- • Fibrous pericardium
- • Periosteum
- • Perichondrium
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Epithelial Membranes – Structure
- Layered
- • Outer epithelial layer
- • Strengthened by connective tissue layer and sometimes smooth muscle layer
- Closely packed cells
- • Manufacture secretions
- • Protect deeper layers from invasion
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Serous Membranes aka Mesothelium
- Structure
- • Layered - One layer lines the walls of a body cavity and then it folds in on itself to line the outermost layer of the organ
- • Although in 2 layers, the membrane is continuous
- • Parietal layer – attaches to wall of body cavity
- • Visceral layer – attaches to organ
- • Does not connect with the outside of the body Function
- • Secretes a thin watery fluid that decreases friction on organs during movement
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