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tissues
cells, the basic units of structure and function in the human organism, organized into groups.
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Epithelial tissues
Covers organs, forms the inner lining of body cavities, and lines hollow organs.
It always has a free (apical) surface exposed to the outside or internally to an open space.
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Basement membrane
the underside of epithelial tissue that is anchored to connective tissue by a thin non living layer
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Types of tissue
- Epithelial
- Connective
- Muscle
- Nurvous
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What is the function of epithelial tissue?
Protection, secretion, absorption, excretion
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What are epithelial tissues located?
cover body surface, covr and line internal organs, compose glands.
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What are the characteristics of epithelial tissues?
Lack blood vessels, readily divide;cells are tightly packed.
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What is the function of connective tissue?
Bind, support, protect, fill spaces, store fat, produce blood cells
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Where are connective tissue found in the body?
They are widely distributed throughout the body.
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What is the characteristics of connective tissue?
Mostly have good blood supply; cells are farther apart than epithelial cells.
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What is the function of muscle tissue?
movement
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Where is the muscle tissue located?
Attached to bones, in the walls of hollow internal organs, heart
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What is the distinguishing characteristics of muscle tissue?
Able to contract in response to specific stimuli
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What is the function of Nervous tissue?
Transmit impulses for coordination, regulation, integration, and sensory reception
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Where is nervous tissue located?
Brain, spinal cord, nerves
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What is the distinguishing characteristics of nervous tissue?
Cells communicate with each other and other body parts.
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Squamous
thin, fattened cell
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cuboidal
cube-shaped cells
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columnar
toll, elongated cells
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simple
single layer of cells
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stratified
two or more layers of cells
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Simple squamous epithelium
- Single layer of thin, flattened cells.
- nuclei are usually broad and thin.
- Function: diffusion and filtration, osmosis: covers surfaces.
- example: air sacs of the lungs, forms the walls of capillaries, lines the insides of blood and lymph vessels, and covers the membranes that line body cavities.
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Simple cuboidal epithelium
- Single layer of cube-shaped cells.
- centrally located, spherical nuclei
- Function: Secretion, absorption
- location: covers the ovaris and lines most of the kidney tubules and the ducts of certain glands.
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Simple columnar epithelium
- single layer of cells with elongated nuclei usually located at about the same level, near the basement membrane.
- Function: Absorption, secretion, protection.
- can be cilia or nonciliate.
- cilia-female reproductiv tract, move the egg cell through the uterine tube to the urterus.
- nonciliated-lines the uterus and portions of digestive tract, stomach, small and large intestines.
- goblet cells secrete mucus onto free surface of tissue.
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Pseudostratified columnar epithelium
- appear to be stratified but are not.
- nuclei lie at two or more levels in the row or aligned cells.
- commonly have cilia
- Function:protection, secretion, movement of mucus
- example: line the passages of the respiratory system.
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Stratified squamous epithelium
- many cell layers .cells divide in the deeper layers, and newer cells push older ones farther outward, where they flatten out.
- function: protection
- Example: outer layer of the skin (epidermis).
- also the oral cavity, esophagus, vagina and anal canal.
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Stratified cuboidal epithelium
- two or three layers of cubodal cells that form the lining of a lumen.
- example: lines the larger ducts of the mammary glands, sweat glands, salivary glands and pancreas.
- line the female and male reproductive systems.
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Statified Columnar epithelium
- Several layers of cells, superficial cells are columnar and basal layers consist of cubodal cells.
- function: protection, secretion
- Found: male urethra and ductus deferns and in parts of the pharynx.
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Transitional epithelium
- Specialized to change in response to increased tension.
- function: distensibility, protection
- Forms the inner lining of the urinary bladder and lines the ureters and the superior urethra.
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Glandular epithelium
- composed of cells specialized to produce and secrete substances into ducts or into body fluids
- Usually found withincolumnar or cuboidal epithelium
- one or more of these cells constituet a gland.
- found in salivary glands, sweat glands, endocrine glands.
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exocrine gland
- Glands that secrete their products into ducts that open onto surfaces, such as the skin or the lining of the digestive tract.
- Three types:
- Merocrine, Apocrine, Holocrine
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endocrine glands
Glands that secrete their products into tissue fluid or blood.
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merocrine glands
- Glands that release fluid by exocytosis.
- Example:Salivary glands, pancreatic glands, sweat glands of the skin.
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Apocrine Gland
- Cellular product and portions of the free ends of glandular cells pinch off during secretion.
- Example: Mmmary glands, ceruminous glands lining the external ear canal.
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Holocrine glands
- Disintegrated entire cells filled with secretory products.
- Example: Sebaceous glands of the skin
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Connective tissues
- Binds structures, provide support and protection, serve as frameworks, fills spaces, stores fat, produce blood cells, protects against infections and help repair tissue damage.
- Have abundace of extracellular matrix between them.
- Two major categories:
- loose and dense connective tissues.
- Specialized connective tissue:
- Cartilage, bone, and blood
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Fibroblasts
- most common type of fixed cell in connective tissue.
- Function: produce fibers
- Three types of connective tissue fibers:
- Collagenous fibers
- Elastic fibers
- reticular fibers
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Macrophages
- or histocyts, originate as white bood cells.
- function:carry on phagocytosis
- can move about and function as scavenger and defensive cells that clear foreign particles from tissues.
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Mast cells
- large and widely distributed in connective tissues. usually near blood vessels.
- function: Secrete heparin and histamine.
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Collagenous fibers
- Thick treads of the protein collagen.
- They resist considerable pulling force.
- Hold structures together such as:
- ligaments
- tendons
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ligaments
- collagenous fibers that hod structures together.
- connects bones to bones
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tendons
- collagenous fibers that hold structures together.
- connect muscles to bone
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Elastic fibers
- composed of springlike protein called elastin.
- Streches easily.
- yellow fibers
- example:vocal cords
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Reticular fibers
- thin collagenous fibers
- form delicate supporting networks like the spleen.
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Loose connective tissue
Includes areolar tissue, adipose tissue, and reticular connective tissue.
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Areolar tissue
- delicate, thin membranes throughout the body.
- mainly fibroblasts.
- Function: binds the skin to the underlying organs and fills spaces between muscles.
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Ddipose tissue
- Fat
- lies beneath the skin in spaces between muscles, around the kidneys, behind the eyeballs, in certain abdominal membranes, on the surface of the heart and around certain joints.
- Function: cushins joins ans some organs, insulates beneath the skin and stores energy in fat molecules.
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Reticular connective tissue
- thin collagenous fibers in a three dimensional network.
- function: provide the framework of certain internal organs, such as liver and spleen.
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