part 1: epithelium
TRANSCRIPT
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HISTOLOGY (A STUDY OF THE HUMAN TISSUES)
PART 1: EPITHELIUM
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The Organization of Life
cells
tissues
organs
organ system
organism
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Differentiation = Specialization
No cell can perform all functions necessary for life; cells differentiate, group together into tissues performing similar functions
Microscopic study of 4 tissue types; unites form and function
Form = shape, appearance, location. (macro)
Function = how it performs it’s tasks on a cellular or microscopic level. (micro)
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Location and Description
A. Location/Description
1. Location
a. surface of skin
b. digestive, respiratory, urinary, reproductive tracts
c. chest cavity (vessels and heart)
d. brain, eye, ear
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Location and Description
A. Location/Description
2. Description
a. always has free surface and attached
surface (basement membrane)
b. exposed to external environment or
passageway
c. no blood vessels; nutrients obtained
through diffusion/absorption
d. mitotic rates may be very high
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The Functions of Epithelium
1. Covers and protects every exposed surface
from abrasion, dehydration, destruction
2. Controls substances that enter/leave the body
3. Detects changes in environment; communicates with nervous system (5 senses)
4. Secretes substances (glands)
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Epithelium Classification
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Epithelium Classification*Squamous Tissue
1. Squamous – thin, flat, irregular shape
a. simple – most delicate; absorption in alveoli in lungs and blood vessels
b. stratified – protection from physical/chemical attack; very abraded areas (mouth, anus, surface of skin)
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Squamous Tissue = “Squashed”
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Drawing
Students, please draw the next slide onto the left side of your ISN notebook. (p. 18)
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Simple vs. Stratified Tissue Simple Stratified
Single Layered Tissue
Communication / Gateway for Tissue
Regulates Transport, Diffusion and Secretion of Materials
Delicate Tissue
Multi Layered Tissue
Protects against Friction or Injury
Barrier to Water, Disease, & Toxins.
Lower Layers Regenerate Upper Layers
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Epithelium Classification*Cuboidal Tissue
2. Cuboidal – hexagonal/square shape; nucleus located in middle of cell.
a. simple – secretion or absorption; kidneys, salivary glands
b. stratified – rare; sweat and mammary glands
c. transitional – tolerates stretching; located in bladder
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Cuboidal Tissue = “Cubed”
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Epithelium Classification*Columnar Tissue
3. Columnar – column shaped; nuclei near basement membrane
a. Simple – secretion or absorption; stomach, small/large intestines
b. Stratified – rare; provides protection; salivary glands, anus, mammary ducts
c. Pseudostratified – nuclei located at different heights; always possess cilia; respiratory tract
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Pseudostratified Tissue = “False Stratified”
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Epithelium Classification*Glands
1. endocrine – secrete substances into surrounding; “ductless”; hormones
2. exocrine – secrete substances through a duct; mucus, sweat, oil
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Exocrine vs. Endocrine
Exocrine Gland Endocrine Gland
Secretes substances onto a surface. Secretes substances into the blood
Contains a Duct (=Ducted) No Duct (=Ductless)
EX: sweat glands, mammary glands, salivary glands
EX: pituitary, thyroid, adrenal
Students: draw this chart on the page that your notes are attached to.