Lecture 2 Outline
II. Cellular structure (cont'd)
c. Anatomy of a cell -- 3 main parts: plasma membrane, cytoplasm, nucleus.
i. Plasma membrane
ii. Cytoplasm -- 2 main parts:
-Cytosol
-Organelles: beginning with those that are membrane-bound:
--Endoplasmic reticulum (ER)
Rough ER
Smooth ER
--Golgi body
--Lysosomes
--Mitochondria
--Cytoskeleton -- not membrane-bound. Three parts:
Microtubules
Microfilaments
Intermediate filaments
iii. Nucleus
d. Specialized cell contacts (cell junctions)
Tight junctions
Desmosomes
Gap junctions
TISSUES
Histology = the study of tissues
I. Epithelium
a. Introduction
Definition of epithelium: Tissue that:
(1) covers or lines surfaces and cavities of the body, or
(2) forms glands (= secretory structures)
b. General characteristics
Cellularity: composed almost entirely of cells
Make specialized contacts
Display polarity (sidedness)
Basement membrane (anchors epithelium to the underlying connective tissue)
Ability to regenerate quickly
Avascular (no blood vessels)
c. Function
Absorption
Secretion and Excretion
Diffusion and Filtration
Propulsion
Protection
d. Classification
By layering: simple or stratified
By shape: squamous, cuboidal, or columnar
A. Simple epithelium
1. Simple squamous -- thinnest kind
2. Simple cuboidal
3. Simple columnar
Can be further modified:
-Microvilli
-Goblet cells
-Cilia
4. Pseudostratified columnar
B. Stratified epithelium
1. Stratified squamous -- thickest
2. Stratified cuboidal -- rare
3. Stratified columnar -- very rare
4. Transitional (changes shape)
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August 24, 2009
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