chapter 05 histology: epithelium
TRANSCRIPT
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CHAPTER 05
ANATOMY & PHYSIOLOGY I BIO 211:
Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.
Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.
Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.
Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.
Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.
Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.
Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.
Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.
Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.
Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.
Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.
Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.
Histology: EPITHELIUM Part 01: Brief Introduction Part 02: Survey of Types
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TISSUES Group of cells closely associated in: a) structure (similar) b) function (common or related)
HISTOLOGY = the study of tissues
TYPES In general, FOUR (4) MAJOR TYPES:
1. EPITHELIAL (this week's topic) 2. CONNECTIVE (supportive) 3. MUSCLE (movement) 4. NERVOUS (control)
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EPITHELIA
LOCATIONS: COVERING or LINING EPITHELIUM of-
a) FREE SURFACES (i.e. SKIN)
b) LINING of OPEN CAVITIES (i.e. DIGESTIVE, RESPIRATORY SYSTEMS)
c) LINING of CLOSED CAVITIES (i.e. VENTRAL BODY CAVITY)
d) LINING of BLOOD VESSELS and HEART May also serve as a GLANDULAR EPITHELIUM To be discussed…
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5 EPITHELIA MANY FUNCTIONS
PROTECTION Bacterial Infections, Injury etc
ABSORPTION Example: lining of digestive tract
FILTRATION Example: Renal (renal = kidney)
SECRETION Example: glandular epithelium
…or any COMBINATION of the above.
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6 EPITHELIAL FEATURES
TIGHTLY PACKED:Little extracellular space
Surface view ofsimple squamous epithelium
stripped from underlyingconnective tissue
in the peritoneal cavity.
EXISTS as SHEETS:
Cells attached by
tight junction points and
desmosomes (binding bodies).
TIGHT JUNCTION impermeable
OPEN SPACE
CELL 1 CELL 2
DESMOSOME anchoring junction
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7 EPITHELIAL FEATURES POLARITY
APICAL surface: often contain MICROVILLI: highly folded EXTENSIONS of the PLASMA MEMBRANE Increases ABSORBTION area Note: “brush border” = many microvilli
MICROVILLI from SMALL INTESTINAL
EPITHELIUM
TEM: 3 Cells shown ^
N N N
BRUSH BORDER
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CILIA
BASAL BODY (centriole) 9 Microtubule triplets
CORE 9 + 2
Microtubule doublets
FLAGELLA: simply longer projections from BASAL BODY;
cell propels itself
(cilia move substances over a surface)
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9 EPITHELIAL FEATURES POLARITY
BASAL surface: bottom - most layer of epithelial tissue is always attached to a BASEMENT MEMBRANE.
Acts as a barrier between the EPITHELIUM and the underlying CONNECTIVE TISSUE.
BASEMENT MEMBRANE
EPITHELIUM
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10 EPITHELIAL FEATURES POLARITY
BASAL surface: The BASEMENT MEMBRANE is composed of two layers.
Closest to the epithelium Actually secreted by the epithelium.
BASAL LAMINA
- thin, non - cellular adhesive layer - selective filter of materials from blood - template for wound repair
Below the BASAL LAMINA Extracellular network of collagen fibers
RETICULAR LAMINA BASAL LAMINA + RETICULAR LAMINA = BASEMENT MEMBRANE
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11 EPITHELIAL FEATURES
SEM: BASEMENT MEMBRANE
EPITHELIAL
CELLS
BASAL
LAMINA
RETICULAR
LAMINA collagen fibers
BM
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12 EPITHELIAL FEATURES
AVASCULARITY - No blood vessels
- Nutrients etc. via DIFFUSION (upward)
- IS innervated
REGENERATION - High MITOTIC INDEX (turnover)
END of PART 01: Brief Introduction
NEXT: Part 02: Survey of Types
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13 EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
Number of Layers
SIMPLE epithelium: one layer of cells
cells
BM
BM
STRATIFIED epithelium: multiple layers of cells
SHAPE of cells
SQUAMOUS flattened CUBOIDAL height = width COLUMNAR height > width
STRATIFIED EPITHELIUM: layers may have DIFFERENT SHAPES but nomenclature based upon the CELL SHAPE of the free (APICAL) surface.
Number of Layers
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SIMPLE epithelium: Little protection; other functions
EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
TYPES SIMPLE SQUAMOUS SIMPLE CUBOIDAL SIMPLE COLUMNAR PSEUDOSTRATIFIED PSEUDO = FALSE OR FAKE
In other words, ALL of the shapes May exist in the one cell layer arrangement!
Looks stratified but really NOT!
ONE LAYER of cells but different heights
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SIMPLE epithelium: Little protection; other functions
PSEUDOSTRATIFIED PSEUDO = FALSE or FAKE
TYPES EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
SIMPLE SQUAMOUS EPITHELIUM
Types SIMPLE SQUAMOUS SIMPLE CUBOIDAL SIMPLE COLUMNAR
PSEUDOSTRATIFIED PSEUDO = FALSE or FAKE
FLATTENED SINGLE LAYER usually quite permeable
LUNGS: DIFFUSION KIDNEY:
FILTRATION
In certain locations-‐ special names:
ENDOTHELIUM: LINING of BLOOD VESSELS/CAPILLARIES
MESOTHELIUM: SEROSAL MEMBRANES
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SIMPLE epithelium: Little protection; other functions
Also see:
EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
SIMPLE SQUAMOUS EPITHELIUM
Endothelium
(RBCs in a CAPILLARY)
LAB ATLAS PLATES 9-‐C and 9-‐E
ALVEOLUS (LUNG)
LAB ATLAS PLATE 85-‐D
BOWMAN'S CAPSULE (KIDNEY) LAB ATLAS PLATE 97-‐D
Picture Equivalent
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SIMPLE epithelium: Little protection; other functions
TYPES: SIMPLE SQUAMOUS SIMPLE CUBOIDAL SIMPLE COLUMNAR
Also see:
EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
DISTAL TUBULE (KIDNEY) Lab Atlas: PLATE 9-‐F
KIDNEY: ABSORPTION (Many MICROVILLI)
usually quite permeable
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SIMPLE epithelium: Little protection; other functions
EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
NO CILIA
EXAMPLE: DIGESTIVE TRACT (STOMACH to ANUS)
CILIATED
EXAMPLE: UTERINE TUBES
BOTH TYPES: GOBLET CELLS
MAY BE PRESENT (MUCOUS PRODUCTION)
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SIMPLE epithelium:
Little protection; other functions
SIMPLE SIMPLE SIMPLE
EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
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SIMPLE epithelium Little protection; other functions
TYPES EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
SIMPLE COLUMNAR EPITHELIUM
cilia
non-‐ciliated (mucous -‐ producing)
OVIDUCT PANCREATIC DUCT PHOTO EQUIVALENT: 10a
also in STOMACH
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SIMPLE epithelium: Little protection; other functions
TYPES EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
MAY HAVE CILIA EXAMPLE: RESPIRATORY TRACT
REALLY SIMPLE EPITHELIUM !!!!
why??? -‐ALL CELLS REST ON BM -‐SOME DO NOT REACH
APICAL SERVICE -‐NUCLEI AT DIFFERENT
LEVELS GIVING FALSE APPEARANCE of BEING STRATIFIED
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SIMPLE epithelium: Little protection; other functions
TYPES EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
MONKEY TRACHEA
PICTURE EQUIVALENT: LAB ATLAS: Human Trachea
PLATE 10-‐B
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SIMPLE epithelium: Little protection; other functions
EPITHELIA: SURVEY of TYPES
CLASSIFICATION of EPITHELIA
PSEUDOSTRATIFIED COLUMNAR EPITHELIUM (ciliated)
SEM of CILIA in TRACHEA
CILIA
GOBLET CELLS
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24 STRATIFIED SQUAMOUS EPITHELIUM
MOST COMMON TYPE Of STRATIFIED EPITHELIUM
-‐PROTECTION vs. ABRASION -‐HIGH MITOTIC INDEX
-‐CELLS SHED FROM APICAL REGION
STRATIFIED epithelium: Different layers may have
different shapes BUT
nomenclature:
BASED ON CELL SHAPE of the
free (APICAL) surface
BASAL LAYERS: -‐USUALLY NOT SQUAMOUS
-‐SITE OF NEW CELL GENERATION
APICAL SURFACE MAY POSSESS KERATIN, A
WATER INSOLUBLE PROTEIN
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25 STRATIFIED SQUAMOUS EPITHELIUM
HUMAN SKIN (keratinized) PICTURE EQIVALENT:
Lab Atlas: Fig. 11-‐A
ORAL CAVITY
PICTURE EQUIVALENT: Atlas: Fig. 10-‐D
Keratinized Cells
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REMINDER: STRATIFIED EPITHELIUM NAMED ON BASIS of
APICAL LAYER
STRATIFIED COLUMNAR EPITHELIUM
VERY RARE! -‐URETHRA of MALE
-‐some LARGE DUCTS of GLANDS
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27 STRATIFIED CUBOIDAL EPITHELIUM
ALSO VERY RARE!
-‐2 to 3 CELLS DEEP
-‐ LARGEST DUCTS of: SWEAT GLANDS
MAMMARY GLANDS
SALIVARY GLANDS
SURROUNDING EGGS
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RELAXED DISTENDED
CUBOIDAL
COLUMNAR
“UMBRELLA CELLS”
TRANSITIONAL EPITHELIUM
THINK URINARY BLADDER !
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Bladder
TRANSITIONAL EPITHELIUM
PICTURE EQUIVALENT: ATLAS:
Fig. 11-‐B (RELAXED) Fig. 11-‐C (DISTENDED)
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LAST SLIDE
TRANSITIONAL EPITHELIUM