9/8/2016 1 Epithelium Four primary tissue types: • Epithelial (covering) • Connective (support) • Nervous (control) • Muscular (movement) • Smooth muscle • Cardiac muscle • Skeletal muscle
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9/8/2016
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Epithelium
Four primary tissue types:
• Epithelial (covering)
• Connective (support)
• Nervous (control)
• Muscular (movement)• Smooth muscle• Cardiac muscle• Skeletal muscle
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Epithelial Tissue Features• Epithelial tissues always have an apical and
basal surface.• Avascular with no direct blood supply;
nutrients must diffuse.• Epithelial tissues have a high capacity for
regeneration.
• Cells are in close contact with each other with little or no intercellular space between them.
• May have junctions for both attachment and communication.
• Always resting on a basement membrane
Classified based on:
• Number of layers:• 1 layer = simple• 1 layer irregularly shaped=
pseudostratified• >1 layer = stratified• >1 layer of similar cells =
transitional
• Shape of the cells of outermost layer:• Flat: Squamous• Square, round, cubical: Cuboidal• Tall: Columnar
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Simple Squamous EpitheliumThin single cell layer attached to a basement membrane
Simple squamous: with flattened nuclei. Present in the alveoli of lungs,
Kidneys, Lining of visceral organs and all blood vessels.
Function: selective diffusion, filtration absorption or secretion.
Mesothelium: simple squamous that
lines body cavities and cover organs.
Endothelium: simple squamous that
lines the inside of blood vessels and
capillaries.
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Simple Cuboidal EpitheliumSimple cuboidal: with central rounded nuclei.
Present in liver, pancreas, acini of glands, lines
small ducts and tubules of kidney. Function:
excretory, secretory or absorptive.
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Simple Columnar EpitheliumSimple columnar: with basal oval nuclei.
Present in the absorptive surfaces (intestine);
secretory surfaces (stomach); lining gall bladder
(absorbs water).
Simple Columnar Epithelium (cont’d)
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Pseudostratified Columnar Epithelium
Function: to trap and remove unwanted
particles from the respiratory tract
Pseudostratified
columnar
ciliated: nuclei
disposed at
different levels;
basal cells do not
extend to surface;
Present in larger
airways of
respiratory system
(trachea, bronchi).
Transitional Epithelium
Function:
distension- supplying
elasticity/tension to
urinary bladder
Transitional: urinary tract; accommodates stretching
and toxicity of urine; surface cells larger, pale-staining,
scalloped surface outline; luminal surface appears
thickened; may be binucleate; large, round, prominent
nucleoli.
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Transitional Epithelium (cont’d)
Stratified epithelium = more than 1 layer
Function: protection
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Stratified Squamous nonkeratinized (SSNK)
Function: protection
Stratified squamous non-keratinizing (mucous
membrane): resists abrasion; moistened by glandular
secretions. Present in oral cavity, pharynx, esophagus,
anal canal, uterine cervix, and vagina.
Stratified Squamous keratinized (SSK)
Function: protection
Stratified squamous keratinizing: Upper
cell layer composed of squamous cells.
Present in surface of skin
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Concept Check
The type of epithelium indicated by the arrow lines the:
a) skin
b) mucosa of the esophagus
c) respiratory tract
d) urinary tract
f) mesentery
The type of epithelium shown in this image is:
a) Simple cuboidal
b) Simple columnar
c) Stratified columnar
d) Pseudostratified
columnar (respiratory)
e) Transitional
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GLANDULAR EDPITHELIUM
Glandular Epithelium
Two Main Types of Glandular Tissues:
• Exocrine – release secretions through ducts
• Endocrine - release secretions directly to the blood (covered in subsequent lectures)
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Glandular Epithelium structure
• Glands are classified structurally based on the duct and the secretory portions.
• Ducts considered compound when they are branched and are simple when they are not branched.
• shapes of the secretory portions of glands:• tubular, acinar (rounded), or
• tubulo-acinar (rounded with tubular end)
• branched tubular or coiled tubular (long and not branched)
Nature of secretions
• Serous secretion: secret watery fluid rich in protein (parotid glands)
• Mucous secretion: secret mucus; poor in protein (goblet cells)
• Muco-serus secretion: as in mixed salivary glands
• Milky secretion: mammary gland
• Wax secretion: glands in external ear
• Fatty secretion: sebaceous glands
• Watery secretion: sweat glands
• Cellular secretion: ovary and testis.
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Apocrine glands: a small portion of the apical
cytoplasm discharged with the secretory products.
e.g.. Mammary glands and some sweat glands.
Holocrine glands: discharge whole cell;
sebaceous glands (sebum).
Merocrine glands: in which secretion occurs by
exocytosis; i.e. no cellular changes as parotid
glands.
Modes of Secretions
Simple Tubular Gland
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Simple Branched Tubular Gland
Simple Coiled Tubular Gland
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Compound Acinar Gland
Compound Tubuloacinar Gland
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Mucous cells produce mucus, which doesn't stain very darkly, so the mucous cells look almost clear on these images and on slides. Serous cells produce a watery secretion that contains a lot of proteins and enzymes. Serous cells stain fairly dark.
Endocrine Gland
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Epithelium Summary Tables
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Connective Tissue
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Connective Tissue’s Functions
• Binding and Support• Protection• Mineral storage• Insulation• Energy Storage• Transportation (blood)• Immunity• connective tissues (CT) consist of material between
or outside of cells, largely fibers and a gel-like ground substance.
C.T. Structure• Cells are widely separated among the masses of
fibers and ground substances.
• Fibers and ground substance are termed the extracellular matrix (ECM).
• Fibers, composed of collagen or elastin, are responsible for the tensile strength and elasticity of the tissue.
• Ground substance, composed of hydrated proteoglycans, provides the medium through which dissolved substances pass from capillaries to cells and back.
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Connective Tissue is composed of:
• Cells
• Extracellular Matrix (material outside of cells)
Extracellular matrix, ECM, is composed of fibers of protein and ground substance
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Ground substance consists of glycosaminoglycans and glycoproteins
Cells of the CT
• Mitotically active = “blasts”
• Mature cells = “cytes”
• Fibroblasts = cell that synthesizes the extracellular matrix and collagen
• Mast Cells = histamine release
• Plasma Cells = antibody release
• Adipocytes
• Leukocytes
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Different Cell Types found in C.T.
Connective Tissue Types1) Loose Connective Tissue = loose arrangement of
cells; not very organizedAreolar
Adipose
Reticular
2) Dense Connective Tissue = Tightly packed cells; more organized
Dense Regular
Dense Irregular
Elastic
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Areolar Loose Connective Tissue
Loose Connective Tissue
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Loose Areolar C.T.
• Found in the
lamina propria;
in between muscles,
in lungs.
•Acts as space filler
Loose Reticular C.T.
• Loose arrangement of Reticular fibers: Makes the framework for lymphatic organs i.e. (tonsils, thymus, spleen, lymph nodes)
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Adipose Tissue
Dense Elastic CTFound in arteries, e.g. (aorta)
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Dense Irregular Connective TissueFound in Dermis, pericardium of heart, synovial joint capsule
Dense Regular Connective TissueFound in Tendons & Ligaments
Tendons: attach bone to muscle, Ligaments: attach bone to bone
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Dense Regular Connective Tissue(cont’d)
Dense Regular Connective Tissue(cont’d)
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Quiz # 2 next week 09/17 on this lecture &Assignment #1 due to be handed in at the BEGINNING of class
Assignment #1
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1. Identify the basic tissue indicated by the arrow
Answer
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2. Identify the type of epithelium indicated by the arrow
Answer
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3. Identify the type of epithelium & the cell type indicated by the arrow
Answer
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4. Identify the type of epithelium indicated by the arrowsAnswer
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5.Identify the type of epithelium & name the apical structure (i.e. cilia or microvilli)
Answer
__________________________________
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6. Identify the 2 different cell types in this submandibular gland:-Indicated by the wide and thin arrows
Answer
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7. Identify the type of epithelium and where it is found
Answer
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8. Identify the type of Epithelium and where it is found
Answer
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9. Identify the type of Epithelium & where it is found
Answer
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10. Classify the type of connective tissue
Answer
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11. Classify the type of connective tissue & identify the cell types indicated by the arrow
Answer
__________________________________
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12. Classify the type of connective tissue and the type of fiber stained black
Answer
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13. Classify the type of connective tissue and the type of fiber stained black
Answer
__________________________________
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14. Classify the type of connective tissueAnswer
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15. Classify the type of connective tissueAnswer
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16. Classify the type of connective tissueAnswer
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17. Classify the type of connective tissue
Answer
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18. Classify the type of glandular epithelium
Answer
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19. Classify the type of glandular epithelium
Answer
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20. Classify the type of glandular epitheliumAnswer
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