Intro/ Epithelial Cells-Histology

Front 1

What is histology?

Back 1

-The study of the microscopic structure of cells, tissues, and organs
-fundamental to study of pathology and clinical sciences

Front 2

What discovery did light microscopes allow?

Back 2

the discovery of cells as the basic building blocks of the human body

Front 3

What did light microscopes led scientists to understand?

Back 3

led to our current understanding of health and disease in terms of cellular function

Front 4

What is the four basic tissues and their basic functions?

Back 4

1. epithelial (cover and lining)
2. connective (support and protection)
3. Muscle (movement)
4. Nerve (transmission of nervous impulses)

Front 5

What are the general features of epithelial tissue?

Back 5

-covers surfaces or lines cavities
-rests on basal lamina (basement membrane)
-lacks internal blood vessels
-contains little or nor extracellular matrix (very little space between them)
-cells linked by junctional complexes
-polarized
-forms exocrine and endocrine glands

Front 6

What is one layer of epithelia called?

Back 6

simple

Front 7

What are two or more layers of epithelia called?

Back 7

stratified

Front 8

Define pseudostratified epithelia

Back 8

all cells rest on basal lamina but not all reach the surface

Front 9

what is epithelia celled when it has a variable number (3-6) of layers?

Back 9

transitional

Front 10

What are the 3 types of simple epithelia?

Back 10

1. squamous-flattened cell. ex. blood vessel endothelum (endothelium of arteriole)

2. Cuboidal- nuclei is centrally located.
ex. kidney tubules

3. Columnar- cells are taller than they are wide standing up and connected to the basement membrane..
ex. gall bladder

Front 11

What is the stratified or multi-layered epithelia usually named after?

Back 11

named after the most superficial layer

Front 12

what epithelial surface is skin classified as?

Back 12

stratified squamous keratinising epithelium

Front 13

What does pseudostratified epithelium refer to?

[give example]

Back 13

all cells touch the basement membrane but not all reach the surface

ex. thachea (pseudostratified columnar ciliated epithelium with globlet cells)

Front 14

What function does transitional epithelium have?

[give example]

Back 14

Transitional epithelium: changes the number of its layers according to functional need

Example: Urinary bladder

Front 15

What is the name of transitional epithelium derived from?

Back 15

the name is derived from a functional change in height, not the shape of the surface cells

Front 16

How are epithelial cells attached to each other?

Back 16

cell junctions

The adjacent or lateral surfaces of epithelial cells are linked by cell junctions so that the epithelium forms a continuous cohesive layer. The various types of cell junction are composed of trans-membrane proteins that interact with similar proteins on adjacent cells and are linked to intracellular structures on the cytoplasmic side.

Front 17

What are the three functional types of cell junctions?

Back 17

1. tight junctions (occluding junctions)
2.Zonula adherens (adhering belt) and desmosomes
3. communicating junctions (AKA gap or nexus juctions) [provide a conduit for the passage of small molecules directly]

Front 18

What is the function of terminal bars on the surface of cells?

Back 18

to seal the intercellular space completely

Front 19

What are the functions of Zonula adherens and desmosoms?

Back 19

give the epithelium strength by linking to cytoskeletons of adjacent cells

Front 20

What are the functions of Tight junctions?

Back 20

block passage of molecules between adjacent cells

Front 21

What are two types of surface specialization of the cell?

Back 21

microvili and cilia

Front 22

What is the function of microvilli?

Back 22

increases surface membrane area for more effective interaction with lumen (e.g., small intestine)

small intestine has microvilli brush border

Front 23

What is the function of cilia?

Back 23

ciliary activity helps propel contents in tubular organs (e.g., respiratory tract, oviduct)

beat in a consistent direction.
trachea is lined with cilia

Front 24

Why are some cells keratinized?

Back 24

protection

Front 25

Why are some cells pigmented?

Back 25

protection from excess light (e.g., pigmented cells of the retina)

Front 26

What are some examples of secretory cell surface specialization?

Back 26

some epithelia possess exocrine glandular cells (goblet cells in intestine or respiratory tract; mucous cells lining the stomach) or endocrine cells interspersed among other epithelial cells (enteroendocrine cells; diffuse endocrine system)

Front 27

What is the importance of excretory cell surface specialization?

Back 27

very important interchanges occur through the vascular endothelium, the respiratory alveolar epithelium, and the various epithelia of the kidney.

Front 28

What are the two classes are glandular epithelia?

Back 28

-exocrine
-endocrine

Front 29

How do exocrine glandular epithelium secrete their products?

Back 29

use ducts to secrete their products to an internal or external surface)
o Unicellular (goblet cells)
o Multicellular (glands)

Front 30

How do endocrine glandular epithelium secrete their products?

Back 30

(ductless, secreting their products into surrounding space [paracrine] or blood stream [endocrine])
o Unicellular (diffuse paracrine-endocrine system)
o Multicellular (pituitary, thyroid, etc.)