TOB epithelium

Question 1

Describe the term ‘peritoneal’ organs.

Answer 1

Peritoneal organs are covered in serosa (a layer of mesothelium, the visceral peritoneum). (Stomach, liver, colon)

Question 2

Describe the term ‘retroperitoneal organ’.

Answer 2

Retroperitoneal organs lie outside the peritoneum, they are coveted in adventitia (loose connective)

Question 3

Define epithelia

Answer 3

Sheets of contiguous cells, of varied embryonic origin, that cover the external surface of the body and line the internal surfaces.

Question 4

What is meant by the term simple squamous epithelia?

Answer 4

Simple means that the epithelia is one layer thick. With all the cells being in contact with the basement membrane. Squamous is the cell shape, its very thin and flat, with the nucleus making a bulge in the cell.

Question 5

What are the main functions of squamous epithelia?

Answer 5

Lubrication (Peri, pleu, perit/viscera)
Gas exchange (Pulmonary alveoli)
Barrier (Bowmans Capsule)
Active transport by pinocytosis (Mesothelium and endothelium)

Question 6

What is meant by the term simple cuboidal epithelia?

Answer 6

One cell thick. Central nuclues, as wide as they are long. Lining the ducts of most galnds.

Question 7

What is meant by the term simple columnar epithelia?

Answer 7

One cell thick. Basal nuclei, taller than they are wide. Lining most of the GI tract

Question 8

What is meant by the term pseudostratified epithelia?

Answer 8

One cell thick, give the appearance of being stratified because of the position of the nuclei. Line the trachea, bronchi, nasal cavity and the epididymis.

Question 9

What is meant by the term stratified squamous (non-keritinized) epithelia?

Answer 9

more than one cell layer thick. Flattened with nuclei. Line the mouth, oesophagus, vagina.

Question 10

What is meant by the term stratified squamous keratinized epithelia?

Answer 10

more than one cell thick, flattened with out nuclei. Epidermis of the skin and cornea of eye. (invaginated on the soles of feet so cells don’t sloughed off)

Question 11

What is meant by the term stratified cuboidal epithelia?

Answer 11

More than one cell thick, each cell is as tall as it is wide. Line the ducts of the sweat glands.

Question 12

What is meant by the term stratified columnar?

Answer 12

More than one cell thick, basal nuclei. Conjunctiva of the eye, lining of some large excretory ducts.

Question 13

What is meant by the term transitional epithelia?

Answer 13

More than one cell thick. Large dome-shaped cells, which get flattened when distended. Line the bladder, renal calayces, renal pelvis, ureter, urinary bladder, proximal portion of the urethra.

Question 14

What is the basement membrane?

Answer 14

It is the thin, flexible, acellular layer which lies between epithelial cells and the subtending connective tissue.

Question 15

What is the structure and position of the basement membrane?

Answer 15

It consists of basal lamina which is laid down by the epithelial cells and therefore lies closest to them.

Question 16

How is the thickness of the basement membrane varied?

Answer 16

The thickness of the basement membrane can be augmented by a variably thick layer of reticular fibrils (type III collagen) elaborated by the subtending connective tissue.

Question 17

What is the function of the basement membrane?

Answer 17

Serves as a strong and flexible layer to which the epithelial cells can adhere. It also serves as a cellular and molecular filter.

Question 18

What is a bowmans capsule?

Answer 18

the cup shaped end of a nephron, which encloses a knot of blood capillaries (gomerulus). It is the site of primary filtration of the blood into the kidney tubule. Simple squamous epithelia line the parietal layer of the B.C.

Question 19

What is the term given to simple squamous epithelia that lines all vascular elements (arterial, venous, capillary and lymphatic)?

Answer 19

endothelium

Question 20

Define the term mesothelium.

Answer 20

The simple squamous epithelia that lines the; pericardial sac, the pleural sac and the peritoneum.

Question 21

What is the function of the simple cuboidal epithelium linging the collecting ducts of the kidney?

Answer 21

these cells partly determine the urine volume and concentration by reabsorbing urea and water. (They respond to ADH and aldosterone)

Question 22

What are the functions of simple cuboidal epithelium?

Answer 22

Absorption and Conduit (Exoctine glands)
Absorption and secretion (kidney tubules)
Barrier/covering (ovary)
Hormone synthesis, storage and mobilisation (thyroid)

Question 23

What are the functions of the simple cuboidal epithelia lining the thyroid?

Answer 23

lining the follicles, cells synthesise thyroxine, store it in the colloid and transport it in to the blood stream.

Question 24

What are the main locations of simple columnar epithelium?

Answer 24

Stomach lining and gastric glands

Small intestine and colon

Question 25

What are the functions of the simple columnar epithelium?

Answer 25

Absorption (S.I and colon, gall bladder) Secretion (stomach lining and gastric glands, small intestine and colon) Lubrication (s.i and colon) Transport (oviduct)

Question 26

What is the function of simple columnar epithelium in the gall bladder?

Answer 26

Absorb water and electrolytes from the bile produced by the liver thus reducing its volume

Question 27

Where do you find straited columnar epithelia?

Answer 27

in part of the parotid salivary gland, the basal portion of each epithelial cell is striated. This refers to the basal membrane being infolded.

Question 28

What epithelial cells line the fallopian tube?

Answer 28

Simple columnar, some cells are ciliated; others are non-ciliated.

Question 29

What is the name given to the proein that binds adjacent membranes?

Answer 29

Occludin

Question 30

What is the 'zonula occludens'?

Answer 30

A basolateral surface modification. Occuldin binds adjacent PM tightly together in the apical portions of some epithelia. Membrane proteins cannot bypass this, allowing the cell to restrict certain proteins to its apical surface and segregate others to the lateral and basal surface.

Question 31

What disrupts occudin and thereby affects the zonula occudens?

Answer 31

Cholera

Question 32

How many microvilli on average are there per cell?

Answer 32

~1000

Question 33

What is a Lacteal?

Answer 33

A dilated lympahtic capillary vessel in the small intestine which absorbs digested fats

Question 34

What lines the villus of the small intestine?

Answer 34

Simple columnar epithlium

Question 35

What epithelium lines the upper respiratory tract?

Answer 35

ciliated pseudostratified epithelia. | The cilia beat at 12Hz within a watery solution exuded by the epithelium

Question 36

How are particles that enter the trachea swallowed?

Answer 36

the mucous layer that lies on top of the ciliated psuedostratifed, this mucous is secreted by the goblet cells and immobilises particles and lubricates there passage to the pharynx where they are then swallowed

Question 37

What is the epididymis and what epithelia lines it?

Answer 37

The epididymis is a highly coiled tube that transports the sperm from the testis. pseudostratified epithelium bearing stereocilia line the ducts.

Question 38

What are stereocilia?

Answer 38

elongated microvilli, not cilia

Question 39

What are principle cells in the epididymis?

Answer 39

Principal cells found in the epididymis absorb fluid and secrete substances which promote sperm maturation and also phagocytose residual bodies and any degenerate sperm.

Question 40

What are the functions of pseudostratifed epithelium?

Answer 40

Secretion and conduit (Respiratory tract, ductus deferens) Absorption (epididymis) Mucus secretion (respiratory tract) Particle trapping and removal (respiratory tract)

Question 41

Where do you find pseudostratifed epithelia?

Answer 41

Lining of the nasal cavity, trachea, bronchi epididymis and ductus deferens auditory tube and part of the tympanic cavity lacrimal sac large excretory ducts

Question 42

Why are the stratified squamous epithelia that line the vagina rich in glycogen?

Answer 42

A substrate for lactobacilli which produce lactic acid and thereby maintain a suitably low pH

Question 43

What happens to the epithelial cells in the vagina in response to lack of hormonal stimulation?

Answer 43

They atrophy (pre-puberty and menopause)

Question 44

What epithelia lines the epiglottis?

Answer 44

pseudostratified on one side and stratified squamous non-keratinized epithelium lines the other. (elastic cartilage inbetween).

Question 45

What are the functions of stratified squamous (non-k) epithelia?

Answer 45

protection against abrasion (all sites) | Reduces water loss but remains moist (all sites)

Question 46

What are the functions of stratified squamous keratinized epithelium?

Answer 46

Protection against abrasion and physical trauma Prevents water loss prevents ingress of microbes Shields against UV light damage

Question 47

What are the functions of transitional epethelium?

Answer 47

Distensibility | Protection of underlying tissues from toxic chemicals

Question 48

Why does the rate of renewal of different epithelia vary? What can accelerate renewel?

Answer 48

turnover differs depending upon location and function. The time frame for each type of epithelium remains constant unless injury leads to acceleration.

Question 49

Whats the renewel rate for skin epithelia?

Answer 49

approx 28 days

Question 50

What is the renewel rate of cells lining the small intestine?

Answer 50

Replaced by regenerative cells in the base of the crypts every 4 to 6 days

Question 51

What are microvilli?

Answer 51

Apical extensions which greatly increase the surface area for selective absorption of intestinal contents

Question 52

What are cilia?

Answer 52

elongated, motile, plasmalemma- covered extensions of the cytoplasm that move material alone the cell surface

Question 53

Cilia structure

Answer 53

9 pairs of peripheral doublets and two single centrally placed microtubles (singlets). nexin linking protein joins the doublets. Dyenin arms are present on each microtuble doublet, these have ATPase activty. radial spoke connects doublets to central sheet composed of elastin.