Histology

Question 1

Columnar and cuboidal cells are involved in ————–

Answer 1

secretion and obsorption

Question 2

Functions of epithelium
stratified → ————-
Squamous → ——————
Keratinised → —————

Answer 2

stratified → protective (lots of layers)
Squamous → thin for diffusion (squashed cells
Keratinised → skin (mechanical stress)

Question 3

Ends of epithelial cells
apical end = ———————-
basal end = ———————–

Answer 3

Ends of epithelial cells
apical end = upper end (exposed to outside of body, or internal cavity)
basal end = attached to basement membrane, anchored to connective tissue

Question 4

——— are the absorptive cells of the intestine

Answer 4

enterocytes

Question 5

GALT

Answer 5

Gut Associated Lymphoid Tissue = lymphocytes in the GI tract wall, part of the immune system

Question 6

Myenteric plexus location

Answer 6

Between the two muscle layers of the muscularis externa

Question 7

Layers of GI tract wall

Answer 7

M,S,M,S
Mucosa&raquo_space; epithelium (enterocytes), lamina propria (loose connective tissue + GALT), muscularis mucosae (thin SM)
Submucosa&raquo_space; loose connective tissue, submucous plexus (part of ENS)
Muscularis externa&raquo_space; inner circular layer, myenteric plexus (part of ENS), outer longitudinal layer
Serosa/adventitia&raquo_space; connective tissue

Question 8

The enteric nervous system has two nervous plexuses in the GI tract wall. They are ———-

Answer 8

1) Submucous plexus (in submucosa) - controls LOCAL intestinal secretion, absorption and contraction of submucosal muscle
2) Myenteric plexus (between muscle layers) - increased muscle tone, increased rhythmic contractions, increased conduction velocity of slow wave activity

Question 9

In the mouth and pharynx, stratified squamous epithelium covers the ———— and respiratory epithelium covers ————–

Answer 9

In the mouth and pharynx, stratified squamous epithelium covers the oral cavity, oropharynx, laryngopharynx, and tongue, and respiratory epithelium covers the nasopharynx and nasal cavity.

Question 10

———- papillae cover most of the dorsal surface of the tongue

Answer 10

Filiform papillae (no taste buds)

Question 11

The pharynx houses the tonsils (4) =

Answer 11

1) Pharyngeal tonsils (adenoids)
2) Palatine tonsil (tonsils)
3) Lingual tonsil
4) Tubal tonsil (leads to ear - covered in ENT)

Question 12

Tonsils are ——– tissue

Answer 12

Lymphoid tissue (part of the immune system)

Question 13

Stratified squamous epithelium covers the mouth because ——–

Answer 13

it comes into contact with food which may abrase the surface of these structures so needs a protective function (also these cells are easily replaced)

Question 14

There is —— AND ——– epithelium present in the nasal cavity.

Answer 14

Olfactory AND respiratory

Question 15

Gastro-oesophageal junction: ——— epithelium&raquo_space; ——– epithelium

Answer 15

stratified squamous epithelium&raquo_space; simple columnar epithelium (of the stomach)

Question 16

Mucosa of stomach - key differentiators

Answer 16

Gastric pits → mucus cells (produce mucus + bicarbonate to protect against the acidic environment)
Gastric glands → stomach secretions
Isthmus → the point where the pit becomes the gland

Question 17

Cells in the gastric glands of the stomach

Answer 17

Parietal cells → HCl
Stem cells → make more cells
Chief cells → secrete digestive enzymes
Enteroendocrine cells → produce hormones to control secretions and motility

Question 18

In Barrett’s oesophagus ——– epithelium of the oesophagus changes to ———- epithelium because ——–
This can predispose to ———

Answer 18

In Barrett’s oesophagus the stratified squamous epithelium changes of the oesophagus changes to the simple columnar epithelium in order to protect the oesophagus from increased exposure to gastric acid. This change in cell type can predispose to cancer development.

Question 19

The gastroduodenal junction is marked by the —–sphincter

Answer 19

pyloric sphinctor

Question 20

Mucosa of small intestine - key differentiators

Answer 20

Villi (projections)

Crypts of Lieberkuhn (pits)

Question 21

Small intestine - cell functions
Enterocytes →
Goblet cells →
Paneth cells →

Answer 21

Enterocytes → absorptive cells, covered in microvili
Goblet cells → mucus for lubrication and protection
Paneth cells → antibacterial products to keep bacterial flora in check

Question 22

Small intestine parts - key differentiators

Answer 22

Duodenum = Brunners’s glands (alkaline mucus to protect from acidic chime)
Jejunum = tallest villi in small intestine (located on plicae circularis)
Ileum = Peyer’s patches (GALT)

Question 23

Large intestine parts - key differentiators

Answer 23

Arranged into crypts (tubular glands which extend down to the muscularis mucosae)
No villi
Taeniae coli: outer longitudinal muscle (of muscularis externa) is in 3 strips instead of being continuous - creates haustra

Question 24

The outer longitudinal muscle of the large intestine is in —– strips instead of being continuous - these are called ————– and create pouches called ————

Answer 24

The outer longitudinal muscle of the large intestine is in 3 strips instead of being continuous - these are called taeniae coli and create pouches called haustra.

Question 25

The appendix has a large amount of --------------- tissue

Answer 25

lymphoid tissue

Question 26

Hexagonal lobules of the liver have a ---------- in the centre and ------------ at each corner.

Answer 26

Hexagonal lobules of the liver have a central vein in the centre (branch of the hepatic vein) and portal triads at each corner (portal vein, hepatic artery, bile duct).

Question 27

Sinusoids in the liver lobules

Answer 27

gaps between hepatocytes that blood flows through (take blood from the hepatic artery and portal vein to the central vein)

Question 28

Kupffer cells

Answer 28

macrophages in the sinusoids

Question 29

Perisinusoidal space (space of Disse)

Answer 29

Between hepatocytes and sinusoid

Question 30

Porta hepatis

Answer 30

opening where vessels enter at the liver hilum

Question 31

Hepatic stellate cells

Answer 31

Fibroblasts (make connective tissue) in the perisinusoidal space (space of Disse) - make scar tissue in liver disease

Question 32

Liver blood supply

Answer 32

Hepatic artery → supplies liver with oxygenated blood Portal vein → carries deoxygenated, nutrient rich blood from spleen, stomach and intestines Hepatic vein → takes deoxygenated blood from the liver to the IVC

Question 33

Bile is produced by hepatocytes and flows via bile canaliculi to the bile ducts

Answer 33

Bile is produced by hepatocytes and flows via ------------ to ----------------

Question 34

------------ are the cells lining the biliary tree

Answer 34

Cholangiocytes

Question 35

Gallbladder = ----------- epithelium

Answer 35

simple columnar

Question 36

What causes gallbladder contraction?

Answer 36

Nervous → vagal (via vagus nerve) | Hormonal → cholecystokinin release in the duodenum when fatty food enters it

Question 37

The majority of the function of the pancreas is {endocrine/exocrine}

Answer 37

exocrine (important for GI)

Question 38

Pancreas - exocrine function

Answer 38

producing digestive pancreatic enzymes

Question 39

The enzymes produced by the exocrine pancreas are inactive proenzymes and become activated when --------------

Answer 39

they arrive in the duodenum (trypsinogen is converted into trypsin which activates other enzymes)

Question 40

Acinus

Answer 40

small cavity surrounded by secretory cells (acinar cells) in the exocrine pancreas.

Question 41

Acinar cells

Answer 41

functional unit of the exocrine pancreas. Produce, store and secrete digestive enzymes.

Question 42

Intercalated duct

Answer 42

collects secretions from acinar cells in the exocrine pancreas.

Question 43

Centroacinar cells

Answer 43

extension of intercalated duct cells into the acinus of the exocrine pancreas

Question 44

Zymogen granules

Answer 44

organelle responsible for sorting, packaging, and regulation of secretion of digestive enzymes (within acinar cells of the exocrine pancreas)

Question 45

endocrine cells of pancreas

Answer 45

Islets of Langerhans

Question 46

In the pancreas, the intercalated duct extends into the ------- because -----------------

Answer 46

In the pancreas, the intercalated duct extends into the acinus because the pancreas must be protected from the harmful enzymes produced.