Histology

Question 1

What are the oral cavity, oropharynx and laryngopharynx covered by?

Answer 1

Stratified squamous epithelium which is generally not keratinised

Question 2

What are the nasal cavity and nasopharynx covered by?

Answer 2

Respiratory epithelium

Question 3

What is the tongue covered by?

Answer 3

Anterior 2/3 - stratified squamous epithelium, thin on the ventral surface and thick with papillae on the dorsal surface

Posterior 1/3 - Smooth stratified squamous epithelium which except for the circumvallate papillae, lacks papillae

Question 4

What is the entrance to the oropharynx covered by?

Answer 4

A ring of lymphoid tissue composed of the palatine tonsils, lingual tonsils, tubal tonsils and pharyngeal tonsils

Question 5

What are the layers of the digestive tract?

Answer 5

1. Mucosa:
   a. Epithelium which sits on a basal lamina
   b. Lamina propria (loose connective tissue)
   c. Muscularis mucosae (thin layer of smooth muscle)
2. Submucosa (loose connective tissue)
3. Muscularis externa
   a. Inner circular layer
   b. Outer longitudinal later
4. Serosa/ Adventitia (outer later of connective tissue that either suspends the digestive tract or attaches it to other organs

Question 6

What are some special adaptations of the oesophagus?

Answer 6

1. Has submucosal glands (secrete acid mucin for lubrication)
2. Has a gastroesophageal junction - abrupt transition from stratified squamous epithelium of the oesophagus to the simple columnar epithelium of the cardia of the stomach

Question 7

What are some special adaptations of the stomach?

Answer 7

1. Has gastric pits (each holds 1-7 glands) - lined by mucus cells
2. Has gastric glands - can be made up of chief cells or parietal cells
3. Has different regions:
   a. Cardia - deep gastric pits that branch into loosely packed glands
   b. Body - shallow gastric pits with long straight gastric glands
   c. Pylorus - deep gastric pits, with branched coiled gastric glands at a higher density in the cardia
4. Muscularis externa has an extra oblique muscle later internal to the circular layer
5. Gastroduodenal junction - An abrupt transition from stomach mucosa to duodenal mucosa

Question 8

What are some special adaptations of the small intestine?

Answer 8

Duodenum - contains Brunner’s glands (neutralize chyme)

Jejunum - tallest villi, located on permanent circular folds of the mucosa

Ileum - Peyer’s patches found in the submucosa (lymphoid tissue)

Question 9

What are some special adaptations of the large intestine?

Answer 9

1. Longitudinal muscle in 3 muscle strips called teniae coli
2. Appendix - far less abundant crypts and a circular arrangement of lymphoid tissue
3. Rectoanal junction - the anal canal is continuous with the keratinised stratified squamous epithelium of the surrounding skin

Question 10

Which are the 2 plexuses of the enteric nervous system?

Answer 10

Submucosal - regulates secretion of the epithelium

Myenteric - between the muscle layers of the muscularis externa - controls gut motility

Question 11

What is the enteric nervous system?

Answer 11

The nervous system for the digestive tract

Question 12

Where does the enteric nervous system receive input from?

Answer 12

Autonomic nervous system

Question 13

What is the liver capsule?

Answer 13

The liver is covered by a collagenous connective tissue capture which is in turn covered by a layer of simple squamous epithelium

Question 14

What is the liver made up of?

Answer 14

Segments called lobules

Question 15

Describe hepatic lobules

Answer 15

Hexagonal

Have a branch of the hepatic vein and portal triads (bile ductule, portal vein, hepatic artery)

Question 16

What are hepatocytes?

Answer 16

The main cells of the liver

Question 17

What do hepatocytes form?

Answer 17

Sinusoids

Question 18

What is the liver parenchyma?

Answer 18

The collagenous connective tissue of the liver

Question 19

What is liver parenchyma produced by?

Answer 19

Hepatic stellate cells

Question 20

What are Kupffer cells?

Answer 20

Resident macrophages in sinusoids

Question 21

What is the function of Kupffer cells?

Answer 21

Remove toxins and old blood cells from the sinusoids

Question 22

What is bile produced by?

Answer 22

Hepatocytes

Question 23

What is the structure of the gall bladder?

Answer 23

Lined by simple columnar epithelium backed by a lamina propria of loose connective tissue rich in blood an lymphatic vessels

Question 24

What is the function of the gall bladder?

Answer 24

To store and modify bile

Question 25

What is the functions of the exocrine pancreas?

Answer 25

To produce the digestive juice with inactive proenzymes

Question 26

Which cells produce the digestive juice of the pancreas?

Answer 26

Centroacinar cells

Question 27

What is the endocrine pancreas made up of?

Answer 27

Islets of Langerhans which produce a number of hormones including insulin and glucagon