Histology

Question 1

What are the four layers of the GI tract?

Answer 1

1) Mucosa (epithelium, lamina propria, muscularis mucosae) 2) Submucosa 3) Muscularis 4) Serosa or adventitia

Question 2

What are two functions of the muscularis mucosae

Answer 2

1) mixing of digestive enzymes and chyme 2) selective increase or decrease of the surface area

Question 3

Where are the two nerve plexi located ,what are they named, and what is the primary function of each? Are they located in the entire GIT?

Answer 3

The submucosal plexus (Meissner’s) is located on the inner surface of the muscularis externa and regulations secretion and blood flow. The myenteric plexus (Auerbach’s) is located between the longitudinal and circular layers and regulates motility. The stomach and everything north only have a myenteric plexus, no submucosal plexus

Question 4

What is the difference between serosa and adventitia? Where is each found?

Answer 4

Serosa has a mesothelium on top of the connective tissue that secretes a lubricating fluid. Retroperitoneal organs will have adventitia (thoracic esophagus, part of duodenum, cecum and ascending colon, descending colon, rectum) Intraperitoneal organs will have a serosa (abdominal esophagus, stomach, first part of duodenum, ileum, jejenum, transverse colon, sigmoid colon

Question 5

What are the three surfaces of the lip?

Answer 5

The outer cutaneous surface (on the left- keratinized skin, under it is the obicularis oris muscle)

the inner oral mucosa (contains some salivary glands- labial glands)

the vermillion border (where you wear lipstick, between the other two)

Question 6

What kind of mucosa is on the hard palate? What are the glands in the submucosa called and what do they secrete?

Answer 6

Masticatory muscosa

Palatine glands- secrete Purely mucus

Question 7

What separates the anterior and posterior parts of the tongue?

Answer 7

The sulcus terminalis- a V-shaped groove.

Question 8

What are the different types of lingual papillae? What is their function?

Answer 8

• Filliform papillae: no taste buds, mechanical function..like bristles on a toothbrush
• Fungiform papillae: have taste buds in the upper surface, mushrrom shaped, are covered by parakeratinized epithelium
• Circumvallate papillae: cone shaped, have easliy visible tastebuds on the inferior surface so that thigns can be washed away by the saliva from salivary glands in the surrounding tongue.

Question 9

What are the three different major salivary glands?

Answer 9

Parotids: purely serous

submaxillary: mixed seromucous
sublingual: mixed seromucous

Question 10

What kind of muscle fiber is the muscularis externa in the esophagus?

Answer 10

Upper 1/3: both skeletal

Middle 1/3: inner smooth, outer skeletal

Lower 1/3: both smooth