Digestive System

Question 1

what are the two subdivisions of the digestive system

Answer 1

• gastrointestinal tract

- accessory organs

Question 2

What are the four main processes of digestion?

Answer 2

1. ingestion
2. digestion
3. absorption
4. defecation

Question 3

name the five basic layers of the GI tract and their composition.

Answer 3

1. Mucosa
   - epithelium with multiple goblet cells. Stratified squamous: mouth, pharynx, esophagus, and anal canal. Simple columnar: stomach, intestines
2. Submucosa
   - areolar CT: blood, lymphatic vessels, submucosal nerve plexus
3. Muscularis Externa
   - smooth muscle, inner circular layer, outer longitudinal layer, myenteric nerve plexus between layers
4. Serosa or adventitia
   - cavity = lumen
5. Enteric Nervous System
   - myenteric nerve plexus controls muscularis externa. submucous plexus controls the activity of mucosal glands and muscle

Question 4

What composes the oral cavity?

Answer 4

1. lips
2. cheeks
3. palate
   - hard palate - 2 maxillae and palatine bones
   - soft palate - posterior projection = uvula = closes nasopharynx when ingestion
4. tongue
   - connected to hyoid bone
   - papillae = taste buds

Question 5

Name the 3 salivary glands.

Answer 5

1. parotid
   - inferior and anterior to ears
2. submandibular
   - floor of the mouth
3. sublingual
   - below tongue on the floor of mouth

Question 6

Describe tooth structure.

Answer 6

crown
- above the gums, dentin
root
- dentin with cementum
neck
peridontal ligaments 
- attaches root to the bone
root canal to pulp cavity

Question 7

Four regions of the stomach.

Answer 7

1. cardiac region
2. fundus
3. body
4. pyloric region

Question 8

What is the composition of gastric glands?

Answer 8

1. chief cells - secrete pepsinogen and gastric lipase
2. parietal cells - secrete HCl and intrinsic factor
3. goblet cells - mucus
4. G cells - secrete gastrin

Question 9

List the components of the small intestines.

Answer 9

1. duodenum - the first fold, extra glands secrete alkaline fluid to protect against stomach acid
2. Jejunum - middle section
3. Ileum - attached to caecum, has lymph nodes called Peyer’s patches that protect against infection

Question 10

Which part of the pancreas secretes hormones such as insulin and glucagon?

Answer 10

islets of Langerhans

Question 11

List and describe the components of the large intestines.

Answer 11

1. caecum - home to masses of bacteria
2. appendix
3. colon
   - ascending
   -hepatic flexure
   - transverse
   -splenic flexure
   descending
   -sigmoid
4. rectum
5. anus

Question 12

Which body part is known as the “fatty apron”?

Answer 12

greater omentum