GI System 1

Question 1

Main role of the GI Tract

Answer 1

to transfer water & nutrients from food into the body

Question 2

GI Tract Main Organs

Answer 2

• Oral Cavity
• Esophagus
• Small Intestine
• Rectum
• Stomach
• Large Intestine

Question 3

Oral Cavity Function

Answer 3

Digstion
- only carbs
- salivary amylase & chewing

Question 4

Esophagus Function

Answer 4

passage to stomach

Question 5

Stomach Function

Answer 5

continued digestion
- only proteins
- chyme churned & pepsin

Question 6

Small Intestine Function

Answer 6

• most digestion & absorption
• only chemical, lipids, carbs, proteins
• pancreatic enzymes

Question 7

Large Intestine Function

Answer 7

• colon absorbs water and electrolytes, produces feces
• rectum houses gut microflora

Question 8

GI Tract Sphincters

Answer 8

1. Upper Esophageal Sphincter
2. Lower Esophageal Sphincter
3. Pyloric Sphincter
4. Ileocecal Sphincter
5. Internal/External Anal Sphincters

• internal = smooth muscle & autonomic
• external = skeletal muscle & controlled

Question 9

Layers of the GI Tract

Answer 9

1. Mucosa
2. Submucosa
3. Muscularis Externa
4. Serosa

Question 10

Mucosa

Answer 10

• Epithelium - single layer epithelial cells with transporting/secretory/stem cells (ions/water/enzymes/mucus)
• Lamina Propria - loose connective tissue (blood supply/nerves)
• Muscularis Mucosae - thin layer of smoorh muscle, can contract for absorption

Question 11

Submucosa

Answer 11

• loose connective tissue
• submucosal plexus (enteric nervous system)

Question 12

Muscularis Externa

Answer 12

Inner Circular Muscle Layer - constrict lumen
Outer Longitudinal Muscle Layer - shorten tract
- Myenteric Plexus (located between the 2 muscle layers)

Question 13

Serosa

Answer 13

outer covering of the entire GI Tract, comprised of secretory epithelium & connective tissue layers
- lubricating/protecting fluid

Question 14

Secretion

Answer 14

secretes gastric juice/saliva into the lumen

Question 15

Digestion

Answer 15

chemical (enzymes) & mechanical (chewing) breakdown

Question 16

Absorption

Answer 16

moving from lumen into ECF/blood (glucose/AA’s)

Question 17

Motility

Answer 17

movement of material through the GI Tract as a result of muscle contraction

Question 18

Peristaltic Contractions

Answer 18

• propel contents forward
• circular muscles contract behind bolus to push it forward

Question 19

Segmental Contractions

Answer 19

• mixing contents to break up food and increase exposure to enzymes
• segments of intestine alternately contract & relax

Question 20

Enteric Nervous System Function

Answer 20

• self sufficient nervous system containing a complete reflex circuit
• regulates motility and GI tract secretions

Question 21

Short Reflexes

Answer 21

integrated in the enteric nervous system (entirely in gut wall)
- sensory receptors send info to ENS through interneurons

Question 22

Long Reflexes

Answer 22

integrated within the CNS
- signals may originate inside the GI tract or from higher centers (brain)
- feedforward & emotional reflexes

Question 23

GI Peptides

Answer 23

can be hormones, paracrines, neurotransmitters
- alter GI secretions/motility/eating behaviors