Lecture 1.A. - Intro to GI Physiology

Question 1

______ is the term used in GI to describe movement of nutrients from lumen into the body/blood, while _____ describes movement of food through the GI tract.

Answer 1

Transport

Motility

Question 2

The first layer of the GI tract tissue is the _____, consisting of:

epithelium lining the lumen,

_____ _____ (connective tissue deep to the epithelial lining),

and the ______ mucosae.

Answer 2

Mucosa

Lamina Propria

Muscularis mucosae

Question 3

The second layer of GI tract tissue is the ______, which is comprised of connective tissue containing most major nerves and blood vessels.

Answer 3

Submucosa

Question 4

The third layer is the ______ externa, comprised of a circular layer and longitudinal layer, and the _____ plexus between them.

Which layer is deeper?

Answer 4

Muscularis externa

Myenteric plexus

The longitudinal layer is deeper.

Question 5

The _______ of the mucosal layer is responsible for secretion and absorption. Which of these two processes is HORMONALLY regulated?

This layer is also partly involved with interactions with gut ______ –> epithelial receptors and immune cells “sense” microbes.

Answer 5

Epithelium

Secretion is hormonally regulated, but keep in mind absorption is regulated via “nutrient sensing.”

Microbiota

Question 6

The submucosal layer is largely responsible for interacting with the gut _______. This layer houses capillaries and _____ cells, which transport O2 and sense microbes, respectively.

Answer 6

Microbiota

Immune cells

Question 7

While most of the GI tract tissue’s 3rd layer is comprised of bi-layer ______ muscle, the _____, upper 3rd of the _____, and external _____ sphincter are comprised of ______ muscle.

Answer 7

Smooth muscle

Pharynx

Upper 3rd of the Esophagus

External Anal Sphincter

Skeletal muscle

Question 8

The ____ and Pelvic nerves arise from the spinal cord and innervate the GI tract to stimulate motility and secretions.

These nerves are part of the ________ nervous system and act via the neurotransmitter ______.

Answer 8

Vagus and Pelvic nerves

Parasympathetic nervous system

Ach

Question 9

The _____, _____ ______, and _____ _____ nerves arise from prevertebral sympathetic ganglia and innervate the foregut, midgut, and hindgut derivatives, respectively

Since they are part of the Sympathetic nervous system, they act to ______ (stimulate or inhibit?) motility and secretions via the neurotransmitter ______.

Answer 9

Celiac

Superior Mesenteric

Inferior Mesenteric

Inhibit

Norepinephrine

Question 10

On average, the proximal GI tract secretes ____L of fluid per day, 80% of which is absorbed in the small intestine. Only about ____mL of this fluid is passed in the stool.

Answer 10

9L

100mL