1 - Gastrointestinal Physiology Overview PPT

Question 1

What are the four main functions of the gastrointestinal (GI) tract?

Answer 1

Ingestion, Digestion, Absorption, Excretion

Acronym: “IDAE”

Question 2

What is the hard palate?

Answer 2

The roof of the oral cavity (aka the mouth)

Question 3

What role does the hard palate play in an infant’s ingestion?

Answer 3

Helps create a vacuum effect for suckling milk

Question 4

What enzyme do infants secrete to break down milk fat?

Answer 4

Lingual lipase

Question 5

What is the uvula’s role in digestion?

Answer 5

The uvula secretes saliva to moisten the throat

Question 6

What are the three salivary glands?

Answer 6

Sublingual gland (below the tongue)
Submandibular gland (below the mandible)
Parotid gland

Mnemonic: Saliva Still Pours

Question 7

What enzyme is within saliva to break down long carbs into small sugars?

Answer 7

Salivary amylase

Question 8

What is the mass of mechanically chewed food mixed with saliva and enzymes called?

Answer 8

a BOLUS!!! (vine boom and airhorn)

Question 9

Where on earth does that dang BOLUS go after it is swallowed through the pharynx?

Answer 9

Into the esophagus

Question 10

What structure blocks off the airway allowing the BOLUS to move into the esophagus?

Answer 10

The epiglottis

Question 11

Where does digestion start?

Answer 11

The mouth

Question 12

What’s the first layer of the GI tract?

Answer 12

Adventitia/serosa

Question 13

What is the adventitia/serosa composed of?

Answer 13

Thick, fibrous connective tissue and a slippery serous membrane

Question 14

What’s the second layer of the GI tract?

Answer 14

Muscularis externa

Question 15

What is the muscularis externa composed of?

Answer 15

Smooth muscle

Question 16

What is the function of muscularis externa?

Answer 16

Moves BOLUS down the GI tract by constricting two muscle groups

Question 17

What two muscle groups are used to move that frickin’ BOLUS down the GI tract?

Answer 17

Inner circular m. layer and an outer longitudinal m. layer

Question 18

What is the term for a series of coordinated, wave-like muscle contractions that squeeze the BOLUS in one direction?

Answer 18

Peristalsis

Question 19

What plexus is located between the two layers of the muscularis externa?

Answer 19

Myenteric plexus (aka Auerbach’s plexus)

Question 20

What is the function of the Myenteric plexus (aka Auerbach’s plexus)?

Answer 20

Coordinates muscle contraction and relaxation

(Contraction-relaxion)

Question 21

What’s the third layer of the GI tract?

Answer 21

Submucosa

Question 22

What is contained within the submucosa?

Answer 22

Blood vessels
Lymphatics
Nerves

Question 23

What plexus is located in the submucosa?

Answer 23

Submucous plexus (aka Meissner’s plexus)

Question 24

What is the function of the Submucous plexus (aka Meissner’s plexus)?

Answer 24

Controls the size of blood vessels and the secretion of digestive juices

Question 25

What’s the fourth layer of the GI tract?

Answer 25

Mucosa

Question 26

What does the mucosa possess for a larger surface area for absorption?

Answer 26

Villi

Question 27

What three components make up the mucosa?

Answer 27

Muscularis mucosa - smooth m. that contracts/breaks down food
Lamina propria - contains blood/lymph vessels
Epithelial layer - absorbs/secretes mucus and digestive enzymes

Question 28

Define intrinsic innervation.

Answer 28

Operates via enteric nervous system to ɪɴᴅᴇᴘᴇɴᴅᴇɴᴛʟʏ control digestive activities. It is ɪɴᴅᴇᴘᴇɴᴅᴇɴᴛ!!

Question 29

Define extrinsic innervation.

Answer 29

Operates via sympathetic nervous system to inhibit digestion, and operates via the parasympathetic nervous system to enhance digestion.

Inhibit: Fight or Flight
Enhance: Rest and Digest

Question 30

Which innervation type do Meissner’s plexus and Auerbach’s plexus operate on?

Answer 30

Intrinsic innervation

Question 31

What is a short reflex and what is it mediated by?

Answer 31

The process of:
- detecting food entering the GI tract via receptors
- conditioning the tract to begin peristaltic contractions to move food one direction

Its afferent and efferent components are mediated by the enteric nervous system (intrinsic innervation).

Question 32

What’s a long reflex?

Answer 32

A long reflex is the CNS’s act of receiving afferent information and sending efferent information to the GI tract via sympathetic and parasympathetic systems (extrinsic innervation).

Question 33

When is a long reflex used?

Answer 33

Two scenarios to observe a long reflex:
- Sympathetic is used to inhibit digestion (Fight or Flight)
- Parasympathetic is used to enhance digestion (Rest and Digest)

Question 34

What are the two types of muscle contractions?

Answer 34

1. Tonic (continuous)
2. Phasic (waves, aka peristalsis)

Question 35

What in tarnation do interstitial cells of Cajal do?

Answer 35

They act as pacemakers and control the contraction rate via rhythmic potentials of de and repolarization, pardner

Question 36

Which potentials cause tonic contractions?

Answer 36

Slow wave potentials from enteric nervous system

Question 37

Which potentials cause peristaltic contractions?

Answer 37

Slow wave potentials PLUS action potentials from the extrinsic nervous system

Question 38

Which component of the GI tract has the lowest rate of contraction at 3 slow waves per minute?

Answer 38

The stomach

Question 39

Which component of the GI tract has the highest rate of contraction at 12 slow waves per minute?

Answer 39

The duodenum