Lecture 1: Structure + Innervation of Gastrointestinal Tract

Question 1

What is the linear sequence of the GIT

Answer 1

Mouth > Esophagus > Stomach > Small intestine > Large intestine > Anus

Question 2

Mouth digestive processes and goal

Answer 2

Acquiring and mastication
Goal: To breakdown particles for absorption

Question 3

Stomach digestive processes

Answer 3

Mixing and hydrolyzes protein

Question 4

What does majority of absorption occur?

Answer 4

Small intestine

Question 5

Small intestine digestive processes

Answer 5

Digests and absorbs protein, carbs, fat, absorbs vitamin and minerals

Question 6

Large intestine digestive processes

Answer 6

Reabsorption of water, fermentation of fiber

Question 7

What are the supportive structures of the GIT?

Answer 7

Salivary glands
Pancreas
Liver
Gallbladder

Question 8

Salivary glands responsibilities

Answer 8

Saliva for lubrication and digestion of starch and fats

Question 9

Pancreas responsibilities

Answer 9

Buffering, digestion of carbs, proteins, fat

Question 10

Liver responsibilities

Answer 10

“First pass” metabolism
Receives all nutrients absorbed from gut before blood returns to heart (takes up some nutrients and sotres)
Makes bile for fat digestion

Question 11

Where does “first pass” metabolism occur?

Answer 11

Liver

Question 12

Gallbladder responsibiltiies

Answer 12

Stores all bile made by the liver

Question 13

What are the two surfaces of the GIT wall?

Answer 13

Mucosal
Serosal

Question 14

What does the mucosal surface of the GIT wall face?

Answer 14

Lumen

Question 15

What does the serosal surface of the GIT wall face?

Answer 15

Blood

Question 16

Name the layers of the mucosal layer

Answer 16

Epithelial cells
Lamina propria
Muscularis mucosae

Question 17

Function of epithelial cells of mucosal layer

Answer 17

Important absorptive and secretory functions - sloughed and replaced often

Question 18

Function of lamina propria of mucosal layer

Answer 18

Connective tissue, blood and lymph vessels

Question 19

Function of muscularis mucosae of mucosal layer

Answer 19

Smooth muscle cells, change shapes + surface area of epithelium

Question 20

What does the submucosal layer of the GIT wall contain?

Answer 20

Collagen, elastin, glands, blood vessels

Question 21

What are the two layers of smooth muscle in the GIT wall?

Answer 21

Circular muscle
Longitudinal muscle

Question 22

Which layer of muscle is very thick and has more nerves?

Answer 22

Circular muscle

Question 23

Which layer of muscle and thin and has few nerves?

Answer 23

Longituindal muscle

Question 24

Name layers of GIT wall starting with the lumen

Answer 24

Mucosal layer (lumen)
- Epithelium
- Lamina propria
- Muscularis mucosae
Submucosal layer
Circular muscle
Longitudinal muscle
Serosal layer

Question 25

Where is the submucosal plexus (meissner's plexus) located?

Answer 25

Between submucosa and circular muscle

Question 26

Where is the myenteric plexus (auerbach's plexus) located?

Answer 26

Between circular and longitudinal muscle

Question 27

Name the components of the autonomic nervous system involved in innervation of the GIT

Answer 27

Extrinsic component Intrinsic (enteric) component

Question 28

What component of ANS involved in innervation of the GIT corresponds to sympathetic and parasympathetic innervation?

Answer 28

Extrinsic component

Question 29

What component of ANS involved in innervation of the GIT corresponds to the enteric component?

Answer 29

Intrinsic component

Question 30

Where does the intrinsic (enteric) component begin and end?

Answer 30

Begins in esophagus, extends to anus

Question 31

What does the intrinsic (enteric) component communicate with / what is it influenced by?

Answer 31

Influenced by and communicates with extrinsics

Question 32

How does the enteric nervous system control functions of GIT in the absence of extrinsic system?

Answer 32

Short reflex arcs

Question 33

Define short reflex arcs

Answer 33

Fast internal response to digestive stimuli

Question 34

Where is the enteric nervous system located?

Answer 34

In ganglia of myenteric and submucosal plexuses

Question 35

The ganglia of the myenteric and submucosal plexuses not only receive input from digestive stimuli, but also from

Answer 35

Parasympathetic and sympathetic systems

Question 36

The parasympathetic and sympathetic nervous systems putting input on the ganglia of the myenteric and submucosal plexuses are able to

Answer 36

Modulate the activity of the ganglia

Question 37

The ganglia of myenteric and submucosal plexuses are able to receive sensory information from

Answer 37

Receptors in mucosa

Question 38

The ganglia of myenteric and submucosal plexuses are able to send motor information directly to

Answer 38

Smooth muscle, secretory, and endocrine cells

Question 39

What are some examples of sensory information that the ganglia of myenteric and submucosal plexuses are able to receive?

Answer 39

Wall stretch, changes in nutrient concentration, osmolarity, pH changes, irritation

Question 40

Name the two enteric plexuses

Answer 40

Myenteric Submucosal

Question 41

Both enteric plexuses communicate with each other using innervations and with

Answer 41

CNS via vagal, pelvic, and splanchnic nerves

Question 42

The enteric nervous system controls what functions of the GIT?

Answer 42

Contractile, secretory, and endocrine

Question 43

Enteric nervous system can release

Answer 43

Neurotransmitters/Neuromodulators

Question 44

Enteric nervous system can operate independent of

Answer 44

Brain and spinal cord

Question 45

If the vagus nerve is severed, the enteric nervous system will

Answer 45

Still function!

Question 46

The parasympathetic innervation of the GIT is supplied by the

Answer 46

Vagus nerve (CNX) and pelvic nerve

Question 47

The vagus nerve innervates which portion of the GIT

Answer 47

Upper (Striated muscle in upper third of esophagus, wall of stomach, SI, and ascending colon)

Question 48

The pelvic nerve innervates which portion of the lower GIT

Answer 48

Lower (Striated muscle of external anal canal, walls of transverse, descending, and sigmoid colon)

Question 49

PSNS preganglionic fibers long or short?

Answer 49

Long

Question 50

Where do PSNS preganglionic fibers synapse?

Answer 50

In ganglia in or near target organs

Question 51

PSNS ganglia specific location in GIT

Answer 51

Myenteric and submucosal plexuses within walls of GIT

Question 52

Postganglionic neurons of PNS are classified as

Answer 52

Classified as cholinergic or peptidergic

Question 53

Cholinergic postganglionic neurons release

Answer 53

Acetylcholine

Question 54

Peptidergic postganglionic neurons release

Answer 54

Substance P and Vasoactive inhibitory peptide (VIP)

Question 55

Substance P and Vasoactive inhibitory peptide then release..

Answer 55

Neurotransmitters and neuromodulators

Question 56

Vasovagal reflexes are

Answer 56

Reflexes in which both afferent and efferent limbs containtained in the vagus nerve

Question 57

Afferent fibers in vagus nerve delivery sensory information from and to

Answer 57

Periphery (receptors in wall of GIT) to CNS

Question 58

Efferent fibers in vagus nerve deliver motor information from and to

Answer 58

From CNS to target tissues (smooth muscle, secretory, endocrine cells)

Question 59

Vagus nerve is what % afferent and what % efferent?

Answer 59

~75% afferent, 25% efferent

Question 60

Neuromodulators are usually secreted with

Answer 60

Neurotransmitters

Question 61

Neuromodulators and act to increase/decrease what?

Answer 61

Amount of neurotransmitter released

Question 62

What can act to modify the response of the postsynaptic cell?

Answer 62

Neuromodulators

Question 63

Neuromodulators target the slower

Answer 63

G-protein neuroreceptors