Final Exam GI Physiology Questions Flashcards Preview

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Flashcards in Final Exam GI Physiology Questions Deck (66):
1

What hypothalamic neurotransmitters help control hunger and satiety centers?

CCK, CRH, Neuropeptide Y, and Leptin

2

What control mechanisms help to achieve INTRINSIC control of the GI Tract?

Enteric Nervous System
Endocrine Cells in the gut wall
Cells that secrete paracrine substances
Local tissue factors

3

Where would you find interneurons of the enteric nervous system and what are they commonly known as? What do they do?

Submucosa (Meissner's) plexi
Myenteric (Auerbach's) plexi
They synapse onto muscles, glands, and secretory and absorptive epithelium.

4

What do endocrine cells in the gut wall respond to?

Directly to GI tract luminal contents
NTs
Paracrine substances

5

Histamine, somatostatin, prostaglandins, and serotonin are examples of what kind of substance?

Paracrine substances

6

What are the MOST important sites of hormone production in the GI Tract?

Stomach and Small Intestine

7

What is a local tissue factor?

Simple products of metabolism whose concentrations affect neighboring blood vessels.

8

Increased concentration of tissue factors (CO2, H+, and K+) result in ____________ of neighboring blood vessels.

Vasodilation

9

What control mechanisms help to achieve EXTRINSIC control of the GI Tract?

Afferent neurons projecting from GI Tract to either extramural plexi or CNS

Afferent neurons that convey sensory info to the CNS

SNS and PSNS EFFerent neurons

Somatic nervous system EFFerent neurons

Endocrine cells outside the gut wall

10

What control mechanisms help to achieve DIRECT control of the GI Tract?

The direct interaction of NTs, hormones and paracrine substances with gut wall muscles, glandular tissue, and secretory or absorptive epithelium

11

How is INDIRECT control of the GI Tract achieved?

Through regulation of perfusion

12

The GI system can receive up to what percent of cardiac output when active?

30%

13

What is the overall effect of SNS stimulation?

Vasoconstriction and decreased blood flow

14

What do SNS postganglionic neurons secrete?

NE

15

What receptors predominate at GI vasculature?

alpha-1 adrenergic receptors

16

What do PSNS postganglionic neurons secrete?

VIP and ACh

17

What does VIP do?

Inhibits actin-myosin interaction in muscle

Promotes production of NO which leads to vasodilation

18

What does ACh do?

Promotes production of NO which leads to vasodilation

19

What does Epinephrine from the adrenal medulla do when stimulating alpha-1 adrenergic receptors?

Vasoconstriction

20

What does Epinephrine do when stimulating beta-2 adrenergic receptors?

Vasodilation

21

The effects of epinephrine stimulation prevail on which receptors?

alpha-1

22

What does gastrin and other peptide hormones of the GIT do?

Vasodilation

23

Which two substances have a powerful vasoconstrictive effect resulting from a decreased ECV (effective circulating volume)?

Angiotensin II and ADH

24

Histamine and Prostaglandins (paracrine secretions) are _______ in effect.

Histamine and prostaglandins are vasodilatory

25

Local tissue factors like CO2, H+ and K+ are __________.

CO2, H+, and K+ are vasodilatory

26

At rest, the kidneys require what percent of cardiac output?

22%

27

At rest, the GI tract and Liver together require what percent of cardiac output?

23%

28

Where in the GI Tract would you find VSM (visceral smooth muscle)?

From the esophagus to the internal anal sphincter.

29

The VSM (visceral smooth muscles) exhibit a spontaneous pattern of depolarization and repolarization called ____ ____.

Slow waves

30

Where are slow waves generated?

In the myenteric plexus by interstitial cells.

31

Slows waves give rise to what?

BER (basic electrical rhythm)

32

Where is the BER (basic electrical rhythm) greatest?

In the duodenum

33

What are the propagated motility patterns?

Peristalsis and Antiperistalsis are both propagated motility patterns.

34

Peristalsis is a classic example of a ______ reflex.

Peripheral reflex

35

PSNS innervation of of GI tract musculature are most pronounced where?

At the esophagus, stomach, and rectum.

36

T or F: Peristalsis occurs in the absence of CNS input.

True

37

What is the gastrocolic reflex initiated by? What is the effect?

Gastric distension initiates the gastrocolic reflex.
The effect is mass movements at the distal colon promoting the movement of feces into the rectum.

38

What is the ileogastric reflex initiated by? What is the effect?

Ileal distension initiates the ileogastric reflex.
The effect is DECREASED gastric motility.

39

Distension of the stomach is recognized by mechanoreceptors which stimulate vagal neurons in the medulla. This stimulates neurons in the gastric mucosa to secrete gastrin, histamine, and HCL. This process is an example of what?

A vagovagal reflex

40

What is the overall effect of SNS innervation on GI Tract function?

Inhibition- SNS

41

What is the overall effect of PSNS innervation on GI Tract function?

Excitatory- PSNS

42

What is an example of PSNS control of GI Tract function?

LES (lower esophageal sphincter)

43

As gastric motility increases, PSNS excitatory fibers (via ACh) promote contraction of the LES. What is the purpose of this?

To prevent backflux of acidic chyme into the esophagus

44

Relaxation of the LES is due to ________ firing of Vagal inhibitory fibers (VIF)

relaxation from increased firing of VIF

45

Contraction of the LES is due to ______ firing of vagal excitatory fibers (VEF)

contraction from increased firing of VEF

46

Which secretion protects and lubricates GIT mucosa?

Mucin

47

Which secretion creates the optimum pH for enzymatic activity in the GIT?

HCO3-

48

Which secretion destroys food-borne bacteria in the GIT?

HCl

49

Which secretion solubilizes ingesta?

H20

50

Which secretion hydrolyzes ingesta?

H20 and hydrolytic enzymes

51

Which secretion emulsifies lipids?

Bile

52

What drives the secretion of Na+, K+, and H+ (and water then follows)?

Cl-

53

What happens to the volume of plasma when the volume of secretions increases?

The volume of plasma decreases

54

Where would you find Cl- entering secretory cells by way of secondary active transport?

Basolateral membrane

55

What is a secretagogue?

A neurotransmitter, hormone, or paracrine molecule that promotes secretion.

56

Reception of secretagogues ________ the uptake of Cl- into the basolateral membrane

Increases the uptake of Cl-

57

What are the most important modifications made by ductular cells to primary secretions?

Reabsorption of Na+ and Cl-
Secretion of K+ and HCO3-

58

The secondary secretion, the secretion that actually enters the lumen of the tubular gut at the mouth or small intestine, is distinctly more _______ than the primary secretion.

Secondary secretion is distinctly more ALKALINE than primary secretion.

59

What are the 3 types of salivary glands?

Serous, Mucus-secreting, and Mixed

60

Which animals use saliva for evaporative cooling?

Dogs and cats

61

Which animals primarily use saliva for buffering?

Ruminants

62

What cells produce saliva?

Acinar cells

63

What are the components of saliva?

Water, Electrolytes, Amylase, Lipase, IgA, Mucin, I-
Ruminants also have: (PO4)-2 and urea in their saliva

64

What is the effect of PSNS and SNS on saliva?

Both act to immediately INCREASE the volume of saliva

65

Is salivary gland secretion subsequent to SNS stimulation long or short-lived?

Short-lived

66

Do salivary glands receive endocrine signals from the GI Tract?

NO!