Intro to Physiology I Lopez Flashcards Preview

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Flashcards in Intro to Physiology I Lopez Deck (131):
1

Main functions of GI system

Digestion and absorption

2

Main properties of digestion and absorption

motility and secretions

3

Purpose of sphincters

restrict the passage of intestinal content to optimize digestion and absorption

4

7 sphincters of GI tube

UES, LES, Pylorus, Sphincter of Oddi, Ileocecal valve, Internal anal sphincter, external anal sphincter

5

4 functional laters of the GI

1. mucosal
2. submucosal
3. muscle layer
4. serosa

6

2 muscles in the muscle layer

circular and longitudinal muscles

7

What is the nervous system of the GI tract

Enteric nervous system

8

What are the 2 plexi in the ENS

submucosal plexus and myenteric plexus

9

What is the GI tract innervated by

ANS and ENS

10

What innervates the extrinsic nervous system

ANS

11

What innervates the intrinsic nervous system

END

12

What nervous system are the cell bodies located on the outside of the gut wall

extrinsic

13

Where are the cell bodies of the intrinsic nervous system located

within the wall

14

What innervates the parasympathetics of the GI system

vagus nerve and pelvic nerves

15

Where are preganglionic nerve cell bodies for vagal innervation

brainstem

16

Preganglionic nerve cell bodies for pelvic nerves

sacral spinal cord

17

Where are postganglionic neurons for parasympathetic

wall of the organ- enteric neuron in gut wall

18

What neurotransmitter is used for preganglionic parasymp

Ach

19

What is the postganglionic neurotransmitter for parasymp

Ach

20

What is the pathway for sympathetic neurons of the GI

spinal cord to prevertebral ganglia to ganglia to organs of the gut

21

Where do preganglionic efferent fibers for sympath come from

spinal cord

22

Where do preganglionic efferent fibers of sympathetic end

prevertebral ganglion

23

Where do postganglionic fibers of sympath start

prevertebral gang

24

What do the prevertebral ganglia innervate

myenteric and submucosal plexuses

25

What neurotransmitter is released by preganglionic efferent fibers of the sympathetic nervous system

Ach

26

What neurotransmitter is released by postganglionic efferent fibers of sympath

NE

27

What neurons are part of the integrating center of the ENS

afferent neurons, interneurons, efferent neurons

28

What are afferent neurons

sensory neurons

29

what are efferent neurons

motor neurons

30

T/F Enteric needs the CNS to function

F- the ENS can function without CNS input

31

What reflex is associated with the CNS regulation of GI functioning

Vago-vagal reflex

32

Other name for vago-vagal reflex

gastric receptive relaxation reflex

33

CNS effect on ENS

can modulate ENS response but ENS can function without it

34

Where are centers that control food intake

in the brain

35

What is the sensory ganglion of the vagal nerve

nodose ganglion

36

What is the part of brainstem that receives sensory info

nucleus of the tractus solitarius

37

What does the nucleus of the tractus solitarus send out

vagal efferent signals

38

Where do the vagal efferent signals end up

in/on the organ wall

39

Paracrine regulation

action of peptides or other messenger molecules on local/neighboring target cells

40

Two paracrine messengers/peptides

somatostatin and histamine

41

What cells secrete peptides/messengers for paracrine regulation

enteroendocrine cells

42

T/F Paracrines act locally

T

43

How do paracrine signals reach their targets?

diffusion over short distance

44

What is secreted by D cells?

somatostatin

45

Where are D cells located?

GI mucosa

46

Stimuli for somatostatin

decrease in pH (more acidic environment)

47

Actions of somatostatin

inhibit gastric H+ secretion (parietal cells)

48

Where is somatostatin released outside of the GI tract?

hypothalamus, and gamma cells of the exocrine pancreas

49

Where is histamine stored and secreted?

stomach

50

What cells secrete histamine

enterochromaffin-like cells

51

Where are enterochromaffin cells located?

gastric glands

52

What cell is the target of histamine?

parietal cells

53

Function of histamine

stimulate parietal cells to secrete more acid (HCl)

54

Endocrine regulation

action of hormones

55

What cells contain granules filled with hormone peptides?

enteroendocrine cells

56

How do hormones get to target cell?

portal circulation --> live --> systemic circulation --> specific receptors on target cell

57

T/F hormones can bind to target cell that doesn't have specific receptor

F - hormone binds to target cell with specific receptor

58

Gastrin site of secretion

G cells of stomach

59

Gastrin stimuli of secretion

small peptides and amino acids, distention of stomach, vagal stimulation

60

CCK site of secretion

I cells of the duodenum and jejunum

61

CCK stimuli of secretion

small peptides and amino acids and fatty acids

62

Secretin site of secretion

S cells of the duodenum

63

Secretin stimuli of secretion

H+ (acidic) in the duodenum and fatty acids in the duodenum

64

Glucose dependent insulinotropic peptide site of secretion

duodenum and jejunum

65

GIP stimuli of secretion

fatty acids, amino acids, and oral glucose

66

Function of gastrin

increase gastric H+ secretion

67

What stimulate growth of gastric mucosa

gastrin

68

What is Zollinger-Ellison syndrome

gastrin-secreting tumor

69

S/S of Zollinger-Ellison syndrome

hypertrophy of gastric mucosa, duodenal ulcers, steatorrhea

70

What is steatorrhea

excretion of abnormal quantitites of fat with feces due to reduced absorption of fat by intestine

71

What increases during Zollinger-Ellison syndrome

increase circulatin gastrin and increase acid secretion by parietal cells

72

Actions of CCK

- increase pancreatic enzyme secretion
- increase pancreatic HCO3 secretion
- inhibit gastric emptying

73

Effect of CCK on gallbladder/sphincter of Oddi

stimulate contraction of gallbladder and relaxation of sphincter of Oddi

74

T/F CCK can act as a paracrine signal

T

75

Actions of Secretin

- increase pancreatic HCO3 and biliary HCO3 secretion
- decrease gastric H+ secretion

76

Secretin actions on gastrin

inhibit trophic effect of gastrin on gastric mucosa

77

T/F Secretin can not act as a paracrine signal

F - Secretin can act as a paracrine signal

78

GIP actions

- increase insulin secretion from pancreatic beta cells
- decrease gastric H+ secretion

79

What would be more effective increasing insulin secretion?
1. Oral glucose administration
2. Intravenous glucose administration

Oral- because stimulates GIP which stimulates insulin secretion and directly effects stimulation of beta cells

80

Neural regulation

action of neurotransmitters to make action potential and diffuse across synapse to bind postsynaptic cells

81

Where are the neurotransmitters released from during neural regulation

nerve terminals stimulated by action potential

82

Source of Ach

cholinergic neuron

83

Action of Ach

contraction of smooth muscle and relaxation of sphincters

84

What does Ach increase

salivary secretion, gastric secretion, pancreatic secretion

85

Source of norepinephrine

adrenergic neurons

86

Function of NE

Relaxation of smooth muscle and contraction of sphincters

87

What does NE increase

salivary secretion

88

What does the neuronal centers of the hypothalamus control

feeding and satiety

89

What are the 5 neuronal centers of the hypothalamus

lateral nucleus, ventromedial nucleus, paraventricular nucleus, dorsomedial nucleus, arcuate nucleus

90

What occurs in the lateral nucleus

feeding center

91

What occurs in the ventromedial nucleus?

satiety

92

What maintains energy balance?

neural and hormonal regulations

93

5 ways hypothalamus can receive a signal

- neural signals from GI
- chemical signals from nutrients in blood
- GI hormones
- signal from adipose tissue
- signal from cerebral cortex (sight, smell, and taste)

94

Where does most of the integration of signaling/regulating food intake and energy expenditure occur?

arcuate nucleus

95

What are the two pathways of the arcuate nucleus

Alpha melanocortin pathway, and neuropeptide Y pathway

96

What releases a-MSH

pro-opiomelanocortin (POMC) neurons

97

Receptor for a-MSH

MCR-4

98

Where is the MCr-4 receptor located

second-order neurons

99

Main function of the a-MSH pathway

inhibit food intake and increase metabolism (anorexigenic)

100

What stimulates the NPY pathway

hunger

101

Receptor for NPY pathway

Y1R

102

What can neurons that release NPY also release

agouti-related peptide (AGRP)

103

Main function of NPY pathway

Increase feeding behavior and storage of calories (orexigenic)

104

How do the a-MSh pathway and NPY pathway work together

antagonize one another
- peptides that stimulate a-MSH, inhibit NPY
- AGRP released from NPY antagonize MCR-4

105

Pathway of vagus nerve

vagal -->NTS-->hypothalamus circuit

106

Where is ghrelin secreted?

by endocrine cells in the stomach

107

What receptor does ghrelin bind to?

growth hormone secretagogue

108

Ghrelin function in hypothalamus

stimulates neurons that release NPY

109

What does ghrelin increase

appetite, gastric motility, gastric acid secretion, adipogenesis, insulin secretion

110

What can initiate feeding response?

ghrelin

111

What centers does insulin initiate in the hypothalamus?

satiety and hunger centers

112

What are the receptors insulin binds to?

POMC and NPY

113

Insulin effect on NPY pathway

inhibit

114

Insulin effect on POMC pathway

stimulate

115

Actions of insulin

decrease appetite and increase metabolism

116

Insulin in diabetes mellitus type I patients

increase in food intake associated with decrease in insulin

117

CCK function

elicits satiety

118

CCK on ghrelin

decrease ghrelin

119

CCK on gastric secretion

decrease gastric emptying and increase gastric distention

120

PYY is released by...

L cells of enteroendocrine cells of the ileum and colon following a meal

121

What receptors do PYY bind to?

Y2 receptors

122

Where are the Y2 receptors located

hypothalamus

123

PYY on NPY neurons

inhibit

124

PYY on POMC neurons

inhibit

125

PYY on appetite

suppressor

126

Where is leptin secreted?

adipose tissue and endocrine cells in stomach

127

Where are the receptors that leptin binds to?

satiety and hunger centers in hypothalamus

128

Leptin on NPY pathway

inhibit

129

Leptin on POMC pathway

stimulates

130

Appetive-supressing hormone function

- decrease appetite
- increase metabolism
- ghrelin release

131

Appetive-supressing hormone on food intake

negative feedback system for regulation of food intake