Intro to Physiology I Lopez Flashcards Preview

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

Main functions of GI system

A

Digestion and absorption

2
Q

Main properties of digestion and absorption

A

motility and secretions

3
Q

Purpose of sphincters

A

restrict the passage of intestinal content to optimize digestion and absorption

4
Q

7 sphincters of GI tube

A

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

5
Q

4 functional laters of the GI

A
  1. mucosal
  2. submucosal
  3. muscle layer
  4. serosa
6
Q

2 muscles in the muscle layer

A

circular and longitudinal muscles

7
Q

What is the nervous system of the GI tract

A

Enteric nervous system

8
Q

What are the 2 plexi in the ENS

A

submucosal plexus and myenteric plexus

9
Q

What is the GI tract innervated by

A

ANS and ENS

10
Q

What innervates the extrinsic nervous system

A

ANS

11
Q

What innervates the intrinsic nervous system

A

END

12
Q

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

A

extrinsic

13
Q

Where are the cell bodies of the intrinsic nervous system located

A

within the wall

14
Q

What innervates the parasympathetics of the GI system

A

vagus nerve and pelvic nerves

15
Q

Where are preganglionic nerve cell bodies for vagal innervation

A

brainstem

16
Q

Preganglionic nerve cell bodies for pelvic nerves

A

sacral spinal cord

17
Q

Where are postganglionic neurons for parasympathetic

A

wall of the organ- enteric neuron in gut wall

18
Q

What neurotransmitter is used for preganglionic parasymp

A

Ach

19
Q

What is the postganglionic neurotransmitter for parasymp

A

Ach

20
Q

What is the pathway for sympathetic neurons of the GI

A

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

21
Q

Where do preganglionic efferent fibers for sympath come from

A

spinal cord

22
Q

Where do preganglionic efferent fibers of sympathetic end

A

prevertebral ganglion

23
Q

Where do postganglionic fibers of sympath start

A

prevertebral gang

24
Q

What do the prevertebral ganglia innervate

A

myenteric and submucosal plexuses

25
Q

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

A

Ach

26
Q

What neurotransmitter is released by postganglionic efferent fibers of sympath

A

NE

27
Q

What neurons are part of the integrating center of the ENS

A

afferent neurons, interneurons, efferent neurons

28
Q

What are afferent neurons

A

sensory neurons

29
Q

what are efferent neurons

A

motor neurons

30
Q

T/F Enteric needs the CNS to function

A

F- the ENS can function without CNS input

31
Q

What reflex is associated with the CNS regulation of GI functioning

A

Vago-vagal reflex

32
Q

Other name for vago-vagal reflex

A

gastric receptive relaxation reflex

33
Q

CNS effect on ENS

A

can modulate ENS response but ENS can function without it

34
Q

Where are centers that control food intake

A

in the brain

35
Q

What is the sensory ganglion of the vagal nerve

A

nodose ganglion

36
Q

What is the part of brainstem that receives sensory info

A

nucleus of the tractus solitarius

37
Q

What does the nucleus of the tractus solitarus send out

A

vagal efferent signals

38
Q

Where do the vagal efferent signals end up

A

in/on the organ wall

39
Q

Paracrine regulation

A

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

40
Q

Two paracrine messengers/peptides

A

somatostatin and histamine

41
Q

What cells secrete peptides/messengers for paracrine regulation

A

enteroendocrine cells

42
Q

T/F Paracrines act locally

A

T

43
Q

How do paracrine signals reach their targets?

A

diffusion over short distance

44
Q

What is secreted by D cells?

A

somatostatin

45
Q

Where are D cells located?

A

GI mucosa

46
Q

Stimuli for somatostatin

A

decrease in pH (more acidic environment)

47
Q

Actions of somatostatin

A

inhibit gastric H+ secretion (parietal cells)

48
Q

Where is somatostatin released outside of the GI tract?

A

hypothalamus, and gamma cells of the exocrine pancreas

49
Q

Where is histamine stored and secreted?

A

stomach

50
Q

What cells secrete histamine

A

enterochromaffin-like cells

51
Q

Where are enterochromaffin cells located?

A

gastric glands

52
Q

What cell is the target of histamine?

A

parietal cells

53
Q

Function of histamine

A

stimulate parietal cells to secrete more acid (HCl)

54
Q

Endocrine regulation

A

action of hormones

55
Q

What cells contain granules filled with hormone peptides?

A

enteroendocrine cells

56
Q

How do hormones get to target cell?

A

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

57
Q

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

A

F - hormone binds to target cell with specific receptor

58
Q

Gastrin site of secretion

A

G cells of stomach

59
Q

Gastrin stimuli of secretion

A

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

60
Q

CCK site of secretion

A

I cells of the duodenum and jejunum

61
Q

CCK stimuli of secretion

A

small peptides and amino acids and fatty acids

62
Q

Secretin site of secretion

A

S cells of the duodenum

63
Q

Secretin stimuli of secretion

A

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

64
Q

Glucose dependent insulinotropic peptide site of secretion

A

duodenum and jejunum

65
Q

GIP stimuli of secretion

A

fatty acids, amino acids, and oral glucose

66
Q

Function of gastrin

A

increase gastric H+ secretion

67
Q

What stimulate growth of gastric mucosa

A

gastrin

68
Q

What is Zollinger-Ellison syndrome

A

gastrin-secreting tumor

69
Q

S/S of Zollinger-Ellison syndrome

A

hypertrophy of gastric mucosa, duodenal ulcers, steatorrhea

70
Q

What is steatorrhea

A

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

71
Q

What increases during Zollinger-Ellison syndrome

A

increase circulatin gastrin and increase acid secretion by parietal cells

72
Q

Actions of CCK

A
  • increase pancreatic enzyme secretion
  • increase pancreatic HCO3 secretion
  • inhibit gastric emptying
73
Q

Effect of CCK on gallbladder/sphincter of Oddi

A

stimulate contraction of gallbladder and relaxation of sphincter of Oddi

74
Q

T/F CCK can act as a paracrine signal

A

T

75
Q

Actions of Secretin

A
  • increase pancreatic HCO3 and biliary HCO3 secretion

- decrease gastric H+ secretion

76
Q

Secretin actions on gastrin

A

inhibit trophic effect of gastrin on gastric mucosa

77
Q

T/F Secretin can not act as a paracrine signal

A

F - Secretin can act as a paracrine signal

78
Q

GIP actions

A
  • increase insulin secretion from pancreatic beta cells

- decrease gastric H+ secretion

79
Q

What would be more effective increasing insulin secretion?

  1. Oral glucose administration
  2. Intravenous glucose administration
A

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

80
Q

Neural regulation

A

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

81
Q

Where are the neurotransmitters released from during neural regulation

A

nerve terminals stimulated by action potential

82
Q

Source of Ach

A

cholinergic neuron

83
Q

Action of Ach

A

contraction of smooth muscle and relaxation of sphincters

84
Q

What does Ach increase

A

salivary secretion, gastric secretion, pancreatic secretion

85
Q

Source of norepinephrine

A

adrenergic neurons

86
Q

Function of NE

A

Relaxation of smooth muscle and contraction of sphincters

87
Q

What does NE increase

A

salivary secretion

88
Q

What does the neuronal centers of the hypothalamus control

A

feeding and satiety

89
Q

What are the 5 neuronal centers of the hypothalamus

A

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

90
Q

What occurs in the lateral nucleus

A

feeding center

91
Q

What occurs in the ventromedial nucleus?

A

satiety

92
Q

What maintains energy balance?

A

neural and hormonal regulations

93
Q

5 ways hypothalamus can receive a signal

A
  • 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
Q

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

A

arcuate nucleus

95
Q

What are the two pathways of the arcuate nucleus

A

Alpha melanocortin pathway, and neuropeptide Y pathway

96
Q

What releases a-MSH

A

pro-opiomelanocortin (POMC) neurons

97
Q

Receptor for a-MSH

A

MCR-4

98
Q

Where is the MCr-4 receptor located

A

second-order neurons

99
Q

Main function of the a-MSH pathway

A

inhibit food intake and increase metabolism (anorexigenic)

100
Q

What stimulates the NPY pathway

A

hunger

101
Q

Receptor for NPY pathway

A

Y1R

102
Q

What can neurons that release NPY also release

A

agouti-related peptide (AGRP)

103
Q

Main function of NPY pathway

A

Increase feeding behavior and storage of calories (orexigenic)

104
Q

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

A

antagonize one another

  • peptides that stimulate a-MSH, inhibit NPY
  • AGRP released from NPY antagonize MCR-4
105
Q

Pathway of vagus nerve

A

vagal –>NTS–>hypothalamus circuit

106
Q

Where is ghrelin secreted?

A

by endocrine cells in the stomach

107
Q

What receptor does ghrelin bind to?

A

growth hormone secretagogue

108
Q

Ghrelin function in hypothalamus

A

stimulates neurons that release NPY

109
Q

What does ghrelin increase

A

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

110
Q

What can initiate feeding response?

A

ghrelin

111
Q

What centers does insulin initiate in the hypothalamus?

A

satiety and hunger centers

112
Q

What are the receptors insulin binds to?

A

POMC and NPY

113
Q

Insulin effect on NPY pathway

A

inhibit

114
Q

Insulin effect on POMC pathway

A

stimulate

115
Q

Actions of insulin

A

decrease appetite and increase metabolism

116
Q

Insulin in diabetes mellitus type I patients

A

increase in food intake associated with decrease in insulin

117
Q

CCK function

A

elicits satiety

118
Q

CCK on ghrelin

A

decrease ghrelin

119
Q

CCK on gastric secretion

A

decrease gastric emptying and increase gastric distention

120
Q

PYY is released by…

A

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

121
Q

What receptors do PYY bind to?

A

Y2 receptors

122
Q

Where are the Y2 receptors located

A

hypothalamus

123
Q

PYY on NPY neurons

A

inhibit

124
Q

PYY on POMC neurons

A

inhibit

125
Q

PYY on appetite

A

suppressor

126
Q

Where is leptin secreted?

A

adipose tissue and endocrine cells in stomach

127
Q

Where are the receptors that leptin binds to?

A

satiety and hunger centers in hypothalamus

128
Q

Leptin on NPY pathway

A

inhibit

129
Q

Leptin on POMC pathway

A

stimulates

130
Q

Appetive-supressing hormone function

A
  • decrease appetite
  • increase metabolism
  • ghrelin release
131
Q

Appetive-supressing hormone on food intake

A

negative feedback system for regulation of food intake