Intro to Physiology I Lopez Flashcards
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
- mucosal
- submucosal
- muscle layer
- 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
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
