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Intro and Development to GI > GIT Intro > Flashcards

GIT Intro Flashcards

(65 cards)

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1
Q

Liver

A

Glucose and fat metabolism
Protein synthesis (plasma proteins: albumin, fibrinogens, apolipoproteins)
Bile production
Hormone production (e.g. angiotensinogen, insulin-like growth factor)
Urea production
Detoxification
Storage (e.g. glycogen)

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2
Q

Pancreas

A

Exocrine pancreas: produces digestive enzymes
Endocrine pancreas: produces hormones such as insulin, glucagon, somatostatin, etc.

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3
Q

Mucosa

A

Layer of epithelial cells (transporting cells, exocrine and endocrine secreting cells, stem cells)
Lamina propria (connective tissue, small blood and lymph
vessels, nerve fibers, wandering immune cells)
Mucularis mucosae

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4
Q

Submucosa

A

Connective tissue with lymphatics and blood vessels
Submucosal plexus

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5
Q

Muscularis externa

A

Longitudinal layer of smooth muscle
Myenteric Plexus- circular layer of smooth muscle

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6
Q

Structure of a smooth muscle cell

A

Non-straited
Dense bodies present with actins attached
Myosin
Side polar cross bridge arrangement
Thick filament regulated
Contraction at low levels of energy .

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7
Q

PI3K/AKT leads to

A

Bcl-2 expression (anti-apoptosis)

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8
Q

JAK/STAT leads to

A

Increased cell proliferation

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9
Q

Dense bodies serve that same role as

A

Z disks in skeletal muscles

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10
Q

Smooth muscle contraction

A

is thick-filament regulated and requires an alteration in myosin before it can interact with actin

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11
Q

Striated muscle contraction

A

is thin-filament regulated and requires movement of the troponin-tropomyosin complex on the actin filament before myosin can bind to actin.

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12
Q

Smooth muscle can contract in response to

A

electrical or hormonal signals and exhibits the ability to remain contracted for extended periods at low levels of energy consumption, which is important for functions such as maintaining vascular tone and hence blood pressure

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13
Q

Unitary Smooth Muscle also called Syncytial Smooth Muscle

A

Contract at the same time, joined together by gap junctions

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14
Q

Multi-unit smooth muscle is composed of

A

discrete, separate, smooth muscle fibers

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15
Q

Important characteristics of multi-unit smooth muscle fibers are that

A

each fiber can contract independently of the others, and their control is exerted mainly by nerve signals. EX: piloerector muscles that cause erection of the hairs when stimulated by the sympathetic nervous system

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16
Q

Tonic Contractions

A

Constant level of contraction or tone without regular periods of relaxation.
Orad (upper) region of the stomach and in the lower esophageal, ileocecal, and internal anal sphincters.

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17
Q

Phasic Contractions

A

Periodic contractions followed by relaxation
Esophagus, gastric antrum, and small intestines. all tissues involved in mixing and propulsion.

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18
Q

Smooth muscle exhibiting rhythmic or intermittent activity is termed

A

phasic smooth muscleand includes smooth muscles in the walls of the gastrointestinal (GI) and urogenital tracts

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19
Q

Vascular smooth muscle, respiratory smooth muscle, and some sphincters are

A

continuously active and proportional to membrane potential.

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20
Q

Tonic Contractions are considered

A

Multi unit smooth muscle

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21
Q

Phasic and tonic contractions of smooth muscle result from interactions of

A

actin and myosin filaments

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22
Q

Interstitial cells of Cajal (ICC) are located

A

located in the myenteric plexus and are connected to each other and adjacent smooth muscle cells.

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23
Q

Describe slow wave pattern

A

successive depolarizations (influx of Ca2+) and repolarizations (efflux of K+)

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24
Q

Slow waves are spread by

A

Gap junctions

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25
Stomach Waves
4 waves/min
26
Sigmoid Waves
6 waves/min
27
Distal Ileum
8 waves/min
28
Cecum Waves
9 waves/min
29
Duodenum Waves
12 waves/min
30
The frequency of slow wave potential
not influenced by neural or hormonal input.
31
What is the fate of the Ca2+ once it enters the smooth muscle cell?
1.Intracellular Ca2+ increases when Ca2+ enters the cell and is released from the SR 2. Ca 2+ binds to calmodulin 3. Calmodulin activates MLCK 4. MLCK phosphorylates and increases myosin ATPASE activity 5. Active myosin crossbridges create muscle tension
32
Smooth muscle myosin has
hinged heads along its length
33
Smooth Muscle Relaxation
1. Free Ca2+ in cytosol decreases when Ca2+ is pumped out of the cell or back into the sarcoplasmic reticulum. 2. Ca2+ unbinds from calmodulin (CaM). MLCK activity decreases. 3. Myosin phosphatase removes phosphate from myosin light chains, which decreases myosin ATPase activity. 4.Less myosin ATPase activity results in decreased muscle tension.
34
Contractions lead to
grinding, mixing and fragmenting of food in order to prepare it for digestion and absorption, also propel food in oral to adoral direction
35
The myenteric plexus 
is mainly involved with control of gut motility and innervates the inner circular and outer longitudinal smooth muscle layers.
36
The submucosal plexus
coordinates intestinal absorption and secretion through its innervation of the glandular epithelium, intestinal endocrine cells, and submucosal blood vessels.
37
Hirschsprung's disease 
is a congenital absence of the myenteric plexus, usually involving a portion of the distal colon. The pathologic aganglionic section lacks peristalsis and undergoes continuous spasm, leading to functional obstruction. The normally innervated proximal bowel dilates; sustained obstruction can lead to “toxic megacolon!” 
38
Parasympathetic innervation to the GI system is via
the vagus nerve and the sacral (S2–S4) spinal outflow.
39
Efferent innervation generally causes 
excitation (more secretion, more propulsive motility). 
40
Vagal efferent stimulates
upper GI tract motility, gastric secretion, pancreatic secretion, and contraction of the gallbladder.
41
Postganglionic efferent sympathetic fibers are
are inhibitory through vasoconstriction and decreased motility.
42
Vagovagal reflexes are
responses in which the afferent and efferent signals are confined to the vagus nerve; for example, distension of the stomach during a meal gives rise to an afferent signal, which results in stimulation of gastric acid secretion via the vagal efferents.
43
Acetylcholine
is the primary neurotransmitter involved in the stimulation of secretion and motility. Drugs that interact with cholinergic systems often have GI side effects as a result.
44
nitric oxide 
function as inhibitory neurotransmitters.
45
vasoavasoactive intestinal polypeptide (VIP)
a potent stimulator of intestinal fluid and electrolyte secretion but inhibits motility.
46
Long reflexes
signals are sent to CNS from the receptors inside and/or outside the GI tract.
47
Short reflex
stimulus is sensed by the receptors within the GI tract and the information is entirely processed in the enteric nervous system.
48
Amylin is similar to the incretins with one exception
amylin, by itself, does not cause insulin secretion, but it does all of the other things that the incretins do to prevent the big spike that occurs after food is eaten (e.g., it slows gastric emptying and therefore decreases the plasma glucose load which improves glycemic control). 
49
Anorexigenic
decreases appetite
50
orexigenic
increases appetite
51
orexigenic
increases appetite
52
leptin
Stimulate anorexigenic neurons and inhibit orexigenic neurons, Decreases appetite ,increases energy expenditure
53
Ghrelin
Stimulate orexigenic neurons and inhibit anorexigenic neurons, Increase appetite
54
Gastrin G Cells
Stimulates gastric. acid and secretion and mucosal growth
55
Gastrin inhibited by
Somatostatin
56
CCK
Stimulates gallbladder contraction and pancreatic enzyme secretion, produces satiety
57
CCK inhibits
Gastric emptying and acid secretion
58
Secretin
Stimulates bicarb secretion
59
Secretin inhibits
gastric emptying and acid secretion
60
Motilin
Stimulates migrating motor complex
61
Motilin inhibited by
Eating a meal
62
GIP AND GLP-1
Stimulates insulin release
63
GLP-1
Inhibits glucagon release and gastric function
64
GLP-1 target
Endocrine Pancreas
65
GIP target
Beta cells of pancreas

Intro and Development to GI (4 decks)

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