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GI Physiology > Gastrointestinal > Flashcards

Gastrointestinal Flashcards

(53 cards)

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1
Q

5 main functions of the GI system

A
  • digestion
  • absorption
  • excretion
  • fluid and electrolyte balance
  • immunological (respond to antigens and microbial pathogens)
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2
Q

In order to perform its functions, the GI system has two essential properties. Name them.

A

-motility and secretion

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3
Q

Motility (contractions of smooth muscle) allows for

A
  • increased surface area for digestion by enzymes which decreases size of nutrients
  • mixes nutrients with enzymes in the lumen
  • optimize time for digestion and absorption by propelling bolus from mouth to anus
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4
Q

Secretion of GI system is

A

The release of enzymes, lipids, detergents, ions, and water in the GI lumen by the GI epithelial and associated glands

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5
Q

Motility and secretion are regulated by (list 3 factors)

A

-various hormones, ENS, and CNS

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6
Q

Most important part of GI system

A

Duodenum

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7
Q

Liver synthesized _______ and stores it in the ______

A
  • bile

- gallbladder

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8
Q

3 parts of the small intestine are

A

Duodenum, jejunum and ileum

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9
Q

Enteroendocrine cells (EEC) are

A

Sensor cells in the GI system. Release peptides to control GI system

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10
Q

Associated glands of the GI system

A

Salivary, pancreas, liver & gallbladder, endocrine glands or cells

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11
Q

Define Sphincters

A

Specialized circular muscle structures (smooth or skeletal muscle) controlling the flow of GI content between distinct structure

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12
Q

Name the sphincters in the GI system

A
  • upper esophageal (bw pharynx and esophagus)
  • lower esophageal (bw esophagus and stomach)
  • pyloric
  • ileocecal
  • internal and external anal sphincters
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13
Q

Lymph transports

A

Hydrophobic substances (lipids, drugs, hydrophobic vitamins- A,D,E,K

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14
Q

Only organ to metabolize ammonia

A

Liver

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15
Q

Percentage of cardiac output received by GI

A

25%

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16
Q

Thoracic duct (lymphatic system) dumps into

A

Systemic blood

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17
Q

Epithelial cells of the mucosa are connected by

A

Tight junctions

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18
Q

Mucosa consists of three parts, the-

A
  • epithelium
  • lamina propria
  • muscularis mucosae
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19
Q

What are the functions of the epithelial cells of the mucosa and what is present in this layer

A
  • Glands and gland cells are present,
  • functions of the epithelial cells called enterocytes are secretion and absorption
  • enteroendocrine cells release peptides that control GI function
  • cells can vary among the GI tract
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20
Q

Lamina propria consists of

A
  • connective tissue
  • collagen
  • elastic fibers
  • also glands, lymph vessels and nodes, capillaries and nerve fibers are present
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21
Q

Muscularis mucosae is

A

The thin layer of smooth muscle cells in a folding configuration caused by contractions, (bottom of mucosa layer before submucosa)

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22
Q

Microvillar membrane of epithelial cells in the GI tract has a high % of

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A

Cholesterol and sphingolipids

23
Q

Enterocytes

Study These Flashcards
A

Epithelial cells in GI that secrete and absorb

24
Q

Main distinction between paracrine and endocrine

Study These Flashcards
A

Paracrine does not release hormones into the blood circulation, endocrine does.

25
ECL stands for ? And does what?
Enterochromaffin-like cells. They secrete histamine into interstitial space.
26
Describe how ECL leads to increased acid secretion
ECL release histamine>histamine diffuses through interstitial fluid>histamine binds to parietal cells>parietal cells secrete HCl
27
Describe Celiac diseases (gluten enteropathy):
- affects 2 million people in North America; - Allergic response to a component in gluten of wheat flour, rye, and barley (gliadin- glycoprotein: antigenic -Pro-Ser-Gln-Gln- and -Gln-Gln-Gln-Pro-) - Density and length of microvilli are reduced; - Reduced absorption of nutrients; - Not restricted to GI only (example: neuropathies);
28
IBD is
(Inflammatory bowel disease)~400,000 people in North America: Large proliferation of lymphocytes and macrophages in the lamina propria;inflammation of intestine (severe pain and diarrhea);
29
2 major types of IBD
- Crohn's disease (can affect any part of the GI tract and affects the whole bowel wall) - Ulcerative colitis (restricted to the colon and the rectum and only affects the mucosa)
30
Sympathetic innervation does..
In general it inhibits GI function; - Exception: Sphincter muscles are activated by sympathetic innervation; - Sympathetic fibers ALSO carry sensory information toCNS.
31
Parasympathetic Innervation
- In general it enhances GI function - Synapses between pre- and post-ganglionic fibers are nicotinic - Parasympathetic fibers ALSO carry sensory information to CNS.
32
Law of intestine
How the GI system propels food down the tract. The muscles behind a bolus contract while the muscles ahead of the bolus dialate so the food can be propelled along the system. -independent of CNS
33
CGRP
calcitonin gene related peptide
34
VIP
vasoactive intestinal peptide
35
Ach binding on muscarinic receptors causes
- Contraction of smooth muscles, | - increased salivary, gastric, and pancreatic secretion
36
Ach binding on nicotinic receptors causes
-contraction of the sphincters
37
The sensation of pain in the GI is caused by what and what can relieve the pain?
The pain is caused by smooth muscle contracting too tightly. It can be relieved by blocking muscarinic receptors.
38
NE causes what in GI
It causes - relaxation of smooth muscles - contraction of sphincters - increased salivary secretion
39
Ach and NE both ________ salivary secretions
Increase
40
VIP causes what in GI system
- relaxation of smooth muscle | - increased intestinal, pancreatic, and gastric secretions
41
NO stimulates
VIP release creating a positive feedback cycle bw the two
42
Substance P is co-secreted with _____ and causes what?
- it is co-secreted with Ach by cholinergic neurons | - it causes contraction of smooth muscle and salivary secretion
43
GRP is ____ and causes what?
- Gatrin Releasing Peptide | - causes increased gastric secretion and pancreatic secretion
44
Enkephalins (opiates) cause
- Increased contraction of smooth muscle | - and decreased intestinal
45
Neuropeptide Y causes
- increased relaxation of smooth muscle | - decreased intestinal secretion
46
Name 2 pacemakers for the smooth muscle contraction
- one in stomach | - one in pharynx
47
Describe an important role of the interstitial cells between longitudinal and circular muscle layers
They are the pacemaker cells that transfer electrical activity to smooth muscle via GAP JUNCTIONS
48
Action potentials and contractions
Longer durations (10-20 ms), poor overshoots; • Caused by inflow of Na+ and Ca 2+; • Ca2+ inflow helps and initiates contractions; • Trains of APs that are modulated by various stimuli; • Repolarization caused by various K+channels; • Smooth muscle tone: baseline of muscle tension that is modulated by neurons,hormones, paracrine factors, drugs.
49
CEPHALIC PHASE
• IDEA OF FOOD, OLFACTION, VISUAL STIMULI, AUDITIVE STIMULI TRIGGER RESPONSES IN THE GI SYSTEM IN THE ABSENCE OF FOOD INGESTION.
50
The dorsal motor vagal nucleus
It's the cell bodies of the vagal preganglionic neurons and is located in the lower pons/upper medulla
51
The path of stimulation for parasympathetics during cephalic or oral phases
Sensory inputs-->cortex and hypothalamus-->dorsal motor vagal nucleus--> increase secretion of salivary, gastric, and pancreatic glands, contraction of gallbladder and relaxation of Oddi's sphincter
52
Sympathetic stimulation is inhibitory in the ______ but NOT for the ______
- It inhibits the GI system | - it does NOT inhibit salivary system
53
Oral phases response to meal
* RESPONSES ARE THE SAME AS IN THE CEPHALIC PHASE BUT FOOD IS PRESENT IN THE MOUTH. * ADDITIONAL ACTIVATION OF GI FROM SENSORY INPUTS FROMTASTE BUDS (TONGUE) AND MECHANICAL RECEPTORS IN THE MOUTH AND UPPER PHARYNX.

GI Physiology (1 decks)

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