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Physiology > Exam3Lec8GI:PharyngealEsophagealFxn,Stomach > Flashcards

Exam3Lec8GI:PharyngealEsophagealFxn,Stomach Flashcards

1
Q

Phagocytosis/Endocytosis of larger particles, digestionm and absoption is done by what organelle?

A

Lysosomes

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2
Q

The digestive system is set up to have which structures to increase surface area and absorb macromolecules?

A

Villi and Microvilli

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3
Q

What is the shape of multicellular organisms in the digestive system?

A

Hollow and have a cavity or lumen for optimal digenstion and absorption. This maximizes surface area for exchange

If the shape is not hollow: Greater Ratio of Volume to Exterior Surface Area than in a Single Cell

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4
Q

What is the fxn of the GI?

A

Take relatively large, solids or gels, and digest them into smaller molecules that can be absorbed as nutrients, while still serving as a secondary nervous system (ENS) and a barrier to toxins, bacteria, parasites, etc.

have lots of NT and aff and eff signals from gut

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5
Q

Most of your immune system/ cells are where?

A

In the gut

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6
Q

What acts as a “blender, acid sterilzer, reservoir”?

A

Stomach

chopper=mouth for mastication
acid in stomach is needed to start proleotic digestion and neutralize pathogens

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7
Q

What acts as a “detergent supplier” in the GI?

A

Gallbladder

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8
Q

Most absorption in the GI occurs where and what is its anatomy?

A

Small intestine, hollow tube

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9
Q

What are the phases of digestion?

A
  • Cephalic
  • Gastric
  • Early intestinal
  • Late intestinal
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10
Q

The intensity of the cephalic response in digestion depends on what?

A

Intensity of response varies with food type (sweet, sour, salty, bitter) to influence our preference, digestion and possibly energy balance

can dictate the amt of food we eat

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11
Q

Explain the cephalic phase of digestion

A
  1. Stimuli: auditory (pavlov’s dog), cognitive, visual, olfactory, taste
  2. Higher brain centers
  3. Dorsal vagal complex in brainstem
  4. Incr PNS signaling by activating vagal nerve
  5. Effector response: saliva,gastric, and pancreatic juice secretion, Mild contraction of the gall blader (sphincter closed)
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12
Q

What is the 2 stage model of saliva secretion?

A

Primary secretion: ptyalin, mucous, extracellur fluid, Amylase-containing (isotonic, lvs of Na+, K+, Cl-, and HCO3- similar to plasma)

Secondary secretion: modification of ionic contens (absorbs Na+, Cl- and dumps K+ and HCO3- to neutralize activity)

oral microbiomse inflences gut microbiome an d can cause dysbiosis

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13
Q

Fxn of saliva

A

neutralize acidity

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14
Q

What is the mechanism of Acinar cells in salivary secretion?

A
  • Secretion of K+ and HCO3-
  • Also secrete enzymes fats including alpha-amylase, lingual lipase, and kallikrein and mmunoglobulin A (IgA)

kallikrein and mmunoglobulin A (IgA): impt for neutralizing pathogens, sterilizing/barrier fxn
lingula lipase digest fats

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15
Q

What is the role of the salivary ductal cells in salivary secretion?

A

Ductal cells modify initial saliva to produce final saliva
* Absorb Na+ and Cl- decr concentration in saliva
* Secrete K+ and HCO3- incr concentrations in saliva
* salivary HCO3- neutralize oral bacterial acids

part of secondary secretion

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16
Q

pg 15 table

A
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17
Q

What does chewing (mastication) do? How does these components play a role?
* Incisors
* Molars
* Saliva
* Chunks of food

A

increases surface area
* Incisors: 30-80 pounds of pressure
* Molars: 100-160 pounds of pressure
* Saliva: provides lubrication, pre-digestion
* Chunks of food: turns into liquid bolus before food in stomach moves to SI

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18
Q

What are the 5 types of taste qualities in gustation and olfaction?

A
  • Bitter (toxins)
  • Salt
  • Sweet
  • Sour
  • Umami (MSG)

umamu=detects glutamate in food (Monosodium glutamate)

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19
Q

What is the swallowing reflex coordinated by?

A

The medulla oblongata which transmits the contraction of skeletal muscle, sphincter, and smooth muscle groups

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20
Q

What is dysphagia?

A

Difficulty/discomfort swallowing (MS, ALS, injury)

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21
Q

What are the 3 integrated phases of normal swallowing (deglutition)

A
  1. Oral
  2. Pharyngeal
  3. Esophageal
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22
Q

Fill in the black boxes for each phse of normal swallowing

A
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23
Q

Explation the coordination between different structures within the esophagus in order to deliver food to the stomach

A
  1. Perilstalsis of bolus to the stomach by UES contraction
  2. Opening/relaxing of LES to allow food and contents to enter
  3. Receptive relaxtion in stomach

the coordinated sequence of contracrio and relaxtion in the upper esophageal sphicnter, the esophagus, and the lower esophageal sphicnter is necesarry to deliver food to the stomach

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24
Q

Which nerve coordinates swallowing response?

A

Glosso pharyngeal + vagal afferents

tongue is under autireg and some conscious regulation

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25
Q

LES is part of which organ?

A

Diaphragm

site of hiatal hernia

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26
Q

What prevents influx of air into the stomach?

A

Sphincters and reflux gastric contents into the esophagus

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27
Q

Can we sense acid in the esophgus?

A

NO, we could have lots of damage to esoph but might not feel it

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28
Q

Explain how the pressure changes as we reach the LES

A
29
Q

What are the 3 states of GI sphincter?

A

Resting state: tone/closed
Relaxation/open
Constriction/Tightly closed

30
Q

Resting State: Tone/Closed
pressure
fxn

A

Pressure in Sphincter > Adjacent Segments
Inhibits movement through sphincter

31
Q

Relaxation/Open
pressure
fxn

A

Pressure in Sphincter = Adjacent Segments
Allows movements through sphincter

32
Q

Constriction/Tightly Closed
Pressure
Fxn

A

Pressure in Sphincter&raquo_space;> Adjacent Segments
Important to prevent flow

33
Q

What is the fxn of the lower esophagus? (2)

A
  • Swallowing–> triggers Promary peristalsis
  • Distention in Esophagus–> triggers secondary peristalsis (backup mechanism)
34
Q

Distention in the esophagus can initiate can initiate peristalsis through both ____ and ____ reflexes

A

local and vago-vagal reflexes

35
Q

What two ligans are the major mediatirs for peristalsis through local and vago-vagal reflexes?

A

Ach (contraction)
NO (relaxation)

36
Q

Why do secondary peristaltic waves occur ?

A

to clear any remnants of the food bolus.

37
Q

What is Dysphagia?

A

Difficulty in Swallowing

38
Q

What can cause Dysphagia?

A

abnormalities that alter the mechanics of swallowing (e.g. GERD, Achalasia, Cancer)
Can also arise secondary to neurological problems (patients with a stroke or ALS)

39
Q

What the 3 stimuli stimulates the esophagus? What is their receptor and response?

A

facilitates esophageal contration

40
Q

Ingestion of cold substances does what to the esophagus?

A

Causes inhibition of esophageal peristlasis and can produce pain

ingesting cold slows down neuroactivity

41
Q

What are common factors that incr and decr pressure?

A

INCREASE: Increased intra- abdominal pressure and Elevated gastric pH
DECREASE: Fat, Chocolate, Peppermint * Alcohol, Smoking (nicotine), Gastricdistension (aerophagia)

aerophagia: eating too much air

42
Q

What occurs with esophagitis and what is the therapy used?

A

decreased resistance of mucosa to acid and pepsin
Tx: GERD therapy

43
Q

What is GERD therapy?

A

focuses on control of gastric secretion.
Consists of: Lifestyle modification, medication (PPIs -protein pump inhibitrs can decr gastric acid, overuse can inhibit B12)
If severe: can perfomr fundoplication (fundus wrapped around lower part of esophagus) essentially a sphincter wrapped around a sphincter

44
Q

What state is the stomach in during swallowing?

hy

A

Receptive relaxation

hy

45
Q

What occurs during receptive relaxation?

A
  • Decreased SM tone
  • incr stomach compliance
  • incr acid secretion
46
Q

What occurs in the stomach during mixing and grinding?

A

Jet like retropulsion (contents moves from fundus to body to antrum and can move back to fundus)
liquid content needs to be isotonic

food can move back and forth

47
Q

What is the fxn the pace maker region located in the the stomach?

A

Pacemaker region: facilitates contraction through the interstitial cells of cajal (part of myenteric plexus )

48
Q

What is the myogenic bases of GI phasic contraction?

A

Slow Waves/Basal Electrical Rhythm

49
Q

What is slow wave threshold?

A

The potential which must be reached before a slow wave can be propagated in smooth muscle

50
Q

How long is BER (freq of contraction) in different segments of the gastro intentinal tract?

A

Stomach ~ 3/min
Duodenum ~ 11-12/min ( more contraction b/c longer distance to push)
Distal Ileum and Colon ~ 6-7/min (stronger force needed)

51
Q

Emesis (vomiting) is impt for what?

A

Neural control
can be activated by pain and sight of someone vomiting

52
Q

What occurs with emesis?

A
  1. Incr salivation (bicarb)
  2. Retching (somatic muscle actions)
  3. Suppression of respiration (prevent aspiration)
  4. BER suspended & replaced with bursts of orally propogating electrical activity.
  5. Retroperistaltic contractile complex (to propel food backwards-back out)
53
Q

Fxn of pariteal and chief cells

A

Parietal: makes HCL and IF, needed to absorb Vit B12
Chief: located in gastric pit; makes pepsinogen proenzyme, is converted to pepsin in presence of acid

54
Q

For HCL, IF, and Pepsinogen what is the source of these gastric secretory product and the function?

A

HCL
* source:parietal cell
* fxn: hydrolysis: sterilization of meal
IF
* source: parietal cell
* fxn: viramin B12 absorption
Pepsinogen
source: chief cells
fxn: protein digestion

55
Q

What the fxn of histamine, gastrin, gastrin releasing peptide,ACh, and Somatostatin?

A

regulation of grastric secretion

56
Q

What enzyme is essential for production of H+ ions? (HCl)

A

carbonic anyhdrase

an inhinbitor of this enzyme inhibits bicarb so there is more neutralization

57
Q

What occurs in the rapid transition from resting to secreting state in the parietal cell

A

there is a 5-10x incr in surface area
mediated by: Ach, Histamine, Gastrin
M3, H2, and CCk-B are all activated synergistically

58
Q

What 3 stimuli work in a synergistic manner leading to potentiation (release of acid)

A

Histamine
ACh
Gastrin

59
Q

What does vagal activation stimulate?

A

Multiple cell responses via neurotransmitter

60
Q

What does vagal activation stimulate?

A

Multiple cell responses via neurotransmitter?

61
Q

Pepsinogen and acid secretion are?

A

Tightly connected

62
Q

What does acid in the antrum stimulate?

A

Somatostatin release to inhibit meal-stimulated gastrin secretion

how we stop acid from dumping into stomach
we have HCL stim D cell in lower part of stomach

63
Q

What does Vagovagal reflex and endocrine release of gastrin stimulate?

A

Acid and pepsinogen secretion during the gastric phase

64
Q

What are 4 pharmaceutocal that can limit stomach acid? Give ex of each

A
  1. Antacids: buffer stomach acid
    EX: Tums, Maalox, PeptoBismol
  2. Block ACh receptor (affects many targest, not practical)
    EX: Atropine (not oral, many side effects)
  3. Histamine Receptor Antagonists
    EX: Pepcid, Tagamet, Zantac, Axid
  4. H+/K-ATPase Inhibitors (PPIs)
    EX: Prilosec, Prevacid, Nexium
65
Q

Explain how acid secretion works before/during/after meal

A
  1. In between meals (interdigestive phase) acid secretion is normally low.
  2. When anticipating a meal (cephalic phase of digestion), acid secretion increases
  3. Acid secretion increases even more while eating, and tapers off as the meal is emptied from the stomach.
66
Q

What is the importance of mucus?

A

bicarb is released to neutralize acidic environment

67
Q

What is Gastrinoma (Zollinger-Ellison Syndrome)
Lxn?
treatment?

A

Gastrin-Secreting Tumor
* Unregulated gastrin secretion ➔ ↑ stomach acid
* Can cause duodenal ulcers; enzyme inactivation (lipase)
lxn: extragastric (outside stomach)
TX: surgery, proton-pump inhibitors (to prevent damage from acid)

68
Q

Summary of Gastric Phase of Digestion, Fill in the boxes

A

Physiology (22 decks)

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