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GI Tract Physiology > GI Intro and Overview > Flashcards

GI Intro and Overview Flashcards

1
Q

Why Can the GI tract work as an “independent” system?

A

Because of the Enteric Nervous System:

  1. Myenteric Plexus
  2. Submucosal Plexus
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2
Q

Why does the GI Tract make sounds?

A

“Borborygmi” is the name of the sounds that are made when the movement of fluids and gases in and out of the intestines can be heard

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3
Q

What is the point of the Esophagus?

A

A tube that acts like a “Conduit” to get food through the pressurized thoracic cavity

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4
Q

What organs feed into the first part of the small intestine?

A
  1. Liver
  2. Gallbladder
  3. Pancreas
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5
Q

What is Chyme?

A

Term for the nutrients, juices, and secretions that come into the duodenum to facilitate reabsorption

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6
Q

To leave the Small Intestine and enter the large intestine, you pass through what?

A

Ileocecal Sphincter

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7
Q

What part of the Digestive Tract has a Villus (Microvilli layer) lining?

A

Small Intestine

NOTE: Villus lining is also in Proximal Convoluted Tubule of Kidneys

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8
Q

What is the effect of Villus lining on Small Intestine?

A

INCREASES SURFACE AREA for Reabsorption

-makes it 300x bigger

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9
Q

Intestinal Epithelial cells are called (BLANK) and they are (BLANK) cell(s) thick allowing for (BLANK) Reabsorption

A

Intestinal Epithelial cells are called ENTEROCYTES and they are 1 cell thick allowing for EFFICIENT Reabsorption.

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10
Q

What goes into every Villi? Why?

A

Capillaries and Lymph for ABSORPTION

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11
Q

Glands in Submucosa provide what?

A

Mucous to protect the lining all the way down the tract

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12
Q

What kind of muscles are present in the GI tract?

A

Longitudinal and Circular muscle layers to promote movement

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13
Q

What are the Myenteric and Submucosal Plexuses?

A

Nerve nets that run from Esophagus to Internal Anal Sphincter

  1. Myenteric is between Longitudinal and Circular Muscle Layers to promote movement via contraction
  2. Submucosal Plexus is between Submucosa and Circular Muscle layers and is stimulated to produce secretions
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14
Q

What makes up the Enteric Nervous System?

A
  1. Myenteric Plexus

2. Submucosal Plexus

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15
Q

What is “Ileus”?

A

No movement in the intestines

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16
Q

What are the three places in the GI tract that are voluntary?

A

The 3 places with Skeletal Muscle:

  1. Mouth
  2. Upper Esophagus
  3. External Anal Sphincter
17
Q

Cells in the GI tract last how long? How are they replaced?

A
  1. 3-5 Days

2. Replaced by Stem/Progenitor Cells constantly replacing cells

18
Q

What is the only nutrient that goes through the Lymph in majority instead of the blood?

A

Lipids

They go through Lacteals

19
Q

What is the First Pass Effect?

A

Blood flows from the intestines through the Portal Veins to the Liver before it is put out into circulation

20
Q

What are the functions of the GI tract?

A

“DEEP MASS”
• Digestion– Enzymes and HCl
• Endocrine– LOTS of hormones which act on GI
tract and other tissues
• Elimination– rids body of undigested waste
• Protection– HCl, IgAs, opsonins, and other immune
cells
• Motility– propels and mixes chyme
• Absorption– of ALMOST EVERYTHING you eat
• Secretion– buffers mucus, hormones (blood), enzymes
• Storage– stomach and colon

21
Q

How much fluid does the GI Tract secrete daily? What is it used for?

A
  1. 7 or 8 liters which means it has to absorb 9-10 Liters of Fluid each day
  2. Secretions help lubricate, digest, and buffer chyme
22
Q

What is the pH of HCl?

A

1.5-2

23
Q

What is the pH of Chyme at the start of the Jejunum? Why? How does it get there?

A
  1. pH is 7 because that is physiologic pH and Jejunal enzymes work optimally at this pH
  2. It is raised via buffers
24
Q

How much of digestion takes place before the Duodenum?

A

25-30% PRE-Duodenum

25
Q

How much digestion must take place in the small intestine?

A

70-75% by Pancreatic Enzymes in the Small Intestine

26
Q

How can you Regulate the GI Tract?

A
  1. Enteric Nervous System:
    A. Myenteric Plexus (muscle/movement)
    B. Submucosal Plexus (secretions)
  2. Lumenal chemo- (chemical composition and pH activate submucosal), mechano- (stretch activates myenteric) and osmoreceptors (sense osmolarity of chyme and activate submucosal)
    (act on the enteric NS)
  3. Parasympathetic Nervous System “Pro-Digestion” (MAINLY VAGAL to
    transverse colon, then pelvic nerves to anus)
  4. Sympathetic Nervous System “Stop-Digestion” (post-ganglionic
    adrenergic fibers from celiac, superior and inferior
    mesenteric and hypogastric plexes)
  5. Central Nervous System (Anticipatory)
  6. Hormones

GI Tract Physiology (7 decks)

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