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Exam 4 Physiology > Chapter 21: The Digestive System > Flashcards

Chapter 21: The Digestive System Flashcards

1
Q

what are the folds in the small intestine called

A

Plicae

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2
Q

What are the folds in the stomach called

A

Rugae

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3
Q

What are the three layers of the inner lining of the gastrointestinal tract

A

mucosal epithelium, lamina propria, muscularis mucosae

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4
Q

Why is intestinal epithelium considered leaky

A

because some water and some solutes can be absorbed between the cells.

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5
Q

Where do nutrients enter the lymph and the blood

A

In the Lamina propria

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6
Q

What does absorption mean

A

movement of substances from lumen of GI tract to extracellular fluid.

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7
Q

What are the two meanings of the word secretion

A
  1. movement if water and ions from ECF to digestive tract lumen.
  2. The release of substances synthesized by GI epithelial cells into the lumen or the ECF
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8
Q

What three challenges does the digestive system face

A
  1. avoiding autodigestion: prevent the stomach from eating itself
  2. mass balance:
  3. defense: protection from foreign invaders
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9
Q

Are gastrointestinal cells polarized

A

yes

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10
Q

How are enzymes released

A

by exocytosis

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11
Q

What is a Zymogen

A

an inactivated enzyme

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12
Q

What are tonic contractions

A

sustained for minutes or hours. They occur in some smooth muscle sphincters and in the anterior portion of the stomach.

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12
Q

What are tonic contractions

A

sustained for minutes or hours. They occur in some smooth muscle sphincters and in the anterior portion of the stomach.

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12
Q

What are tonic contractions

A

sustained for minutes or hours. They occur in some smooth muscle sphincters and in the anterior portion of the stomach.

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13
Q

What are phasic contractions

A

lasting only a few seconds, in posterior region of stomach and small intestine

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14
Q

What are the interstitial cells of Cajal

A

act as an intermediary between neurons and smooth muscle. It functions as a pacemaker for slow wave activity in the GI tract

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15
Q

What are the interstitial cells of Cajal

A

act as an intermediary between neurons and smooth muscle. It functions as a pacemaker for slow wave activity in the GI tract

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16
Q

What happens when slow wave potential reach the threshold

A

voltage-gated Ca2+ channels in the muscle fiber open, CA2+ enters, and the cell fires one or more action potentials. Depolarization is due to the entry of Ca2+ into the cell. The entry also initiates muscle contracts

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17
Q

What happens if the duration of the slow wave is longer?

A

the more action potentials fire, the greater the concentration force in the muscle.

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18
Q

Contraction in the digestive system occur in 3 patterns. What are those patterns

A
  1. Migrating motor complex(sweeps food and bacteria into the large intestine)
  2. Peristalsis: moves bolus
  3. segmental contractions: short segments of the intestine alternately contract and relax. circular muscles contract while the longitudinal muscles relax.
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19
Q

What does the receptor GC-C used for, and what peptides activate it.

A

It is used to regulate fluid secretion in the intestine. It is activated by uroguaylin and guanylin

20
Q

What is the difference between absorption and secretion

A

Absorption moves material from the GI luman into the ECF. Secretion moves substances from the cells or the ECF into the lumen

21
Q

What are the 5 features the CNS shares with the ENS

A
  1. Intrinsic neurons
  2. neurotransmitters and neuromodulators
  3. Glial support cells
  4. Diffusion barrier
  5. integrating center
22
Q

What are short reflexes

A

reflexes that originate within the enteric nerous system and are integrated there without outside input

23
Q

What are long reflexes

A

digestive reflexes integrated into the CNS

24
Q

What are the three families that gastric hormones divided into

A

Gastrin family, secretin family, gastric inhibitory pepside

25
Q

What hormones are associated with the gastrin family

A

gastrin and CCK. Gastrin and CCk can bind to the same CCKB receptor

26
Q

What hormones are associated with the secretin family

A

secretin, vasoactive intestinal peptide (VIP), a nonadrenergic-noncholonergic neurotransmitter, GIP, GLP-1

27
Q

What do GIp and GLP-1 do

A

They work together to create a feed-forward signal for insulin release.

27
Q

What does motilin do

A

increases in this secretion are associated with migrating motor complex

28
Q

Where do anticipatory stimuli and stimulus of food activate neurons

A

In the medulla oblongata. It then sends a signal to the enteric nervous system. Secretion is then produced in anticipation of food.

29
Q

Is saliva an exocrine or endocrine secretion

A

It is an exocrine secretion

30
Q

How is saliva produced

A

It is secreted by the acini cells and then dumped into the ducts. This NaCL is isotonic and as it makes its way though the ducts, the NaCl is reaborbed while K and HCO3- is dumped into the lumen

31
Q

How is the swallowing reflex activated

A

with the pressure of the bolus as the tongue pushes it against the soft pallet and the back of the mouth

32
Q

What are the phases of digestion

A

the cephalic phase, the gastric phase, and the intestinal phase

33
Q

What are the three functions of the stomach

A

It stores food and regulates its passage into the small intestine. The stomach chemically and mechanically digests food into chyme. It destroys bacteria that are swallowed

34
Q

What starts the cephalic phase

A

the vagal reflex

35
Q

What is receptive relaxation

A

When the stomach relaxes to hold increased volume. Helps the stomach regulate the amount of food entering it.

36
Q

What does the lower stomach do during digestion

A

peristaltic waves push food towards the pyloric, mixing it with acid and digestive enzymes. Chyme is squirted into the duodenum.

37
Q

What do G cells in the gastric glands do

A

They promote acid release bu acting on parietal cells and indirectly stimulating histamine release.

38
Q

How is gastrin release stimulated

A

By the presence of amino acids and peptides in the stomach. Also triggered by neural reflexes 670

39
Q

What is Gastrins role?

A

Gastric is released by G cells. Gastrin then activates parietal cells to create HCL. The accumulation of HCL activates the secretion of pepsinogen. Somoza ton is released in response to stop gastrin as a negative feedback response.

40
Q

What are the functions of gastric acid

A

inactivates salivary amylase,kills bacteria, denatures protiens to make pepsin digestion more accessable, triggers D cells to release somatostatin, releases and activates pepsin

41
Q

What is an alkaline tide

A

when the blood leaving the stomach is less acidic because of the buffer HCO3-

42
Q

What is the function of PPI

A

They reduce the amount of acid in the stomach

43
Q

Why does blood from the digestive tract go through the hepatic portal system first

A

It brings nutrients to the liver and picks up absorbed nutrients in the intestine.

44
Q

Where does the most amount of digestion occur

A

The small intestine

45
Q

How are protiens digested in the SI

A
46
Q

How are carbs digested

A
47
Q

How are lipids digested

A
48
Q

How do the pancreas, gallbladder and the liver function

A

Exam 4 Physiology (6 decks)

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