Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

23 > 23 11-13 > Flashcards

23 11-13 Flashcards

1
Q

Gross anatomy of the stomach?

A

15-25cm/6-10” long

Regions: cardiac (surrounds area where food enters from esophagus), fundus (dome shaped part tucked beneath diaphragm - storage), body (midportion), pylorus (inferior, funnel shaped)

Convex lateral surface is the greater curvature, medial is lesser curvature.

Lesser omentum (runs from liver to lesser curvature) and greater omentum (drapes inferiorly from greater curvature to cover small intestine.)

Pyloric canal - where food is churned.

Served by vagus nerve and thoracic splanchnic. Arterial supply from gastric/splenic/veins to hepatic portal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Functions of the stomach?

A

Storage (50-4liters)

Mechanical/chemical breakdown of food, forming chyme

Production of intrinsic factor (glycoprotein required for absorption of B12 in small intestine)

Protection

Absorption (small nonpolar substances, i.e. alcohol/aspirin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Structural modifications of the wall of the stomach that enhance the digestive process?

A

Oblique layer: Has an extra (though incomplete) layer of muscularis which runs obliquely allowing food to be mixed.

Rugae: longitudinal folds that increase surface area.

Sphincters: Pyloric, gastroesophageal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the mucosal layer of the stomach.

A

Simple columnar epithelium of mucous/goblet cells which produce a protective coat of alkaline mucus (surface is insoluble mucus, bicarbonate rich fluid underneath). Indented with gastric pits from which gastric glands extend deep into mucosa.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What type of cells do the gastric pits contain?

A

Chief cells, parietal cells, mucous neck cells, and surface epithelium at the beginning

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q
  1. Name the cell types responsible for secreting the various components of gastric juice
A

mucous neck cells, parietal, chief, enteroendocrine, surface mucous cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Mucous neck cells

A

Scattered in the neck, produce a thin, soluble mucus. Acidic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Parietal cells

A

Fuzzy pitchfork shape, lots of surface area for secretion of HCl and intrinsic factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Chief cells

A

Mainly in basal region of gastric glands. Produce pepsinogen (inactive form of pepsin) and gastric lipase - 15% of lipolysis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Enteroendocrine cells

A

Release chemical messengers: Histamine, serotonin, somatostatin, gastrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Surface mucous cells

A

Continously secrete an alkaline product containing mucin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What creates the mucosal barrier (protection) in the stomach?

A
  1. Thick coating of bicarbonate rich mucus
  2. Epithelial cells of the mucosa are joined by tight junctions that prevent gastic juice from entering underlying tissues
  3. Damaged epithelial cells are shed an quickly replaced by division of undifferentiated stem cells where the gastric pit meets gastric glands.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q
  1. What are the 3 reflexes that regulate gastric secretion and stomach motility?
A

Cephalic phase, gastric phase, intestinal phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Cephalic phase

A

Happens before food enters the stomach - triggered by the sight/taste/aroma/thought of food.

Sight/thought of food –> cerebral cortex
OR
stimulation of taste and smell receptors

THEN –> Hypothalamus –> Vagus nerve –> stomach secretions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Gastric phase

A

Most important stimuli: distension, peptides, low acidity.

Stomach distension –> local reflexes –> stomach secretions
OR
stomach distension –> vagovagal reflexes –> Medulla –> vagus nerve –> stomach secretions
OR
Food chemicals (esp. peptides/caffeine) and rising pH –> G cells –> gastrin release –> Stomach secretions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Intestinal phase

A

Presence of partially digested food or distention in duodenum –> gastin release to blood –> brief stomach secretions.

17
Q

Enterogastric reflex?

A

Actually 3 reflexes:
inhibits local reflexes,

inhibits vagal nuclei,

activates sympathetic fibers that tighten the pyloric sphincter.

Protects the small intestine from excess acidity, matches the small intestine’s capacity to process chyme.

18
Q

Define and account for the alkaline tide

A

Alkaline tide is the phenomemon of the blood leaving the stomach being more alkaline than the blood that enters.

Happens because of HCl formation - from carbonic acid, H+ is pumped into the stomach lumen, bicarbonate into the blood.

19
Q

HCl formation

A

Histamine/Ach/Gastrin must be bound.

Co2 from IF enters parietal cell.

Co2 +H20 –> H2CO3 –> HCO3- + H+.

H+ is pumped into the stomach lumen.

HCO3- in the cell and Cl- in the IF are transferred by antiporter.

Cl- enters the stomach lumen.

H+ and Cl combine

20
Q

Helicobacter pylori

A

Can burrow like a drill through the mucus and destroy the protective mucosal layer. More than 1/2 population has helibacter, but pathological effects occur in 10-20% of infected individuals. Cause ulcers.

21
Q

HCl functions

A
  1. Denature food/cellulose/collagen/protein
  2. Pepsinogen –> pepsin
  3. Protection (too acid for bacteria)
22
Q

Sphincters (ape oil)

A

Anal, pyloric, esophageal, oddi, ileococal

23
Q

Aside from preparing food for the small intestine, what is the only essential stomach function?

A

Releasing intrinsic factor

24
Q

CCK cholecystokinin

A

Site: Duodenal mucosa

Stimulus: Fatty chyme

Target: Stomach - inhibit secretion

Liver/pancreas - potentiates secretin’s action on these organs

  • Pancreas - increases enzymatic secretions
  • Gallbladder - stimulates to contract and expel bile

Hepatopancreatic sphincter - relaxes sphincter to allow entry of bile and pancreatic juice into duodenum.

25
Q

Gastrin

A

Site: Stomach mucosa/G cells

Stimulus: Food, particularly proteins in stomach. Also ACh from nerve fibers.

Target: Stomach - ↑ HCl production, also gastric emptying

Small intestine - stimulates contraction Ileocecal valve - relaxes

Large intestine - stimulates mass movements.

26
Q

Histamine

A

Site: Stomach mucosa

Stimulus: Food in stomach

Target: Stomach - activates parietal cells to release HCl

27
Q

Intestinal gastrin

A

Site: Duodenal mucosa

Stimulus: Acidic and partially digested foods in duodenum

Target: stomach - Stimulates gastric glands and motility

28
Q

Motilin

A

Site: Duodenal mucose

Stimulus: Fasting, periodic release every 1.5-2 hours

Target: Stimulates migrating motor complex

29
Q

Secretin

A

Site: Duodenal mucosa

Stimulus: Acidic chyme, proteins/fats

Target: Stomach - Inhibits gastric secretion and motility during gastric phase of secretion

  • Pancreas - Increase output of pancreatic juice rich in bicarbonate, potentiates CCK action
  • Liver - ↑ bile output
30
Q

Serotonin

A

Site: Stomach mucosa

Stimulus: Food in stomach

Target: Causes stomach muscle contraction

31
Q

Somatostatin

A

Site: Stomach mucosa, Duodenal mucosa

Stimulus: Food in stomach, sympathetic nerve fibers

Target: Stomach - inhibits secretion of all products Pancreas - inhibits secretion

Small intestine - Inhibits GI blood flow, thus absorption

Gallbladder/liver - Inhibits contraction and bile release

32
Q

GIP

A

Site: Duodenal mucosa

Stimulus: Fatty chyme

Target - pancreas, insulin release

33
Q

VIP

A

Site: Enteric neurons

Stimulus: Chyme with partially digested foods

Target: Small int. - stim buffer secretion, dilates caps, relaxes intest smooth muscle

Pancreas - ↑ secretion

Stomach - inhibits acid secretion

34
Q

Inhibitory action of cephalic phase

A

Loss of appetite/depression

Cerebral cortex

Lack of stimulatory impulses to parasympathetic center

35
Q

Inhibitory action of gastric phase

A

Excessive acidity inhibits G cells, ↓ gastin secretion

OR

Emotional stress, sympathetic activation, overrides parasympathetic

36
Q

Inhibitory action of intestinal phase

A

Distension of duodenum, presence of fatty/acidic/hypertonic chyme or irritants –>
Release of enterogastrones (secretin/cholecystokin/asoactive peptide) –>
entero-gastric reflex.

37
Q

Enterogastrones include?

A

Secretin, CCK, VIP

All inhibit gastric secretion.

38
Q

Gastric emptying

A

Empties w/in 4 hours of a meal.

Bigger meal = faster emptying.

More fat = slower through sm. intestine

Depends more on contents of duodenum than stomach. (enterogastric reflex and enterogastrones that inhibit acid and pepsin secretions and contractions)

23 (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions