Brainscape's Knowledge GenomeTM

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


See full index

Human Physiology > GI System 4 Roane > Flashcards

GI System 4 Roane Flashcards

1
Q

How is the pyloric sphincter regulated?

A

The presence of food in the stomach -> contraction of pyloric sphincter

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

What is the gastric pacemaker?

A

Regulates the wave and the strength of contraction for gastric motility

The smooth muscle cells spread electric activity through gap junctions -> squeezing of the stomach -> movement of food and mixing of fluid

The more depolarized the membrane is, the stronger the contraction

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

How is more strength in contraction accomplished?

A

By raising the level of resting potential -> when the next wave comes you get more action potentials because more cells are depolarizing

The hormone gastrin, the presence of food, peptides, amino acids, and signal of the sympathetic system will change the resting membrane potential

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

How is gastric emptying controlled? (movement into small intestine)

A

By signals coming from the Duodenum - closure of the pyloric sphincter

Food starting to enter duodenum -> so there is a signal to stop to process the food

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

What are the factors that stops movement to small intestine?

A

-Mechanoreceptors respond to filling (stretching)
-Fat
-low pH
-these factors inhibit pepsinogen and HCl secretion -> through CCK Secretin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens when these factors (Fat, low pH, stretching) arrive in the duodenum?

A

-Stimulation of neuroreceptors (Osmo, amino, acido, mechanoreceptors) -> sending a signal to the stomach and CNS (parasympathetic) to delay gastric emptying

-Secretion of enterogastrones (CCK and Secretin)

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

What is the short and long neural reflex?

A

Short neural reflex: to the stomach
Long neural reflex: Signal to the CNS (Parasympathetic efferents)

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

How is the secretion of pancreatic juices (acids) regulated?

A

By bicarbonate in the intestinal phase when food comes in:

H+ acid stimulates secretin release from S cells
-> HCO3- release from pancreas and liver
+ inhibition of gastrin (G cells) responsible for acid secretion

Fats and amino acids stimulate CCK release from I cells
-> CCK stimulates the secretion of pancreatic enzymes and bile from gall bladder
+ inhibition of gastrin release

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

What are the two main functions of the pancreas?

A

1) Exocrine: makes bicarbonate (stimulated by secretin), and releases factors for digestion -> goes through pancreatic duct and sphincter of Oddi

2) Endocrinic (hormonal): Islets producing Insulin and Glucagon

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

Which part of the pancreas secretes enzymes and which secretes bicarbonate?

A

The exocrine cells secrete enzymes stimulated by CCK (I cells)

The duct cells secrete bicarbonate stimulated by secretin (S cells)

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

What specific cells of the pancreas produce bicarbonate and enzymes

A

Enzymes to digest fat and amino acids: Exocrine cells -> more specifically: Acinar cells (target of CCK)

Bicarbonate to bring pH up: Duct cells -> more specifically: ductal cells (target of secretin)

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

How is bicarbonate released?

A

HCO3- is formed by carbonic anhydrase (CO2 + H2O)
H+ is exchanged with Na+ on the apical side and HCO3- is exchanged with Cl on the basolateral side to maintain electrical neutrality

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

REVIEW for EXAM: Secretin and CCK

A

What stimulates secretin release: Acids in stomach
Secretin is released by: S Cells
The target of Secretin: Ductal cells -> release bicarbonate

What stimulates CCK release: Fats and amino acids
CCK is released by: I Cells
The target of CCK: Acinal cells -> Digestive enzymes

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

What are the digestive enzymes released by pancreas?

A

Proteases for proteins: Trypsin, Chymotrypsin, elastase, carboxypeptidase

Pancreatic amylase (for carbs)

Lipase, Phospholipase (for fats and phospholipids)
Cholesterol esterase for cholesterol breakdown
RNAse DNAse

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

How are the digestive enzymes activated?

A

Trypsinogen ac chief enzyme gets activated to Trypsin by membrane-bound enterokinases -> Trypsin activates the other enzymes

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

Review: Other functions of CCK:

A

-Contraction of Gall bladder -> Bile flows into the bile duct

-Relaxation of Sphincter of Oddi -> Blie flows into duodenum

17
Q

Where does all the blood go that picked up the nutrients in the intestines?

A

They travel to the liver through the hepatic portal vein -> The liver monitors blood content -> enters general circulation by hepatic vein

18
Q

What are the structures in the liver?

A

It consists of hexagons = hepatic lobules
Each hexagon has a portal triad -> an arterial, a vein, a bile duct

  • Bile produced goes to the intestine through the bile duct
  • Branch of hepatic portal vein receives blood from the GI tract -> and forwards it to the central vein
  • Branch of arteries carries blood for the liver back to the central vein?
19
Q

What are hepatic sinusoids?

A

Blood coming through branches of portal veins travel through gaps -> optimizes the liver’s ability to extract substances out of the blood (glucose, drugs,…)

20
Q

How is the blood transport organized in the liver?

A

In portal systems: (Artery -> capillary -> Vein -> capillary -> Vein)
Like in the kidney (Afferent -> glomerulus -> Efferent -> to the next capillary system (Vena vecta)

21
Q

How many blood supplies are there in the liver?

A

1) Portal vein: carries blood from the intestine
2) Hepatic artery: carries oxygenated blood

22
Q

How much of the bile salts are recycled?

A

95% of bile salts travel after emulsification in the small intestine, back to the liver from the Ileum through the hepatic portal vein

23
Q

What are MMCs (mass migrating complexes) and segmentation?

A

MMC: Peristalsis -> Pushing down of Bolus to the duodenum

Segmentation: Back and forth, squeezed, relaxed, squeezed
mixing and exposure of the chyme to the surface area for absorption

24
Q

How is MMC stimulated?

A

By Motilin (hormone) secreted from M cells
-> its receptors can be stimulated by erythromycin and similar antibiotics
-> pro kinetic effect, often used for elder patients

25
Q

Where does food enter the large intestine?

A

After the Ileum is through the Ileocecal valve (controlled by the Ileocecal sphincter) -> content poured into Cecum

26
Q

How does the Ileocecal valve open and close?

A

Similar to heart valves
The fluidity of content, pressure, chemicals relaxes the valve -> as the content fills the Cecum it feeds back and it closes

Important to prevent backflow because of high bacterial load in large intestine

27
Q

Sequence of the large intestine:

A

1) Illeum -> Cecum -> goes up to Ascending Colon -> goes across to transverse Colon -> goes gown to discending Colon -> S-turn to the Sigmoid Colon -> Rectum

28
Q

Explain the surface area of the sigmoid colon:

A

Rough surface area in the sigmoid colon to increase absorption, in the Rectum smooth surface area because absorption should be done by now

29
Q

Anatomy of Rectum:

A

Muscles in the internal and external anal sphincters
Internal and external Hemmorhoidal veins

30
Q

Main functions of large intestine:

A

Content that enters LI is pretty liquid and we want salt and water back
-Absorption of remaining
-Formation, storage and excretion of feces

31
Q

How does the food move in the large intestine?

A

-Haustration (mixing -> relax, constriction, relax)
-Mass movement (Peristalsis)

32
Q

How is the Defecation (emptying the LI) initiated?

A

Stretch receptors recognize the filling of LI and start movement toward the rectum

Valsalva maneuver: a forced expiration against a closed glottis

33
Q

How is the Defecation reflex stimulated?

A

After a meal:
-Gastrocolic reflex, Gastrin, Parasympathetic

  • Local reflex in the rectum: Rectosphincteric reflex -> when the walls are stretched -> signal to the spinal cord -> stimulate motor neurons that relax the internal anal sphincter
34
Q

What highly contributes to the formation of feces?

A

Indigestible fibers, intestinal epithelial cells, bile pigment, bacteria, water, mucous

35
Q

What does flatus consist of?

A

Indigestible fiber converted to gases
-> N2, CH4, CO2, H2, H2S

Human Physiology (34 decks)

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