60 - Intestinal Transport 🟢

LECTURE 60 POWERPOINT INFO

LECTURE 60 POWERPOINT INFO

enterosystemic fluid cycle

The _____ is very important to reabsorb secretions delivered to proximal part of small intestine

ECF volume

Secretory fluids from accessory organs, stomach and intestine itself → SUBSTANTIAL fraction of _____

enterosystemic fluid cycle

Daily exchange of several times total volume of body water

herbivores

There is a larger volume of secretions in _____

fluid & electrolytes

Epithelial cells lining intestinal crypts secrete _____

Cl-

The apical membrane of the intestine has _____ channels

basolateral

Na+/K+ ATPase and Na+/K+/2Cl- cotransporter that be found on the _____ membrane of the intestine

hormones & neurotransmitters

Cl- channels normally closed, but will open in response to _____ binding basolateral membrane

transcellular & paracellular

There are _____ routes for fluid and electrolyte absorption

permeability

_____ of tight junctions between enterocytes determines the route

"tight"; leaky

Tight junctions can be _____ or _____

isosmotic

Fluid absorbed in the intestines is always _____

jejunum

-Major site for Na+ absorption

-Occurs via Na+-dependent co-transporters in enterocyte apical membrane

ileum

-Also absorbs Na+

-Cl-/HCO3- exchange in enterocyte apical membrane

-Cl- transporter in enterocyte basolateral membrane

-Overall, net absorption of NaCl

Na+

The jejunum is the major site for _____ absorption

NaCl

The ileum is the major site for _____ net absorption

colon

The _____ has Na+ and K+ channels in the apical membrane

aldosterone; Na+ absorption; K+ secretion

In the colon, the synthesis of Na+ channels is induced by _____ → increased _____ AND increased _____

K+; increased

Diarrhea is associated with increased loss of _____ due to [increased/decreased] flow rate of intestinal fluid

fecal

There are _____ concentrations of K+ in herbivores

all decreased

Loss of large volumes of ECF-type fluid from GI causes.....

-[increased/decreased] ECF volume

-[increased/decreased] intravascular volume

-[increased/decreased] arterial pressure

severe diarrhea

The following are issues and losses associated with _____:

-Circulatory collapse

-High HCO3- losses relative to Cl losses can lead to hyperchloremic metabolic acidosis with normal anion gap

-High K+ losses

normal anion gap

The following are associated with a _____:

-hyperchloremic acidosis

-GI or renal loss of bicarb

-impaired renal acid secretion

-reabsorption of chloride

-examples: diarrhea, renal tubular acidosis, & carbonic anhydrase inhibition

infections & inflammation of the SI

With diarrhea, there is a decreased surface area for absorption due to.....

osmotic

_____ diarrhea is associated with non-absorbable solutes

secretory diarrhea

-Excessive secretions of fluid by crypt cells

-Permanently activates adenylyl cyclase and cAMP levels high

LECTURE 60 PRACTICE QUESTIONS

LECTURE 60 PRACTICE QUESTIONS

B. ECF volume and blood pressure

The absorption of secretory fluids is essential for maintaining:

A. Red blood cell volume

B. ECF volume and blood pressure

C. Brain function

D. Blood oxygen levels

B. The daily exchange of water through the GI tract

The enterosystemic fluid cycle primarily involves:

A. Constant loss of fluids through sweat

B. The daily exchange of water through the GI tract

C. Fluid retention in the kidneys

D. Absorption of water from the lungs

A. Herbivores

Which of the following animals is likely to have larger volumes of secretions?

A. Herbivores

B. Carnivores

C. Omnivores

D. Insectivores

C. Their permeability affects fluid and electrolyte absorption

Which of the following is true regarding tight junctions in the intestines?

A. They are always tightly closed

B. They have fixed permeability

C. Their permeability affects fluid and electrolyte absorption

D. They are absent in the small intestine

B. Jejunum

Which part of the intestine is the major site for Na+ absorption?

A. Stomach

B. Jejunum

C. Colon

D. Esophagus

C. Cl-/HCO3- exchange and NaCl absorption

In the ileum, Na+ absorption is coupled with which of the following mechanisms?

A. Na+/K+ ATPase only

B. Na+/glucose cotransport only

C. Cl-/HCO3- exchange and NaCl absorption

D. Simple diffusion

C. Colon

Aldosterone increases Na+ absorption and K+ secretion in which part of the intestine?

A. Stomach

B. Ileum

C. Colon

D. Jejunum

C. Potassium (K+)

Diarrhea can result in increased loss of which ion due to elevated intestinal flow rate?

A. Sodium (Na+)

B. Calcium (Ca2+)

C. Potassium (K+)

D. Chloride (Cl-)

B. Cl- channel

Which channel is normally closed in the intestinal crypt cells but opens in response to certain signals?

A. Na+ channel

B. Cl- channel

C. Ca2+ channel

D. K+ channel

A. Adenylyl cyclase, increasing cAMP

Excessive secretions in secretory diarrhea are primarily due to the activation of:

A. Adenylyl cyclase, increasing cAMP

B. Na+/K+ ATPase, decreasing Na+

C. Phospholipase A2, decreasing Cl-

D. K+ channel, increasing K+ loss

C. Intestinal secretory fluid

Which fluid is primarily reabsorbed to prevent excessive loss from the ECF?

A. Lymph

B. Bile

C. Intestinal secretory fluid

D. Sweat

B. Maintain low intracellular Na+ to drive absorption

What role do Na+/K+ ATPase pumps play in intestinal absorption?

A. Transport of Cl- into the lumen

B. Maintain low intracellular Na+ to drive absorption

C. Directly secrete Na+ into the lumen

D. Increase K+ absorption

C. Elevated Na+ absorption

Which of the following is NOT typically a cause of diarrhea?

A. Increased osmotic pressure in the lumen

B. Decreased surface area in the intestine

C. Elevated Na+ absorption

D. Excessive secretions by crypt cells

B. Decreased ECF volume and blood pressure

The main effect of severe diarrhea on the body includes:

A. Increased blood volume

B. Decreased ECF volume and blood pressure

C. Increased iron levels

D. Increased calcium absorption

B. Permanent activation of Cl- channels in crypt cells

Secretory diarrhea results from:

A. Reduced Na+ intake

B. Permanent activation of Cl- channels in crypt cells

C. Temporary closure of tight junctions

D. Enhanced Na+ absorption

C. High Cl- and low HCO3-

Which electrolyte imbalance might occur with hyperchloremic metabolic acidosis due to diarrhea?

A. High HCO3- and low K+

B. Low Cl- and high Na+

C. High Cl- and low HCO3-

D. Low Na+ and high K+

B. It occurs via a Cl-/HCO3- exchange mechanism

Which statement about Cl- absorption in the ileum is correct?

A. It is absorbed passively without transporters

B. It occurs via a Cl-/HCO3- exchange mechanism

C. It does not require energy

D. It is coupled with K+ absorption

B. Non-absorbable solutes in the intestine

The main cause of osmotic diarrhea is:

A. Excessive secretion of Cl-

B. Non-absorbable solutes in the intestine

C. Aldosterone deficiency

D. Increased permeability of tight junctions

C. Infections and inflammation

Which of the following increases fluid loss in diarrhea by impairing intestinal absorption?

A. Decreased activity of adenylyl cyclase

B. Low luminal Na+ concentration

C. Infections and inflammation

D. Reduced tight junction permeability

B. Hyperchloremic metabolic acidosis

A significant loss of HCO3- in diarrhea can lead to which condition?

A. Hypochloremic alkalosis

B. Hyperchloremic metabolic acidosis

C. Respiratory acidosis

D. Metabolic alkalosis