Lecture 52- Intestine Transport And Liver Physiology

Question 1

What is the importance of the enterosystemic fluid cycle?

Answer 1

Reabsorb secretions delivered to proximal part of SI

Question 2

What is a substantial fraction of the ECF volume?

Answer 2

Secretory fluids from accessory organs, stomach and intestine itself

Question 3

What is the enterosystemic fluid cycle?

Answer 3

Net movement of fluid into and out of intestinal lumen every 24 hours

Question 4

Do herbivores, carnivores, or omnivores have the largest secretions during the enterosystemic fluid cycle?

Answer 4

Largest volumes of secretions in herbivores

Question 5

Where are the major reabsorpitive sites?

Answer 5

Distal SI and LI

Question 6

What is the definition of reabsoprtion in relation to the enterosystemic fluid cycle?

Answer 6

Ions and fluid recovery need to recover to maintain ECF volume AND the BP

Question 7

What type of cells line intestinal crypts? What do they secrete?

Answer 7

Epithelial cells line intestinal crypts

Secrete fluid and electrolytes

Question 8

_____ follows _____ passively into lumen, then ___ follows _____

Answer 8

Na follows Cl passively into lumen, water follows NaCl

Question 9

What channels does the Apical membrane have?

Answer 9

Cl Channels

Question 10

What does the basolateral membrane contain?

Answer 10

Na+/K+ ATPase

Na+/K+/2Cl- co-transporter

Question 11

What do Cl- channels open in response to?

Answer 11

Hormones and neurotransmitters binding basolateral membrane

Choleratoxins also cause Cl channels to open

Question 12

What are two mechanisms for fluid and electrolyte absorption?

Answer 12

Transcellular and paracellular routes

Question 13

What happens if tight junction is “tight”? Where are the junctions “tight”?

Answer 13

If tight, then goes transcellular route

Tight in stomach and colon

Question 14

What happens if tight junction is “leaky”? Where are the junctions “leaky”?

Answer 14

If leaky, then go paracellular route

leaky in duodenum and Jejunum

Question 15

What determines which route for fluid and electrolyte absorption?

Answer 15

Permeability of tight junctions between enterocytes

Question 16

In intestinal absorption the fluid absorbed is always _______.

Answer 16

Isosmotic

Question 17

Where is a major site for Na absorption?

Answer 17

Jejunum

Question 18

How does Na absorption occur in the Jejunum?

Answer 18

Occurs via Na dependent co-transporters in enterocyte apical membrane

Question 19

What is exchanger is present in the enterocyte apical membrane in the ileum? What is the transporter that the ileum uses in the basolateral membrane?

Answer 19

Cl-/HCO3- exchange in enterocyte apical membrane

Cl- transporter in enterocyte basolateral membrane

Question 20

What is the overall net absorption that occurs in the Ileum?

Answer 20

NaCl

Question 21

In the Ileum _____ and ____ are absorbed.

Answer 21

Na+ and NaCl

Question 22

In the colon what are the channels located in the apical membrane?

Answer 22

Na+ and K+

Question 23

Synthesis of Na channels induced by aldosterone in the colon causes what?

Answer 23

Increased Na absorption AND increased K secretion

Question 24

Why is there an increased loss of K+ during diarrhea?

Answer 24

Due to increased flow rate of intestinal fluid

Question 25

Are fecal concentrations of K+ in herbivores higher or lower?

Answer 25

potassium high in grass, colon helps excrete excess K+

Question 26

What is the term for high K+ losses?

Answer 26

Hypokalemia

Question 27

What happens when there is a loss of bicarbonate from the GIT?

Answer 27

Kidneys are signaled to reabsorb NaCl because Na is usually lost when bicarbonate is lost. The kidney excretes more H, because it needs more ammonia for buffering.

Question 28

What can lead to hyper holte ich metabolic acidosis with normal anion gap?

Answer 28

High HCO3- losses relative to Cl losses

Question 29

What are clinical examples of things that result in normal anion gaps?

Answer 29

Diarrhea, Renal tubular acidosis, carbonic anyhdrase inhibition

Question 30

What are four things that result in a normal anion gap?

Answer 30

1. Hyperchlomeric acidosis 2. GI or renal loss of bicarbonate 3. Impaired renal acid secretion 4. Reabsorption of chloride

Question 31

What causes osmotic diarrhea?

Answer 31

Non-absorbable solutes -> causes Renton of water

Question 32

What causes secretory diarrhea? What does secretory diarrhea permanently activate? What levels are very high?

Answer 32

-excessive secretions of fluid by crypt cells -permanently activates Adenylyl cylase -cAMP levels

Question 33

Where does liver receive portal blood from?

Answer 33

Stomach, SI, LI, pancreas, spleen

Question 34

What are the (5) functions of the liver?

Answer 34

1. Process absorbed substances 2. Synthesis and excretion of bile acids 3. Bilirubin production and excretion 4. Metabolism of nutrients 5. Detoxification and excretion of waste products

Question 35

What organ is considered the “first pass metabolism”?

Answer 35

The LIVER because it receives all substances absorbed from the GIT

Question 36

What are bacteria phagozytized by?

Answer 36

Hepatic Kupfer cells

Question 37

What is considered a phase I reaction?

Answer 37

Oxidation/reduction/hydrolysis/cyclization reaction (mixed function oxidases)

Question 38

What is considered phase II reactions?

Answer 38

Conjugation reactions (solubility compound; transferases)

Question 39

What occurs during lipid metabolism in the liver?

Answer 39

Fatty acid oxidation

Question 40

What does lipid metabolism synthesize?

Answer 40

Lipoproteins, cholesterol, phospholipids, bile acids

Question 41

What does protein metabolism synthesize?

Answer 41

Non-essential amino acids and plasma proteins (albumin)

Question 42

What does protein metabolism in the liver modify? What does it convert?

Answer 42

Modify: amino acids -> so glucogenic AA can enter gluconeogenesis Convert: ammonia (toxic) -> urea (non-toxic)

Question 43

What are the three metabolisms of the liver?

Answer 43

1. Carbohydrate metabolism 2. Protein metabolism 3. Lipid metabolism

Question 44

In what species does glucogenesis continue to make glucose from propionate?

Answer 44

Ruminants

Question 45

How does glycogenolysis function in the carbohydrate metabolism of the liver?

Answer 45

Breaks down glycogen to release glucose — stimulated by glucagon and epinephrine

Question 46

How does glycogenesis function in the carbohydrate metabolism of the liver?

Answer 46

Highly branched chains of stored glucose (occurs after a meal)

Question 47

How does gluconeogenesis function in the carbohydrate metabolism of the liver?

Answer 47

uses glycerol and glucogenic AA to synthesize glucose after glucose stores are depleted (Glucose storage = glycogen)

Question 48

What is jaundice a result of? (4)

Answer 48

Increase destruction of red blood cells, obstruction of bile ducts, liver disease, conjugated bilirubin that can’t be excreted in bile

Question 49

Conjugated bilirubin excreted in urine AND secreted in bile -> terminal _____ and colon _____ -> deconjugated to ________ AND _____ + _______

Answer 49

Ileum and colon Deconjugated to urobilinogen AND urobilin + stercobilin

Question 50

What does the mononuclear phagocyte system remove?

Answer 50

Senescent RBC

Question 51

When bilirubin binds albumin in blood and conjugated to glucoronic acid…what does this result in?

Answer 51

Resulting compound of detoxification/degrade in liver

Question 52

The mononuclear phagocyte system purpose is to degrade ______, which results in ______, and the end product is _______.

Answer 52

Hemoglobin Biliverdin Bilirubin