RAT 16

Question 1

if a waste molecule is in the peritubular capillary lumen, which structures must it pass through in order to move into the tubule lumen? what is this process called?

Answer 1

• from filtrate in the lumen of the tubule, across/between the tubule cells, into the endothelial cells of the peritubular capillaries to re-renter the blood
• tubular reabsorption

Question 2

what is the paracellular route?

Answer 2

substances pass between adjacent tubule cells; tight junctions

Question 3

what is the transcellular route?

Answer 3

• substances must move through the tubule cells
• glucose and amino acids
• first crosses apical membrane to the cytosol and exits through basolateral membrane

Question 4

what is the apical side of the tubule cell?

Answer 4

membrane facing the tubule lumen

Question 5

what is the basolateral side of the tubule cell?

Answer 5

side of the membrane facing the interstitial fluid

Question 6

define facilitated diffusion

Answer 6

carrier protein passively transports a solute with its concentration gradient, no ATP

Question 7

define primary active transport

Answer 7

carrier protein “pump” directly uses ATP to move a solute against its concentration gradient

Question 8

define secondary active transport

Answer 8

concentration gradient set up by a primary active transport pump is used to drive the transport of a second solute against its concentration gradient

Question 9

define antiport pumps (antiporter)

Answer 9

move two or more solutes in the opposite directions

Question 10

define symport pumps (symporter)

Answer 10

move two or more solutes in the same direction

Question 11

define transport maximum

Answer 11

where all carrier protein sites are full

Question 12

define saturation

Answer 12

when a carrier protein has all its protein sites full

Question 13

what cellular feature is found on the apical surface of the cells lining the proximal tubule? how does this aid in the fucntion of these cells?

Answer 13

• sodium leak channels
• allows for a slower more gradual diffusion of ions to control gradients

Question 14

how active are the cells in the PT? what are the primary roles of these cells?

Answer 14

• very active! most metabolically active part
• reabsorption of a large percentage of electrolytes, reabsorption of 100% of nutrients, reabsorption of many bicarbonate ions, reabsorption of 65% of water

Question 15

what substances are reabsorbed in the PT?

Answer 15

• electrolytes, nutrients, bicarbonate ions, water
• sodium, calcium, potassium, phosphate, glucose, amino acids

Question 16

why is sodium ion reabsorption so important?

Answer 16

key to reabsorbing many other substances in the PT

Question 17

what are the carriers/pumps in sodium ion reabsorption?

Answer 17

• carrier proteins specific for sodium ions
• sodium ion symporter
• sodium/hydrogen ion antiporter

Question 18

what are the carriers/pumps in the reabsorption of organic solutes?

Answer 18

• sodium/glucose symporters
• faciltiated diffusion

Question 19

what other substances are transported in a similar fashion? (reabsorption of organic solutes)

Answer 19

chloride ions

Question 20

what are the carriers/pumps in the reabsorption of chloride ions?

Answer 20

• paracellular route
• faciltiated diffusion

Question 21

what is the name of the enzyme that catalyzes the bicarbonate reabsorption reaction?

Answer 21

carbonic anhydrase

Question 22

what creates the gradient that drives the passive reabsorption of water?

Answer 22

accumulation of solutes in the cytosol and interstitial fluid

Question 23

what is obligatory water reabsorption?

Answer 23

water reabsorption in the kidneys that occurs without the regulation of hormones and irrespective of the medullary concentration gradient

Question 24

what is an aquaporin?

Answer 24

a type of water channel in the plasma membrane that greatly enhances rapid water reabsorption

Question 25

what substances are secreted in the PT?

Answer 25

- nitrogenous waste products and drugs - uric acid - ammonium ions - creatine - small amounts of urea - penicillin and morphine

Question 26

describe the permeability of the descending limb of the nephron loop to water and solutes. how does this impact the osmolarity of the filtrate?

Answer 26

- freely permeable to water but much less permeable to solutes ( like sodium and chloride ions) - water can move out by osmosis but few solutes follow, causing osmolarity to increase as it passes down the descending limb

Question 27

describe the permeability of the ascending limb of the nephron loop to water and solutes. how does this impact the osmolarity of the filtrate?

Answer 27

- impermeable to water but, transport NaCl with sodium/potassium/chloride symporters - filter loses solutes gradually and becomes less concentrated as ions are pumped unto the interstitial fluid

Question 28

what is reabsorbed in the nephron loop?

Answer 28

- water - sodium ions

Question 29

about how much sodium and water has already been reabsorbed before reaching the DT?

Answer 29

- 85% of water - 90% of sodium ions

Question 30

what is the major difference in the histology of the cells in the DT composed to the PT?

Answer 30

cells of the DT lack microvilli

Question 31

why is reabsorption in the DT important?

Answer 31

if we excreted the remaining water and sodium in urine, we would lose 29 liters of water, which is incompatible with life

Question 32

what is facultative water reabsorption

Answer 32

water reabsorption that is controlled by hormones to maintain a constant extracellular fluid osmolarity

Question 33

describe the three hormones involved in facultative water reabsorption.

Answer 33

- aldosterone (increase permeability to sodium ions) - antidiuretic hormone (diuresis) - atrial natriuretic peptide (triggers natriuresis)

Question 34

what are the major modifications to filtrate that occur in the collecting ducts and papillary ducts?

Answer 34

- impermeable to water in the absence of ADH - permeable to urea - continue to reabsorb ion (sodium, calcium, bicarbonate) from the filtrate

Question 35

explain how the lining of the digestive tract is considered an external body surface

Answer 35

because it is open to the outside of both ends

Question 36

what is the endocrine fucntion of the pancreas?

Answer 36

insulin and glucagon released from pancreatic islets into the blood and affect most cells in the body

Question 37

what is the exocrine function of the pancreas?

Answer 37

enzymes secreted primarily by clusters of acinar cells - they help with digestion

Question 38

where is the pancreas located and what are the regions of the pancreas?

Answer 38

- left upper quadrant of the abdomen extends from the duodenum to the spleen - head, body, tail

Question 39

what is an acinus?

Answer 39

clusters of acinar cells

Question 40

what is found in pancreatic juice?

Answer 40

- water - multiple digestive enzymes - other proteins - bicarbonate ions

Question 41

what are the two ducts that deliver pancreatic juice to the duodenum?

Answer 41

- main pancreatic duct - accessory pancreatic duct

Question 42

name two hormones that stimulate pancreatic secretion

Answer 42

- cholecystokinin (CCK) - secretin

Question 43

describe the shape and location of the liver

Answer 43

- pyramid shaped - located in the right upper quadrant against the inferior surface of the diaphragm

Question 44

describe the shape and location of the gallbladder

Answer 44

- small sac - located on the liver's posterior side

Question 45

name the four lobes of the liver

Answer 45

- right lobe - left lobe - caudate lobe - quadrate lobe

Question 46

what separates the left and right lobes?

Answer 46

falciform ligament

Question 47

what does the hepatic artery carry?

Answer 47

oxygen-rich blood to the liver

Question 48

what does the hepatic portal vein carry?

Answer 48

nutrient-rich, deoxygenated blood to the liver

Question 49

what does the hepatic vein carry?

Answer 49

drains blood from the sinusoids

Question 50

what is the basic unit of the liver?

Answer 50

liver lobule

Question 51

what cells compose the liver lobule?

Answer 51

hepatocytes

Question 52

what is found in the center of the liver lobule?

Answer 52

central vein

Question 53

what is found at each corner of a lobule?

Answer 53

portal triad

Question 54

what three structures compose the portal triad

Answer 54

- hepatic arteriole - portal venule - bile duct

Question 55

what is the main digestive function of the liver?

Answer 55

produce bile

Question 56

what are the two primary functions of bile?

Answer 56

1. required for digestion and absorption of lipids 2. it is the mechanism by which the liver excretes wastes and other substances that they kidney cannot excrete

Question 57

what are some other functions of the liver?

Answer 57

- nutrient metabolism - detoxification - excretion

Question 58

what is the primary function of the gallbladder?

Answer 58

stores bile, concentrates it, and release it when stimulated

Question 59

what hormone triggers the release of bile?

Answer 59

CCK

Question 60

what is the source of CCK?

Answer 60

cells in the lining of the duodenum

Question 61

which duct is connected to the gallbladder?

Answer 61

cystic duct

Question 62

which sphincter controls release of bile into the duodenum?

Answer 62

hepatopancreatic sphincter

Question 63

do we really need to "detox"? why or why not?

Answer 63

no because of our liver, which convert harmful chemical (toxins) into nonharmful substances that can be excreted in bile or urine

Question 64

what hormone leads to the release of bile?

Answer 64

CCK

Question 65

what is the source of CCK?

Answer 65

duodenum cells

Question 66

what is the stimulus for the release of CCK?

Answer 66

fats, digestive proteins

Question 67

what is another important stimulus that leads to the release of bile? how is this a positive feedback loop?

Answer 67

- bile salts - bile salts re0renter the liver, bile secretion increases dramatically, bile secretion continues until the duodenum empties