Chapter 24 From Question #10 on of Study Guide

Question 1

What are the 3 processes involved in urine formation?

Answer 1

Filtration, reabsorption & secretion.

Question 2

Describe filtration

Answer 2

The movement of substances from the blood within the glomerulus into the capsular space.

Question 3

Describe reabsorption

Answer 3

THe movement of substances from the tubular fluid back into the blood.

Question 4

Describe secretion

Answer 4

The movement of substances from the blood into the tubular fluid

Question 5

Describe the structure of the renal corpuscle

Answer 5

It is an enlarged, bulbous region of a nephron housed withing the renal cortex. It’s composed of the goomerlus and the glomerular capsule.

Question 6

Describe filtrate

Answer 6

Filtrate is the water and solutes that are filtered from the blood plasma as the blood flows through the glomerulus.

Question 7

Describe glomerular filtration

Answer 7

FIltration passively separates some water and dissolved solutes from the blood plasma in the glomerular capillaries. Water and solutes enter into the capsular space of the renal corpuscle due to pressure differences across the filtration membrane.

Question 8

Describe glomerular filtration rate

Answer 8

It is the rate at which the volume of filtrate is formed, and it is expressed as volume per unit time (usually 1 minute).

Question 9

Describe renal regulation (intrinsic)

Answer 9

Renal autoregulation maintains GFR by alterizing size of the afferent arteriole in response to changes in systemic blood blood pressure.

Question 10

Describe sympathetic division (extrinsic)

Answer 10

Direct stimulation by the sympathetic division, and the subsequent production of angiotensin II, decreases GFR by causing vasoconstriction of afferent arterioles, contraction of mesangial cells that dcrease the surface area of the glomerulus, or both.

Question 11

ANP regulation (extrinsic)

Answer 11

Increases GFR through vasodilation of the afferent arteriole, inhibition of renin release and the subsequent relaxation of mesangial cells that increase the surface area of the glomerulus, or both.

Question 12

Paracellular transport-Tubular reabsorption and secretion

Answer 12

Movement of substances between epithelial cells.

Question 13

Trancellular transport-tubular reabsorption & secretion

Answer 13

Movement of substances across an epithelial cell

Question 14

Transport proteins-tubualr reabsorption and secretion

Answer 14

Different transport proteins are embedded w/in the 2 membranes. They control the movement of various substances using cellular processes that include simple or facilitated diffusion, osmosis, primary and secondary active transport, and vesicular transport.

Question 15

Bulk flow–tubular reabsorption and secretion.

Answer 15

Peritubular capillaries have both low hydrostatic pressure because of the loss of fluid during filtration, and high colloid pressure exerted by protein, because most proteins stay in the blood during filtration. These two important properties facilitate reapbsorption of substances through bulk flow.

Question 16

Transport maximum

Answer 16

Tm is the maximum amount of a substance that can be reabsorbed (or secreted) across the tubule epithelium in a given period of time (it’s rate of movement).

Question 17

Renal threshhold

Answer 17

The maximum plasma concentration of a substance that can be carried in teh blood without eventually appearing in the urine.

Question 18

Describe the process of tubular reabsorption.

Answer 18

Tubular fluid flows through the proximal convoluted tubule, nephron loop, distal convoluted tubule, and then into collecting tubules and collecting ducts. Substances are reabsorbed when they move from the tubular fluid back into the blood. 60-70% occurs in the PCT (virtually all nutrients are reabsorbed here). DCT is where final adjustments are made.

Question 19

Hormones that regulate tubular reabsorption

Answer 19

Aldosterone increases Na reabsorption. ANP inhibits Na reabsorption. Aldosterone increases water reapsorption. Antidiuretic hormone increases water reabsorption. Parathyroid hormone stimulates Ca reabsorption.

Question 20

Describe the functions of tubular secretion

Answer 20

Disposes of substances not already in filtrate; removes substances reabsorbed passively; removes excess K+, controls plood pH by the removal of H+, mostly occurs in PCT, some in DCT

Question 21

Countercurrent multiplication

Answer 21

Occurs in the nephron loop.The descending limb loses water and the tubular fluid becomes more concentrated.The ascending limb loses salts and the interstitial fluid becomes more concentrated. The nephron loop sets up osmotic pressure for maximum water reabsorption into the blood.

Question 22

Countercurrent exchange

Answer 22

Vasa recta carries excess solutes away so we can maintain osmotic pressure gradient.

Question 23

The concentration gradient

Answer 23

Establishing a concentration gradient in the interstitial fluid surrounding neqhrons is dependent upon activity of the nephron loop, vasa recta, and urea recycling. The concentration gradient establishes the osmotic “pull” to move water from the tubular fluid into the interstitial fluid (and then into the capillaries) when ADH is present.

Question 24

Obligatory water reabsorption

Answer 24

Water follows solutes so that water concentration of filtrate is = to water concentration in interstitial fluid (occurs in PCT & Nephron Loop.

Question 25

Facultative water reabsorption

Answer 25

ADH controls permeability to water at DCT and collecting ducts.

Question 26

Explain how ADH affects water conservation

Answer 26

ADH increases aquaporin production (pores that allow water to be taken from tubular fluid, back into the blood). Increases ADH = more concentrated urine. Decreased ADH = more dilute urine.