Weeks 1-2: Unit 1 (Kidney Physiology)

Reabsorption shifts solute from the ___ to the ___

Tubules, blood

Secretion shifts solute from the ___ to the ___

Blood, tubules

Nearly 100% of ___ and ___ are reabsorbed

Sugars, AAs

The bulk of reabsorption occurs in the ___

PCT

Roughly 99% of ___ and 70% of filtered ___ is reabsorbed

NaCl, water

The peritubular blood is ___

Hyperosmotic

Most of the filtered solutes are reabsorbed through ___ ___ by ___

Active transport, pumps

Secondary active transport is done by ___ and ___

Symporters, antiporters

Aquaporins transport water through ___ ___

Facilitated diffusion

In the PCT, some water moves via osmosis through ___ ___

Tight junctions

Excess intracellular ___ leaks out through channels

Potassium

The two sources of an osmotic gradient are ___ ___ of solutes and ___ ___

Active transport, plasma proteins

About 80-90% of filtered ___ is reabsorbed in the PCT via ___ active transport

Bicarbonate, secondary

The tubular fluid becomes slightly ___ due to apical ___ pumps

Acidic, H+

Bicarbonate pumps are on the ___ membrane of tubular cells

Basal

Protein reabsorption in the PCT occurs through ___-___ ___

Receptor-mediated endocytosis

Too much protein in the filtrate saturates the endocytotic capacity and results in ___

Proteinuria

What are the two proteins involved in PCT protein reabsorption?

Cubulin and megalin

Fanconi syndrome usually results in ___ and ___

Glycosuria, aminoaciduria

The maximum rate of transport for a particular solute is known as ___ ___

Tubular maximum

Is plasma concentration exceeds tubular maximum, the substance will be found in the ___

Urine

Glucose threshold is exceeded in ___

DM

___ allows the kidneys to remove some compounds from the blood at a faster rate than filtration alone

Secretion

Secretion occurs by way of organic ___ and ___ transporters

Cation, anion

Cation and anion transporters are abundant in the ___

PCT

Some toxins and drugs are bound to ___ and cannot be removed through filtration, so they require ___

Plasma proteins, secretion

An example of a secreted anion is ___, which is used to estimate RBF

Para-aminohippurate

PAH is very ___ secreted in the PCT, meaning that it accurately reflects ___ because nearly ___ of it is removed as blood passes through the kidneys

Efficiently, RBF, 100%

What is the name of the anion transporter that allows for the secretion of PAH?

OAT1

PAH can be actively transported by ___

Multidrug resistance protein

Sympathetic stimulation ___ RBF and ___ GFR

Decreases, decreases

Alpha-1 receptors in afferent arterioles induce ___, decreasing glomerular blood flow

Vasoconstriction

Another stimulator of smooth muscle contraction in the kidneys is ___

Angiotensin II

The volume of plasma cleared of a substance per unit of time is known as the ___

Urinary clearance rate

___ is a good estimate of GFR because it is always in the blood and neither reabsorbed nor secreted

Creatinine

Under normal conditions, the amount of creatinine in the ___ reflects the amount in the ___

Urine, plasma

If GFR = C, then a substance is filtered, (is/is not) reabsorbed, and (is/is not) secreted

Is not, is not

If GFR < C, then a substance is filtered, (is/is not) reabsorbed, and (is/is not) secreted

Is not, is

If GFR > C, then a substance is filtered, (is/is not) reabsorbed, and (is/is not) secreted

Is, is not

GFR tends to equal C for ___

Creatinine

GFR tends to be less than C for ___

PAH

GFR tends to be greater than C for ___ and ___

Glucose, AAs

GFR/RBF is used to calculate ___ ___

Filtration fraction

Filtration fraction is used to estimate the fraction of plasma that is filtered through the ___ ___

Glomerular membrane

The loop of Henle reabsorbs solute in the ___ ___ ___

Thick ascending limb

The ascending limb of the loop of Henle is ___ to water

Impermeable

The TAL contains ___ pumps in the basolateral membrane

Na+/K+

The TAL contains ___ cotransporters in the apical membrane

Na+/K+/2Cl-

The TAL contains ___ symporters in the basal membrane

K+/Cl-

The fluid leaving the loop of Henle is ___

Hypoosmotic

Reabsorption in the DCT takes place through a ___ symporter on the apical surface

Na+/Cl-

Reabsorption in the DCT is inhibited by ___ ___, which increase ___ and ___ in the filtrate

Thiazide diuretics, Na+, Cl-

Thiazide diuretic usage can lead to ___ and ___

Hypokalemia, hypochloremia

In the collecting duct, principal cells reabsorb ___ when needed and secrete ___ if there is an excess

Sodium, potassium

___ cells are considered the major site of potassium secretion

Principal

___ cells reabsorb potassium if plasma levels are low in the ___ ___

Intercalated, collecting duct

___ blocks sodium channels in the collecting duct, which inhibits the ___ of sodium

Amiloride, reabsorption

Amiloride inhibits the secretion of ___

Potassium

Regulation by ADH begins in the ___ and extends through the ___ ___

DCT, collecting ducts

Low urine osmolality is seen in patents with ___ ___

Diabetes insipidus

Low ADH levels correspond to a ___ volume of ___ urine

Large, dilute

High ADH levels correspond to a ___ volume of ___ urine

Low, concentrated

ADH is synthesized in the ___ and stored in the ___

Hypothalamus, neurohypophysis

___ inhibits the secretion of ADH

Alcohol

The response of ADH to dehydration is generally ___

Rapid

ADH is stimulated by a ___ in blood volume and a ___ in blood pressure

Decrease, decrease

___ in the left atrium sense low blood volume and report it to the hypothalamus

Mechanoreceptors

AVP stimulates the movement of ___ to the apical surface of tubule cells to ___ the cells’ permeability to water

Aquaporins, increase

Water is reabsorbed from the ___ ___ as urine becomes more concentrated

Collecting ducts

The reabsorption of water requires high ___ pressure in the kidney ___, which is created by ___ solute concentration

Osmotic, medulla, high

Diabetes insipidus results in ___ and ___

Polyuria, polydipsia

Neurogenic DI presents with ___ plasma AVP, whereas nephrogenic DI presents with ___ plasma AVP

Low, high

The vasa recta in the kidneys help concentrate urine through ___ ___

Countercurrent exchange

The loop of Henle generates a ___ solute concentration in the medulla, which generates a ___ osmotic pressure in the vasa recta

High, high

Through countercurrent exchange in the kidneys, water flows from the ___ ___ to the ___ in the vasa recta

Collecting duct, blood

Corresponding loops of Henle are known as ___ ___

Countercurrent multipliers

Corresponding vasa recta are known as ___ ___

Countercurrent exchangers

Osmotic pressure in the medullary interstitial fluid is ___

High

___ leaves the descending limb of the loop of Henle

Water

The ascending limb of the loop of Henle transports ___ into the medullary ISF

Salt

Are there aquaporins in the ascending limb?

No

NaCl leaves the ascending limb via ___ ___

Active transport

Filtrate becomes more ___ as salt leaves the ascending limb

Dilute

Water leaves the descending tubule by ___

Osmosis

In the vasa recta, there is net ___ of water and salt

Reabsorption

Blood leaving the medulla is always slightly ___

Hyperosmotic

Urea is filtered at the ___

Glomerulus

All urea transport is ___

Passive

___ is responsible for roughly 50% of the interstitial osmotic pressure in the renal medulla

Urea

The distal tubule and collecting duct are both ___ to water

Impermeable

A ___ osmotic gradient is present in the medulla when urine is more dilute

Smaller

Adult males are roughly ___% water, adult females are roughly ___%, and infants are roughly ___%

60, 50, 80

Variation in total body water is dependent on ___ content, ___, and ___

Fat, gender, age

In the elderly, water per kg of body weight ___ and is replaced by ___

Decreases, fat

Extracellular fluid is composed of what three things?

Plasma, ISF, transcellular fluid

The major osmolarity of ECF is driven by what three things?

Sodium, chloride, bicarbonate

Intracellular water is ___% of BW

40

Total body water is ___% of BW

60

Extracellular water is ___% BW

20

Major anions are ___ and ___

Bicarbonate, chloride