Unit 7 RENAL

Which of the following substances is not secreted into the filtrate in the distal convoluted tubule?

H2o

What are the steps for how blood moves in the kidney?

Heart generates hydrostatic pressure to pump the blood to the aorta. then it goes to the renal artery, and then the afferent arteriol where it will be filtrated by the glomerian capilaries. Then it gets back to the heart by entering the efferent arteriole traveling in the pertubulant capilaries and going to the venuels and veins to the vena cava then the heart. -These two capillary beds in sequence form the renal portal system.

Name the three pressures and what they do.

Hydrostatic (changes) Pulls stuff out Colloid (constant) pulls stuff back in Back Pressure (constant) helps colloid pull stuff in.

When the Afferent Arteriole constricts... what happens to the preassure?

Hydrostatic pressure will decrease thus creating less GFR and less blood will be filtrated.

When the Afferent Arteriole dialates... what happens to the preassure?

Hydrostatic pressure will increase and GFR will be higher and more blood and more filtrate.

___________ pressure can change when the Afferent arteriole constricts or dialates.

Hydrostatic pressure. It always wins, and pulls stuff out into the filtrate.

Water follows ______ and other solutes when it can.

NA

Put the following in the appropriate sequence to indicate the pathway a substance must travel to be reabsorbed: (a) basolateral membrane of the tubular epithelial cells (b) peritubular space (c) luminal membrane of the tubular epithelial cell (d) capillary pore of the peritubular capillary

c, a, b, d

Factors that favor filtration at the glomerulus include __________.

capillary blood pressure and the concentration of proteins in Bowman's capsule

Poisoning the Na-K-ATPase in the proximal tubule would likely __________.

decrease the amount of glucose reabsorption in this segment

The ability of the nephron to filter substances based on size and charge is not due to the __________.

hydrostatic pressure

Which is unlikely to be a consequence of kidney disease?

hyperglycemia

An ACE (angiotensin converting enzyme) inhibitor would be used to treat __________.

hypertension since ACE inhibition will result in decreased secretion of anti-diuretic hormone and aldosterone

The effects of angiotensin II on the central nervous system are to __________.

increase thirst, increase cardiac output, and cause peripheral vasoconstriction

Which of the following would not result in an increase in GFR?

increased resistance in the afferent arteriole

When insufficient water intake leads to dehydration, compensatory mechanisms to preserve plasma volume and homeostatic osmolarity include __________.

increasing the amount of water that is reabsorbed from the filtrate in the collecting duct

Angiotensin II leads to an alteration in kidney function by __________.

increasing water reabsorption from the collecting ducts and increasing sodium reabsorption along the distal tubules

In a normal kidney in a healthy individual, glucose __________.

is freely filtered at the glomerulus

The movement of water across the late distal tubule and collecting duct is __________.

passive, through channels called aquaporins, and driven by the medullary osmotic gradient

glucose transporters are only on the _________.

pct

Tubular reabsorption __________.

permits reclamation of filtered items from the plasma, occurs in the loop of Henle, and is responsible for the movement of amino acids, CA2+, Cl- and water at the proximal convoluted tubule

The urine of an individual will contain glucose when __________.

plasma glucose concentration has reached renal threshold

The renal corpuscle is the site where __________.

plasma is filtered from the glomerulus into Bowman's capsule

People suffering from central diabetes insipidus (a disorder of the hypothalamus or pituitary gland) may have increased __________.

plasma osmolarity and urine volume. their urine would be clear, like water, no osmols because its all in their blood. Cannot be converted.

A vasopressin receptor antagonist would __________

prevent membrane recycling in collecting duct cells

Angiotensin II stimulates the __________.

release of aldosterone and release of ADH

The renal filtrate is formed in the kidney's outer shell, called the __________.

renal cortex

Secretion differs from filtration in that __________.

secretion is selective because it is carrier-mediated

Glucose reabsorption from the renal filtrate is due to __________.

sequential active transport and facilitated diffusion by the cells of the proximal tubule

Name Factors that decrease GFR = vasoconstrictors - conserve fluid volume if plasma osmolarity gets too high or MAP gets too low

↑ ADH (due to ↓MAP or ↑plasma osmolarity) ↓GFR in response to big ↓in MAP ↑ ANG II (from ↓ renal blood pressure - RAAS) requiring conservation of water ↑↑↑ Symp output at α-adrenergic R's

Name Factors that increase GFR =vasodilators - get rid of excess fluid

↑ atrial stretch → ↑ ANP → vasodilation → ↑ GFR→ ↑ urine output and ↓ blood volume→ ↓ MAP

1. Describe the four main functions of the renal system: 1) homeostatic control of ECF volume and ionic composition, 2) excretion, 3) as an endocrine gland and 4) organ of gluconeogenesis.

1.)Filtration--> reabsorption vs. Secretion 2.)Excretion of dietary and metabolic wastes. Eg. bilirubin, urea from protein metabolism 3.) decreased renal blood pressure → ↑ renin or decreased PO2 in blood → increased EPO→bone marrow → erythropoiesis or When calcium levels are low in the blood, vitamin D3 is converted in the kidneys to calcitriol ('roid) which leads to greater absorption of dietary calcium. 4.). Gluconeogenesis. The kidneys play a minor role in making new glucose during times of fasting - most is done in the liver.

About ____ of the blood that enters the glomerular capillaries is squeezed out as filtrate. The other enters the peritubular capillaries and _____ reabsorbs water and solutes as they leave the different parts of the nephron.

20% 80%

_____ of solutes will be reabsorbed. ________ of glucose will be reabsorbed.

70% 100%

When mean arterial pressure decreases, which of the following may increase in response?

ADH levels and water reabsorption

Hemorrhage would tend to increase the secretion of which of the following?

ADH, aldosterone, and erythropoietin Because: A hemorrhage results in the loss of blood volume as well as the loss of red blood cells. This usually occurs associated with trauma where large amounts of blood loss are involved. In order for the body to counteract these problems, additional fluid loss needs to be prevented and new red blood cells need to be synthesized.

Describe the response of the kidney to acidosis and alkalosis

Acidosis is when the pH of the plasma is too slow. The kidney will bind with hydrogen, or increase respiration rate. Alkalosis is when the pH of the plasma is too high. The lungs will reduce respiration rate to increase CO2, kidneys cann reabsorb H+ which will loose K+ or execrete my bicarbonate into the blood.

An osmotic gradient develops in the renal medulla because various parts of the loop of Henle differ from each other in which of the following characteristics?

Active transport of solutes Direction of fluid movement Permeability to water

Which part of the nephron always has low permeability to water, regardless of hormone levels?

Ascending loop of Henle

What part of the nephron is not permeable to water?

Ascending loop of henle, water can't leave!

make sure you can label a blank nephron

Be able to draw a diagram of the nephron and label the following: each region of the nepthron, the renal medulla, cortex and salt gradient, areas of high, low and hormonally regulated permeability to water, the renal portal system, the afferent and efferent arterioles, the vasa recta, "always-on" sodium pumps, glucose transporters, hormonally-regulated sodium pumps. ADH receptors, osmolarity of the filtrate in each region of the nephron.

If a human drinks 200 ml of seawater, how will the body correct for the increase in plasma osmolarity?

By increasing the release of vasopressin. Why? One of these stimuli is an increase in blood osmolarity. When blood osmolarity is high, the kidney will reabsorb water under the influence of vasopressin in order to dilute the blood and bring the osmolarity back to normal.

Describe the response of the kidney to hypokalemia.

Cells are less excitable and could lead to failure of muscle. Causes loss of fluids (vomiting/diarrea)requires an external input of K+.

How does filtrate get to the renal pelvis and out of the body.

Filtrate is squeezed from the glomerular capillaries into the Bowman's capsule → proximal convoluted tubule (PCT)→ descending Loop of Henle → ascending Loop of Henle → distal convoluted tubule (DCT) →collecting duct →renal pelvis.

When mean arterial pressure increases, which of the following may increase in response?

GFR and Urine Volume -Glomerular filtration rate (GFR) is dependent on several different factors. One of these is the hydrostatic pressure of the plasma within the glomerulus, which is established by the mean arterial pressure. This pressure ensures that there is a positive outward pressure, making the process of filtration efficient. If mean arterial pressure increases, the net outward pressure will also increase, which leads to a higher GFR. Because of this, there is more fluid filtered, resulting in a higher urinary output. Additionally, to enhance the increased urinary output, cells in the heart will release atrial natriuretic peptide, which will enhance the excretion of sodium and water.

Relate hyperkalemia to the function of excitable cells.

Hyperkalemia: If too acid then H+ will be secreted causing absorption of K+ which could lead to acidosis. Resting membrane potentials are less negative, cells depolarize easily, can lead to hear arrhythmia. How? a sensor in the adrenal cortex increases aldosterone synthesis and increases secretion of K+ (Na+ retention) in the distal tubule.

If a person with a normal body fluid osmolarity drinks a large quantity of water, which of the following would occur if the kidneys could not excrete any of the water?

Hypervolemia and decreased plasma osmolarity

Another factor that affects GFR is tubuloglomerular feedback or renal autoregulation. This is a process that maintains constant glomerular filtration despite small fluctuations in MAP. You don't need to make more urine every time you get up from your seat to leave class and you have a small increase in your MAP! If your MAP is between 80 and 180 mm Hg, then the diameter of your afferent arteriole will contract or relax based on how much flow is occurring in the distal tubule. If flow goes up a bit (if your MAP goes up a bit) then it contracts to reduce GFR, and if flow slows down too much (if your MAP goes down a bit) then it dilates to increase GFR. These small adjustments result in a nearly constant GFR as long as you don't have a major disturbance to volume or osmotic homeostasis. Here is a summary of how tubuloglomerular feedback works:

If MAP drops below 80 mmHg then vasoconstriction occurs to conserve fluid volume

Para-aminohippuric acid (PAH) is used under clinical conditions to estimate and assess healthy kidney clearance function because _________

PAH clearance rate equals the renal flow rate of the kidney and it is not freely reabsorbed by any segment of the nephron and the remnants of PAH in renal capillaries are completely secreted and it is freely filtered at the glomerulus

Urine is carried from the collecting duct to what structure next?

Renal pelvis

"water follows ________ and other solutes when it can"

Sodium

Moderate changes in blood pressure (mean arterial pressure not less than 80 mmHg or greater than 180 mmHg) generally do not affect the glomerular filtration rate due to which known local control processes within the kidney?

The myogenic response and tubule-glomerular feedback

Ang 2 apparently increases ______.

Thirst

In the absence of ADH, which of the following will decrease?

Urine osmolarity and aquaporin synthesis

Vasoconstrictors reduce the amount of filtrate, and therefore urine formed, and vasodilators increase the amount of filtrate and therefore urine formed. Name some vasoconstrictors and VasoDilators.

VC= ADH, Epi, Ang 2, A-adrenergic stimulation VD= ANP

Describe the response of the kidney to disturbances in calcium balance.

Via PTH! Low calcium in plasma???Increased calcium reabsorption from distal tuble of the nephron. Increase osteoclast activity to dissolve bone and increased activity of calcitrol to stimulate absorption of dietary calcium from the small instestine. Calcitrol is a active form of vitamin D. It is a steroid that aids in the conversion of Vitamin D which happens in the Kidneys.

what is counter current flow?

When blood moves in opposite direction of filtrate.

The plasma can gain or lose water and/or solutes by __________.

exchange with extracellular connective tissue, such as bone respiration exchange with the lumen of the GI tract

In and around the urinary bladder, skeletal muscle can be found in the __________.

external urethral sphincter

In kidney renal tubules, all of the following substances normally are excreted into urine as it forms except __________.

glucose

what is GFR?

how much filtrate you have! The diameter of the afferent arteriole determines what the GFR will be.

The organ(s) that regulate water loss to maintain water balance is (are) the __________.

kidneys

Filtrate leaving the loop of Henle is __________ in volume and __________ to the fluid entering the loop.

lower; hypo-osmotic

The primary function of the vasa recta is to __________.

maintain the medullary concentration gradient. The vasa recta is a blood vessel that comes very close to the loop of Henle of the nephron. As water moves out of the descending limb of the loop, the role of the vasa recta is to pick up this water so that it is delivered back into general circulation for the maintenance of blood volume.

By the end of the proximal tubule, approximately 70% of the water and solutes have been reabsorbed. However, the fluid in the tubule is still iso-osmotic to plasma. This is because within the proximal tubule __________.

many solutes are actively transported, and water follows the solutes by passive diffusion

If clearance of a substance is greater than GFR, the substance is __________.

net secreted by kidney

Water moves by _________. As long as there is a gradient conducted by primary and secondary ATP transport.

osmosis. these transporters can be saturated and cause excessive peeing like wiht diabetes.

In order to measure the clearance of a substance, one would need to know which of the following?

the concentration of the substance in the plasma, the concentration of the substance in the urine, and the urine flow rate

The signals controlling ADH release come from __________.

the macula densa, arterial baroreceptors, osmoreceptors in the hypothalamus.

The nephron is the functional unit of the kidney because __________.

the nephron filters the plasma, reabsorbs critical molecules, and excretes the rest

The proximal and distal tubules differ in that __________.

the proximal tubule is "leakier" than the distal tubule, distal tubule cells possess a higher concentration of hormone receptors compared to proximal tubule cells, and proximal tubule cells have larger numbers of mitochondria

The proximal tubule is where __________.

the reabsorption of the majority of ions, organic molecules, and vitamins takes place