when things go wrong in the kidney

from physio lecture

one of the kidney’s main functions is hormonal control of other systems including the release of calcitriol. what happens as a result of high serum Ca_²⁺?

calcitonin from thyroid signals kidney to decrease Ca2+ reabsorption, promoting it’s excretion

one of the kidney’s main functions is hormonal control of other systems including the release of calcitriol. what happens as a result of low serum Ca_²⁺

the kidney responds to PTH by increasing Ca2+ reabsorption from urine and making calcitriol to increase Ca2+ GI absorption.

a decrease in circulating volume (like one of the effects of ANP/BNP), does this to blood pressure

decreases it

diuresis (like one of the effects of ANP/BNP), does this to blood pressure

decreases it 

in kidney failure, low calcitriol can lead to low serum Ca2 due to these conditions

secondary hyperparathyroidism, increased bone breakdown

what happens when pH is not in it’s normal range (7.35-7.45) 

enzymes denature and can’t perform catalytic function 

excess serum ammonia can be toxic. it is caused by liver disease. it is termed

hyperammonemia

unexplained vomiting and mental status changes may be indicative of liver disease and thus,

hyperammonemia

tx for hyperammonemia that allows it to increase stool water content, and eliminate ammonia through colon instead of as urea in the kidney 

lactulose

common site for abdominal aortic aneurysms due to many branches 

infrarenal aorta

region located on the floor of the bladder characterized by two openings (where the ureters enter the bladder) and the single opening of the urethra (where the urine exits) often site for infections 

trigone

short urethra (3-4 cm) in females makes women more susceptible for these

UTIs

compress to prevent reflux of urine back to kidneys

distal ureters

in this situation, there is a temporary decrease in GFR, to increase blood volume, blood pressure, and blood to vital organs

fight or flight, sympathetic stimulation

vasoconstriction of afferent arterioles has this affect on renal filtration 

decreases renal blood flow and filtration, helps dilute higher Na+ conc 

if these neural receptors signal a drop in arterial BP, afferent arterioles are signaled to vasoconstrict

aortic arch and carotid sinus (baroreceptor reflex)

vasoconstriction of afferent arterioles reduces GFR and thus water and sodium excretion, helping maintain blood volume and eventually increase it. explains this reflex

baroreceptor reflex

in severe hypoxemia, signals from chemoreceptors act to alter GFR how?

decreases it

higher than normal serum creatinine indicates this about the kidneys

poor ability of kidneys to filter waste effectively

elevated BUN effect on kidney

can impair kidney function

high levels of creatinine may be caused by these conditions 

hyperthyroidism or rhabdo (muscle breakdown)

low levels of creatinine may be caused by these conditions

malnutrition or muscle wasting (bed-bound pts)

low levels of BUN may be caused by these conditions

can be seen in severe liver disease, malnutrition, nephrotic syndrome

high levels of BUN may be caused by these conditions

dehydration (concentrates urea), high protein diet, or GI hemorrhage (increased protein load from digested blood)

originates from vascular endothelium. causes vasodilation

c-type natriuretic peptide 

released from DCT and CTs, causes vasoDILATION, natriuretic effects, and diuretic effects (increasing sodium and water excretion from the kidneys to lower blood pressure and volume)

urodilatin

when levels of this are high, it signals kidney to increase Ca++ excretion

calcitonin from thyroid gland

secrete renin

JG cells

potent vasoconstrictor of RAAS system

angiotensin II

angiotensin II role on kidneys

increase Na+ reabsorption → K+ secretion → water retention → increased BP

angiotensin II effect on adrenal cortex

secrete aldosterone

angiotensin II effect on thirst

increases thirst, encourages water intake

lead to increased diuresis. decrease circulating volume by promoting sodium and water loss. increased urine formation (diuresis) 

ANP/BNP

these cells are especially useful in low hydration to conserve water.

JG cells

ANP/BNP trigger: 

elevated ANP/BNP levels indicate increased circulating volume

ANP/BNP mechansims:

glomerular filtration: anp/bnp vasodilate afferent arterioles and constrict efferent arterioles. more GFR

decrease reabsorption of Na+ and H2O

block renin and aldosterone secretion

all ANP/BNP wants to do is stop this

stop further increases in circulating volume (lower BP)

every hormone/substance that can be released to cause afferent arteriole vasoconstriction

• macula densa cells (in response to high serum Na+)

• sympathetic stimulation (fight or flight)

• angiotensin II

the main effect of vasoconstriction of the afferent arterioles with respect to blood flow

decreased renal flow, GFR

the main effect of vasoconstriction of the afferent arterioles with respect to blood pressure

increases it

the main effect of vasodilation of the afferent arterioles with respect to blood flow 

increases renal blood flow, GFR 

the main effect of vasodilation of the afferent arterioles with respect to blood pressure

lowers it

every hormone/substance that can be released to cause afferent arteriole vasodilation

• macula densa cells (in response to low Na+ serum)

• c-type natriuretic peptide

• urodilatin

• ANP/BNP

less pressure on afferent arterioles (vasodilation) does this to GFR

increases it

GFR and blood pressure have this relationship 

inverse

high GFR (from vasodilation) = lowers BP

low GFR (from vasoconstriction) = increases BP

how does a high GFR lower BP?

increases urine output: increased GFR means the kidneys filter more blood, which leads to a greater volume of urine being produced.

• decreases blood volume: excreting more fluid through urine reduces the total volume of blood in the circulatory system.

• lowers blood pressure: a lower blood volume leads to a lower overall blood pressure. 

both diuretics and natriuretic peptides lower ________ by reducing __________

blood pressure

reducing fluid volume