renal function Flashcards
what are the functions of the kidney?
- maintain a stable internal environment (homeostasis)
- endocrine functions (secrete hormones)
- gluconeogenesis
- form urine
what is maintained in homeostasis within the functions of the kidney?
solutes + water
acids + base
nutrients
waste
what hormones are secreted within the functions of the kidney?
renin
EPO
vitamin d3 (calcium metabolism)
what is gluconeogensis?
create glucose from things such as amino acids
what is contained in the kidney function of forming urine?
filtration
reabsorption
secretion
storage
removal (waste)
what force favors filtration?
capillary hydrostatic pressure
BHP, CHP
how much do the kidneys filter in a healthy individual?
120mL/minute
in a healthy individual, how much of the content that os filtered is reabsorbed and returned to the body by the tubules?
99%
what effect does vasoconstriction of the afferent renal arteriole have on GFR and body fluid conservation?
GFR decreases
BFC increases
what effect does vasoconstriction of the efferent renal arteriole have on GFR and body fluid conservation?
GFR increases
BFC decreases
what effect does severe malnutrition (without dehydration) have on GFR and body fluid conservation?
GFR decreases
BFC increases
what effect does obstruction to the outflow of urine have on GFR and body fluid conservation?
GFR decreases
BFC increases
what does the PCT reabsorb?
glucose
sodium
H2O
what does the DCT reabsorb?
H2O directly stimulated by ADH
Which hormone leads to increased reabsorption of Na?
aldosterone
How does tubular secretion occur in the nephron?
-Movement of substances from the peritubular capillaries to the tubular lumen
-Proximal tubule and CD receive secretions of H +
-Distal tubule and CD receive secretions of K + (aldosterone)
what ways do we access renal function?
urine output
plasma creatine-PCR
blood urea nitrogen-BUN
How do PCR levels help to access renal function?
Creatinine is a product of muscle metabolism (breakdown of macromolecules), and is filtered by the glomerulus
How do BUN levels help to access renal function?
Urea is filtered by the glomerulus
what is urea?
The molecule urea is formed from protein and amino acid degradation
when GFR is low, what happens to PCR and BUN?
they are high
when protein malnuturton occurs, what happens to PCR and BUN?
they are decreased INITIALLY
how do we classify kidney disfunction?
acute or chronic
reversible or irreversible
how is considered decreased renal reserve?
less than 25% kidney function
-require increased demands of kidneys
what are the BUN and PCR levels during decreased renal function?
increased
how does increased fluid intake effect decreased renal function?
the kidneys unable to keep up with urine production
– fluid overload
-can affect heart function and BP
how does insuffienct fluid or fluid loss effect decreased renal function?
-Urine not concentrated properly - risk of fluid deficit
-Kidneys trying to hold on to as much as possible
what is considered renal insufficiency?
25-10% of normal kidney function
what are the manifestations of renal insufficiency?
polyuria
nocturia
what is polyuria?
increased urine output
-appears with the loss in the concentrating ability (lack of water reabsorption)
what is nocturia?
Increase of urine output at night
-Normally, the kidneys are more efficient at reabsorption at night - that way you don’t have to get up and pee in the middle of the night
what is considered end-stage renal failure?
less then 10% of renal function
what does end-stage renal failure lead to in the body?
-accumulation of nitrogenous waste products in the body
-uremia
Both azotemia and uremia involve the accumulation of —–?
nitrogenous waste products in the blood
what is uremia?
-Syndrome of renal failure - past renal insufficiency, already renal failure. Farther along
-Elevated blood urea and creatinine levels
what are the manifestations of uremia?
Fatigue, anorexia, nausea, vomiting, pruritus, and neurologic changes
hat does uremia lead to?
Retention of toxic wastes, deficiency states, electrolyte disorders, and proinflammatory state
what is azotemia?
buildup of nitrogenous waste products - urea, creatinine. Earlier in the disease process
-Increased serum urea levels and frequently increased creatinine levels
what are the manifestations of azotemia?
May not be showing symptoms from the increased nitrogen
what is acute kidney injury (failure)?
Sudden decline in kidney function with a decrease in GFR and accumulation of nitrogenous waste products in the blood
what would BUN and PCR in acute kidney injury (failure)?
it would be increased
what is oliguria?
severe reduction in urine output
what causes pre renal acute injury (failure)?
renal hypoperfusion: decreased circulation of blood to the kidneys
what happens to the GFR in pre renal acute injury (failure)?
it decreases
what could cause decreased blood to the kidneys?
-Left sided heart failure
-Atherosclerosis
-Hypovolemia
-Hypotension
-Lack of blood flow or oxygen
what is intrarenal acute injury (failure)?
intrinsic-problem within the kidney
what can causes infrarenal acute injury (failure)?
-Acute glomerulonephritis
-Acute tubular necrosis (ATN)
what is glomerular nephritis?
inflammation and damage to the glomerulus
-primary or secondary
what is primary glomerular nephritis caused by?
some sort of injury that trigger inflammatory response
-Allergic reactions
-Trauma
-Infections
-Ischemic injuries
-Free radical damage
what is secondary glomerular nephritis caused by?
this is a consequence of systemic diseases such as diabetes mellitus, lupus, and others
what are the steps in acute glomerular nephritis?
- Immune complexes (antigen-antibody) deposited in the glomerulus
- The antibodies cross react with the glomerular cells
- Activation of the complement
- Recruitment and activation of immune/inflamm cells and immune/inflamm mediators
following acute glomerular nephritis, what initial effect does activation of the immune/inflammatory response have on the capillaries and capillary forces inside the glomerulus?
-Vasodilation
-increased vascular permeability
-COP decreases. (fewer proteins because of the increased vascular permeability)
what are the manifestations of acute glomerular nephritis?
-Hematuria (blood in the urine, smoky, brown-tinged urine)
-Proteinuria exceeding 3 to 5 g/day (Albumin excreted from the plasma)
- possibly edema
-Inflammatory response causes glomerular cells to proliferate, and can block the glomeruli
-oliguria
what would happen in a response to glomerular cells blocking the glomeruli
-GFR decreases
-glomerular perfusion decreases
-BHP increases (due to body fluid retention)
-edema, HTN, heart problems
what would BUN and PCR be in acute glomerular nephritis?
BUN, PCR would increase and cause azotema
what is nephrotic syndrome caused by?
acute glomerulonephritis along with other diseases
what is nephrotic syndrome?
-Excretion of 3.0 g or more of protein in urine
-Protein excretion as a result of glomerular injury
-less Vitamin D is transported to the liver and kidneys by proteins in the blood to become active
-less Activated Vitamin D is required for absorption of calcium from the small intestine
What happens to allow the proteins to leave the capillaries in nephrotic syndrome?
Increased capillary permeability from the inflammatory response
What happens following the loss of these proteins in nephrotic syndrome?
-Decreased BOP
-initial increase in GFR
What does the smaller amounts of vitamin D mean for calcium in nephrotic syndrome?
-Calcium lost if there is less activated vitamin D
-get calcium from the bones (weak bones, osteomalacia)
what are the causes of acute tubular necrosis (ATN)?
Damage caused by renal ischemia, hypertension, and renal poisons (like antifreeze)
what is the result of acute tubular necrosis?
-Causes necrosis of the epithelial cells that form the renal tubules
-These cells slough off and block the renal tubules
—-Bowman’s capsule pressure is affected. BHP and Bowmans pressures are opposing each other
—-GFR is decreased
what is post-renal acute injury caused by?
Results from conditions that arise after the nephrons
-Urinary tract obstructions (Kidney stone, enlarged prostate)
what happens in the initiation phase of acute kidney injury?
-occurs during the injury itself
-reduced perfusion or toxicity
what happens during the matienance or oliguric phase of acute kidney injury?
-Decrease GFR
-Increase plasma nitrogen
-Increase water and Na
-Edema can develop, hypertension
-Metabolic acidosis (not getting rid of H+, it is building up in the body)
-This phase could last week or months
what happens in the recovery phase of acute kidney injury?
-Renal injury is repaired
-Normal renal function is reestablished
-GFR is increasing
-Tubules have trouble concentrating the filtrate
-Diuresis
-Nitrogen decreasing from body
-Na+, K+, H2O decreasing
-Return to normal may take 3-12 months
what are the the treatments for acute kidney injury?
-Hemodialysis
-Correct fluid and electrolyte disturbances
-BP balance
-Prevent and treat infections
-Maintain nutrition
at would your bp be in the maintenance and recovery phase of acute kidney injury?
hypertension
What kind of diet might be important to minimize elevation of BUN?
low protein (less amino acids)
what is chronic kidney disease?
-Progressive loss of renal function associated with systemic diseases
-GFR less than 60 mL/min/1.73 m 2 for 3 months or more, irrespective of cause
what are the clinical manifestations of chronic kidney disease?
Do not occur until renal function declines to less than 25% of normal
what are the causes of chronic kidney disease?
-Chronic glomerulonephritis
-Diabetic nephropathy
-Renal vascular disease
-Recurrent pyelonephritis
-Benign nephrosclerosis
how does chronic glomerular nephritis lead to chronic kidney disease?
Glomeruli are replaced with scar tissue
how does diabetic nephropathy lead to chronic kidney disease?
Hyperglycemia damages the nephrons
how do renal vascular diseases lead to chronic kidney disease?
Atherosclerosis of the renal vessels results in progressive loss of nephrons
how does recurrent pyelonephritis lead to chronic kidney disease?
kidney infection
how does begin nephrosclerosis lead to chronic kidney disease?
(Result of aging) Small arteries in the kidneys become thickened and narrowed over time
what is chronic glomerular nephritis?
-Slow, progressive destruction of the glomeruli
-Many glomeruli are completely replaced by fibrous tissue leading to loss of nephron function
is chronic GN reversible?
no
what is chronic GN caused by?
-recurrent streptococcal infections
-more commonly: an autoimmune condition
what are the manifestations of chronic GN?
-Proteinuria - inflammation causes proteins to leak out because of increased vascular permeability
-HTN - body compensating
-Azotemia - GFR decreases, you are holding on to nitrogen
-Uremia - azotemia further along
what are the treatments for chronic GN?
-Dialysis
-Transplantation
