An elderly female patient has a history of chronic type II diabetes mellitus, and high blood pressure. She has come to the doctor today because she has notice blood in her urine. Her doctor is now primarily concerned about the effect of high blood pressure on her kidneys. What could be going on that explains all of this? How are blood pressure and kidney function related?
anatomy of urinary system
functions of urinary system
structure of kidney
filtration, reabsorption and secretion in nephron
GFR: amount of filtrate produced by kidneys each minute
Link from Renin to GFR, macula densa cells and HTN
effects of juxtamedullary nephron on the osmotic gradient
regulation of electrolyte balance w/ aldosterone and anti-diuretic hormone
- Regulating plasma ionic concentrations (Na+, K+, H+, Ca2+, Mg2+, Cl-, HCO3-, HPO4 2-
Location: retroperitoneal
structure: looks like a bean
stabilized by 3 layers:
fibrous capsule:
- a layer of collagen fibers
- covers outer surface of entire organ
perinephric fat:
- thick layer of adipose tissue
- surrounds fibrous capsule
renal fascia:
- a dense, fibrous outer layer
- anchors kidney to surrounding structures
ureter: paired tubes that come from kidneys
urinary bladder: muscular sac inferior to ureter and superior to urethra
urethra: exit tube
- regulating plasma volume and BP (H2O)
- regulating plasma osmolarity (solute vs. H2O)
- Regulating pH balance (H+ secretion; HCO3- reabsorption)
- Secrete metabolic waste products and toxins/ foreign chemicals
renal cortex: superficial region of kidney (in contact w/ fibrous capsule
renal medulla: layer deep to renal cortex and consists of renal pyramids
renal pyramids: triangular structure part of renal medulla
renal papilla: tip of each renal pyramid which projects into renal sinus
renal column: bands of cortical tissue that extend into medulla and separate adjacent renal pyramids
minor calyx: area that each renal papilla duct discharge urine
major calyx: merging area of minor calyces
renal pelvis: combo of major calyces
hilum: section between renal pelvis and ureter
structure of nephron:
efferent arteriole: arteriole carrying blood away from glomerulus of kidney
afferent arteriole: arteriole that carries blood towards the glomerulus of kidney
bowman's capsule: cup-shaped chamber that envelopes capillary network called glomerulus
glomerulus: knot of capillaries that projects into enlarged, proximal end of nephron; site of filtration, first step in production of urine
proximal convoluted tubule: segment of nephron between the glomerular capsule (Bowman's capsule) and nephron loop; major site of active reabsorption from filtrate
nephron loop: segment of nephron that creates the concentration gradient in renal medulla; composed of descending limb and ascending limb
distal convoluted tubule: segment of nephron closest to connecting tubules and collecting duct; an important site of activation secretion
juxtaglomerular complex: macula densa, extraglomerular mesangial cells, and juxtaglomerular cells; a complex responsible for release of renin and erythropoietin
filtration: glomerulus --> Bowman's capsule:
- water, small ions/ molecuules, glucose
- NOT PROTEINS
-BULK FLOW
Takes place in glomerulus/ bowman's capsule: H2O, glucose, all ions and no protein
reabsorption: tubule --> capillary; selective transport:
- passive (osmosis)
-facilitated (co/counter transport)
-active transport
Proximal convoluted tubule: H2O, glucose, Na+, K+, HCO3-
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descending limb of loop of henle: H2O
Ascending limb of loop of Henle: Na+, K+
Distal convoluted tubule: H2O, Na+
collecting duct: H2O, Na+, K+, HCO3-
secretion: capillary --> tubule
- passive (osmosis)
- facilitated (co/counter transport)
-active transport
proximal convoluted tubule: H+
distal convoluted tubule: K+, H+
collecting duct: H+, K+
GHP is a major driving force for GFR: dictates how much filtrate you have and how much urine you end up with
luminal diameters
afferent arterioles: constriction reduces GFR
efferent arterioles: constriction increases GFR
glomerular capillaries: constriction reduces GFR
Renin: enzyme released by cells of juxtaglomerular complex when renal blood flow decreases; converts angiotensinogen to angiotensin I
purpose of renin: big effect is at regulation that triggers aldosterone --> regulation at distal convoluted tubule
affects macula densa bc of distal convoluted tubule looping around and affecting GFR via increasing blood volume by stimulating sympathetic nervous system to inc arterial pressures throughout body
inc. arterial pressures throughout body --> HTN direct effect
HTN also creates high pressure system which inc GFR as another outcome
filtrate goes through proximal convoluted tubule into descending limb of nephron loop until reaches ascending limb which is permeable to ions
soluttes pushed out into intterstitial fluid --> inc osmolarity of plasma
descending limb permeable to water, which is pushed out of capillary to accomodate inc osmolarity in plasma
aldosterone: rate of Na+ reabsorption and K+ loss in kidneys
ADH: water conservation at kidneys; stimulates thirst
water follows salt
DMII:
High blood glucose levels
result from lack of response to insulin
can result in kidney damage bc stressing filters in kidney from high blood glucose levels
can result in frequent urination because kidneys constantly trying to filter out waste
glucose can be found in urine as a result of constant filtration
Hypertension
high blood pressure
can be caused because of kidney problems
high arterial pressure can lead to inc rate of filtration, reabsorption and secretion which also can cause renal failure and vice versa
How her previous DX relate to her kidney function
Hypertension:
high blood pressure
force of blood high --> vessels stretch more easily
stretching weakens blood vessels especially those in kidney
if damaged --> can result in not removing waste and extra fluid from body
extra fluid raises blood pressure more
DMII:
high blood glucose levels
many solutes being filtered through kidney
can stress filtration system w/ abundance of glucose
results in frequent urination filtering out waste and glucose can be found in urine as result of stressing kidneys
any other factors that could be taken into account:
How often does she urinate?
how much water does she take in?
Does she get thirsty often?
what does her diet consist of?
effects of high blood pressure on kidneys:
constant high blood pressure cause arteries around kidneys to narrow, harden or weaken
- damaged arteries not able to supply kidney enough blood
damaged arteries can't filter well
- nephrons cannot get essential nutrients
- kidneys lose ability to filter blood
-unable to regulate fluid, hormones, acids and salts
effects of DMII on kidneys:
high levels of blood sugar make kidney filter too much blood
- hard on filters
- after years, can start to leak and protein lost in urine
- if waste products fill up in kidney --> kidneys fail
how they can affect each other:
high levels of blood glucose can lead to renal failure/ damage which can affect GFR, which can affect MAP which can result in high blood pressure
why patient is seeing blood in their urine: This is most likely because the kidneys are failing and are unable to reabsorb large solutes/ hemoglobin --> the pores are allowing larger solutes to get through and is getting lost in urine
what happens if untreated?
if nothing changes --> could possibly lead to seizure, coma or death