Renal Flashcards
Total body water is …. .percent of body weight, consists of ….. ECF and …. ICF
ECF is …. plasma & ….. ISF
60 1/3 2/3 1/4 3/4
The osmolarity of plasma is …… than that of ISF, because of …….
higher, plasma proteins
Transcellular fluid includes ……
CSF, ocular, urine ….
Why NaCl solutions is confined to the ECF??
because of the activity of the Na-K pump
What is the function of :
- Isotonic NaCl
- Hypertonic NaCl
- Hypotonic NaCl
- Increases ECF by the same amount administered
- Increases ECF volume by extracting from ICF
- Increases both ECF and ICF
Hypertonic solution of mannitol is used in patients with …..
cerebral edema to mitigate brain swelling
* mannitol acts like NaCl
Edema is caused by movement of fluid from ….. to ……
plasma to ISF , and retention of salt and water by kidney
Distribution of edema depends on …… & …..
- tissue tension: lowest around the eyes and medial side of the ankle
- forces of gravity
Capillary pressure is more affected by increased venous pressure than arterial, because ……….
it is protected from the arterial pressure by the precapillary sphincter (which respond to increased pressure by constriction)
Forces promoting efflux are ……, while the ones promoting influx are …….
Pc & πi
Pi & πc
* π is the oncotic pressure
* fluid movement = Kf [(Pc + πi) - (Pi + πc)]
* Kf is the capillary permeability constant
Why patients with high blood pressure but no heart failure do not develop edema??
because of the presence of the precapillary sphincter. So the venous pressure remains relatively low
* Veins are more permeable than arteries
Anasarca is caused by …….
drop in capillary oncotic pressure
* An increased πi causes localized edema
The main causes of edema are ….. , ….., ….. & ……
increase Pc
decreased πc
increased permeability
blockage of the lymphatic draingae
Glomerulonephritis causes …….. retention due to ……… . The main cause for the retention…..
NaCl & water retention
damaged kidney
reduced GFR
* The water & NaCl retention is primary, not secondary like congestive heart failure
Decreased GFR leads to increased …..
Capillary pressure
- This leads to increased vascular volume, EDV, CO, hypertension, transudation of fluids and edema
- Hypertension inhibits renin release
In glomerulonephritis, increased CVP leads to release of ….. from the atria
ANF, which acts on the collecting duct to inhibit Na reabsorption
Liver cirrhosis may lead to the development of ascites caused by ……
Hypoalbuminemia leads to …..
fibrosis and mechanical venous obstruction
decreased oncotic pressure allowing fluid to leak out of the capillaries, and causing generalized edema
Define nephrotic syndrome
The loss of more than 3.5 g protein/day in urine, which is the maximum amount the liver can produce in an adult
Leads to generalized edema, and secondary salt/water retention
What is the difference between edema in nephrotic syndrome and edema in glomerulonephritis??
Glomerulonephritis: caused by increased Pc
Nephrotic syndrome: decreased πc with secondary decreased Pc
Burns act on the capillary wall causing …… and locally increased ….. in the tissues
increased permeability
πi (from protein transudation)
* This leads to localized edema
Nephritic syndrome is ……
inflammation of the glomerulus allowing proteins and RBC to pass into urine. Signs are hematuria, proteinuria, oliguria, edema, azotemia (reduced waste elimination), hypertension). GFR is reduced
* Proteinuria here is less severe than nephrotic syndrome
Filariasis is caused by ……..
Wuchereria bacrofti
* blocking of the lymphatic channels causes elephantitis
Radical mastectomy involves the removal of …….
the breast, the underlying muscle & axial lymph node
* Leads to local edema
Decreased activity of the Na-K pump leads to ……..
cellular swelling
What is the difference between transudate and exudate?
Exudate fluid has less pH & higher protein content. Transudate has the opposite characterisitic
……. is the functional unit of the kidney. It consists of a vascular filter (……) and ….
the nephron
glomerulus, Bowman capsule
* Each kidney has about 1.5 million
What are the types of nephrons?
- Cortical: have short loops
- Juxtamedullary nephrons: Deep in the cortex, at the corticomedullary junction. They account for 15% of all nephrons. Have long loops of Henle (extend deep inside the medulla)
Nephrons have capillary beds associated with their ……..
convoluted portions
The nephron consists of …..
Bowman’s capsule, glomerulus, proximal convoluted tubule, descending tubule, ascending tubule, distal convoluted tubule, collecting duct, and macula densa
The glomerular filtrate represents ….
20% of renal plasma flow
* Glomerular filtrate is protein free
Total GFR is the ……….
sum of all filteration rates in all functional nephrons.
Serves as an index of overall renal function
The net filteration pressure is ….
(Pc - Pi) - (πc - πi)
- Pc = 45
- Pi = 10
- πc = 28
- πi = negligible
- Net filteratio is (45 - 10) - (28 - 0) =7 mm Hg
Glomerular capillaries are ….. with …. radius
short, large
* the blood pressure drop is small
Permeability of the glomerulus is determined by ……….
the number and the size of the pores
- the glomerulus has more pores than muscle capillaries, hence, the permeability is greater
- anything up to m.w of 5000 dalton passes freely
Podocytes are ……
epithelial cells maintaining the basement membrane of Bowman’s capsule. It scavenges proteins that slip across the filtration barrier
What is the fate of the filtered urea?
half the filtration is reabsorbed in the PCT, and some in the deepest portion of the collecting tubule (ADH dependent)
What is the fate of the filtered creatinine??
It is not reabsorbed, and small amount is added to the filtration from the nephron
- Excreted amount is about 20% more than the filtered amount
- Trimethoprim, cimetidine & ketoacids reduce the secreted creatinine, leading to more accurate estimation of GFR
The best method to estimate the GFR is by measuring ……….
creatinine clearance
- GFR = U creatinine x V / P creatinine
- V is the urine flow rate, P is plasma
- inulin (polymer of fructose) clearance is also used
What is the fate of the filtered glucose??
Freely filtered, then reabsorbed in the PCT by transport maximum (Tm)
In diabetes, the increased plasma glucose leads to ……. in filtered load of glucose exceeding the …..
increase
Tm
* Renal glycosuria is the genetic defect in the reabsorption pump
What is the fate of the filtered amino acids??
Freely filtered then reabsorbed in the PCT by transport maximum (Tm)
Ca and PO4 levels in the plasma are …… related
inversely
* Ca x PO4 = constant
What is the fate of the filtered Na??
97% of Na filtered is reabsorbed
- 70% is reabsorbed in PCT (water & Cl follow passively)
- 20% is reabsorbed in ascending limb (in exchange for K or Cl, impermeable to H2O)
- 5% is reabsorbed in DCT (in exchange for Cl, aldosterone controlled, relatively impermeable to water)
- 3%-5% is reabsorbed in collecting duct (regulated by aldosterone). Water permeability is controlled by ADH
- About 25 mmol/filtered every day
What are the effects of hypercalcemia on GIT??
anorexia, vomiting, nausea, constipation, weight loss
What is the fate of the filtered water??
99% is passively reabsorbed.
* 180 liter is filtered daily, 1.8 liter is excreted in urine
Rate of water reabsorbtion depends on ADH, which is activated by …… & ………
increased plasma osmolarity (main stimuli) & decreased blood volume (detected by baroreceptor)
Hypoaldosteronism causes ….., ….. & ……
Na loss (with decreased CO and blood flow), K retention (leading to arrhythmia), H retention (leading to acidosis)
Countercurrent multiplier is ….., and it consists of …………
a system that concentrates urine in the renal medulla before excretion.
two parallel limbs of Henle running in an opposite direction
When ADH is absent (in high water intake), the collecting tubule becomes …… to water
impermeable
* No exchange occurs despite the osmotic difference between the tubule fluid and the adjacent interstitium
Very little K is filtered (compared to Na) because of …..
low level of K in plasma
What is the fate of the filtered Potassium?
- 100% reabsorbed, except for the small amount which is secreted
- 70% is passively reabsorbed in the PCT
- 20% is actively reabsorbed in the ascending limb of Henle
- 10% is actively reabsorbed in the collecting duct
- The amount secreted depends on the ingested amount, acidosis, increased aldosterone
The renin-angiotensin system is ….. dependent
volume
Fixed acids are buffered by ….
- half H reacting with HCO3 in the ECF, giving H2O & CO2
2. The other half enters the cells (through the Na/H pump) to react with protein, phosphate, bone
Volatile acids are buffered by ……..
All H ions entering the cells, with one third reacting with Hb in the RBC, and the other 2/3 reacting with protein, organic phosphate & bone
In the nephron, H ions are …….. secreted in the ….. & …..
actively
PCT & collecting duct
* very small amount is secreted since plasma H concentration is small
What is the fate of H in the urine??
- Reacts with HCO3, to give H2O and CO2
- Reacts with ammonia, to give ammonium (NH4)
- Reacts with phosphate, giving H2PO4
For each H secreted in the urine, ….. is returned to the interstitial fluid and then the blood.
one HCO3
* HCO3 returned after titration with H is called reabsorbed
* If H reacts with NH3 or PO4, the HCO3 returned is called new HCO3
see p. 507 (if not clear)
Renal compensation for respiratory acidosis means ……
Increased HCO3 return when PCO2 is high in case of hypoventilation
* H secretion will be increased
Aldosterone stimulates the active release of ….. in exchange for Na when K concentration is low
H
* Note that K is passively release in exchange for the Na absorbed
The lung handles ……. , while the kidney usually handles …..
H2CO3 (volatile acids)
other acids and replaces HCO3 used for titration
Respiratory acidosis means ….., while alkalosis means ….
- increased PCO2 due to hypoventilation, cardiac arrest, pneumonia
- Decreased PCO2 due to hyperventilation, high altitude, pulmonary embolism
see p. 507 (if not clear)
Metabolic acidosis means ……, while alkalosis means ……
- Decreased HCO3 due to acids accumulation
- Increased HCO3 due to vomiting, ingestion of base
see p. 508 Table if the response is not clear
The glomerular and the peritubular capillary are arranged in …., while the peritubular capillary and the vasa recta are in ……
series, parallel
* The glomerular efferent arteriole is considered a true portal vessel
The glomerular efferent capillary is divided into ….. & ……
- peritubular capillary (in the cortex)
2. Vasa recta (in the medulla)
About 10% of renal blood flow perfuses the …… . The remaining 90% is in the ……
renal capsule, perirenal fat, and the upper ureter nephrogenous zone (5% in the vasa recta, while the rest in the cortical peritubular capillary)
Renal blood autoregulation ensures ….., and is accomplished by ……… as the pressure increases
constant flow over a wide range of blood pressure
constricting the afferent arteriole
* This ensures constant GFR
The kidney receives …….. innervation only
sympathetic
- alpha receptors activation will cause constriction of the afferent (which has a thicker muscular coat than the efferent)
- beta1 receptors activation (on myoepithelial cells) will cause release of renin, and hence constriction of the “efferent”
Renin is released from the juxtaglomerular cells by 3 stimuli, which are ……
- stimulation of beta 1
- reduction in perfusion pressure
- reduction in Na delivery to macula densa (tubuloglomerular feedback)
Renal clearance is ……….
volume of plasma that is completely cleared of the substance per unit time
PAH is used to …. , because it is ……..
(para amino hippuric acid) used to calculate the effective renal plasma flow (ERPF) through the peritubular capillaries, since it is completely secreted in the PCT
Erythropoietin is released from……. in response to ….. causing the formation of …..
endothelium of peritubular capillaries
hypoxia
new RBCs from the bone marrow
* It is a glycoprotein
Creatinin levels are …. males, …. females
- 7 - 1.2
- 5 - 1.0
* increased by increasing the body mass
Define SIADH
it is symptom of inappropriate ADH
- High level of ADH released, mostly due to cancer in the post. pituitary
- Strong association with small cell lung carcinoma
- causes hypertonic urine with high Na
Chronically low serum Na causes ……
intracellular fluid expansion, or cellular burst
What are the characteristics of urine
Yellow, clear, slightly acidic, specific gravity is 1. 005.
* 1-2 liter excreted everyday
