Renal Pathophysiology Flashcards
How many renal pyramids does the medulla of the kidneys contain?
6-18
How many nephrons are in the cortex of the kidney ?
1.25 million
Where does the blood supply to the kidneys derive from?
Renal and venous blood supply to nephrons is required.
Describe how the arteries change further into the kidneys and why this occurs.
Arteries become thinner further into the renal system which allows arterioles to supply bloody to each individual nephron.
Name the basic processes of renal function.
- Glomerular filtration
- Tubular secretion
- Tubular reabsorption
Outline the purpose of the proximal convoluted tubule (PCT).
Reabsorption of water, ions and all organic nutrients.
Outline the purpose of the distal convoluted tubule (DCT).
Secretion of ions, acids, drugs and toxins.
Variable reabsorption of water, sodium ions and calcium ions (under hormonal control).
Outline the purpose of the collecting duct.
Variable reabsorption of water and reabsorption or secretion of sodium, potassium, hydrogen and bicarbonate ions.
Outline the purpose of the papillary duct
Delivery of urine to minor calyx.
Outline the purpose of the loop of Henle.
Further reabsorption of water (descending limb) and both sodium and chloride ions (ascending limb).
Describe the purpose of the renal corpuscle.
Production of filtrate.
What is the diameter of each renal corpuscle in the kidneys?
150-250um
What does the renal corpuscle consist of?
The Bowman’s Capsule and Glomerulus.
Outline the functions of the nephron.
- Produce filtrate
- Reabsorption of organic nutrients
- Reabsorption of water and ions
- Secretion of waste products into tubular fluid.
Compare the cortical and juxtamedullary nephrons.
The cortical nephrons make up 85% of the nephrons in the human kidney and have smaller loops of Henle. Whereas juxtamedullary nephrons make up only 15% and have a larger loop of henle.
What is the purpose of the longer loop of henle in juxtamedullary nephrons?
Allows for greater reabsorption
How does urine production maintain homeostasis?
- Regulating blood volume and composition
- Excreting waste products such as urea, creatinine and uric acid.
What are the basic processes of urine formation and explain each.
- Filtration (blood pressure, water and solutes across glomerular capillaries).
- Reabsorption (the removal of water and solutes from the filtrate).
- Secretion (transport of solutes from the peritubular fluid into the tubular fluid).
What processes are used to accomplish reabsorption and secretion in the kidneys?
Diffusion (passive and facilitated) , osmosis and carrier-mediated transport.
What is Tm?
The renal threshold for reabsorption of substances in tubular fluid.
What carrier mediated transport processes occur to aid filtration in the kidneys?
Facilitated diffusion, active transport, cotransport, counter transport.
What determines renal threshold?
Transport maximum of the carrier proteins.
What is glomerular filtration reliant on?
The concentration of solutes, passage of liquid taking solutes away, filtration slits to allow materials to pass through and blood pressure forcing material out.
Define glomerular filtration rate (GFR)?
The amount of filtrate produced in the kidneys each minute.
What happens if a drop in glomerular filtration pressure drops?
Stimulates juxtaglomerular apparatus and activates a release of renin and erythropoietin to aid regulation of blood pressure.
Explain what happens during sympathetic activation of the kidneys and how this alters glomerular filtration rate.
- Produces powerful vasoconstriction of afferent arterioles which decreases GFR and slows production of filtrate.
- Changes the regional pattern of blood flow by altering GFR.
- Stimulates the release of Renin by juxtaglomerular cells.
What is the difference between glomerular filtrate and plasma?
Glomerular filtrate doesn’t contain proteins.
What % of filtrate is reabsorbed by the proximal convolute tubule?
60-70%
Describe counter current multiplication in the loop of henle
An osmotic gradient is created between the ascending and descending limbs in the loop of henle. This facilitates reabsorption of water and solutes before the distal convoluted tubule is reached and permits passive reabsorption of water from the tubular fluid.
How does osmotic pressure change through the loop of henle
Osmotic pressure increases in the descending limb and decreases again in the ascending limb.
Describe the permeability of the descending limb of the loop of henle.
Permeable to water but impermeable to solutes.
Water is lost via the descending limb and so osmotic pressure increases.
Describe the permeability of the ascending limb of the loop of henle.
Impermeable to water but has the ability to actively uptake solutes.
What part of the nephron performs final adjustment of urine and how does it do this?
The distal convoluted tubule by active secretion and absorption.
What happens during absorption at the distal convoluted tubule?
Tubular cells actively reabsorb Na+ and Cl- in exchange for potassium or hydrogen ions.
Describe the effects of Arginine Vasopressin on urine.
When AVP is present, small volumes of concentrated urine is produced whereas when AVP is not present, large volumes of dilute urine are produces.
What is the renal threshold for glucose ?
10 mmol/L
What will happen if renal threshold for glucose is exceeded?
If the Tm is exceeded, glucose will appear in the urine. Glycosuria.
What is the renal threshold for amino acids?
65mg/dl
When will amino acids appear in the urine?
After a protein-rich meal
What is it called when amino acids appear in the urine?
Aminoaciduria
Where does urine transport, storage and elimination occur?
In the urinary tract; ureters, urinary bladder, urethra.
Describe peristaltic convulsions of the urinary system.
Begin at the renal pelvis and sweep along the ureter. They force urine towards the urinary bladder and occur every 30 seconds.
What issues in the respiratory system can renal problems cause and how?
- Tachpnea
- Dyspnoea
- Pleural effusions - Fluid balance must be maintained within the blood supply to ensure fluid balance within the lungs isn’t affected. If it isn’t, fluid could collect in the pleural regions or in the lungs themselves.
- If the kidneys are not filtering effectively, material ill travel into the venous supply and may affect the respiratory system.
What effects can renal problems have on the renal system?
- Small kidneys
- Nocturia
- Oliguria and polyuria
What effects can renal problems have on the haematological system?
Anaemia - may occur if the blood becomes too diluted.
Bleeding tendency
Low resistance to infection
Describe the neurologic symptoms that can be caused by renal problems.
- Depression
- Coma
- Peripheral neuropathy
Describe the issues that can arise in the skin and mucosae due to renal problems.
Pruritus
Describe the issues that can arise with the cardiovascular system due to renal problems.
Hypertensive heart disease
Arrhythmia
Pericardia
Increased jugular venous pressure
How many increased blood pressure affect the kidneys?
May put pressure on the glomerulus that causes issues with the kidneys.
What are they key symptoms of kidney failure?
- Erythropoietin synthesis is decreased leading to anaemia.
- Fluid volume overload can lead to oedema and pulmonary oedema.
- Blood pressure is increased due to fluid retention. This may lead to hypertension and congestive heart failure.
- Hyperkalaemia causes cardiac arrhythmias and malaise.
- Uraemia damages the organs by causing pericarditis and encephalopathy.
Describe the issues that may occur within the GI system due to kidney problems
Nausea
Anorexia
Vomiting
Describe the issues that may occur within the musculoskeletal system due to kidney problems.
- Myopathy and muscle weakness
- Bone Bain and radiographic findings.
Describe how Urea and Creatinine can be used as measures of kidney function and why.
- Urea can be higher in prerenal failure due to changes avid tubular reabsorption.
- Creatinine in the small frame suggests poor muscle mass
- Creatinine is higher if muscle breakdown is occurring.
- Creatinine is freely filtered by the kidney and is not reabsorbed or metabolised.
What can be used to measure proximal tubule function?
Creatinine - this should be freely filtered by the kidneys.
What % of creatinine is secreted into the proximal tubule?
15
What are the 2 types of total kidney failure?
Acute renal failure
Chronic renal failure
What is acute renal failure?
A sudden insult results in insufficient kidney function.
What is chronic renal failure?
A gradual accumulation of kidney damage eventually resulting in insufficient kidney function.
Name some syndromes caused by partial kidney syndrome.
Nephritic syndrome
Nephrotic syndrome
What is Nephritic syndrome?
Thin glomerular basement membrane with pores that allow protein and blood into the tubule which isn’t normally the case.
Name some of the issues caused by nephritic syndrome.
Haematuria - red cell casts seen in the urine.
Hypertension (mild)
Oliguria
Uraemia
Proteinuria (<3g/24 hours)
What is nephrotic syndrome?
Increased permeability of the glomerulus leading to loss of proteins into the tubules.
Name some of the issues caused by nephrotic syndrome.
Massive proteinuria (>3g/ 24 hours)
Hyperalbuminaemia (<25g/L)
Oedema - fluid retention in various tissues.
What is chronic renal failure?
A progressive deterioration of renal function.
Describe the progressive time period over which chronic renal failure acts.
Slow - months to years.
What defines chronic renal failure
Abnormally low glomerular filtration rate which indirectly causes elevated creatinine levels.
How can chronic renal failure be treated?
Renal replacement therapy
What happens during the asymptomatic phase of chronic renal failure?
Up to 75% of neurones can be lost.
Name some of the causes of acute renal failure.
- Blood from renal artery is delivered to glomeruli causing perfusion.
- Glomeruli form ultafiltrate which can flow into tubules and cause acute tubular necrosis.
- Urine leaves the kidney and drains into the renal pelvis, ureters, bladder and urethra leading to obstruction.
- Hypovolaemia
- Pigment induced damage - e.g. following haemolysis
- Cardiovascular failure
- Obstruction outside and inside the kidneys
- Poison
Describe the length of acute and chronic renal failure.
Acute - short (days to weeks).
Long - (months to years).
Describe the Hb concentrations in acute and chronic renal failure.
Acute - normal Hb
Chronic - low Hb
Describe the renal size in acute and chronic renal failure.
Acute - normal
Chronic - reduced
Describe the peripheral nephropathy presence in acute and chronic renal failure.
Acute - none
Chronic - peripheral nephropathy occurs
Describe the change in creatinine concentration in acute and chronic renal failure.
Acute - acute reversible increase in serum creatinine concentration.
Chronic- irreversible increase in creatinine concentrations.
What are the 2 types of intrinsic renal disease.
Systemic and primary
Name some infrarenal causes of kidney failure.
- Damage to the kidney
- Polycystic kidney disease
- Nephrotoxcitiy
- Autoimmune processes
- Diabetes nephropathy
- Renal trauma
- Acute tubular necrosis
What are the causes of renal impairment due to obstruction of the renal tract?
- Tumours
- Fibrosis
- Blood clots
- Kidney stones
