Block 10 - Kidney function and failure Flashcards
Define hydronephrosis
1 possible cause
Urine builds up in the kidneys
Rapid weight loss causing the kidneys to drop
What are the two types of nephrons?
What is their percentage?
Corticol nephron (85%) mainly in the cortex Juxtamedullary nephron (15%) mainly in the medulla
Explain the myogenic mechanism of blood pressure control
The afferent arteriole smooth muscle adapts to systemic blood pressure
To increase blood pressure it constricts to decrease filtration
To decrease blood pressure it dilates to increase filtration
Explain how the macula densa cells control blood pressure
Macula densa cells in the ascending loop
Increase the GFR = high blood pressure
Increase GFR = more NaCl in tubule
NaCl detected by macula densa cells = release vasoconstrictive agents = less blood to glomerulus = lower GFR and less NaCl in the tubule
Less macula densa mediators if a low blood pressure
Draw the RAAS pathway
Renin –(angiotensinogen)–> ANG1 –(ACE)–> ANG2 –> Aldosterone
Can sodium be secreted?
NO - only filtered
What is it called when there is glucose in the urine?
Glycosuria
How are sodium and glucose reabsorbed by the kidney?
Glucose and Na co-transported into the nephron cell
Glucose into the blood via a GLUC transporter
Na into the cell via an ATP pump (3 Na in and 2K out)
What does progesterone act as?
A diuretic
Blocks aldosterone
Give 2 hormones which are similar to aldosterone
Oestrogen
Corticosteroids
What parts of the heart produce naturietic peptides?
Atrial NP produced by overstretched cardiomyocytes in the atria
N-Type NP produced by overstretched cardiomyocytes in the ventricles
Explain how bicarbonate is reabsorbed and hydrogen ions are secreted in the PCT
Which enzyme is involved
In the filtrate H+ + HCO3- –> H2CO3 (impermeable)
H2CO3 –> H20 + CO2 (enter the cell)
In the cell they recombine and separate again
H+ (re-enters tubule in exchange for Na+ using ATP)
HCO3- (enters capillary in exchange for Cl-)
CARBONIC ANHYDRASE
Why do you need to take care with using loop diuretics with heart and kidney failure?
Can lose sodium and potassium
Which transporter is found in the Loop of Henle?
Na/K/Cl
Which 3 things act on the DCT?
Na/Cl transporter
PTH
Thiazide diuretics
What are the 2 cells found in the CD?
What are their roles?
Principal cells: Water and sodium balance
Intercalated cells: Acid base balance
How much potassium is absorbed in the PCT?
What happens when levels in the body increase/decrease?
90% reabsorbed regardless of need
Principal cells absorb or excrete it in exchange for sodium
What is it called when there is too much water in the urine?
Diabetes insipidus
Give two methods to assess kidney function
Glomerular filtration rate (eGFR)
Renal clearance
What is renal clearance?
How is it measured?
Volume of plasma cleared of a substance in 1 min
Clearance = (urine conc x urine vol) / plasma conc
What is renal clearance standardised against
How can you tell if a substance is all reabsorbed or secreted
Standardised against a substance which is not secreted or absorbed (all is filtered) e.g. inulin (or creatinine)
If glucose level is LOWER than the inulin standard then it is all REABSORBED
(higher = secreted)
Does the blood pressure increase or decrease if you have renal disease?
Increase
Where does pain from the kidney radiate to?
Groin
6 causes of haematuria from the kidneys
Polycystic, tumour, scarring, cystitis
Glomerular nephritis, vessels
What age group suffers from LUTS?
Elderly
What does it mean if the urine is a brown/red colour?
Increased myoglobin
Breakdown product of muscles
What does it mean if the urine is cloudy?
Infection (increased WBC)
What does it mean if the urine is gravely?
Stone fragments
What does it mean if the urine is airy?
Vesico-colic fistula
What does it mean if there are debris in the urine?
Infection, vesico-colic fistula, infarction
3 causes of anuria
Severe acute kidney injury
Longstanding end stage renal failure
Post renal obstruction
2 causes of oliguria
3 examples
Acute kidney injury (reversible)
Usually drug induced (NSAID, steroid, antibiotic)
2 causes of polyuria
Early chronic kidney disease (can’t concentrate urine)
Osmotic diuretic
Define Nephrotic and Nephritic syndrome
3 symptoms of nephrotic
2 symptoms of nephritic
Nephrotic: PrOtein in the urine
(increased lipids, decreased albumin, oedema)
Nephritic: Protein and blood in the urine
(inflammation of the glomeruli, oliguria)
Define oliguria
Reduced urine output
What is angiography used to look at in the kidneys?
Chronic kidney injury
5 biochemical markers of renal failure
Are they increased or decreased?
Increased urea, creatinine and phosphate
Decreased calcium and albumin
What happens to the levels of protein bound drugs in chronic renal disease
Decreased albumin means decreased protein bound drugs
Side effects may occur
What defines chronic kidney failure?
GFR less than 6 ml/min for more than 3 months
4 pre-renal causes of AKD
Decreased perfusion
Heart failure
Decreased blood pressure (shock)
Hypovolemia
4 renal causes of AKD
Ischaemia
Nephrotoxic drugs
Nephron disorders
Sepsis
2 post-renal causes of AKD
Urethral/bladder obstruction (tumour or prostate)
Kidney/bladder stones
6 causes of chronic kidney disease
Diabetes Increased blood pressure Glomerular disease Hereditary Nephritis Tumours
What are the 5 stages of chronic kidney disease?
- Normal GFR (more than 90)
- Mild decrease (60-89)
- Moderate decrease (30-59)
- Severe decrease (15-29)
- End stage renal disease (less than 15)
One major advantage for genetic screening
Know if they will pass it on to any children
What is the name of the main genetic kidney disease?
When are the two types diagnosed?
Autosomal dominant polycystic kidney disease
T1: 30-40 yrs
T2: 70+ yrs
How can CKD lead to metastatic calcifications in vessels?
Decreased GFR decreases Vitamin D synthesis so decreases Ca absorption from the GI tract
Decreased Ca increases PTH so increases the amount of Ca released from bones causing vessel calcifications
How does heart failure cause kidney disease?
Heart failure –> Decreased CO –> Decreased blood to the kidney –> Renal hypoxia and necrosis
What are the 3 systems which regulate blood pH?
Seconds: Chemical buffers
Minutes: Respiratory centres
Days: Renal system
What are the 3 main kidney buffering systems?
Bicarbonate
Phosphate
Ammonia
What is the main intracellular buffering system?
H+ + Hb HHb
Explain the bicarbonate buffer system
H20 + CO2 –> H2CO3 –> H(+) + HCO3(-)
H(+) secreted
HCO3(-) reabsorbed in the PCT