Renal Therapeutics I Flashcards
List the 2 major roles of the kidneys
Homeostatic regulation of water and inorganic ion balance
Removal of metabolic waste products and foreign chemicals from the blood and their excretion in the urine
Label the kidney
[Labelled kidney]
What is a nephron?
The functional unit of the kidney
Loops between the cortex and the medulla
List 4 essential secretions (from blood to tubular fluid)
Renin
Vitamin D3
Prostaglandins
Erythroprotein
List the 3 processes involved in the elaboration of the urine complex
Filtration
Reabsorption
Secretion
Explain the process of filtration during the elabortion of the urine complex
Occurs in the glomerulus under very high pressure
Forms the filtrate, which then enters the tubules
Then called tubular fluid
Explain the process of reabsorption during the elaboration of the urine complex
Movement from tubular fluid to blood
Transcellular or paracellular
Explain the process of secretion during the elaboration of the urine complex
Movement of molecules from blood to tubular fluid
Transcellular or paracellular
Why are the 3 process which occur during the elaboration of the urine complex so important?
In order to conserve electrolytes and regulate osmolality
Explain the route the blood takes in order to pass the Bowman’s capsule
Afferent arteriole
- -> Efferent arteriole
- -> Peritubular capillary
Where are molecules reabsorbed to from the nephron?
Peritubular capillary
Where are molecules secreted from the blood and into the nephron?
Peritubular capillary
How does the kidney regulate blood pressure?
By controlling how much water is removed from the bloodstream and excreted as urine (during reabsorption)
What happens to the electrolytes present in the tubular fluid at the Loop of Henle?
Descending loop = H2O passes out via passive diffusion (tubular fluid becomes more concentrated compared to its environment)
Ascending loop = NaCl passively and then actively transported out, little water permeability
What happens to electrolytes present in the tubular fluid at the collecting duct?
Water and urea passively pass out of the nephron
The urea passes back into the descending Loop of Henle
List 3 molecules which can pass into the tubular fluid
Glucose
Water
Urea
Where is renin produced?
Kidney
Protease/enzyme
Where is angiotensinogen produced?
Liver
Protein
What role does renin play in the renin-angiotensin-aldosterone system (RAAS)?
Renin cleaves angiotensinogen into angiotensin I
Explain the processes which occur in the renin-angiotensin-aldosterone system (RAAS)
The kidney produces the enzyme renin which cleaves angiotensinogen made in the liver
This produces angiotensin I
Angiotensin I is cleaved by ACE (protease) to produce angiotensin II
What is ACE?
Angiotensin-converting enzyme
Protease
Where is ACE produced?
Either the kidney or the lungs
What effects can angiotensin II have on the body?
The arterioles - vasoconstriction to increase/maintain BP
Pituitary gland - ADH secretion affecting H2O absorption at the collecting duct
Sympathetic activity
Causes the adrenal gland to secrete aldosterone
What is aldosterone
Steroid hormone
Controls BP
Causes water to be reabsorbed as well as sodium = increased blood volume = increased BP
What is the role of ADH/vasopressin?
It regulates plasma volume by controlling how much water is secreted/reabsorbed in the kidneys
ADH/vasopressin makes the distal convoluted tubule and collecting duct more permeable to water (excretes less)
How is ADH/vasopressin released?
Pre-optic nerve detects drop in BP from losing too much water
Osmoreceptors in the hypothalamus detect changes in the osmotic pressure
So it releases ADH to keep more water in the body
What is ADH also known as?
Vasopressin
What does ADH stand for?
Anti-diuretic hormone
Where is ADH produced?
Hypothalamus
Where is ADH released?
Posterior pituitary gland
What do osmoreceptors do?
Detect changes in osmotic pressue
What is Diabetes insipidus caused by?
Caused by the inability of the kidney to conserve water
Therefore frequent urination and extreme thirst
What is Central diabetes insipidus caused by?
Caused by lack of ADH due to damage of hypothalamus or result of surgery
What is Nephrogenic diabetes insipidus caused by?
Kidneys fail to respond to ADH
Name the 2 types of diabetes insipidus
Central diabetes insipidus
Nephrogenic diabetes insipidus
What are micturition abnormalities?
Problems with the process of passing urine
What is normally the root of micturition abnormalities?
The lower urinary tract
What do abnormalities in urine volume usually imply?
A more serious cause
List 5 symptoms of micturition abnormalities
Dysuria = painful Hesitation = difficulty starting Frequency Incontinence = difficulty stopping Noctuia = frequency at night
List 5 possible causes of these micturition abnormalities
UTI/inflammation Outflow obstruction Heart failure Diabetes Polyuria = production of an abnormally large amount of urine
List 3 symptoms of urine volume abnormalities
Polyuria = production of an abnormally large amount of urine Oliguria = production of an abnormally small amount of urine Anuria = failure of the kidneys to produce urine
List 4 possible causes of urine volume abnormalities
Diet Climate Renal tubular disease (RTD) Diabetes (mellitus or insipidus) Chronic renal failure (CRF)
List 3 systemic symptoms of renal impairment
Fluid and electrolyte imbalances
Osmotic imbalance can cause neurological issues
Uraemia = high level of blood urea –> lethargy, nausea, vomiting
Name 3 measurements which can be used for urine analysis
Specific gravity = concentration of the urine
pH
Abnormal constituents
List 5 abnormal constituents which could be found in the urine and what this could indicate
Proteins (proteinuria) = glomerular diease
Blood (haematuria) = infection, inflammation, tumour
Haemoglobin = haemolytic anaemia
Pus (pyuria) = renal or urinary tract infection
Crystals (crystalluria) = depends on crystals
What is the rate of filtration?
Initial filtrattion of compounds from the bloodstream to the collecting duct
Indication for efficacy of kidney
Difficult to measure
What is Clearance?
Hypothetical volume of blood from which a substance would be completely removed by filtration in 1 minute
Which 3 pieces of information are required in order to calculate the rate of filtration and clearance?
Plasma concentration of substance
Urine flow rate (over 24 hours)
Urine concentration of substance
List 4 things which may result from problems with kidney function
Loss of nutrients from the body
Failure to remove toxins
Affect drug treatments
Affect BP
What is GFR?
Glomerular filtration rate
Used to measure clearance
Dependent on the net filtration pressure, glomerular surface and the permeability if the glomerular membrane
Describe the relationship between plasma clearance and GFR and the implications of this
Plasma clearance should = GFR
Plasma clearance GFR = substance filtered and secreted but not reabsorbed
List 3 factors that must apply to a substance if its renal clearance is to equal the GFR
The substance is:
Freely filtered from the blood capillaries into the Bowman’s capsule
Neither absorbed or secreted by the tubules
Has no overt effect on renal metabolism
Which substance is used to calculate GFR?
Creatinine
What is the equation used to calculate GFR from creatinine?
CrCl = [F(140-age) x weight] /SrCr F = 1.04 in females, 1.23 in men
What is RPF?
Renal plasma flow
The volume of blood plasma delivered to the kidneys oer unit time
What is the relationship between PAH and RPF?
PAH clearance is used to estimate RPF
This is because PAH enters via glomerular filtration and is secreted but not reabsorbed
Therefore clearance = RPF
What is filtration fraction?
The fraction of plasma through the kidney which is filtered
= GFR/RPF
List 6 things that should be monitored in order to estimate renal function
Creatinine Plasma sodium Plasma bicarbonate Plasma calcium Plasma phosphate pH
What is an intravenous excretory urogram (IVU)?
Use of x-ray contrast medium to produce a series of images which will show any inequality of perfusion of kidneys, rate of renal and bladder filling etc
What is the purpose of a kidney biopsy?
Useful in differential diagnosis of nephritis and in assessing transplant rejection
