urinary (renal) system Flashcards
what are the 4 main parts of the urinary system
kidneys
bladder
ureter (from kidney to bladder)
urethra (bladder to exterior)
where are the adrenal glands located and what to they secrete
on top of the kidneys. secreted adrenaline and aldosterone
what is the function of the ureter
carry urine from kidney to bladder
what are the 6 functions of the kidney
regulate body fluid volume electrolyte balance formation of urine/excretion of metabolic waste acid-base balance production of hormones and enzymes activation of vit d
what is the function of the bladder
reservoir for storing urine (holds up to 250-300ml)
draw urinary system
draw it
what is the function of the urethra
pass bladder from bladder to exterior
4cm in women/18-20cm in men
what % of body weight is fluid and where is it distributed
70% (32-40L)
intracellular fluid (25L)
Interstitial fluid (11L)
Plasma (3-5L)
what do you call the concentration of solutes in body fluid
osmolality (mOsm per KgH2o-1)
draw and label kidney
draw it
what supplies the kidneys with blood
renal vein and artery
what is the name of the functional unit within the kidney
nephron
how many kidney nephrons are there per kidney
1 million
draw and label nephron
draw it
what are the 2 types of nephron
cortical nephron- most are this type of nephron (only a little into medulla) juxtamedullary nephron (deep into medulla)
what are the 4 functions of the nephron
Glomerular filtration - creates plasma like filtrate of blood
Tubular reasborbtion - removes useful solutes from filtrate back to blood
Tubular sectretion - removes additional waste from blood
water conservation - removes water from urine and returns it to blood
blood enters the renal corpustule (glomerular capsule) at high or low pressure
high
what is the inside of the glomerulus made up of in order for it to filter efficiently
fenestrations (pores in endothelial cells) and pedicels (filtration slits)
what is Glomerular Filtration
GF = filtration of a protein free plasma from the glomerulus to the Bowmans capsule
what is the GFR (glomerular filtration rate) for males and females
females (115ml/min) 160 litres per day
males (125ml/min) 180 litres per day
how do you work out GFR (glomerular filtration rate)
Urine concentration x urine volume (produced in a given time period) divided by plasma concentration
what is creatinine
Serum creatinine (a blood measurement) is an important indicator of renal health because it is an easily measured byproduct of muscle metabolism that is excreted unchanged by the kidneys
where does most of the absorption take place within the kidney nephron
proximal convoluted tubule
where are 100% of glucose and 100% of amino acids reabsorbed within the nephron by secondary active transport
proximal convoluted tubule
what else, beside glucose and amino acids are absorbed at the proximal convoluted tubule
sodium - 65% (active transport)
water - 65% (osmosis)
what is glucose in the urine called
glycosuria (usually due to untreated diabetes mellitus)
what is reabsorbed at the loop of Henle
sodium - 25%
water - 25%
what is the name of the unique kidney mechanism which means that concentrated urine can be produced when there is a need to conserve water
counter current mechanism
what is reabsorbed/excreted at the distal convoluted tubule
sodium - 8-10% (regulated by hormones here)
water - 8-10% (regulated by hormones here)
potassium also secreted
what does aldosterone do
stimulate sodium reabsorption in the distal tubule which increases blood volume
what does atrial natriuetic peptide do
increases soduim excretion which decreases blood volume
what does anti diuretic hormone (ADH) do
increases reabsorbtion of water at the collecting ducts increasing blood volume and blood pressure
describe the hormonal control process in 6 stages
1) Decresed plasma volume means decreased arterial blood pressure
2) Decreased pressure recorded by macular densa cells of distal convoluted tubule leads to release of renin (enzyme)
3) Renin converts angiotensinogen (inactive) to angiotensin 1 (still inactive)
4) ACE (Angiotensin-converting enzyme) converts angiotensin 1 to angiotensin 2 (active)
5) Angiotensin 2 acts on the adrenal gland to secrete Aldosterone and ADH
6) Aldosterone and ADH increase sodium Na+ reabsorption and therefore water reabsorption to increase blood volume
why is acid-based balance important
PH measures the concentration of hydrogen ions in blood
what is the average PH of blood
arterial PH 7.45
venous PH 7.35
describe when acid-based balance becomes dangerous
PH below 7.35 is acidosis (depression of CNS, disorientation, coma)
PH above 7.45 is alkalosis (convulsions, respiratory spasms)
describe 3 metabolic processes which affect Acid-base balance
1) carbonic acid formation: CO2 + H2O ↔ H2CO3 (carbonic acid) ↔H+ (hydrogen) + HCO3- (bicarbonate)
2) catabolism of organic nutrients meat and proteins produce sulphuric acid and phosphoric acid
3) metabolism of fatty acids during fat metabolism and lactic acid from muscles during excercise
the lungs can maintain acid-based balance by blowing off CO2 but how do the kidneys do it
they increase or decrease the excreation of hydrogen and bicarbonate as required…
e.g If PH falls (becomes more acidic) hydrogen excretion is increased and bicarbonate conserved. this is reversed should PH rise.
Also bicarbonate is generated as a bi product of amino acid breakdown in kidneys; this process generates ammonium (NH4+ an acid which can be quickly excreted)
what is the usual PH of urine
6
what is the chemical composition of urine
95% water
5% solutes
what is the osmolality range of urine
50 mOsm/kg1 - 1200 mOsm/kg1 (dehydrated - higher concentration)
the kidney (and liver) convert vit D to active metabolites but what are they required for
regulation of blood levels of calcium and phosphate
how is bladder function controlled (6 steps)
1) stretch receptors in wall of bladder activated at around 200mls of urine
2) sensory fibres in pelvic nerve relay to sacral region of spinal chord
3) inter-neuron relays sensation to thalamus and then into cerebral cortex (u become aware)
4) parasympathetic motor fibre in pelvic nerve relay to post-ganglionic neuron
5) stimulating detrusor muscle (wall of bladder) to contract
6) micturition (weeing) occurs when external urethral sphincter relaxes
what is the single largest cause of renal failure
diabetes (also hypertension and kidney cancer)
what are kidney stones
build up of calcium, oxalate or phosphate
how do you treat kidney stones
litotripsy (sound waves break up stones)
surgery
reduce calcium intake
increase fluid uptake
what are symptoms of kidney stones
lower back pain
nausea/vom
haematuria (blood in urine)
associated infection
what is glomerulonephritus
inflammation of the kidney glomeruli causes impaired filtering. due to post-infection complication etc. blood and protein in urine
what is acute kidney failure
sudden loss of kidney function. due to very low blood pressure, blockage of renal blood supply, toxic injury (eg alcohol), ureter or bladder obstruction
explain the stages of kidney disease/failure
Normal GFR = 90-140ml/min
5 stages
stage 1 = <15ml/min (requires transplant or dialysis)
what are the symptoms of renal failure
high BP anaemia peripheral neuropathy (nerve damage) itchy skin metabolic acidosis
what are the early warning signs of renal failure
high BP
Frequent urination
difficult or painful urination
swollen hands or feet
what can urinalysis detect
proteinuria (most abundant is albumin) normally around 30mg/day however clinical proteinuria >300mg/day
what else can be tested in urine
1) creatinine clearance (GFR) - break down of muscle metabolism (90-140ml/min)
2) serum creatinine (0.6-1.2 mg/dl)
3) blood urea nitrogen - break down of protein (7-20 mg/dl)
how can you treat CKD
Control blood pressure
diet
dialysis (haemodialysis into blood or peritoneal into peritoneum dialysis)
transplant
aside hypertension and diabetes what other 3 factors may increase risk
obesity,
genetic factors,
race: south asia and Caribbean (due to prevalence of diabetes)
