Anatomy and physionlogy Flashcards
Definition and effects of hyperkalaemia
> 5.5mmoles/l
Depolarisation –> Ventricular fibrillation –> death
Definition and effects of hypokalaemia
<3.5mmoles/l
Hyperpolarisation –> cardiac arrhythmias –> death
Normal potassium concentration
4mmoles/l
Where does reabsorption occur
Proximal tubule
Loop of Henle
Distal tubule
Collecting duct
Where does secretion occur
Proximal tubule
Distal tubule
Collecting duct
Specialised afferent arteriole smooth muscle cells
Juxtaglomerular cells
Functions of the juxtaglomerular cells
Renal baroreceptors Release renin (in response to low pressure)
Specialised cells of the distal tubule
Macula densa
GFR is estimated using…
Serum creatine
Renal plasma flow (RPF) is…
and is calculated using…
A measure of all the plasma flowing through the kidneys at a given time
PAH (para-amino-hippuric acid) clearance
Equation to calculate plasma clearance of X
Cx = [Ux]V / [Px]
Ux = urine conc. of X V = urine flow rate Px = plasma conc. of x
Vertebral level of the kidneys
T12 - L3
Hilum at L1 (transpyloric plane)
Muscles posterior to the kidney
Quadratus lumborum
Psoas major
Autonomic nerve supply to the kidneys
Sympathetic: From T12 - L1 through the coeliac ganglia
Parasympathetic: Derived from the vagus nerve
Lymphatic drainage of the kidneys
To the para-aortic lymph nodes around the origin of the renal arteries
The ureter lies on which muscle as it descends
Psoas major
Peritonisation of the kidneys and ureters
retroperitoneal
What structures cross the ureter superiorly (male and female)
Female: ovarian artery
Male: ductus (vas) deferens
The three constrictions of the ureters
pelviureteric junction
Pelvic brim
vesicoureteric junction
The median umbilical ligament attaches to which part of the urinary bladder?
and then attaches to which structure?
The apex of the bladder
to
the umbilicus
The median umbilical ligament is a remnant of which umbilical structure?
The allantois (drains the urinary bladder through the umbilical cord)
The bladder walls are made of…
Detrusor (smooth) muscle
The superior surface of the urinary bladder is lined by…
Parietal peritoneum
What kind of epithelium lines the urinary bladder and ureter?
Transitional epithelium
allows the bladder to expand as it fills
what divides part of the allantois and cloaca from the gut tube? and what does this divided section become?
Divided by the urorectal septum,
they become the urogenital sinus which forms the urinary bladder and urethra
Early in the 4th week of development, the intermediate plate mesoderm in the neck region becomes the…
Pronephros (rudimentary kidney)
Late in the 4th week, the intermediate plate mesoderm in the thorax forms the…
mesonephros
What is the final fate of the mesonephros?
Becomes the gonad
The mesonephros is drained into the cloaca by the…
Mesonephric duct
The mesonephric duct develops form what?
and what does it eventually form?
Pronephric duct
- -> mesonephric duct
- -> Rete testes
The tubules, collecting ducts, calyces, renal pelvis and ureters are formed from the…
Ureteric bud
(grows off the mesonephric duct)
Branches to form all these structures
The metanephros (definitive kidney is formed from the…
Ureteric bud
Metanephric mesoderm
The nephrons are formed from the…
Metanephric mesoderm (develops from the intermediate plate mesoderm in the lumbar region)
Normal arterial pH =
7.4
Normal Pco2
40mmHg
Normal [HCO3-]
34mmoles
To maintain pH, [HCO3-] : [H2CO3] ration must be…
20:1
actions of interneurons activated by the micturition reflex
- *Excitation pf parasympathetic outflow
- inhibition of sympathetic outflow
- *inhibition of somatic motoneurons to external urethral sphincter
- sensation of fullness ascends to bladder
*=influenced by higher centres
parasympathetic control of bladder
nerves + actions
S2 - 4 (pelvic nerves)
contraction of detrusor muscle
Sympathetic control of bladder
nerve + actions
Hypogastric nerves
inhibits bladder contraction
Substances reabsorbed by carrier mediated transport
Phosphate + sulphate (conc. regulated by Tm)
Amino acids + glucose (Tm way above health levels)
Tm
Maximum transport capacity of a carrier protein
sets the maximum amount of a substance that can be reabsorbed into the blood
Reabsorption of sodium is by…
Na/KATPase
pumps Na into ECF, creating a gradient into the tubule cell that Na follows (bringing glucose with it through SGLTs)
reabsorption of Cl- is by…
passive diffusion following the electrical gradient created by the active transport of Na
reabsorption of H2O is by…
passive diffusion following Na (active transport) and Cl
Reabsorption of K, Ca and urea is by…
passive diffusion, following water
the reabsorption of water leaves the contents of the tubule very concentrated
Substances that are secreted
Protein bound substances (too large for filtration) Harmful substances) K+ (stimulated by aldosterone) Na+ H+
renal threshold
plasma concentration at which carrier saturation occurs
juxtaglomerular cells produce renin in response to…
sympathetic discharge (fired due to low pressure at carotid baroreceptor)
low afferent arteriole pressure
low NaCl at macula densa
Juxtaglomerular production of renin is inhibited by…
ADH
ANP
ANP production is stimulated by
increased atrial stretch
Angiotensinogen is produced by…
the liver
Action of renin
catalyses conversion of angiotensinogen to angiotensin I
Action of ACE
catalyses conversion of angiotensin I to angiotensin II
Actions of angiotensin II
increases CV response
increases vasoconstriction*
stimulates aldosterone release
stimulates thirst and ADH release (in severe hypovolaemia) from hypothalamus
*efferent arteriole constriction –> decreased peritubular hydrostatic pressure –> increased H20 and NaCl reabsorption in proximal tubule
Actions of aldosterone in nephron
increases H2O and NaCl reabsorption in distal tubule
actions of macula densa
detects low NaCl –> stimulates juxtaglomerular cells
detects increased flow –> constricts afferent arteriole –> decreased GFR
Autoregulation
Maintains GFR over changes in BP
(independent of nerves/hormones)
alters afferent arteriole constriction
the descending limb of the loop of henle is…
permeable to H20
impermeable to NaCl
H20 leaves, concentrating the tubule contents, and is then removed by the vasa recta (this maintains the gradient)
the ascending limb of the loop of henle is…
impermeable to H2O
actively transports NaCl out
this “dilutes” the tubule contents
Permeability of the collecting duct is…
under ADH control
recruits AQP2 pores and increases permeability to urea
the mechanism creating a concentration gradient in the interstitium in the medulla (driven by the Na/KATPase)
the counter-current multiplier
hypothalamic osmoreceptors are stimulated by…
high osmolarity (high NaCl concentration)
–> ADH release
ADH is released in response to…
high osmolarity (hypothalamic osmoreceptors)
decreased atrial stretch
low BP detected by carotid + aortic baroreceptors
Actions of ANP
inhibits renin production
inhibits ADH secretion
inhibits aldosterone secretion
decreases CV response