Case 3 Flashcards
What is the peritoneum
A thin, serous membrane that covers all the organs and lines the abdominal cavity
What are the two layers of the peritoneum and where are they
The visceral peritoneum covers the abdominal viscera and organs
The parietal peritoneum lines the abdominal cavity
How would you describe and organ if it is completely surrounded in peritoneum
intraperitoneal
What are retorperitoneal organs
they only have peritoneum on their anterior surface
What organs and viscera are intraperitoneal (6)
Liver Gall Bladder Spleen Stomach Small intestine (most of) Large intestine (some of)
What organs and viscera are retroperitoneal
S uprarenal glands A orta & IVC D uodenum (most of) P ancreas (most of) U reters C olon K idneys O esophagus R ectum
What is the mesentery
It’s an organ that attaches the intestines to the abdominal wall and it allows nerves to communicate between the viscera and the abdominal wall
It is double layered
What is an omentum
The connections between viscera and other viscera
What are ligaments with regards to the peritoneum
These are between viscera and other viscera or viscera and the abdominal wall
Where is the lesser omentum between
The liver and stomach/duodenum
What ligaments are in the lesser omentum
Hepatogastric ligament and heptatoduodenal ligament
What structures are found within the hepatoduodenal ligament
The bile duct, hepatic vein and hepatic artery
Where is the greater omentum between
The stomach down to the transverse colon
How many layers does the greater omentum contain?
4
Where is the phrenicolic ligament between
The colon and diaphragm
Where is the lienorenal ligament between
The spleen and kidney
What are mesentery reflections
Reflections of two layers of visceral peritoneal lying on top of each other and connect to the abdominal wall
What do the lesser and greater sac communicate and pass fluid through
The omental foramen
Where can the omental foramen be found (what ligament is it behind)
The hepatogastric ligament
What three layers can be found within the greater sac
The supracolic, infracolic and pelvic areas
What are recesses in the abdomen
Small places that fluid can congregate
What recesses can be found in the infracolic region of the greater sac and what is their function
The paracolic gutters (either side of the left intestine)
Any fluid that accumulates in the infracolic region can settle in these gutters
What recess can be found in the pelvis in males
The vesicorectal pouch
What recesses can be found in the pelvis in female
Vesicouterine and rectouterine pouches
What is a problem if infectious fluid builds up within one peritoneal reflection
It may spread across the whole peritoneum as the spaces are consistent with one another
What can cause a build up of infectious fluid in peritoneal reflections and cavities?
Bacterial contamination during abdominal surgery
Rupture of the gut as a result fo infection/inflammation
When an ulcer in the stomach or duodenum perforates through the wall of an organ
What is the disadvantage of the paracolic gutters being linked with other recesses
They are able to spread infectious fluid or cancerous cells throughout the peritoneal organs
What is the role of the transversus abdominis muscle
It contains transverse fibres that support the viscera and rotates and flexes the trunk
What does the quadratus lumborum muscle do
Stavilises the 12th rib
What do the muscles psoas major/minor/iliacus do
They work with the hip flexor
Where is the lumbar plexus
This is from the anterior rami of spinal nerves T12-L4
What is the crossover of lumbar and sacral nerves known as and what is its function
the lumbosacral trunk
it allows the passage of information between the two sections
What is the word for something related to the ureter
ureteric
What is the word for something related to the urethra
urethral
What is the word for something related to the uterus
uterine
Are the kidneys intra or retro peritoneal
retroperitoneal
What level of vertebrae are the kidneys found at
T12-L3
Which kidney is lower than the other
The right is lower than the left
What is the renal hilum
Found on the medial surface fo the kidney and it is where the main blood vessels and transport systems in and out of the kidney are found
What structures are anterior to the right kidney
The liver and parts of the small intestine
What retroperitoneal structures are attached to the right kidney
The right colic flexure (large intestine)
Descending part of the duodenum
the suprarenal gland
What intraperitoneal structures lie on the left kidney
The spleen
Stomach
Small intestine
What retroperitoneal structures lie on the left kidney
Pancreas
Left colic flexure (large intestine)
Descending colon
what is the renal capsule
A tough fibrous layer that protects the kidneys
What is the perirenal fat
Its a fatty capsule that surrounds the kidney to keep it protected, a layer within the renal capsule
What is between the two fat layers within the kidney
renal fascia
What is the layer of fat closest to the kidney called
pararenal fat
What five vessels are in the renal hilum
From anterior to posterior Renal vein Renal artery Ureter Renal pelvis Lymphatics and sympathetics
Where does urine drain into after exiting a nephron
minor calyces
What do minor calyces join together and where do these subsequently go
These join to form a major calyx which join to the renal pelvis and then ureter
Where does the ureter join the bladder
The ureteropelvic junction
How does the urine move down the ureters
Peristalsis
Where are the main constrictions in the ureters (3)
renal pelvis, pelvic brim and ureteric orifice
In what cavity is the bladder found
The pelvic cavity
What are the muscles in the bladder walls called
The detrusor muscle
What is the function of the internal urethral sphincter in males
To prevent ejaculatory reflux of semen into the bladder
Why are females more at risk of UTIs
They have a much shorter urethra
What are the four parts of the male urethra from bladder to penis end
Preprostatic
Prostatic
Membranous
Spongy
Where does urethral obstruction result in a calculus forming in males
The external meatus
What do you locate first on females in order to catheterise them
the external urethral meatus
Why is catheterisation more difficult with males
The penis has two angles and it is longer
If catheterisation doesn’t work with regards to through the urethra what can be done
You can catheterise a patient through the anterior abdominal wall, just above the pubic symphis
What are the first two stages of kidney development, what is the functionality of each stage and when do they develop
Pronephros- no functionality
Mesonephros- limited functionality
3-4 weeks
What is the final stage of kidney development and when does it become functional
Metanephros- develops at 5 weeks but becomes functional at 12
When does urine production first occur and how does it work
It begins at the 12th week as the foetus takes on amniotic fluid, filters it through the kidney and then excretes it back into the amniotic cavity
What are the two definitive structures the kidney is formed from
The metanephric mesoderm and ureteric bud
When does the ureteric bud begin to branch and what does it branch into
6 weeks- it branches within the metanephric mass to form the major calyx, minor calyx and renal pelvis
What is the role of the mesonephric duct in males
It forms the male genital tract- it degenerates in females
By what stage do the kidneys need a blood supply and what is this supplied through
6 weeks- the transient renal vessels that are connected to the abdominal aorta
When do the kidneys move cranially, whilst the ureters are still attached
7 weeks
What replaces the transient renal vessels after complete kidney translocation
The renal vessels
What is renal agenesis and hypoplasia
When the kidneys fail to develop and grow
this can be unilateral or bilateral (fatal)
What is supernumerary renal vessels and what complications may arise
This is when the transient renal vessels don’t regress and stay attached
These may trap the ureter with the vessels which leads to hydronephrosis (a build-up of urine)
What is renal ectopia
When the kidneys fail to migrate so a kidney may remain in the pelvis or migrate to the wrong side
There also may be abnormal rotation where the hilum faces ventrally
What is a horseshoe kidney
This is when the caudal ends of the kidney migrate close together to eventually fuse
What is the order of structures the fluid flows through in a single nephron
Bowmans capsule> proximal convoluted tubule> descending limb> loop of Henle> ascending limb>distal convoluted tubule> collecting duct> minor calyx
How does the renal artery branch into a nephron
Reanl artery> interlobar arteries> interlobular arteries> afferent arteriole>glomerulus
How do the blood vessels link after the glomerulus
Glomerulus> efferent arteriole> peritubular plexus> arcuate veins
What are vasa recta
Small arteries associated with the Loop of Henle
What percentage of nephrons cross the cortex and medulla and what are these nephrons called
20%, most are cortical nephrons- juxtamedullary nephrons
What is the name of the tissue between glomerular capillaries and how is it adapted to its function
It’s called the mesangium and contains fenestrated endothelium that contains small spaces within it
What are podocytes
Cells that wrap around the mesangium and capillaries through an interlocking process
What layer is between the podocytes and mesangium in glomerular capillaries
A three layered basement membrane
What cells in the kidney secrete renin
Juxtaglomerular cells
What cells line the inside of the ureters and bladder and how is it adapted to it’s function
Urothelium- it is impenetrable to urine, even when it is stretched as it is made of stratified endothelium and contains umbrella cells on the surface
How is the body fluid split between intra and extracellular fluid (plasma and interstitial)
Intracellular fluid is about 25L~40% of body weight
Interstitial fluid is about 80% of ECF- 12L
What is sensible fluid loss and what are examples of it
Sensible is easy to meausure fluid loss such as
sweat (100ml/day)
Faeces (100ml/day)
Urine (1.5L/day)
What is insensible fluid loss and what are some examples
Hard to measure fluid loss
Evaporation from skin (300-400ml/day)
Humidification during respiration (300-400ml/day)
If a cells volume increases and starts to swell what regulatory response will it take to decrease volume
It will lose solutes such as taurine
If theres a decrease in water content of cells what does the cell do to counteract this
It tries to gain osmotically active particles such as KCl
How do the kidneys regulate plasma volume
e.g. if there is a decrease in blood plasma volume how would the kidneys react
The kidneys use stretch receptors in the body to sense this and then will release renin
This initiates the RAA system that acts to maintain Na+ balance within the body
How is plasma osmolality maintained by the kidneys (e.g. a decrease)
If there is a decrease in plasma osmolality then this is detected by osmoreceptors in the hypothalamus
This leads to the release of ADH down to the kidney byt he posterior pituitary gland and more water is reabsorbed
there is also increased vasoconstriction
What is isotonic dehydration
this is when there is an equal amount of water and solutes lost so the extracellular volume decreases but the osmolality stays the same
What causes isotonic dehydration
vomiting, diarrhoea, haemmorhage and/or burns
It may also be caused by an internal effusion
How do you treat isotonic dehydration
By replacements fluids such as an isotonic NCl solution
What is hypo-osmotic dehydration
this is when the fluid that is lost contains more NCl than water and therefore the fluid volume and osmolality decreases
because there is balancing out between intr and extracellular environments this can result in an increase in cell volume as fluid moves down its concentration gradient, into cells
What causes hypo-osmotic dehydration
Addisons disease or rare cases of vomiting
What is hyper-osmotic dehydration
This is when more water is lost than salt levels
What causes hyper-osmotic dehydration
Osmotic diuresis, increased ADH secretion, high fever, heat stroke and diarrhoea
How is hyperosmotic dehydration treated
Slow water replacement
How is the release of renin stimulated and when
It is stimulated by the sympathetic nervous system in response to a fall in plasma volume or increase in Na+ concentrations
Where is erythropoietin produced
In the kidney by the peritubular interstitium and cells of the inner cortex
What does erythropoietin do
It acts on erythrocyte cells in the bone marrow and stimulates erythrocyte production
What stimulates the release of erythropoietin
hypoxia, anaemia or renal ischaemia
Where is vitamin D synthesised from in the external environment and where is it hydrolysed in our body
It’s synthesised from the sun and is hydrolysed in our liver and then kidney
What is the role of vitamin D in the body
It’s for the mineralisation of bones and it maintains calcium and phosphate homeostasis by promoting absorption form the gut
What is anomalous about glomerular capillaries when compared with other capillaries (3)
They have a relatively constant pressure throughout them
a lot higher pressure than systemic capillaries
Also arranged in a two capillary network with peritubular capillaries
What does vasoconstriction of the afferent arteriole mean for glomerular blood flow and pressure
Reduced blood flow and pressure
What does vasoconstriction of the efferent arteriole mean for glomerular blood flow and pressure
Increased blood flow and pressure
What causes vasoconstriction or dilation of glomerular arterioles
A sympathetic response will initiate the release of renin
Hormones and autacoids such as adrenaline
Autoregulation
What are the macula densa cells and where are they found (3)
These are cells found in direct contact with the afferent and efferent arteriole
They, upon sensing a change in Na+ and Cl- concentration, release paracrines that decrease afferent arteriole diameter
How can you measure renal blood flow
Using a renal arteriography or angiography- uses injection dyes
A flow probe however can be invasive
Ultrasound- only produce 2D image so overlapping organs difficult to distinguish
What is the glycolax and why is it charged
The glycolax is the luminal surface of endothelial cells in the glomerular filtration barrier and is negatively charged in order to repel negatively charged proteins
What are fenestrae
The openings between endothelial cells that allow water and small molecules to pass through
Where is the glomerular basement membrane found and what is its function
It is in the glomerular filtration barrier and acts as a negatively charged barrier to filtration
What is between podocyte cells
filtration slits
What is clearance with regard to glomerular filtration
This is how quickly something in the blood plasma is filtered into the kidney and removed through urine
Why is it hard to estimate GFR
Very few substances meet all the criteria that are required in order to be useful at estimating GFR
What is the gold standard substance for GFR measurements but what is its limitation
Inulin is a plant polysaccharide however it needs to be injected
What natural body waste product is commonly used to estimate GFR and why is it not perfect
Creatinine- there is some tubular secretion of it so it tends to overestimate GFR
How can we calculate the GFR hen given the urinary and plasma concentration of our substance and the urine volume
GFR= (U x V)/P
What is the most important trait of a substance in order to measure renal blood flow
The substance must be completely cleared of the kidney on first pass
What substance is a good measure of renal blood flow but by how much does it underestimate it?
Para-aminohippuric acid (PAH) however it underestimates it by about 10%
What do you need to take into account when measuring renal blood flow from renal plasma flow and how is this done
Haematocrit- the proportion of blood that is composed of RBCs
RBF= RPF/(1-HTC)
What are the differences between Starling’s forces across a glomerular capillary when compared with an extra-renal capillary (6)
The hydrostatic pressure is constant across a glomerular capillary
Glomerular capillaries are less permeable to proteins so the oncotic pressure in the Bowman’s capsule is lower than the interstitium
Plasma oncotic pressure rises along a glomerular capillary whilst it is constant normally
Hydrostatic pressure in the Bowman’s capsule is greater than the interstitium of other tissues
ultrafiltration pressure is greater in glomerular capillaries
There is a net movement out of the glomerular capillaries as the gradient is always down with regards to oncotic and hydrostatic pressure
What is ureas role in the body and what percentage is reabsorbed by the kidney and why
Urea has an important role in nitrogen excretion with 50% being reabsorbed in order to maintain a good concentration gradient to reabsorb water
What are the two size limits for GFR from uninhibited filtration to barely any
7kDa and under have uninhibited filtration whilst molecules over 70kDa barely filter
what percentage of glucose is reabsorbed by the early proximal convoluted tubule and by what transporters
98% by GLUT2 and SGLT2 transporters
Where is the final 2% of glucose reabsorbed
The late proximal convoluted tubule
How does the kidney assist in a compensatory mechanism to metabolic acidosis
It produces ammonium that is excreted in the urine in order to facilitate the excretion of acid and bicarbonate to counter the acidosis effect
hat percentage of glucose production does renal gluconeogensis account for
20-25%
What is Tm or transport maximum- in the kidney
This is the point at which an increased concentration of a substance does not result in increased movement of that substance- this is the point no more is absorbed or secreted in the kidney due to transport channels being saturated
Why does diabetes mellitus produce glucose in the urine
The Tm of glucose is reached as there is high plasma glucose concentration so no more is absorbed and it is excreted in the urine
What is the role of secretion in the kidney (3)
It acts to eliminate exogenous solutes such as drugs and toxins, metabolic byproducts and delivers autacoids and drugs to distal nephron
What is plasma threshold with regards to renal function
Plasma threshold is the concentration of a substance in the plasma required in order for that substance to not be reabsorbed anymore
hat can lead to the overriding of renal blood flow autoreglation and why
Shock, trauma, haemorrhage and extreme exercise
This results in greater efferent arteriole constriction in order to preserve BP
What is nephritic syndrome
This is an inflammatory response in the kidney that increases the permeability of the filtration membrane which can lead to proteinuria, haematuria and hypertension
What is nephrotic syndrome and how is it different to nephritic syndrome
This also increases permeability of the filtration membrane however it doesnt lead to haematuria- nor does it affect renal function
What is a positive Na+ balance and when would this happen
when you are taking on more Na+ than is being excreted- this occurs when there is a sudden dietary or IV influx of Na+ and resultantly more Na+ will be excreted as the ECF volume signals this
What does aldosterone do in response to a decrease in ECF
It acts in the kidney to increase the activity of ENaC and the number of Na/K pumps in principal cells (the cells in the collecting duct and distal tubule epithelium)
This increases Na+ and thus water reabsorption but results in increased K+ and H+ secretion
How does an increase in AGII result in a decrease in BP
It acts as a vasoconstrictor but also stimulates ADH secretion to increase DCT permeability
Where is aldosterone produced in the adrenal gland and what receptors does it act on
The zona glomerulosa- mineralocorticoid receptors
How does AGII effect the afferent and efferent arterioles (3)
It constricts them both however the efferent slightly more in order to decrease Starling’s forces by decreasing HP
It increases oncotic pressure so more Na+ is reabsorbed
What happens if you decrease vasa recta blood flow
This decreases solute washout and less urea is moved away from the Loop of Henle
Therefore there is a higher concentration gradient for NaCl reabsorption
What are the two different mechanisms of GFR control mechanisms and when are they utilised
Spontaneous GFR control prevents effects from postural changes in blood pressure
Compensatory GFR changes modulate GFRs to combat excess in dietary sodium intake
How does atrial natriuretic peptide affect the renal system
It suppresses the sympathetic nervous system
This dilates the afferent arteriole
This increases GFR
Inhibits renin
Increases vasa recta blood flow to decrease Na reabsorption
What is the oncotic pressure like in the efferent arteriole and peritubular capillaries in comparison to the filtrate and intersitium
Much Higher
What cells are on the inner lumen of the PCT
Brush boarder cells
How are brush boarder cells adapted for their function
They have microvilli on their apical surface
What channels is water reabsorbed through
Aquaporin AQP1 channels
What is the process of a substance moving up it’s concentration through the assistance of another substance acting as a power generator by moving down its concentration gradient
Secondary active transport
Where is secondary active transport seen in the PCT
Through the movement of Na and many other substances acting as the secondary molecule
How is a low Na concentration maintained in the brush boarder cells
There are many Na/K pumps that pump Na out of these cells , into the interstitium and thus capillaries
What is paracellular transport
The movement of molecules between the leaky junctions of cells
What results in paracellular backflow of Na into the early PCT
There is a net negative charge as Na moves out due to the high concentration of Cl- ions in the PCT- not many are absorbed at these times- and thus Na+ flows back into the lumen
Why is there no paracellular backflow in the late PCT
Chloride ions are also absorbed alongside Na+ ions at this stage so there is no charge imbalance pulling them back
What do free H+ ions form with after being exchanged with Na+ in the brush boarder cells
They form Carbonic acid, H2CO3 with HCO3-
What reaction does carbonic acid catalyse and where
It catalyses the breakdown of H2CO3 in the apical border to H2O and CO2 so these products can move freely across the apical surface into the brush boarder cells
What carbonic anhydrase substrate reforms H2O and CO2 into H2CO3 in the brush boarder cells
Carbonic anhydrase type 2
Through what route is the HCO3- absorbed into the peritubular capillaries
Through the Na=/HCO3- cotransporter
What is osmolarity
The concentration of solute particles
What is the coritco-papillary gradient
The increase in osmolarity as you go from the cortex to the papilla- down the Loop of Henle
What is water reabsorption dependent on in the DCT
ADH levels
What is the descending limbs permeability to water and ions respectively
It contains AQP1 channels and has a lo permeability to ions
What is the ascending limbs permeability to water and ions respectively
It is impermeable to water and has a high permeability to ions with an Na/K ATPase pump
At which point of the descending limb is the water movement out by osmosis at its highest and why
At the base of it as the interstitium gets increasingly salty and osmolar so more water moves out due to the increase in concentration gradient
How does Na+ move out of the thin ascending limb
Through passive diffusion
How does Na+ move out in the thick ascending limb and why does water not follow it
It is actively pumped out by the many Na/K ATPase pumps
Water doesn’t follow it as there are no aquaporins to channel through
What is the trend of osmolarity of the filtrate as you go up the ascending limb
It becomes increasingly dilute as ions are moving out and water cannot follow
How do chloride ions move out of the thin ascending limb
Passively through chloride channels
How do we transport K and Cl back into the thick ascending limb lumen in order to create concentrated urine
Through Na/K/2Cl transporter as Na+ moves down its concentration gradient into the lumen and transports the other two by secondary active transport
This concentration gradient is maintained by the Na/K ATPase pumps pumping Na out of the lumen
Is the vasa recta permeable to solutes and water?
Yes
How does the vasa recta maintain the hyperosmotic interstitial gradient set up
As it bypasses the ascending limb it releases water down its concentration gradient and into the interstitium whilst salt is reabsorbed down its concentration gradient into the vasa recta
When it bypasses the descending limb it reabsorbs water but gives out salt to maintain the gradient and continue with the Loop of Henle
What is the permeability of the DCT and collecting duct changed by
The activation of ADH
As the filtrate moves down the descending Loop of Henle, what direction does the net movement of urea go in
More goes into the Loop as you go down as there is a higher concentration of urea in the interstitium, the further you go down towards to papillary
Is the ascending Loop permeable to urea and how does this help
No- this means there is a high concentration of urea in the DCT to increase the osmolarity of the filtrate and this results in more water moving out
Ho does ADH assist the movement of urea
It implants a urea transporter in the late collecting duct so urea moves out into the interstitium so it can be recycled back and maintain a cortico-papillary gradient
How does Na move out of the early DCT
There are Na/Cl cotransporters that allow Na to move down its concentration gradient and transport Cl- via secondary active transport
How is Na+ reabsorbed in the late DCT and collecting duct
Through ENaC channels
What are osmoreceptors and what do they do
These are specialised cells found in the anterior hypothalamus that sense the osmolarity of extracellular fluid through AQP4 channels in their apical surface
How do the osmoreceptors respond to an increased osmolarity in the bloodstream
If there is an increased osmolarity water will move out of the osmoreceptors, through the APQ4 channels
this will cause them to shrink and in turn release action potentials that trigger the ‘thirst response’
What does the thirst response do
It activates the posterior pituitary gland to release ADH and retain water from the kidney
How do the juxtaglomerular cells initiate a thirst response
They detect a low blood volume and secrete renin to initiate the RAAS
AGII converges on the hypothalamus to trigger a thirst response
What channels does ADH indirectly promote the binding of after a signaling cascade
AQP2 channels after ADH binds to V2 receptors on the basolateral membrane of principal cells
What is hyponatremia and at what value is it considered
This is a deficiency of sodium and is at <135mM
What is hypernatremia and at what value is it considered
An excess of sodium >145mM
What are the major causes of hyponatremia (3)
A net loss of Na (hypoaldostrenism, thiazides, bodily functions)
Disturbances of water input (voluntary or mental illness water intoxication)
Disturbances of water output (increased ADH secretion)
What are the causes of hypernatremia
A net gain of Na (dietary, Iv, hyperaldostrenism)
Disturbances of H2O input (unconscious patient, lack of water access, voimiting)
Disturbances of H2O output (increased insensible losses, vomiting, diarrhoea)
Diabetes insipidus results in non functional ADH that means excessive water loss
What is neurogenic diabetes insipidus
The failure of ADH secretion as a result of a lesion in the hypothalamus or posterior pituitary gland and is treated with synthetic ADH
What is nephrogenic diabetes insipidus
the failure of the principal cells to respond to ADH caused by a V2 receptor mutation
What do thiazides inhibit
The Na/Cl cotransporter in the DCT
How do Loop diuretics work
They work on th eLoop of Henle by inhibiting the Na/K/2Cl cotransporter in the thick ascending loop
How do aldosterone antagonists work
They don’t allow aldosterone to bind with its mineralocorticoid receptors so it cannot translocate to the nucleus and transcribe the ENaC channels
It also inhibits the generation of K channels so less K is excreted out and the Na/K channels work less effectively
What is specific about potassium sparing diuretics
They antagonise the ENaC channels in the principal cells of the late collecting duct as well
This spares K from being transported into the urine because the function of Na/K pumps is greatly reduced
How does inhibiting the RAAS help to retain sodium
Decrease in ADH to release dilute urine
Reduced Na reabsorption in the PCT and Loop of Henle (increased vasa recta washout so decreased gradient)
There’s decreased sympathetic activity so more arteriole dilation and more Na in filtrate
Decreased binding of Na/H exchanger in PCT
What is the normal body pH
7.4
Why is a constant pH important
To maintain enzymes, receptors and transporters
What is the main reaction in the bicarbonate buffer system to neutralise protons
HCO3- + H+ —> H2CO3
What does H2CO3 dissociate into and what catalyses this reaction
It dissociates into H2O and CO2 by the enzyme carbonic anhydrase
How do protons react with phosphate
2H+ + PO4(2-) –> H2PO4
What do protons and proteins form as part of our internal buffer system
Protonated proteins
How does haemoglobin combine with protons as part of our internal buffer system
It forms haemoglobinic acid
What is the biggest contributor to a potentially acidic pH in our blood and how is this combated
The partial pressure of CO2
It is combated by the bicarbonate system
How can we calculate the pH of the blood using CO2 partial pressure and HCO3- concentration
Pk’ (6.1) +log( {HCO3-}/{dissolved CO2}
Why re endogenous acids dangerous
They are not contributed by CO2 and thus cannot be lost through the lungs
Ho do we normally lose alkali substances
Through stools from the GI tract
What is the rapid response due to a decrease in pH and what takes longer out of the respiratory and renal methods
The respiratory is a rapid response whilst the renal response is a lot slower
What is the main outcome of the renal response to acidosis with regards to the movements of molecules
The kidney removes protons and increases the reabsorption of HCO3-
What main pump releases protons into the tubular lumen
The Na/H pump
What stimulates an increase in HCO3- reabsorption and by what channels are they reabsorbed
A decrease in cell Ph
HCO3- reabsorbed by Na/3HCO3 or Cl/HCO3 pump
Where do the kidneys generate bicarbonate ions and how does this occur (3)
The kidneys generate bicarbonate ions in the PCT
This can occur through gluconeogensis, triggered by the excretion of ammonium salts as bicarbonates are a biproduct of this process
it may also occur through activation of the phosphate buffer system as bicarbonates are generated as acid is removed
Where are alpha intercalated cells found and what is their function
These are found in the collecting duct and they generate a small amount of HCO3- in response to a low pH
Where are alpha intercalated cells found and what is their function
These are in the collecting duct and they respond to a high pH by secreting bicarbonate into the lumen to extrude H+ into the ECF
What is respiratory acidosis and what causes it
This is when the retention of CO2 occurs and is usually down to respiratory problems such as hyperventilating or lung disease
It results in a decrease of Ph and increase of p.p of CO2
How does the body compensate respiratory acidosis
it signals the kidney to retain HCO3- and shift the equilibrium of the bicarbonate dissociation equation back to the middle, increasing pH
What is respiratory alkalosis and what causes it
This is an excessive loss of CO2 generally caused by hyperventilation
This decreases the p.p. of CO2 and the carbonic acid equation shifts to the left to accommodate this, increasing pH
What is the compensatory response to respiratory alkalosis
there is a net loss of bicarbonate by the kidney in order to return to a normal pH and shift equilibrium of the carbonic acid equation back to the right
What is the carbonic acid equilibrium
CO2 +H2O H2CO3 H+ + HCO3-
What is metabolic acidosis and how is it caused
It increases the H+ concentration in the body and is caused by diabetes, heart failure, renal failure and diarrhoea
It shifts the equilibrium of the carbonic acid equation to the left
What is the compensatory response to metabolic acidosis
The lungs blow off more CO2 to decrease p.p. of CO2 and shift the carbonic acid equilibrium to the left to decrease {H+}
What is metabolic alkalosis and what causes it
It’s a net loss of H+ caused by things such as vomiting
This raises pH as the equilibrium is shifted to the right
What compensatory response occurs in reaction to metabolic alkalosis
The lungs blow off less CO2 by hypoventilation
What is the role of potassium in the body (6)
Regulating cell volume
Regulating intracellular pH
Synthesising DNA and proteins for growth
Cellular enzyme function
Maintaining a resting membrane potential
Cardiac and neuromuscular activities and BP
What body function problems can arise during hypokalaemia (<4mM)
Cells become more negative and less sensitive to depolarisation
muscle weakness can lead to paralysis
Abnormal neural conduction leads to confusion and eventually comas
Increased cardiac excitability
What problems can arise due to hyperkalaemia (>5mM)
Cardiac arrhythmia and risk of cardiac arrest
Abnormal neural conduct
What are major sources of K+ in the diet
Meat, fruit and fruit juice
What occurs to potassium as soon as it is ingested
It is distributed around cells in the body and then sloly let out into the ECF until the next meal
What is the uptake of potassium stimulated by
Insulin and adrenaline and aldosterone
How does a build up of plasma protons result in hyperkalaemia
When there is an excess of protons in the plasma they are absorbed into cell through a K/H pump so a build up of K+ can occur in the bloodstream as these are exchanged
How is K+ reabsorption controlled by the kidney
If a person has a high K+ diet less K+ is reabsorbed in the DCT and collecting duct and some may even be secreted into the DCT and collecting duct
How is K+ reabsorbed into the late proximal tubule
The K+ is reabsorbed paracellularly as the lumen is positive so it is driven by a potential difference
How is K+ reabsorbed in the thick ascending Loop of Henle
The Na/K/2CL cotransporter
How do the principal cells drive increased K+ secretion due to an excess in the blood plasma
They contain many Na/K ATPase pumps and as a result reabsorb more Na in exchange for K
This is stimulated aldosterone that is released independently of the RAAS
What bodily state increases K+ secretion- alkalosis or acidosis and why
Alkalosis as it increases Na/K pump activity and increases the number of K+ channels
What are the main symptoms of UTIs (7)
Change in urinary frequency Dysuria (painful urination) Passing of only small amounts of urine Haematuria Pyuria (foul smelling or cloudy urine) Urgency Urinary incontinence
What symptoms of UTIs are specific to upper UTIs (kidneys) (3)
Upper back and flank pain
Shaking and chills
High fever
What are severe symptoms of UTIs
Rigors (feeling weak dizzy and uneasy)
Pyrexia (high temp.)
Nausea and vomiting
Acute confusional state
What is bacteriuria
Bacteria being present in the urine
What is a relapse with regards to bacteriuria
This is when a patient becomes reinfected with the same bacterium they were infected with before
What is urethritis
Infection of the urethra
What is cystitis
Infection of the bladder
What is pyelonephritis
Infection of the kidney
What is the trend of UTI frequency with increasing age
As age increases so does the frequency of UTIs
What are the main risk factors to contracting a UTI
Female gender Increasing age Recent antibiotic use Recent sexual activity New sexual partner Diabetes Presence of catheter Pregnancy
What are uncomplicated UTIs
These are infections in a structurally and neurologically normal urinary tract and persistent infection can lead to kidney problems
What are complicated UTIs
infections of the urinary tract with abnormalities such as Diabetes Kidney stones Blockages Developmental abnormalities
What are the three conditions for a bacteria to cause a UTI
Get into the urinary tract
Adhere to the epithelial surface
Multiply and elicit an inflammatory response
What are the two routes for a bacteria to enter the urinary tract
The ascending route as the bacteria ascend the UT by bowel flora
The haematogenous route is by blood borne bacteria and is mainly due to infection of the renal parenchyma
What is the main causative organism in UTIs
UPEC- uro-pathogen E.coli
Why can catheters lead to increased risk of UTIs
in catheters the urine is not washed away properly by the flow of excreting urine and this gives a chance for bacteria to colonise and develop
What lab tests can be run to clinically diagnose UTIs
Urine microscopy can show leukocytes which indicate the presence of infection
Dipstick analysis of urine
Urine culture
What drugs can be used to treat a lower UTI
Trimethoprim or Nitrofurantoin
with which drugs can you treat pyelonephritis
Cefalexin
What is microscopic haematuria
When blood is present in the urine but not enough to be visible to the naked eye
What is proteinuria
When there is protein in the urine
What is glycosuria
When there is glucose in the urine
What enzyme tests for the presence of leukocytes
leukocyte esterase
What does increased leukocytes in the urine suggest
infection in the kidneys or urinary tracts
What does a positive nitrites result in the urine suggest
it may indicate a UTI as gram negative bacteria converts to nitrites in the bladder
What does increased urobilinogen suggest
Liver cell damage or increased bilirubin excretion to intestines
What does protein in the urine suggest
Kidney disease
What does acidic urine suggest
kidney disease or diet
What does blood in the urine suggest
Infection or disease in the kidney or bladder
What does increased ketones suggest
Diabetes, low carb diet or starvation
What does increased bilirubin concentration suggest
liver damage
What does glucose in the urine suggest
Diabetes mellitus
What factors increase the likelihood of an individual having a kidney stone
Structural abnormalities affecting urine flow (e.g. horseshoe kidney) Loop Diuretics Relative dehydration Diet high in purines Hypercalcaemia Metabolic disorders increasing oxalate levels consequence of necrosis following AKI History of renal calculi or recurrence
How can hyperparathyroidism lead to hypercalcaemia
hyperparathyroidism results in an increase in parathyroid gland and this increases bone reabsorption which releases calcium
What does cystinuria cause an excess of to be released into the urine
Amino acids
What is the most common type of kidney stone
Calcium oxalate stones- approximately 60% of stones
What are the main symptoms of kidney stones
loin to groin pain sweating nausea vomiting dysuria haematuria
Where will stones high up in the kidney cause pain
In the flank
What is the character of the loin to groin pain caused by lower down kidney stones
It has spasms of sharp pain due to dilation of the ureter and small periods of relief but a persistent dull ache
What investigations should take place upon the potential for a kidney stone
An x-ray as 90% of kidney stones are opaque however the gold standard is CT-KUB (kidney ureter bladder)
Ultrasound is used when radiation should be avoided
When should you consider hospital admissions upon the presence of kidney stones
Fever Solitary kidney function Inadequate pain or persistent pain Inability to take adequate fluids Anuria Pregnancy
What drugs can be used to reduce ureteric spasm and help stones pass
Alpha blockers and calcium channel blockers
What technique can be used to break down stones into smaller crystals so they can pass
Extracorporeal shockwave therapy
What is ureteroscopy
This is the insertion of a ureterscope into the ureter via the external meatus to the stone under general anesthesia
What is percutaneous nephrolithotomy
This is the use of keyhole access through the skin in the flank directly into the kidney under anaesthesia
What is a case control study
This is when exposure and outcome have already occurred
It proceeds backwards form effect to cause
It uses a control group to compare
What is a cohort study
two or more groups are selected on the basis of their differences of exposure to a particular agent
these groups are then followed
this can be used to study incidence, causation and prognosis
What is a cross-sectional study
Looks at data on a population at a specific point in time to provide a snapshot
it’s observational so you can’t draw cause and effect conclusions from it
these are inexpensive and fast studies that provide a basis for further research
What are randomised control trials
Aim to compare doses or treatments on two or more groups
The participants are randomly assigned to groups and then these groups are followed up and analysed over time
What are systematic reviews
Overviews of primary literature that focus on a research question
What is meta analysis
This is presenting a balanced summary of all existing research
this is to be done on a quantitative basis
What is fabrication
The making up or manipulation of data
What is improper analysis
using the wrong statistical test
What is selective reporting
This is only including the data that supports the hypothesis the author is after
What is epidemiology
The study of how often diseases occur in different groups of people and why
What is absolute risk
The risk of a patient developing a condition over a given period of time
What is relative risk
This is the comparison of two groups of people and how likely they are to develop a disease
What is the odds ratio
The association between an exposure and an outcome
What is attributable risk
A measure of the proportion of the disease occurrence that can be attributed to a certain exposure
