ANP 1107A Renal Lecture 4 Flashcards
what is urinary retention?
inability to expel urine
- after general anaesthesia, can also result from prostate hypertrophy
what is renal failure?
this happens when there are not enough functioning nephrons
- filtrate formation has been reduced or stopped
what is stress incontinence?
anything that increases intra abdominal pressure, it’s a sharp push on the bladder and pushes a bit of urine out
- an example is cough or sneeze
The regulation of micturition
3 things have to happen
- detruser muscle must contract
- Internal ureathral sphincter must open
- External urethral sphincter must open
what is incontinence?
inability to control urine voluntarily
- due to a weakened pelvic floor muscles, pressure of pregnancy, nervous system problems
what are potential causes to renal failure?
repeated damaging kidney infections
physical injuries to kidneys
prolonged pressure on skeletal muscles
inadequate blood delivery to tubules
what is diarrhea?
nitrogenous wastes accumulate & blood becomes acidic
what is hemodialysis?
A technique in which an artificial kidney machine removes waste products from the blood
- can be done in a clinic or at home – several times a week for 3-5 hr/session
what is peritoneal dialysis?
works by using the blood vessels of the peritoneal membrane
where can peritoneal dialysis be done at?
can be done at home or work
- does not require weekly hospital visits
what happens in peritoneal dialysis?
dialysate is infused into the peritoneal cavity through a catheter
dialysatec omposed mostly of salts and sugar
encourages filtration through the peritoneum
what is removed?
extra fluid and wastes is drawn from the blood into dialysate which is then removed
what are the two types of peritoneal dialysis?
continuous ambulatory peritoneal dialysis (CAPD)
continuous cycling peritoneal dialysis (CCPD)
what are the two types of peritoneal dialysis?
continuous ambulatory peritoneal dialysis (CAPD)
continuous cycling peritoneal dialysis (CCPD)
what happens in continuous ambulatory peritoneal dialysis (CAPD)
happens usually 4-5 times/day
patient puts dialysate (about two litres) into peritoneal cavity through catheter
dialysate stays there for 4-5 hours before it is drained back into the back and thrown away.
there is a new bag of dialysate for each exchange
what happens in continuous cycling peritoneal dialysis (CCPD)
usually is done at home using a special machine called a cycler
number of cycles (exchanges) occur
each cycle is 1-1/2 long and exchanges occur during the night while the patient is asleep
what is the intracellular fluid compartment (ICF)
fluid within cells
= 60% total body fluid
what is the extracellular fluid compartment (ECF)
fluid outside of cells
= 40% body fluid
two components of extracellular fluid
plasma and interstitial fluid
plasma = 20% of ECF
Interstitial fluid = 80%
in ECF what is the chief cation?
sodium
Na+
in ECF what is the chief anion?
chloride
water intake must equal
water output
what are some examples of water intake?
liquids, foods, cellular metabolism
what are some examples of water output?
~60% via kidneys; also lungs, skin, sweat, feces, lungs (add moisture to the air)
what number are we trying to get plasma osmolarity?
usually 280-300 mOsm
what happens if plasma osmolarity goes above 300 mOsm?
you feel thirsty - increase water intake
ADH stimulates renal water reabsorption
what happens in decreased osmolarity?
thirst not stimulated
ADH secretion is not stimulated
what happens in increase in osmolarity 1-2%?
reduce saliva production (makes you dry)
osmoreceptors of the hypothalamic thirst center lose water to the hypertonic ECG (depolarize and become irritable)
what happens in decrease in plasma volume of 5-10%?
baroreceptors
- also triggers the thirst mechanism
what is dampening of thirst?
it begins once mucosa of mouth & throat moistened by water, it prevents overdrinking while water moves to ECF
what are the obligatory water losses?
insensible water loss via lungs/skin
via the feces
minimal sensible urinary loss = 500 ml/day
what is dehydration?
can be loss of only fluid or loss of fluid plus salts
consequence = cells swell
what is hypotonic hydration?
dilutes out sodium in ECF, causing water to move into cells
what is edema?
accumulation of fluid (including salts) in IF, but not inside cells
consequences = cells swell
salt content of the body can vary due to?
diet, sweating, vomiting, etc.
what does Na+ determine
determines both plasma osmolarity and blood volume
sodium content of the body may change
but its concentration in ECF is monitored and usually remains stable due to immediate adjustments in water volume
what happens to blood pressure after a salty meal?
blood pressure goes up
what is aldosterone
most influential agent at level of kidney; acts slowly
even without aldosterone what happens?
65% of Na+ in filtrate reabsorbed in PCT & 25% in loop of Henle; aldosterone secretion essential to life
what is high aldosterone?
virtually all remaining Na+ (chloride co-transported) actively reabsorbed by DCT & collecting ducts
2 pathways to aldosterone secretion
renin-angiotensin system
direct effect of high K+ or low Na+
renin secretion in response
sympathetic ns
decreased filtrate osmolarity
decreased stretch bp
what is Addison’s disease?
autoimmune
hyposecretion of aldosterone
- excess loss of Na+ & water in urine
- only pull back 90%
water reabsorption in collecting ducts relies on?
relies on ADH secretion and will influence plasma sodium secretion
what happens in low Na+?
excess fluid, reduced ADH secretion & dilute urine to unload water
what happens in high Na+?
decreased blood volume and not enough water for correct osmolality, increased ADH secretion & reduced urine volume to move water back into bloodstream
what is atrial natriuretic factor released by
released by cells in the atria of heart when bp is elevated
what do potent diuretic & natriuretic hormone do
(i) inhibits Na+ reabsorption by DCT and collecting duct
(ii) decrease released of ADH, renin, and aldosterone
(iii) induces vasodilation overall effect is to reduce bp
what is pressure diuresis
when blood pressure/volume increases, sympathetic output to kidney from cardiovascular centre
what is the result of pressure diuresis
dilation of afferent arterioles and increase GFR
