Module 6 Flashcards
what does the urinary system consist of
- kidneys
- ureters
- urinary bladder
- urethra
function of the kidneys
- maintain the volume and composition of the body’s extracellular fluids
- process blood, retain useful substances whilst forming urine as a waste product
list the functions of the urinary system
- regulates
- excretes waste
- endocrine
- produces
Functions of the urinary system - regulates
- regulates fluid volume to control blood water content and thus blood volume
- regulates solutes and electrolytes
- regulates acid base balance to control blood pH
Functions of the urinary system - excretes waste
- excretes metabolic waste e.g. urea
- excretes foreign waste e.g. drugs
Functions of the urinary system - endocrine
- erythropoietin (hormone that stimulates RBC)
- renin (maintenance of blood pressure)
Functions of the urinary system - produces
- produces active vitamin D
- produces glucose to maintain levels when fasting
how are the kidneys supplied with blood
by the renal arteries; derived from branches of the ABDOINAL AORTA
(drains through renal veins into inferior vena cava)
what are the 3 regions of the kidney structure
- cortex
- medulla
- pelvis
Kidney - Cortex
outer region containing cortical nephrons
Kidney - Medulla
cone shaped tissue called renal pyramids
Kidney - Pelvis
- funnel shape continuous with ureter
- drains papillae through minor calcyces then to major calyces
The Nephron - Renal Corpuscle
capillaries and glomerular capsule are specialised for filtration
The Nephron - Renal tubule
- Proximal convoluted tubule (PCT)
- Distal convoluted tubule (DCT)
nephron
urine forming units of the kidney
what are the 2 major groups of nephrons
- cortical nephrons (85%)
= juxtamedullary nephrones (renal medulla, concentrates urine)
what does blood pass through to enter and exit the gomerulus
in through afferent arteriole and out by efferent arteriole
what are the 3 major processes of urine production
- Glomerular filtration
- Tubular reabsorption
- Tubular secretion
describe pertibular capillaries
close to renal tubes
low pressure, prous capillaries
readily absorb solutes and water
describe vasa recta
long straight vessels serving juxtamedullary nephrons to form concentrated urine
what does blood pressure drive
filtration
what does the filtration membrane of the glomerulus consist of
- perforated endothelium of golmerular capillaries
- epitheelial cells or podocytes of the inner layer of capsule
- collagenous basement membrane
define glomerular filtration
a non selective process in which hydrostatic (blood) pressure forces fluid through the glomerular membrane
what does the filter allow to pass
free passage of water and most solutes, including ions, glucose,
golmerular filtration rate
total volume of filtrate produced by kidneys per minute
what drives glomerular filtration
hydrostatic pressure pushing the fluid out of the blood
formula for glomerular filtration
GFR=NFPX SAxPERM
what does increased GFR lead to
increased urinary output (vice versa)
what mechanisms regulate GFR
- intrinsic (auto) regulation
- neural control
- renin angiotensin system
describe the function of auto regulation in relation to GFR
automatically adjusts blood pressure in glomerular capillaries to compensate for small changes in systemic blood pressure
define tubular reabsorption
a selective process that reclaims most of the filtrate formed during glomerular filtration
passage of solutes moving through cels in tubular reabsorption
move through cells of tubular epithelium and capillary endothelium back into the blood in the peritubular capillaries
is reabsorption regulated in the proximal convoluted tubule
no it is unregulated
how much water and NA+ is reabsorbed at PCT
65%
where are K+ and uric acid reabsorbed during tubular reabsorption
PCT
where is the majority of absorption in the nephron loop, ascending or descending loop ?
ascending
what is the role of aldosterone in reabsorption at the DCT and CD
stimulates cells to reabsorb more NA+
define tubular secretion
a selective process moving substances from the blood into the filtrate
where does tubular secretion occur
along the length of the tubule and CD
why is tubular secretion essential
- to clear plasma of unwanted substances
- elimination of excess K+
- control of blood pH (secretes H+ when pH of extracellular rises)
define urine
the “stuff” removed from the body after filtration, reabsorption and secretion by the renal tubule
what is the chemical composition of urine
- 95% water
- 5% solutes (NA,K,CA,Mg,HCO)
what does the presence of protein in urine mean
pregnancy, hypertension, renal disease
what does the presence of ketone bodies in urine mean
uncontrolled diabetes mellitus
what does the presence of bile in urine mean
liver disease, obstruction of bile ducts
what does the presence of RBC and WBC in urine mean
RBC - trauma, kidney stones, infection, cancer
WBC - cancer
what is the pathway of urine
papillae of pyramids
minor calyces
major calyces
pelvis
ureter
bladder
structure of urethra
- muscular tube
- involuntary control (smooth muscle)
- voluntary control (skeletal muscle)
micturition
urination or voiding as stretch receptors are activated once impulses are sent to the spinal cord
