urinary system Flashcards
what does the urinary system consist of?
- kidneys
- ureters
- urinary bladder
- urethra
what is the urinary system also called?
the renal system
where are the kidneys located?
in superior lumbar region
what does the kidneys being retro-peritoneal organs mean?
they are located behind the periotoneal membrane
what supplies the kidneys with blood and what are these arteries derived from?
renal arteries, abdominal aorta
what are the functions of the kidneys?
- regulating fluid and electrolyte balance
- excretion of metabolic wastes and foreign substances
- regulation of pH
- maintenance of bp
- regulation of erythropoiesis
what does the regulation of fluid and electrolyte balance of the kidneys include?
solute content and therefore osmolarity of ECF
what is a waste product excreted by the kidneys?
nitrogenous wastes
how do the kidneys regulate pH?
by conserving or eliminating hydrogen
how do the kidneys maintain blood pressure?
through control of blood volume and production of renin
how do the kidneys regulate erythropoiesis?
produces hormones erythropoietin for stimulation of red blood cell production
what are the metabolic functions of the kidneys?
- activates vitamin D
- production of new glucose through gluconeogenesis when fasting/starving
what are the three regions of gross anatomy?
- renal cortex
- renal medulla
- renal pelvis
what is the renal cortex?
outer region containing cortical nephrons
what is the renal medulla?
cone shaped tissue called renal pyramids
what is the renal pelvis?
funnel shape continuous with ureter
what does the renal pelvis drain?
drains papillae into minor calyces, then into major calyces
what is the functional unit of the kidneys?
nephron
what does a nephron consist of?
renal corpuscle and tubule
what is the renal corpuscle of a nephron composed of?
tight collection of capillaries called glomerulus
what is the renal corpuscle of the nephron specialised for?
filtration
what occurs in the renal tubule of the nephron?
reabsorption and secretion
what do nephrons drain into?
collecting duct
what are the two types of nephrons?
cortical and juxtamedullary
where are cortical nephrons found?
renal cortex
what percentage of nephrons are cortical?
85%
what percentage of nephrons are juxtamedullary?
15%
what are juxtamedullary nephrons important for forming?
concentrated urine
what is the renal corpuscle of the nephron specialised for?
filtration
what occurs in the renal tubule of the nephron?
reabsorption and secretion
what do nephrons drain into?
collecting duct
what are the two types of nephrons?
cortical and juxtamedullary
where are cortical nephrons found?
renal cortex
what percentage of nephrons are cortical?
85%
what percentage of nephrons are juxtamedullary?
15%
what are juxtamedullary nephrons important for forming?
concentrated urine
what are the three components of nephron blood supply?
- glomerular capillaries
- peritubular capillaries
- vasa recta
where are glomerular capillaries located?
within renal corpuscle
what are glomerular capillaries specialised for?
filtration
what do peritubular capillaries readily absorb?
solutes and water from tubule cells
what is the vasa recta important for?
forming concentrated urine
what are the three major processes of urine production?
- glomerular filtration
- tubular reabsorption
- tubular secretion
whats the equation for urine production?
filtration+ secretion - reabsorption
is glomerular filtration a passive/active/or both process?
passive
is tubular reabsorption a passive/active/or both process?
passive or active
is tubular secretion a passive/active/or both process?
active
what does the filtration membrane of the glomerular consist of?
- glomerular capillaries
- basement membrane
- podocytes
is basement membrane in the filtration membrane of the glomerular negatively or positively charged?
negative
what are glomerular capillaries composed of?
fenestrated endothelium
what is the basement membrane of the glomerular filtration membrane?
thin gel-like membrane between two cellular layers
what are podocytes of the glomerular filtration membrane composed of?
thin epithelium
what do podocytes of the glomerular filtration membrane form?
cellular sheets with many filtration slits
what is filtration of solutes from blood determined by?
size and charge
does glomerular filtration consume metabolic energy?
no
what does glomerular filtration result in?
positive net filtration pressure
what drives glomerular filtration?
glomerular hydrostatic pressure
what is glomerular filtration?
a non-selective process in which hydrostatic bp forces fluid through glomerular filtration membrane into capsule
what are the three forces determining filtration pressure?
- glomerular hydrostatic pressure
- glomerular colloid osmotic pressure
- capsular hydrostatic pressure
whats the equation for net filtration pressure?
GHP - (GCOP + CHP)
what is glomerular filtration rate?
total volume of filtrate formed each min
what are factors that determine GFR?
- net filtration pressure
- total surface area
- filtration membrane permeability
what is the equation for GFR?
NFP x SA x PERM
what is tubular reabsorption?
selective process that reclaims most of the filtrate formed during glomerular filtration
when does tubular reabsorption start?
as soon as filtrate enters proximal tubule
what cells carry out most reabsorption in the urinary system?
proximal tubule cells
what are substances that are reclaimed during tubular reabsorption?
- water
- glucose
- amino acids
- electrolytes
what hormones are able to fine tune reabsorption at DT and CD?
- ADH
- Aldosterone
- Atrial natriuretic peptide
what does ADH do in the urinary system?
inhibits diuresis
what does aldosterone do in the urinary system?
stimulates cells in DT (primarily) and CD to reabsorb more Na+
what does ANP do in the urinary system?
inhibits reabsorption of Na+ and water in the DT and CD
what occurs in the nephron loop?
reabsorption of water and solutes
what is tubular secretion?
selective process moving substances from blood into filtrate
where does tubular secretion occur?
along length of tubule
what is tubular secretion important for?
- removal of unwanted substances
- elimination of excess K+
- maintenance of blood pH through removal of H+
what is GFR closely regulated in order to?
- remove nitrogenous wastes from blood
- remove excess solutes and water
- ensure body tissues have constant blood volume/pressure
