kidneys (9a) Flashcards
functions of the urinary system
collect water and filter body fluids
concentrate and eliminate waste (nitrogenous waste, toxins, drugs, excess ions) from body fluids
maintain blood pressure
stimulate red blood cell production
anatomy of the urinary system
renal artery, renal hilum, renal vein, kidney, ureter, urinary bladder and urethra
characteristics and function of the ureters
carry urine from renal hilum to bladder using peristalsis (smooth muscle)
also have valves to prevent backflow of urine
characteristics and function of the urinary bladder
made of 3 layers of smooth muscle called the detrusor muscle
walls are folded (rugae like stomach) when empty
mucosa is made of transitional epithelium
located behind the pubic symphysis
stores urine
characteristics and function of the urethra
carries urine from bladder to exterior by peristalsis (and semen in men)
urine release is controlled by
external urethral sphincter (skeletal muscle)
internal urethral sphincter (smooth muscle)
micturition mechanism
voiding (emptying) reflex
stretch receptors fire -> parasympathetic neurons fire and activate detrusor muscle (motor neurons controlling external sphincter stop firing) -> smooth muscle contracts and internal sphincter is pulled open -> urine flows and the feeling of needing to pee is felt -> external sphincter is opened when you want
sympathetic nervous system keeps internal sphincter closed
characteristics of the kidneys
are outside of the peritoneal cavity, protected by bottom ribs, right kidney is lower
what are the structures outside of the kidneys and what do they do
renal hilum: indentation where ureters, vessels and nerves enter/exit
fibrous capsule: encloses each kidney
perirenal fat capsule: cushions
renal fascia: anchors kidneys to surrounding structure
what are the three regions of the kidney
renal cortex
renal medulla
renal pelvis
characteristics of the renal cortex
outermost
contains the major portions of nephrons
characteristics of the renal medulla
has renal pyramids (have parts of nephrons) and renal columns (contain blood vessels)
characteristics of renal pelvis
innermost
papilla of pyramids project into minor calyx which becomes the major calyx which ultimately drains into ureter
what are the components of blood flow in kidneys
aorta -> renal artery -> afferent arteriole -> glomerulus (capillaries) -> efferent arterioles -> peritubular capillaries -> renal vein -> inferior vena cana
characteristics of the nephron
made of epithelial cells
structural and functional units of kidney for urine production
two types: cortical nephron (more abundant) and juxtamedullary nephron
difference between nephron types
juxtamedullary nephrons have their loops in the renal medulla while most cortical nephrons’ loops stay in the renal cortex
juxtamedullary nephrons regulate water balance because their long loops allow for a strong osmotic gradient to be created
structure of nephrons
renal corpuscle: has bowman’s/glomerular capsule and glomerular capillaries
renal tubule: has proximal convoluted tubule (PCT), nephron loop (loop of henle) and distal convoluted tubule (DCT)
anatomy and function of the renal corpuscle
circle around glomerulus (capillaries)
capillaries are surrounded by specialized cells (podocytes) that form the inner layer of the capsule (the circle)
podocytes cling to the capillaries and act as filtration slits which prevents blood cells and most proteins from passing
all plasma components and solute pass and form the filtrate
the outer layer of the capsule is made of epithelial cells and contains the filtrate in the capsule space
anatomy of the renal tubule
capsule opens into the PCT and leads to loop (has descending and ascending limb) which leads to DCT
which capillary beds are present at the nephron and where are they
glomerulus (inside capsule)
peritubular capillary bed (wrapped around renal tubule
