renal system Flashcards
11: what nephrons are involved in making concentrated urine
juxtakedullary nephrons
11: renal blood supply distribution in cortex vs medula vs papilla
cortex - 93%
medula - 7%
papilla - 1%
11: functions of kidney
- homeostatic regulation of water and ion content of blood
- excretion fo metabolic waste products
- production of hormones
11: glomerular filtration - what is filtered
all plasma constituents except proteins
11: glomerular filtration - what do filtration barriers restrict
solute movement on basis of size and charge
11: what % of cardiac output do kidneys receive
25%
11: what does hydrostatic pressure of blood flowing through glomerular capillaries promote
promotes movement of fluid into capsule
11: what does hydrostatic pressure of fluid in bowmans space oppose
opposes movement of fluid into capsule
11: what drives filtration
capillary hydrostatic pressure
11: increase in resistance of afferent arteriole
reduces blood flow to glomerulus
11: increase in resistance of efferent arteriole
increases blood flow/pressure to glomerulus
11: decrease in resistance of afferent arteriole
increase blood flow to glomerulus
11: decrease in resistance in efferent arteriole
decreases pressure in glomerulus
11: auto regulation
maintains renal blood flow and GFR
11: local control mechanisms of auto regulation
- myogenic response
2. tubuloglomerular feedback
11: what does the nephron do so that the ascending limb of loop of hence passes between afferent and efferent arterioles
it loops back on itself
11: where does filtration of blood occur
glomerulus
11: why is regulation of renal blood flow important
in regulating glomerular filtration rate
11: filtrate
solution entering proximal convoluted tubule
11: what does filtrate contain
h20 na+ k+ ca2+ cl- HCO3- glucose
12: formation of urine steps
filtration
reabsorption
secretion
12: formation of urine - amount excreted =
amount excreted = amount filtered - amount reabsorbed + amount secreted
12: reabsorption
movement of of solutes/fluid out of filtrate and into capillaries via epithelial transport mechanisms
12: epithelial transport mechanisms - epithelial transcellular transport
substances cross apical and basolateral membranes of the tubule epithelial cells
12: epithelial transport mechanisms - paracellular transport pathway
substances pass through the cell- cell junction between two adjacent cells
12: epithelial transport mechanisms - passive transport via
diffusion
leak channels
paracellular transport
12: epithelial transport mechanisms - active transport
membrane channels
transporters
co-transporters
pumps carriers
12: how is structure of PCT specialised for its functions
- microvilli on apical surface for reabsorption
- ## ER,golgi,lysosomes, vacuoles = synthesis of membrane proteins
12: reabsorption at PCT - na+ reabsorption
- passively at apical membrane down electrochemical gradient
- co transport with essential solutes
12: reabsorption at PCT - H20 reabsorption
paracellular route via osmosis
12: reabsorption at PCT - glucose
co transport at apical membrane
12: reabsorption of glucose (Tm)
transport maximum rate
12: reabsorption of glucose (renal threshold)
plasma concentration of substrate at transport maximum
12: reabsorption of glucose (diabetes mellitus)
excessive glucose concentration saturates carriers and excess glucose appears in urine
12: formation of urine - what is the descending limb permeable/imperemebale to
water
solutes
12: formation of urine - where is NaCl transported from
ascending limb into interstitium
12: formation of urine - what is the thick ascending limb of loop impermeable to
water
12: formation of urine - what is collecting duct relatively impermeable/permeable to
H20
urea
12: properties of countercurrent exchange systems
- two flows moving in opposite directions
- vessels anatomically close together
- passive transfer of molecules from 1 vessel to another
12: countercurrent multiplier system
countercurrent exchange enhanced by active transport of solutes
12: how can osmotic gradient for reabsorption of H2O be maintained
prevent reduction in osmolarity of medullary interstitium (tissue surrounding the loop of Henle in the medulla)
12: countercurrent exchange - vasa recta and collecting duct
- h2o reabsorbed from collecting duct
- removed from medulla by ascending vasa recta
- results in concentrated urine with high osmolarity
12: countercurrent multiplier exchange - descending limb of loop
H2O reabsorption
increased filtrate osmolarity
12: countercurrent multiplier exchange - descending limb of vasa recta
H2O reabsorption
solute uptake
increased blood osmolarity
12: countercurrent multiplier exchange - ascending limb of vasa recta
H2O reabsorption
deceased blood osmolarity
12: direct renal adjustment
directly by excreting or reabsorbing H+
12: indirect renal adjustment
by excreting /reabsorbing HCO3
12: Where does reabsorption and secretion occur
PCT
12: what are countercurrent mechanisms important in controlling
conc of solutes and water in urine
12: control of H+ and HCO3- exertion regulates
acid base balance
13: diuresis
drugs that promote removal of excess water in urine / urine excretion
13: what does ADH (antidiuretic hormone) control
permeability of cells in collecting duct to H2O
13: effect of ADH on collecting duct
makes collecting duct permeable to H2O
13: main controllers of adh release
osmoreceptos
13: what can stimulate increased ADH release
decreased blood volume / pressure
13: where is ADH stored
vesicles in posterior pituitary gland
13: what detects changes in plasma osmolarity
osmoreceptors in hypothalamus
13: ADH when there is increased plasma osmolarity vs decreased
increased = increased ADH decreased = decreased ADH
13: what is the normal plasma osmolarity
290 mOsm
13: physiological stimuli for ADH secretion
heightened emotions/stress
high temperature
exercise
pain
13: physiological stimuli for ADH secretion - what inhibits release fo ADH
alcohol
13: what alters fluid balance
MDMA
13: decrease in fluid out = MDMA stimulates
ADH secretion
13: when is ADH released
when there is an increase in osmolarity and reduction in blood volume
13: what does ADH promote
reabsorption fo H2O by cells in collecting duct
13: overall effect of ADH
decreased H2O excretion
increased blood volume
13: ADH deficiency - central diabetes insipidus
deficiency of ADH secretion
13: ADH deficiency - nephrogenic diabetes insipidus
nephrons do not respond to ADH
13: aldosterone
steroid hormone synthesised in adrenal cortex following stimulation by angiotensin 2
13: what does aldosterone promote
reabsorption fo NA+ in distal convoluted tubule and in cortical collecting duct
13: overall effect of aldosterone
decreased NaCL and H2O excretion
increased blood volume
13: what does angiotensin 2 stimulate
release of aldosterone from adrenal cortex
13: what does angiotensin 2 inhibit
baroreceptor reflex
increase the release off norepinephrine from sympathetic postganglionic fibres
13: overall effect of angiotensin 2
decreased NaCL and h2o excretion
increased blood volume and BP
13: what does atrial natriuretic peptide control
regulation of plasma volume and na+
13: where are atrial natriuretic peptides produced
by atria in response to stretch
13: what do atrial natriuretic peptides increase
renal water and nA+ excretion
13: what do atrial natriuretic peptides inhibit
thirst
ADH
aldosterone
renin release
13: overall effect of natriuretic peptides
increased Nacl and h2o excretion
decreased blood volume and Bp
13: how does ADH increase blood volume
increasing reabsorption of H2O
13: how does aldosterone increase blood volume
increase reabsorption fo na+
13: who does angiotensin 2 increase blood volume
increase reabsorption of na+ and h2o
13: how do atrial natriuretic peptides decrease blood volume
by increasing excretion fo na+ and h2o
13: micturition (urine)
fluid that leaves the collecting duct
flows through ureter to bladder
13: micturition (bladder)
hollow organ that can expand
smooth muscle wall
13: internal sphincter muscles
smooth muscle with normal tone to keep it contracted
13: external sphincter muscles
skeletal muscle contolled by somatic motor neurones
tonic stimulation from CNS maintains contraction