urinary system Flashcards
(145 cards)
1
Q
what are the major structures in the urinary system
A
2 kidneys
2 ureters
bladder
urethra
2
Q
what are the functions of the urinary system
A
filter blood plasma (conc of ions and remove toxins)
conserves valuable nutrients (prevent loss thru urine)
regulates blood volume and pressure (decrease fluid > decrease blood vol > decrease BP)
regulates blood pH and glucose levels (remove H+ and glucose > maintain homeostasis)
release hormones (erythropoietin and calcitriol)
3
Q
describe the anatomical position of the kidneys
A
either side of vertebral column
left slightly superior to right
retroperitoneal
protected by 11th and 12th ribs
4
Q
what are the 4 structures going in/out of the kidney
A
renal artery
renal vein
hilum
ureter
5
Q
what are the 3 CT layers around the kidney
A
fibrous capsule = collagen fibres
perirenal fat = cushioning layer of adipose tissue
renal fascia = fibrous layer that anchors kidney to surrounding structures
6
Q
what is the renal cortex
A
outermost 1cm of the kidney
where filtration and reabsorption occurs
7
Q
what is the renal medulla
A
2-3cm below the cortex
regulate concentration of urine
8
Q
what is the renal sinus
A
central cavity that contains renal pelvis, renal calyces, blood vessels and fat
9
Q
what are renal pyramids
A
in the medulla
extends from cortex to the renal sinus
transport urine from cortex to sinus
apex = renal papilla
10
Q
what are renal columns
A
in the medulla
bands of tissue that separate adjacent renal pyramids
11
Q
what are kidney lobes
A
in the medulla
they are functional units > where urine is produced
consist of renal pyramid, overlying renal cortex, and adjacent tissues of the renal columns
12
Q
how is filtrate drained into the sinus
A
renal papilla >
minor calyces (collects urine produced by a single kidney lobe) >
major calyces (fusion of 4-5 minor calyces / collects urine from minor calyces >
renal pelvis (continuous w ureter) >
ureter (drains urine from kidney to bladder using peristaltic waves)
13
Q
what are ureters
A
muscular tubes that go from the kidneys to the posterior wall of the bladder
sit retroperitoneal and are firmly attached to the posterior abdominal wall
14
Q
what are the histological layers of the ureters
A
muscosa > transitional epithelium ie urothelium > expansion of ureter
muscularis > peristalsis / upper 2/3 has 2 layers of smooth muscle and bottom 1/3 has 3 layers of smooth muscle
15
Q
what are the histological layers of the bladder
A
mucosa > urothelium + rugae > expansion
muscularis > expulsion of urine / 3 layers of smooth muscle
sphincters > bands of skeletal muscle that control urine flow, like valves
16
Q
what are the 2 sphincters in the bladder
A
internal urethral (involuntary)
external urethral (voluntary)
17
Q
what does the urethra do
A
transport urine from bladder to exterior of body
females = urine only
males = urine + semen
18
Q
what are the histological layers of the urethra
A
mucosa > proximal = stratified transitional epithelium / middle = stratified columnar / distal = stratified squamous
muscularis > expulsion of urine / 2 layers of smooth muscle
19
Q
what do the kidneys do
A
produce urine
20
Q
what do the ureters do
A
carry urine from kidney to bladder
21
Q
what does the bladder do
A
receives and stores urine
22
Q
how does blood flow in the kidney
A
- O2 rich blood via renal artery
- renal artery divides into segmental arteries in renal sinus
- segmental arteries branch into interlobar arteries in renal columns
- interlobar arteries branch into small vessels > culminate in afferent arterioles that supply each nephron > blood enter glomerulus
- efferent arteriole carries blood from glomerulus to peritubular capillaries
- peritubular capillaries surround renal tubule
- peritubular capillaries drain into cortical veins > filtered back to IVC
23
Q
what is a nephron
A
functional units of the kidney
24
Q
what are the two types of nephrons
A
cortical - renal cortex / excrete waste product
juxtamedullary - long nephron loops in renal medulla / produce concentrated urine
25
what are the three main components of the nephron
renal corpuscle
renal tubule
collecting system
26
what does the renal corpuscle do
site of blood filtration
27
what does the renal tubule do
site of filtrate modification
28
what does the collecting system do
urine from each nephron empties into collecting system and then into minor calyces
29
what are the 3 distinct physiological process kidneys use to maintain homeostasis
filtration
reabsorption
secretion
30
what does the filtration structure in the renal corpuscle consist of
glomerulus (afferent and efferent arterioles)
glomerular capsule/bowmans capsule
31
why do efferent arterioles have a smaller diameter than afferent
increase the glomerular pressure which is needed as a driver for filtration to occur as it forces water and solutes out of glomerular capillaries into renal tubule
32
how does filtrate from the blood get filtered and passed onto the glomerulus capsule from the glomerulus
through a filtration membrane
filtrate move into capsular space while non filterable components exit glomerulus via efferent arteriole
33
what is the filtration membrane comprised of
fenestrated endothelium - stops cells and platelets
basement membrane - stops large proteins
filtration slits b/w pedicels (processes from podocytes) - stops medium sized proteins
34
what enhances filtration
thinness of filtration membrane
large SA of glomerular capillaries
higher glomerular BP
35
what is glomerular filtration rate (eGFR)
based on creatinine levels > gives estimation on kidney function
>GFR90 is normal
GFR 60-90 = CKD1
36
what are mesangial cells
b/w adjacent capillaries
contract and relax to control capillary diameter and blood flow rate
phagocytosis to keep glomerular filter free of debris
37
what are the three main parts of the renal tubule
proximal convoluted tubule (PCT)
loop of henle
distal convoluted tubule (DCT)
38
what is the function and structure of the PCT
reabsorbs most of filtrate (e.g glucose and small proteins)
has microvilli to increase SA, mitochondria for active transport, centrally located nucleus and pink appearance
39
what is the function and structure of loop of henle
urine concentration
descending limb
thin ascending limb
thick ascending limb
has vasa recta
40
how does the countercurrent multiplier mechanism work in the loop of henle
descending limb is permeable to water > water leaves descending limb into ISF of medulla
this causes a conc gradient to be established in medulla
the ascending limb is not permeable to water, so in response to ISF becoming dilute, ions such as Na+ and Cl- and K+ are actively transported out into the ISF to make it 'salty'
this creates a conc gradient again so that water exits the DCT and collecting duct
all this, allows for increase water reabsorption
41
what is the function and structure of the DCT
Na+ reabsorbed due to release of aldosterone > increase blood Na+ > water reabsorption > increase blood volume and pressure
K+ secreted due to aldosterone release
bicarbonate ions reabsorbed
ADH/vasopressin
has few microvilli, many mitochondria
42
what is the function of collecting tubules and ducts
tubules unite to form ducts
concentrates urine by passive reabsorption of water into medulla (increase by ADH)
43
what is the juxtaglomerular apparatus (JGA)
regulates systemic blood pressure using RAAS
44
what are the components of the JGA
Jg cells = endocrine cells in afferent arteriole > produce renin > aldosterone > increase Na+ reabsorption in DCT
Macula densa (part of DCT) = monitor Na+ level in filtrate
45
what are diuretics
increase excretion of sodium and water
e.g caffeine, alcohol, medications
46
what are three main metabolic waste products
urea (by-product of AA breakdown)
creatinine (breakdown of creatine phosphate)
uric acid (byproduct of recycling nitrogenous bases of RNA)
47
how is dilute urine formed
decrease ADH > decrease water reabsorption in DCT and collecting ducts > dilute urine
48
how is concentrated urine formed
increase ADH > increase water reabsorption in DCT and collecting ducts > concentrated urine
49
what affect does podocytes contracting have on glomerular filtration
sympathetic stimulation > contract > decrease filtration coefficient and GFR
50
what is the normal range of GFR
90-140 ml/min
51
is GFR same for males and females
no, females are on the lower side of the range
52
does GFR change w age
10% reduction for every 10 years over 20
53
why is it important to keep GFR within a specific range
maintain fluid and electrolyte balance
54
does GFR change w changes in BP
typically not, within the autoregulatory range
55
what starling forces are involved in GFR
glomerular blood hydrostatic pressure = 55mmHg
capsular hydrostatic pressure = 15mmHg
blood colloid osmotic pressure = 30mmHg
56
how is net filtration pressure measured (NFP)
GBHP - CHP - BCOP
57
what is the consequence of being unable to regulate glomerular pressure
rapid decline in kidney function
58
how does vasoconstriction in the afferent arteriole affect GFR
vasoconstrict > decrease blood flow into glomerulus > decrease glomerular capillary BP > decrease net filtration pressure > decrease GFR
59
how does vasodilation in the afferent arteriole affect GFR
vasodilation > increase blood flow into glomerulus > increase glomerular capillary BP > increase net filtration pressure > increase GFR
60
what are the main factors affecting GFR
radius of afferent arteriole
extrinsic sympathetic stimulation
hormonal regulation of AngII and ANP
auto regulation
myogenic mechanism
tubuloglomerular feedback
61
what is the myogenic mechanism
increase afferent arteriole pressure causes stretch that in turn causes the vessel to constrict, increasing resistance and reducing flow
62
what is the tubuloglomular feedback (TGF)
macula densa sense increase Na+ > release ATP > decrease GFR (maintains normal filtered load) and decrease renin secretion (which allows more Na+ excretion)
macula densa sense decrease Na+ > release NO and prostaglandins > increase GFR and increase renin secretion (conserves Na+)
63
how is renal blood flow measured
PAH or inulin are molecules that are not reabsorbed in the tubules so RPF is equal to plasma clearance rate/GFR
RPF = concentration PAH = Urinary PAH x volume / plasma PAH
64
why is inulin clinically important
it is freely filtered ie no tubular reabsorption so it is ideal to use for the measurement of GFR
65
what is plasma clearance
volume of plasma cleared of a particular substance each minute in the kidney
66
why is creatinine often used as a reasonable estimate of GFR
breakdown product of creatine phosphate in muscle > usually produced at a fairly constant rate
67
what are the components of body fluids
water, protein, electrolytes, etc.
68
what are the functions of body functions
transport/carriage, colloid osmotic pressure, membrane excitability buffering
69
what proportion of fluids in the body are ICF
2/3
70
what proportion of fluids in the body are ECF
1/3
71
what percentage of ECF is ISF
80%
72
what percentage of ECF is plasma
20%
73
what is plasma
fluid component of blood
74
what separates plasma and ISF
capillary wall
> mvmt across this is passive via pores due to both sides of the wall having similar compositions
75
what separates ISF and ICF
plasma membrane
> mvmt across this is passive and active due to both sides of wall having different compositions
76
how is fluid gained
ingested liquids, ingested food, metabolic production
77
how is fluid lost
urinary loss, sweating, respiratory evaporation, GI losses
78
how does the thirst mechanism work
dehydration > increase blood osmolarity > stimulates osmoreceptors in hypothalamus > stimulates thirst centre in hypothalamus > increases thirst > increases water intake > increase body water level
79
how is the resp system key in short term acid-base regulation
increase RR > decrease CO2 > decrease H+ (alkalosis)
decrease RR > increase CO2 > increase H+ (acidosis)
80
how can opioids lead to acidosis
depress CNS > decrease RR > increase CO2 > increase H+ (acidosis)
81
what is the normal pH range
7.35 - 7.45
82
why is such a narrow range of pH a must
maintenance of normal excitability of nerve and muscle cells
preservation of structure of proteins and enzymes
83
what is the upper and lower 'border' of pH that leads to death
6.8 and 8.0
84
what can acidosis lead to
coma
85
what can alkalosis lead to
seizures, spasms
86
what is the juxtaglomerular apparatus
specialised cells within the nephron
87
the JGA responds when there is a change in...
blood pressure (stretch)
blood osmolality (Na+)
88
the JGA is responsible for the release of...
Renin from granular cells
89
outline how the renin-angiotensin-aldosterone system works
angiotensinogen (liver) + renin (kidney) > angiotensin I + angiotensin-converting enzyme > angiotensin II > vasopressin (ADH) + thirst + arteriolar vasoconstriction
aldosterone (adrenal cortex) > aldosterone > stimulate kidney > Na+ reabsorption > increase Na+ conserved > Na+ osmotically hold more H2O in ECF > increase H2O conserved
90
what does aldosterone act on and what does it do
principal cells of distal convoluted tubule
promotes Na+ retention and K+ secretion
91
what are diuretic drugs
drugs which increase urine production
92
what are the major uses of diuretic drugs
correction of fluid oedema states
reduction of BP in hypertension
93
how do diuretics work
act on specific targets on renal tubular cells
inhibit sodium reabsorption
94
what are loop diuretics
diuretics used for oedematous states (e.g chronic heart failure) which act (inhibit) on luminal part of Na+/K+/2Cl- co-transporter
95
what are examples of loop diuretics
furosemide
bumetanide
96
how is the suitability of the use of which loop diuretic to use determined
if one is allergic to furosemide
97
what can occur due to the use of loop diuretics that need to be communicated
dramatic diuresis
postural hypotension
need for monitoring
98
what is monitored when prescribed loop diuretics
electrolytes ie decrease in K and H
renal function
edema
weight
99
what are thiazides
diuretics used for milder oedematous states (e.g hypertension) which act (inhibit) on the luminal part of the Na+/K+/2Cl- co-transporter in the DCT
100
what are examples of thiazides
hydrochlorothiazide
chlorthalidone
indapamide
101
how is suitability of thiazides determined
allergy to thiazide
postural hypotension
hyponatremia
gout
102
what effects on thiazide needs to be communicated
mild diuresis
postural hypotension
103
what needs to be monitored when prescribed thiazide
postural hypotension
electrolytes ie decrease in Na, K and H
renal function
edema
weight
104
what are mineralocorticoid antagonists
diuretics used in cases of oedema driven by increase aldosterone (e.g severe heart failure) which bind to mineralocorticoid receptors in collecting tubular cells
105
what is an example of mineralocorticoid receptor antagonist
spironolactone
106
how is the suitability of the use of mineralocorticoid receptor antagonists determined
renal impairment
elevated K
107
what effects of mineralocorticoid receptor antagonists need to be communicated
gynaecomastia
need for monitoring
108
what needs to be monitored when prescribed mineralocorticoid receptor antagonists
electrolytes ie decrease Na and H and increase K
renal function
edema
weight
109
what are potassium sparing diuretics
diuretics used in cases where mild diuretic efficacy is required and to treat low K by inhibiting Na/K exchange in distal nephron
110
what is an example of a potassium sparing drug
amiloride
111
how is the suitability of the use of potassium sparing drugs determined
renal impairment
elevated K
112
what effects of potassium sparing drugs need to be communicated
need for monitoring
113
what needs to be monitored when prescribed potassium sparing drugs
electrolytes ie decrease Na and increase in K and H
renal function
114
what are ACE inhibitors
most commonly used cardiovascular medicines w indications including hypertension, chronic systolic heart failure, diabetic nephropathy etc
generally end in -pril e.g perindopril and ramipril
115
how do ACE inhibitors work
prevent angiotensin I from being converted into angiotensin II, which can lead to the build up of bradykinin resulting in side effects like a cough, angioedema, hyperkalemia etc
116
what are angiotensin receptor blockers
similar uses to ACE
prevents angiotensin II binding to AT1 receptors on adrenal gland
end in -sartan e.g candesartan and irbesartan
117
what are neprolysin inhibitors
neprolysin = neutral endopeptidases
inhibition > increase BNP leading to decrease BP, sympathetic tone, fibrosis, hypertrophy / increase bradykinin > increase angiotensin II
118
what is ARNI (angiotensin receptor antagonist + neprolsyin inhibitor)
combination of neprolysin inhibitor w angiotensin II receptor blocker (e.g sacubitril + valsartan) for patients w heart failure w reduced ejection fraction
119
at what volume of bladder filling do we get the urge to urinate
around 200 mL
120
at what volume of bladder filling do the detrusor muscle contractions force the urethral sphincter to open
around 500mL
121
how does the micturition reflex work
1. receptors detect stretch and sends this message to the brain through the spinal cord (not direct part of the reflex as a reflex can be generated by just the spinal cord)
2. spinal cord signals detrusor muscle to contract bladder > relaxes internal sphincter (this is the micturition reflex)
3. message from brain goes through spinal cord to external sphincter telling it to relax or contract (voluntary)
122
how is the bladder innervated
sympathetic innervation through hypogastric nerves in L1 L2 and L3
parasympathetic innervation through pelvic nerves in S2 S3 and S4
somatic innervation (of external urethral sphincter) through pudendal nerves in S2 S3 and S4
123
how is the detrusor muscle in the bladder wall innervated
sympathetic hypogastric nerves release NA onto beta-3 receptors > relaxes the detrusor muscle
parasympathetic pelvic nerves ACh into M3 receptors > contracts detrusor muscle
124
how is the internal urethral sphincter innervated
sympathetic hypogastric nerves release NA onto alpha-1 receptors > contracts internal urethral sphincter
125
what happens to the three muscles during bladder filling and what is their dominant neural input
detrusor muscle - relaxed - sympathetic
internal sphincter - contracted - sympathetic
external sphincter - contracted - SNS
126
what happens to the three muscles during bladder voiding and what is their dominant neural input
detrusor muscle - contracted - parasympathetic
internal sphincter - relaxed - reduced sympathetic outflow
external sphincter - relaxed - SNS
127
what are the three main centres involved in micturition
cortical centre (inhibitory to pontine centre)
brainstem centre (pons is facilitatory to micturition)
spinal cord (parasympathetic reflex evacuation)
128
what effect would a beta 3 receptor agonist have on bladder/IUS tone
relaxation of the detrusor muscle > contraction of IUS
129
what effect would muscarinic receptor antagonist have on bladder/IUS tone
relaxation of detrusor muscle > contraction of IUS
130
what effect would alpha 1 adrenergic antagonist have on IUS tone
relax the IUS
131
what are 3 types of renal pathologies
UTI
kidney stones
renal failure (chronic and acute)
132
what causes a UTI
bacterial infection in any part of the urinary system
133
what is affected in a lower UTI
bladder, urethra
(less serious)
134
what is affected in an upper UTI
kidneys, ureters
(serious)
135
how can a UTI be treated
drink lots of water, antibiotics
136
what are kidney stones
crystallisation of minerals and salts in urine that can affect any part of the urinary system
137
what can happen if kidney stones get stuck in the ureters
block flow of urine > swelling of kidneys and ureteric spasms
138
what can cause kidney stones
excess Ca2+, dehydration, etc.
139
how can kidney stones be treated
drinks lots of water, pain relief, ultrasonic waves, surgery
140
what is renal failure
when the kidneys cannot filter waste from the blood meaning homeostasis cannot be maintained which leads to issues in all systems of the body, resulting in things like increase BP, dev of anaemia, and CNS problems
141
what is acute renal failure
filtration suddenly stops or slows > kidneys may regain partial or complete function
142
what can cause acute renal failure
renal ischemia, urinary obstruction, trauma, nephrotoxic drugs
143
what is chronic renal failure
kidney function deteriorates gradually > cannot be reversed
144
what can cause chronic renal failure
co-morbidities such as unmanaged diabetes and hypertension
145
what is dialysis
procedure to remove waste products and excess fluid from blood when kidneys stop working properly by using an artificial membrane (which has pores allowing diffusion of ions, nutrients, and wastes but not plasma proteins)
two types: haemodialysis and peritoneal dialysis
