1
Q
What is the function of the urinary system?
A
to filter blood and produce urine which allows us to maintain fluid and electrolyte balances
2
Q
What are the 4 components of the urinary system?
A
- kidneys: process blood, 2
- ureters: passageway from kidney to bladder, 2
- urinary bladder: where urine gets stored
- urethra: exit pathway of urinary system
3
Q
What are 8 functions of the urinary system?
A
- fluid filtration
- regulate blood volume
- maintains salt/water balance
- maintains acid/base balance
- gluconeogenesis
- renin production
- erythropoietin production
- activates vitamin D
4
Q
What are 10 parts of the kidney structure?
A
- capsule: outer portion
- cortex: outer region of kidney
- medulla: deep to cortex
- pelvis: hollowed out region that collects fluid and connects to ureter
- sinus: space in pelvis that holds fluid
- hilum: indentation where ureter attaches
- pyramids: triangle shaped structures in medulla that contain collecting tubules
- columns: b/w pyramids, internal projections of cortex tissue
- major calyces: minor merge together to form these
- minor calyces: renal pyramids collecting tubules empty into this structure
5
Q
What are the 3 supportive layers of the kidney?
A
- renal capsule: tissue surrounding kidney & holds it together
- adipose tissue: surround kidney to cushion, insulate, and protect kidney
- renal fascia: anchors kidney to rear wall of abdominal cavity
6
Q
What is a nephron?
A
functional unit of kidney and make up most of the structure of the kidney
7
Q
What are the components of the nephron?
A
- glomerulus: fenestrated capillary
- renal tubule: contains Bowman/s capsule, proximal convoluted tubule, loop of Henle, & distal convoluted tube
- Glomerular (Bowman’s) capsule: tube that completely surrounds the glomerulus
- proximal convoluted tube: close to glomerulus and connects to descending loop of Henle
- Loop of Henle: contains an ascending and descending portion
- Distal convoluted tube: further from glomerulus and connects to collecting tube
- collecting ducts: connect to many renal tubules and ultimately to a ureter
- renal corpuscle: bowman’s capsule + glomerulus
8
Q
What are two types of nephrons?
A
- cortical: majority, most of nephron located in cortex and small portion of loop of Henle extends to medulla
- juxtamedullary: closer to medulla and loop of Henle descends farther into medulla, concentrates the urine more
9
Q
What are 4 parts of nephron vasculature?
A
- afferent arteriole: delivers blood to glomerular capillaries
- efferent arteriole: exits glomerulus
- glomerulus: fenestrated capillary
- peritubular capillaries: surround renal tubule in cortical nephrons
- vasa recta: peritubular capillaries in medulla found in juxtamedullary nephrons
10
Q
What is the juxtaglomerular apparatus?
A
modification where distal convoluted tubule runs against afferent arteriole
11
Q
What are the two modification of the juxtaglomerular apparatus?
A
- smooth muscle of afferent arteriole wall: changes to juxtaglomerular cells which act as mechanoreceptors which monitor pressure of blood which activates these cells to produce renin
- epithelium of distal convoluted tubule: changes to macula densa cells which function as chemoreceptors and monitor concentration of filtrate and can activate JG cells to secrete renin
12
Q
What occurs to plasma in the tubule?
A
plasma enters -> becomes filtrate -> becomes urine in collecting ducts
13
Q
What makes up the filtration membrane of the glomerulus?
A
- fenestrated epithelium: allows everything to pass except cellular components
- podocytes: surround basement membrane and have extensions called pedicels; reduce SA for exchange and create filtration slits b/w pedicels
- basement membrane: surrounds capillaries and prevents proteins from passing through while also creating an electrical gradient
14
Q
What are 3 processes or urine formation?
A
- filtration: passive & nonselective; occurs at glomerulus and becomes filtrate
- tubular reabsorption: active or passive; modify filtrate by resorbing things out of tubule into bloodstream; occurs along tubule and proximal collecting duct
- tubular secretion: active or passive; modify filtrate by secreting things into tubule; occurs along tubule and proximal collecting duct
15
Q
What are the 4 steps of urine formation?
A
- Blood arrives at glomerulus & through process of filtration we get filtrate that enter tubule
- Filtrate contains all plasma components except for proteins
- Tubular resorption & secretion occur
- After filtrate is modified through these processes, it becomes urine
16
Q
What are 4 types of filtration pressure?
A
- glomerular hydrostatic pressure: pressure inside glomerulus, simply BP
- colloid osmotic pressure of intracapsular space: in bowman’s capsule, should be 0
- colloid osmotic pressure of glomerular blood: pressure created from proteins in the glomerular capillaries, wants to draw things back in
- capsular hydrostatic pressure: pressure outside capillary in bowman’s capsule, lower than GHP, limits exchange
17
Q
what is the driving force of filtration?
A
glomerular hydrostatic pressure
18
Q
What affects GFR (glomerular filtration rate) and RBF (renal blood flow)?
A
- dilation of afferent: increased RBF and GFR
- constriction of afferent: decreased RBF and GFR
- dilation of efferent: increased RBF and decreased GFR
- constriction of efferent: decreased RBF and increased GFR
19
Q
What is different abt the glomerular capillary compared to other capillaries?
A
- higher pressure than most capillaries
- fenestrated epithelium
- located b/w two arterioles
20
Q
What do we usually resorb back into the bloodstream from filtrate?
A
- almost all glucose and amino acids
- some water and ions
21
Q
where does most tubular secretion occur?
A
proximal convoluted tubule
22
Q
What are two limiting factors of filtration?
A
- amount of net filtration
- podocytes have pedicels which form slits that reduce SA
23
Q
What are 4 mechanisms of filtration regulation?
A
- myogenic mechanism: intrinsic; low BP causes dilation of smooth muscle and afferent arteriole which increase filtration & vice versa
- tubular glomerular mechanism: intrinsic; macula densa cells cause vasodilation of afferent arteriole if dilute filtrate or low osmolarity & vice versa; also activate JG
- hormonal mechanism: extrinsic or intrinsic (macula densa or neural mechanism); low BP causes JG cells to release renin causes systemic vasoconstriction, increase in Na+ resorption, and adrenal cortex to secrete aldosterone
- neural control: extrinsic; override mechanism that uses sympathetic impulses and NE to cause vasoconstriction of afferent arteriole which causes increased BP and filtration
24
Q
What are 4 other factors that affect filtration?
A
- prostaglandins: local signaling molecules that act as vasodilators and fine tune our neural and hormonal signals
- nitric oxide: vasodilator
- adenosine: vasoconstrictor in kidneys
- endothelin: released by blood vessels and acts as a vasoconstrictor
25
What two processes can we use for tubular resorption?
- transepithelial process: pass through 3 barriers when leaving the tubule and going into capillary; lumen -> cell _> epithelial space -> BV
- channel proteins: shortcut for ions, only one since these cells have tight junctions
26
What are the 3 barriers of transepithelial process?
- luminal: on tubule side of lumen
- vasolateral: interstitial side of lumen
- endothelial barrier: wall of capillary
27
What occurs w/ resorption in each region?
- proximal convoluted tube: most resorption occurs here, all glucose & amino acids, some water & Na+
- descending loop of Henle: permeable to water
- ascending loop of Henle: impermeable to water, permeable to ions, affected by aldosterone
- Distal convoluted tube: regulated by ADH
- proximal collecting tube: regulated by ADH
28
What is the countercurrent mechanism vs concurrent?
- countercurrent: when flow in opposite direction we have greater ability for exchange
- concurrent: tubes flow in same direction and exchange ends once equilibrium is reached
28
What affect does aldosterone have on the ascending loop of Henle?
controls Na+ resorption & causes more Na+ to be resorbed
29
what are the 4 steps for countercurrent multiplier?
1. fluids in PCT osmotically equal to plasma
2. descending limb freely permeable to water and impermeable to solutes
3. ascending limb impermeable to water and selectively permeable to solutes
4. collecting ducts permeable to urea
30
what is the renal gradient and why is it so important?
occurs in medulla and the deeper we go the more concentrated urine gets
- important because if we lost it BP would crash and toxins would build
31
What is countercurrent exchanger?
vasa recta are freely permeable to water and salt
32
What are 3 steps of urine formation relating to ADH?
1. concentration of urine dependent on ADH secretion
2. low ADH produces dilute urine
3. ADH production increases water reabsorption from collecting duct
33
What does ADH do to the distal convoluted tube and collecting duct?
produces channels (aquaporins) that allow water to go into blodstream
34
What are parts of the urinary bladder?
- urethral orifice: opening in bladder for urethra
- ureteral orifice: two openings in bladder for ureters
- rugae: lining that flattens before stretches
- urethral sphincters: internal (involuntary) and external (voluntary)
- trigone: functional part
35
What is micturition?
act of emptying bladder
36
What are the 4 steps of micturition?
1. urine accumulates
2. stretch receptors activated
3. voiding reflexes under conscious control
4. parasympathetic stimulation contracts bladder and relaxes internal and external sphincters
37
What fluid predominantly makes up our body?
water
38
What are 3 ways our body fluid composition can change?
- age: fluid composition goes down
- body mass: increase in muscle causes an increase in fluid
- adipose tissue: increase in adipose tissue causes a decrease in fluid
39
What are 2 types of fluid compartments?
- intracellular: fluid inside cell; cytosol
- extracellular: fluid outside cell; includes interstitial space (majority) & plasma in blood vessels
40
What is the composition of our body fluid?
- water: universal solvent, used to make things biologically active
- nonelectrolytes: do not dissociate in water; ex. is organic molecules; can contribute to osmotic gradients
- electrolytes: dissociate in water; ex is proteins, acids, bases; create osmotic potential
41
What are 4 general rules about electrolyte composition?
- electrolyte composition varies throughout the body
- buffers exists both inside and outside the cells
- if high intracellular composition we will have low extracellular composition and vice versa
- extracellular compartments are pretty equal
- sodium higher outside cell, potassium higher inside the cell
42
Where do we find proteins in our fluid?
in cells or plasma - but not interstitial space
43
What are 2 types of fluid movement?
- b/w plasma and interstitial fluid -> linked to hydrostatic pressure
- b/w interstitial fluid and intracellular fluid -> linked to osmotic pressure
44
What are two ways we intake water?
- ingestion: drinking or eating, where majority of water comes from
- metabolic water: breaking down glucose creates water
45
What are 5 ways we do water output?
- vaporization (exhalation & perspiration)
- perspiration
- elimination
- urination
- vomiting
46
What are 3 regulation mechanisms of water balance?
- increase in plasma osmolarity or decrease in blood volume promotes thirst
- decrease in extracellular fluid osmolarity decreases ADH production
- large decreases in blood pressure increases ADH production
47
What is the first sign of diabetes?
constant thirst
48
How do we intake electrolytes?
- ingestion: dietary intake, majority
- metabolic production: from nucleic acid metabolism
49
How do we have electrolyte output?
- perspiration
- elimination
- sweating
- vomiting
50
What are 6 ways to regulate sodium?
- aldosterone: increases sodium resorption; low BP signals JG cells to reduce renin which converts angiotensinogen to angiotensin 2 which stimulates adrenal cortex to produce aldosterone and this stimulates ascending loop of Henle
- cardiovascular baroreceptors: near heart & monitor BP, if high BP cause decrease in sympathetic stimulation of kidneys which causes dilation of afferent arteriole and filtration rate increases and Na+ move into renal tubule w/ water and BP goes down
- atrial natriuretic peptide: released from heart when high pressure in chambers and causes dilation of afferent arteriole and increase in filtration while reducing ADH, aldosterone, & renin production (decreases resorption)
- estrogen: increases Na+ resorption & water retention prior to ovulation
- progesterone: produced after ovulation & reduces Na+ resorption
- glucorticoids: regulate glucose in blood & increases Na+ resorption; high glucose releases cortisol which causes Na+ & water to move into blood and dilutes blood and glucose in blood
51
What is one of the most important ions?
sodium - establishes osmotic gradients
52
What is the difference b/w our blood pH & cell pH?
- blood pH: slightly alkaline
- cell pH: 7; due to CO2 causes pH to be lower
53
What is pH?
measure of hydrogen concentration in solution
54
How do we get H+?
- dietary: most of what we eat and drink is acidic
- metabolic: produced from most reactions, mainly redox
55
What are two abnormalities of blood pH?
- acidosis: pH is low -> diarrhea
- alkalosis: pH is high -> vomiting
56
What are 2 mechanisms that cause these abnormalities?
- respiratory: slow breathing -> more CO2 -> respiratory acidosis; vice versa
- metabolic: accumulation of some acid other than CO2 -> acidosis; vice versa
57
what are 3 main types of regulation of ions?
- chemical buffer system: hydrogen acceptor or hydrogen donor; temporarily binds or donates
- physiological buffer system: changes in breathing rate; eliminates or accumulates CO2; slower at changing pH but has twice the buffering compacity than chemical buffer system; permanent change
- renal mechanism: excrete or resorb things other than CO2; permanent change
58
what are 3 chemical buffer systems?
- bicarbonate: in extracellular compartment; accepts or liberates hydrogen
- phosphate: intracellular; accepts or liberates hydrogen
- protein (amphoteric): can function as acid or base, inside cells (mainly functions intracellularly) or in bloodstream, most important
59
What are 3 renal mechanisms?
- resorbing bicarbonate
- bicarbonate synthesis
- bicarbonate excretion
BIOL 2230
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