Module 4: Urinary System Flashcards
1
Q
Role of kidneys?
A
Filter blood and produce urine
2
Q
Role of ureters?
A
Receive urine from kidneys and carry urine down to bladder via gravity and peristalsis
3
Q
Role of bladder?
A
Receives and stores urine; micturition
4
Q
Role of urethra?
A
Carries urine from bladder to external environment
5
Q
Functions of urinary system?
A
- Filters blood plasma
- Prevents nutrient loss, regulates blood volume, pressure, pH, glucose levels
- Releases hormones
6
Q
Location of kidneys?
A
Retroperitoneal paired organs sitting either side of vertebral column; left kidney slightly superior to right because of liver positioning
7
Q
What is the periotoneum?
A
Abdominal sac around intestines
8
Q
What structures protect the kidneys?
A
11th and 12th ribs, visceral organs, fat, and connective tissue layers
9
Q
What is the hilum?
A
Entry/exit point for renal artery, renal nerves, renal vein, and ureter
10
Q
Function of renal artery?
A
Supplies kidney with approximately 20% of resting cardiac output, from the abdominal aorta, to be filtered
11
Q
Function of renal vein?
A
Takes blood out of kidney to inferior vena cavae
12
Q
What is the fibrous capsule?
A
Innermost CT layer of kidney; surrounds entire kidney, comprised of collagen fibres
13
Q
What is the perinephric/perirenal fat?
A
Middle CT layer of kidney; thick, cushioning layer of adipose tissue
14
Q
What is the renal fascia?
A
Outermost CT layer of kidney; dense, fibrous layer anchoring kidney to surrounding structures
15
Q
Where is the renal cortex?
A
Outermost ~1cm of kidney
16
Q
Role of renal cortex?
A
Where filtration and reabsorption - namely, waste products/water removed form blood, glucose/proteins/AAs reabsorbed from filtrate into blood - occurs
17
Q
Where is the renal medulla?
A
~2-3cm region below renal cortex
18
Q
Role of renal medulla?
A
Regulates concentration of urine
19
Q
Where is the renal sinus? What comprises it?
A
Central cavity of kidney; renal pelvis, renal calyces, blood vessels, fat
20
Q
Where are the renal pyramids?
A
Conical structures extending from cortex to sinus
21
Q
How many renal pyramids per kidney?
A
8-18 per kidney
22
Q
Role of renal pyramids?
A
Transport urine from the renal cortex to the renal sinus
23
Q
What is a renal papilla?
A
Apex of a renal pyramid (facing sinus) which projects into the lumen of a kidney calyx and through which collecting ducts discharge urine
24
Q
What are renal columns?
A
Bands of tissue separating adjacent renal pyramids
25
What comprises kidney lobes?
Renal pyramid + overlying renal cortex + adjacent tissues of renal columns
26
Role of kidney lobes?
Functional units where urine is produced
27
Role of minor calyces?
Collect urine produced by a single kidney lobe
28
What are major calyces?
Fusion of 4-5 minor calyces
29
Role of major calyces?
Collect urine from minor calyces
30
What is the renal pelvis?
Large funnel-shaped chamber which is continuous with ureter
31
How frequently do ureters drain urine from the kidney and transport it to the bladder?
Every ~30 seconds
32
What are the ureters?
Pair of retroperitoneal muscular tubes extending from kidneys to urinary bladder, firmly attached to posterior abdominal wall, ~25-30cm long
33
Describe the mucosa of the ureters.
Transitional epithelium (stratified cuboidal/squamous), allowing for expansion of ureter diameter
34
Describe the muscularis externa of ureters.
Layer of smooth muscle outside mucosa that facilitates peristalsis
- Upper two-thirds: 2 layers (inner longitudinal, outer circular)
- Lower one-third: 3 layers (inner longitudinal, middle circular, outer longitudinal)
35
Describe the mucosa of the bladder.
Transitional epithelium (stratified cuboidal/squamous), with rugae
36
Describe the muscularis externa of the bladder.
Layer of smooth muscle outside mucosa that facilitates expulsion of urine; 3 layers (inner longitudinal, middle circular, middle longitudinal), with sphincters
37
What are sphincters of the bladder?
Bands of skeletal muscle that act as valves, controlling urine flow
38
Different between internal urethral sphincter and external urethral sphincter?
- Internal urethral sphincter = involuntary
- External urethral sphincter = voluntary
39
Role and length of urethra in males?
~20-25cm in males, transporting urine and semen
40
Role and length of urethra in females?
~4cm in females, transporting urine
41
Describe the mucosa of the urethra.
- Proximal (near bladder): transitional epithelium
- Middle: stratified and pseudostratified columnar
- Distal: stratified squamous
42
Describe the muscularis externa of the urethra.
- Proximal: 2 layers of smooth muscle (inner longitudinal, outer circular)
- Distal: some skeletal muscle, associated with external urethral sphincter
43
What is micturition?
Urination; expulsion of urine
44
When does the urge to urinate occur?
When urine in bladder is at ~200mL
45
What triggers the micturition reflex?
Stretch receptors in bladder wall
46
What occurs if the micturition reflex is ignored?
Urine continues to accumulate, and at 500mL, detrusor muscle contractions force internal urethral sphincter open
47
In what populations does micturition occur involuntarily? Why?
If neurological pathway for control of external urethral sphincter is not established (infants), or not powerful enough to prevent (elderly), micturition occurs involuntarily
48
How nephrons per kidney?
~1 million per kidney
49
2 types of nephrons?
- Cortical nephrons (~85%)
- Juxtamedullary nephrons (~15%)
50
What are cortical nephrons?
Short nephron loops, located almost entirely renal cortex, and important for excreting waste products into urine
51
What are juxtamedullary nephrons?
Have long nephron loops extending deep into renal medulla, and important for producing concentrated urine
52
3 main components of nephron?
- Renal corpuscle
- Renal tubule
- Collecting system
53
What comprises the renal corpuscle structure?
Spherical filtration structure consisting of glomerulus and glomerular/Bowman's capsule
54
Glomerulus structure?
Capillary network, with afferent arterioles (going in) and efferent arterioles (going out)
55
What increases glomerular pressure?
Smaller diameter of efferent arterioles
56
Role of renal corpuscle?
Site of blood filtration via filtration membrane, driven by blood pressure; water and dissolve solutes are pushed out of glomerular capillaries -> capsule space -> renal tube
57
What is Bowman's capsule?
C-shaped structure partially surrounding the glomerulus
58
What is filtration membrane?
Porous membrane between the blood and the capsular space
59
Role of filtration membrane?
Controls what blood components enter nephron and what remains within vessels and re-enters circulation
60
Layers of the filtration membrane?
- Fenestrated endothelium (stops cells and platelets)
- Basement membrane (stops large/charged proteins)
- Slits between pedicels (stops medium-sized proteins)
61
What are pedicels?
Foot-like processes extending from each podocyte that wrap around glomerular capillaries
62
What is a podocyte?
Epithelial cells surrounding the glomerulus
63
What passes through the filtration of the corpuscle?
Water, small proteins, amino acids, glucose, salts
64
Role of renal tubule?
Site of filtrate modification, where filtrate components are altered via secretion and absorption
65
3 components of renal tubule?
- Proximal convoluted tubule (PCT)
- Loop of Henle/nephron loop
- Distal convoluted tubule (DCT)
66
Function/structure of PCT?
- Beginning of renal tubule
- Cells have microvilli to aid reabsorption of essential substances from filtrate back into blood
67
Function/structure of Loop of Henle?
- Middle segment of renal tubule
- Ascending and descending components
- Descending: reabsorption of water
- Ascending: impermeable to water reabsorption of Na+ and Cl- from filtrate
68
Function/structure of DCT?
- Last segment of renal tubule
- Adjusts filtrate composition via reabsorption and secretion (more so secretion)
- Reabsorption of water, Na+, Ca++ in exchange for secretion of H+, etc.
69
What are the ducts associated with the collecting system?
- Collecting duct
- Papillary duct
70
Role of collecting system?
Tubular fluid (urine) from each nephron empties into collecting system -> minor calyces
71
Role of collecting duct?
- Receives fluid from the DCTs of several nephrons as it passes back into the medulla via the osmotic gradient
- May/may not reabsorb water, depending on hydration status
72
Role of papillary duct?
Collects filtrate from multiple collecting ducts and delivers it to a minor calyx
73
Through what blood vessel does oxygenated blood enter the kidney?
Renal artery
74
Into what blood vessels does the renal artery divide into?
Divides into segmental arteries in the renal sinus
75
Into what blood vessels do segmental arteries divide into?
Interlobar arteries, which run within renal columns
76
Pathway of blood through the kidneys to the glomerulus to out again?
Renal artery -> segmental arteries -> interlobar arteries -> further branched arteries -> afferent arterioles -> glomerulus -> efferent arterioles -> peritubular capillaries -> cortical veins -> inferior vena cavae
77
What are peritubular capillaries? Role?
Tiny blood vessels that surround the entire renal tubule, allowing reabsorption and secretion between blood and the inner lumen of the nephron
78
3 functions of that regulate composition and volume of blood?
Filtration
Reabsorption
Secretion
79
Where does filtration of blood occur?
In the renal corpuscle
80
What is reabsorption?
Transport of water and solutes:
Tubular fluid -> peritubular fluid -> bloodstream
81
What is secretion?
Transport of solutes:
Peritubular fluid -> tubular fluid
82
What is the Glomerular Filtration Rate?
Volume of filtrate formed per minute by both kidneys
83
What are diuretics?
Chemicals that slow/inhibit water reabsorption in the collecting duct, and so enhance urinary output
e.g. substances that encourage diuresis by inhibiting release of ADH (alcohol), substances that inhibit Na+ reabsorption (caffeine)
84
3 most important metabolic waste products?
Urea, creathrine, uric acid
85
What factors enhance filtration?
Thinner filtration membrane, large SA of glomerular capillaries, higher glomerular BP
86
What is urea?
A chemical that comes from the breakdown of proteins in the liver
87
What is creatinine?
Product of muscle breakdown, measurement of kidney function
88
What is uric acid?
Product of nucleic acid catabolism
89
What is body fluid?
Liquid portion of cells and tissues; 55-60% of body mass
90
What is intracellular fluid?
Fluid inside the cell (ICF)
91
What is extracellular fluid?
Fluid outside the cell (ECF)
92
Where does exchange between ICF and ECF occur?
Cell membrane
93
Where does exchange between ECF and blood plasma occur?
Capillary wall
94
What is metabolic water?
Water formed by cells as a metabolic, unregulated by-product (about 200mL of water gain)
95
Where is thirst regulated?
Hypothalamus
96
What 4 organs are responsible for water loss?
Kidneys
Skin
Lungs
GIT
97
What are electrolytes?
Charged ions in a solution
98
Functions of electrolytes?
Controls osmosis
Maintains acid-base balance
Carries electrical currents
99
What electrolytes do we mainly gain from eating a salty meal?
Increase of Na+ and Cl- ions in the blood
100
Response to eating a salty meal?
Water moves from ICF -> ECF -> blood plasma, increasing blood volume and urine output
101
What are acids?
Substances that release H+ ions, thus lowering pH
102
What are bases?
Substances that accept H+ ions, thus raising pH
103
What is acidosis?
Blood pH below 7.35; suppresses CNS -> coma
104
What is alkalosis?
Blood pH above 7.45; excites CNS -> seizures, spasms, convulsions
105
What is a lower UTI?
Infection in bladder, urethra; relatively uncomplicated
106
What is an upper UTI?
Infection in ureters, kidney; serious
107
What is the rate of UTIs in men vs women? Why?
1 in 20 men, 1 in 2 women; more frequent in women due to shorter urethra
108
What are kidney stones?
Crystallisation of minerals and salts in urine, forming hardened lumps of matter, affecting any part of urinary tract (kidney -> bladder)
109
Causes of kidney stones?
Dehydration, excess Ca2+
110
What is renal failure?
Kidney failure; kidneys unable to filter wastes from blood and homeostasis thus cannot be maintained any longer
111
What is acute renal failure?
Sudden, relatively reversible
112
What is chronic renal failure?
Gradual, generally irreversible
113
What is caused by renal failure?
BP increases
Anaemia develops (decreased EPO production)
CNS problems (sleepy, coma)
114
What is erythropoietin?
Hormone secreted by kidneys that stimulates erythropoiesis
115
What is dialysis?
Time-consuming procedure that removes waste products and excess fluid - that is, perform purification of blood - upon kidney dysfunction; glomerular membrane replaced with artificial membrane
116
Role of aldosterone?
Increases retention of sodium and water, and the excretion of potassium, by the kidneys
117
Role of ANP?
Increases glomerular filtration rate (GFR) within the kidney by dilating the afferent arterioles and constricting the efferent arterioles
118
Role of ADH?
Causes the kidneys to release less water, decreasing the amount of urine produced (urine output)
