Urinary System Flashcards
1
Q
Primary Function of Urinary System
A
Forms urine through filtration of blood
2
Q
Functions of Urine
A
- excretion of metabolic wastes esp nitrogenous waste
- regulates blood vol, osmolarity
-regulates acid-base balance
3
Q
Kidneys Function
A
- filter blood
- form urine
4
Q
Ureters Function
A
transport urine to urinary bladder
5
Q
Urinary Bladder Function
A
stores urine
6
Q
Urethra Function
A
excretes urine from urinary bladder
7
Q
Additional Kidney Functions
A
- secrete erythropoietin
- calcitriol synthesis
- detoxify free radicals
8
Q
Erythropoietin
A
hormone that stimulates erythropoiesis (making RBCs)
9
Q
Calcitriol Synthesis
A
- calcitriol is active form of vitamin D
- raises blood calcium
10
Q
Free Radicals
A
atoms with an unpaired electron
- highly reactive, destructive
-oxygen radicals toxic to anerobic organisms
11
Q
Nitrogenous Wastes
A
metabolic wastes through which excess nitrogen is eliminated from the body
*toxic at high enough conc.
12
Q
Types of Nitrogenous Waste
A
- Ammonia (NH3)
- Urea (Co(NH2)2)
- Uric Acid
- Creatinine
13
Q
What is Ammonia (NH3) produced from?
A
amino (NH2) groups during protein breakdown
14
Q
What is Urea (CO(NH2)2) produced from?
A
ammonia by liver (less toxic than ammonia)
15
Q
What is Uric acid produced from?
A
breakdown of nucleic acids
16
Q
What is Creatinine produced from?
A
breakdown of creatine phosphate
17
Q
Renal Capsule/Fibrous Capsule Location, Function, + Composition
A
- external layer
- encloses, protects kidney
- composed of collagen fibers
18
Q
Renal Parenchyma Function + Location
A
function: granular tissue that forms urine
location: encircles renal sinus
19
Q
Renal Sinus
A
cavity near the medial aspect of kidney
20
Q
Regions of Parenchyma
A
- Cortex: more superficial
- Medulla: deeper
> renal columns
> renal pyramids
21
Q
Renal Columns
A
extensions fo cortical tissue
22
Q
Renal Pyramids
A
composed of nephron loops and collecting ducts
23
Q
Function of Kidney Blood Vessels
A
provide blood supply and urine formation
24
Q
Arteries: Blood Flow Through Kidney
A
Renal artery -> segmental arteries -> interlobar arteries -> arcuate arteries -> cortical radiate arteries -> cortex -> afferent arterioles
25
Veins: Blood Flow Through Kidney
peritubular capillaries/vasa recta -> cortical radiate v -> arcuate v -> interlobar v -> renal v
26
Where do interlobar arteries pass through before branching into arcuate arteries?
renal columns
27
Where do Arcuate Arteries lie?
corticomedullary junction- border b/w the renal cortex and medulla
28
What is the name of the capillary bed formed from afferent arterioles?
Glomerulus
29
Where do Efferent arterioles emerge from?
glomerulus
30
What do Efferent arterioles eventually branch into?
peritubular capillaries or vasa recta
31
Unlike kidney arteries, kidney veins do not have ____________ veins.
segmental
32
Functional Unit of Kidney
nephron
33
Nephron Function
- filter blood to form filtrate
- concentrate filtrate
- convert filtrate into urine
34
Filtrate
filtered blood that enters the nephron
35
How many nephrons are there per kidney?
1.2 million per kidney
36
Nephron: Renal Corpuscle Parts
- glomerulus
- bowman's (glomerular) capsule
37
Nephron: Renal Tubule
- proximal convoluted tubule
- nephron loop/loop of Henle
- distal convoluted tubule
- collecting duct
38
Nephron- Renal Corpuscle
filters blood
found in cortex
39
Glomerulus
- cluster of capillaries
- delivers blood to be filtered
40
Bowman's (Glomerular) Capsule
- surrounds glomerulus
- 3 layers: visceral layer, capsular space, parietal layer
41
Bowman's Capsule- Visceral Layer
cells called podocytes surrounding capillaries
42
Bowman's Capsule- Capsular Space
b/w visceral and parietal layer where filtered blood (filtrate) enters corpuscle
43
Bowman's Capsule- Parietal Layer
outer wall of corpuscle
44
Proximal Convoluted Tubule (PCT)
receives filtrate from renal corpuscle
- found in cortex
- long, coiled
45
Nephron Loop/Loop of Henle
receives filtrate from PCT
- descends into medulla, part of pyramids
- U shaped
46
Distal Convoluted Tubule (DCT)
receives filtrate from Nephron Loop
- found in cortex
- finishes forming urine from filtrate
47
Collecting Duct
receives urine from many DCTs; delivers urine to larger urine-collecting structures of kidney
*not usually considered part of a single nephron
- within renal pyramid
48
Urine Formation- Glomerular Filtration
special capillary exchange where blood of the glomerulus is filtered, substances removed enter Bowman's capsule as filtrate
49
Basic Urine Formation- Tubular Reabsorption
solutes are removed from filtrate, returned to blood
- occurs in renal tubule
50
Basic Urine Formation- Tubular Secretion
additional substances are removed from blood, added to filtrate
- occurs in renal tubule
51
Basic Urine Formation- Water Conservation
water is removed from filtrate, returned to blood
- occurs in renal tubule- collecting duct
52
What is the first stage of urine formation?
glomerular filtration
53
Where does Glomerular Filtration take place?
Renal Corpuscle
54
What is the filtration membrane made up of?
capillary endothelium, basement membrane, + filtration slits
55
Capillary Endothelium
fenestrations allow anything smaller than 70 nm out of capillary
56
Basement Membrane
- allows substances smaller than 8nm + neutral or pos charged molecules through
- b/w glomerulus + podocytes
- negatively charged
57
Filtration Slits
- allow substances into capsular space
- spaces b/w foot processes of podocytes
58
What substances are usually in filtrate?
water, glucose, amino acids, fatty acids, nitrogenous wastes, salts, etc
59
T/F: Blood cells and proteins leave the blood.
False; they stay in blood
- cells: too big
- proteins: too big + neg charged
60
Glomerular Filtration Rate (GFR)
amount of filtrate formed per minute by the two kidneys combined
61
What is the average GFR?
- male: 125 mL/min
- female: 105 mL/min
62
What percent of filtrate is reabsorbed (retuned to blood)?
99%
63
How many liters of urine is excreted per day?
1-2L
64
What happens if GFR is too high?
fluid flows too quickly through renal tubule for sufficient reabsorption
65
Does urination increase or decrease if GFR is too high?
increases!
- risk of dehydration
66
What happens if GFR is too low?
wastes not removed from blood or are reabsorbed
67
Higher Glomerular BP = ________ BHP
higher
68
Higher BHP = _______ NFP = ______ GFR
higher, higher
69
BHP
Blood Hydrostatic Pressure
70
NFP
Net Filtration Pressure
71
What equation determines NFP?
NFP = BHP - (CP + COP) = 10 mmHg
(subtracting the forces opposing filtration from forces favoring filtration)
72
Does BHP favor filtration or reabsorption?
filtration
73
Why is BHP very high in glomerulus?
because afferent arteriole is wider than efferent arteriole
74
CP
Capsular Hydrostatic Pressure
75
Does CP favor filtration or reabsorption?
reabsorption
76
Why does CP favor reabsorption?
caused by filtrate in capsular space
77
COP
blood Colloid Osmotic Pressure
78
Does COP favor filtration or reabsorption?
reabsorption
79
Why does COP favor reabsorption?
caused by proteins in plasma
80
Blood Hydrostatic Pressure
the pressure exerted by the blood on the walls of the glomerular capillaries
81
Capsular Hydrostatic Pressure
the pressure exerted by the fluid in Bowman's capsule
82
Blood Colloid Osmotic Pressure
the osmotic pressure exerted by proteins in the blood plasma
83
The afferent arteriole brings blood _____ the glomerulus, while the efferent arteriole carries blood _____ the glomerulus.
into; away from
84
What are the 2 mechanisms of GFR regulation?
1. renal autoregulation
2. sympathetic control
85
What is renal autoregulation?
when nephrons adjust their own blood flow
86
What are the 2 mechanisms of Renal Autoregulation?
1. myogenic mechanism
2. tubuloglomerular feedback
87
Myogenic Mechanism Function
prevents sudden, short-term increases in systemic BP from overly increasing GFR
88
When will smooth muscle of afferent arterioles contract?
when it is stretched by higher BP
89
What do afferent arterioles do in response to stretching/sudden increase in BP?
contract; the constriction reduces amount of blood flowing into glomerulus
90
Does contraction of afferent arterioles raise or lower GFR?
lower
91
Tubuloglomerular Feedback
glomerulus receives feedback of status of downstream tubular fluid and adjusts filtration rate
92
What is the macula densa?
patch of sensory cells in nephron loop just before DCT
93
Macula Densa Function
detects NaCl levels in filtrate
94
If GFR is high is NaCl high or low?
NaCl is also high
95
What does the Macula Densa do in response to high NaCl levels?
stimulates Juxtaglomerular cells
96
Juxtaglomerular Cells (granular cells)
modified smooth muscle cells wrapping around the afferent arteriole
97
Juxtaglomerular Cell Function
constrict if stimulated by Macula densa (less blood flow to glom., lower glo. BP, lower GFR)
98
What occurs during sympathetic control?
sympathetic innervation + catecholamines from adrenal medulla cause vasoconstriction of afferent arterioles
99
When afferent arterioles contract during sympathetic control does that raise or lower GFR?
lower; afferent arterioles contract -> less blood flow to glo -> lower glo BP, lower GFR
100
Where is reabsorbed filtrate from the proximal convoluted tubule sent?
peritubular capillaries
101
Where does reabsorption take place?
proximal convoluted tubule, nephron loop, distal convoluted tubule
102
What percentage of filtrate is reabsorbed in the proximal convoluted tubule?
65%
103
Transport of _______ drives movement of other solutes and osmosis of water.
Na+
104
True/False: reabsorption in the PCT requires energy.
true; 6% of resting ATP use
105
What percentage of filtrate is reabsorbed in the nephron loop?
25%
106
Where is reabsorbed filtrate from the nephron loop sent?
vasa recta
107
What is reabsorbed under hormonal regulation in the DCT?
water, Na+, + Cl-
108
Where is reabsorbed filtrate from the DCT sent?
peritubular capillaries
109
True/False: Water conservation also occurs in the DCT
True
110
Where is urine finished being produced?
distal convoluted tubule
111
Tubular secretion is performed via __________ + _________.
active transport + diffusion
112
3 Purposes of Tubular Secretion
1. acid-base balance
2. waste removal
3. clearance of drugs + contaminants
113
H+ secretion _________ blood pH and HCO3- secretion ________ pH.
raises, lowers
114
What 2 types of waste are removed during tubular secretion?
1. nitrogenous wastes
2. bile acids
115
Nephron Loop Function
generates the high osmolarity/salinity of medulla ECF
116
High osmolarity/salinity = _______ solute concentration
high
117
Osmolarity
the number of particles of solute particles per liter of solution
118
Is salinity higher more superficial or deeper into the medulla?
deeper
119
What occurs in the Collecting Duct?
urine concentration via water conservation
120
Water Conservation
the reabsorption of water from the collecting duct
121
What are the 2 components of the nephron loop?
1. descending limb
2. ascending limb
122
Where does the nephron loop receive filtrate from?
proximal convoluted tubule
123
The Descending Limb descends into the _______.
medulla
124
Is the Descending Limb permeable to water/salts?
thin segment is permeable to water, but NOT salts
125
The Ascending Limb ascends towards the _______.
cortex
126
Is the Ascending Limb permeable to water/salts?
thick segment is permeable to salts, but NOT water
127
Where does the Ascending limb deliver filtrate to?
distal convoluted tubule
128
The Nephron Loop is known as a _____________ bc it uses a system with two adjacent limbs.
countercurrent multiplier
129
Multiplier
multiples the salinity/osmolarity of medulla ECF
130
Countercurrent
fluid moves in opposite directions in the ascending vs descending limb of nephron loop
131
The Descending limb passes through environment of _________ osmolarity.
increasing
132
True/False: Water does not leave the filtrate in the descending limb.
false; water constantly leaves filtrate
133
What is the filtrate concentration at the bottom of loop?
1200 mOsm/L
134
Which limb is filtrate diluted?
ascending
135
What 3 ions are reabsorbed into ECF by active transport?
Na+, K+, and Cl-
136
Is more salt pumped out of ascending limb or more water lost from descending limb?
more salt pumped out of ascending limb
137
Is the filtrate more dilute in DCT or PCT?
DCT
138
What is the result of lots of salt being pumped out of the ascending limb?
generates/maintains high osmolarity of medulla
139
What are vasa recta?
capillaries of medulla
140
Vasa Recta Function
reabsorb material from nephron loop
141
True/False: vasa recta affect the osmolarity of the medulla.
false
142
Do the vasa recta absorb more water or salt?
absorb the same of each
143
Diffusion in Descending Capillaries
- lots of NaCl diffuses into blood
- some water diffuses out
144
Diffusion in Ascending Capillaries
- some NaCl diffuses out of blood
- lots of water diffuses in
145
Collecting Ducts descends from _______ to ________.
cortex, medulla
146
How is water reabsorbed in the CD?
osmosis
147
Does more water reabsorbed increase or decrease the concentration of the urine?
increases
148
Does more water reabsorbed increase or lower the volume of urine produced?
lower
149
Urine becomes up to __x as concentrated in the collecting duct.
4
150
Renin-Angiotensin-Aldosterone Mechanism
hormonal system that regulates blood pressure
151
Renin-Angiotensin-Aldosterone Mechanism Function
regulates GFR (some) and reabsorption (more) of the nephron
152
When does sympathetic stimulation cause juxtaglomerular cells to secrete Renin?
when systemic BP falls
153
What conversion does Renin make?
angiotensinogen to angiotensin I
154
ACE
angiotensin converting enzyme
155
What does ACE convert?
angiotensin I to angiotensin II
156
Angiotensin II
potent vasoconstrictor hormone
157
Angiotensin II raises/lowers BP
raises BP
158
Why does Angiotensin II constrict efferent more than afferent arterioles at the renal corpuscle?
to keep glomerular BP high, preventing huge drop in GFR
159
Angiotensin II stimulates the adrenal cortex to release what hormone?
aldosterone
160
Aldosterone causes reabsorption of what 2 things in the DCT?
Na+ and water
161
Aldosterone _______ blood volume + ________ BP
raises, raises
162
Antidiuretic Hormone
hormone produced in hypothalamus, secreted by posterior pituitary
163
Antidiuretic Hormone Function
reduce urination, increase blood volume + BP
164
Does ADH make the collecting duct more or less permeable to water?
more permeable
165
ADH causes more/less water reabsorption from collecting duct?
more
166
What effect does less water ending up in the urine have on volume of concentrated urine?
lower volume of more concentrated urine
