Chapter 14 - Urinary System Flashcards
1
Q
Main kidney functions
A
-maintain stability of ECF volume
-electrocute composition
-osmolarity
2
Q
Ureters
A
Transport and store
-exists each kidney at the medial border
-carry urine to bladder
3
Q
Urinary bladder
A
-stores urine
-empties via urethra
4
Q
urethra
A
Transports urine out of the body
-shorter in females
5
Q
Nephron
A
Functional unity of kidney
-vascular/tubular
6
Q
Two distinct regions in nephron
A
Outer and inner
7
Q
Outer region
A
Renal cortex
8
Q
Inner region
A
Renal medulla, renal pyramids
9
Q
Afferent arteriole
A
Carries blood to the glomerulus
10
Q
Glomerulus
A
Capillaries that filter a protein free plasma into tubular component
11
Q
Efferent arteriole
A
Carries blood from glomerulus
12
Q
Peritubular capillaries
A
Supplies renal tissue
-exchanges with the fluid in tubular lumen
13
Q
Bowman’s capsule
A
Collects glomerular filtrate
14
Q
Proximal tubule
A
Uncontrolled reabsorption and secretion of selected substances
15
Q
Loop Henle of long looped nephrons
A
-osmotic gradient in renal medulla
-produces urine of varying concentration
16
Q
Distal tubule and collecting duct
A
-reabsorbs Na+ and H2O
-secretes K+ and H+
-fluid leaving is urine
17
Q
Juxtaglomerular apparatus
A
Produces substances involved in the control of kidney function
18
Q
A comes before
A
E
19
Q
Vascular component of nephron
A
-dominant part is glomerulus
20
Q
Tubular component of nephron
A
Hollow, fluid filled tube formed by a single layer
21
Q
Draw out the direction of kidney function
A
22
Q
All nephrons originate in the
A
Cortex
23
Q
Glomeruli of cortical nephrons life in
A
The outer layer of cortex
24
Q
Glomeruli of juxtamedullary nephrons lie in
A
The inner layer of the cortex
25
Most abundant type of nephron
Cortical
26
Long looping vasa recta
Juxtamedullary nephrons
27
Peritubular capillaries
Cortical nephrons
28
Three basic processes
-glomerular filtration
-tubular reabsorption
-tubular secretion
29
Glomerular filtration
Non discriminate filtration of protein free plasma
-glomerulus into bowman’s capsule
30
Tubular reabsorption
Selective movement of filtered substances
-tubular lumen into Peritubular capillaries
31
Tubular secretion
Selective movement of non filtered substances
-Peritubular capillaries into tubular lumen
32
Amount of glomerular filtration
180 L/day
33
Tubular reabsorption amount
178.5 L/day
34
Kidneys receive ___% of cardiac output
20 to 25
35
Total blood flow through the kidneys is
> 1L/min
36
80 percent of plasma that entered the glomerulus is ___ ____ and leaves through the efferent arteriole
Not filtered
37
Filtered fluid from glomerulus into bowman’s capsule passes through ___ layers of glomerular membrane
Three
38
Type of glomerular capillary wall
Fenestrated capillary
-large gaps
-more permeable
39
Cell body of podocyte is
Outside of capillary
40
Podocytes
Terminate in foot processes
-surround the basement membrane of the glomerulus
41
Clefts between the foot processes are called
Filtration slit
-where filtrate enters the bowman’s capsule
42
Glomerular filtration is a __ process in which
-passive process
-hydrostatic pressures force the fluids and solute through a membrane
43
How are glomeruli efficient filters
1. The filtration membrane is a large SA and very permeable to water and solutes
2. Glomerular pressure is higher vs other capillaries
44
Three physical forces involved
-glomerular capillary bp
-plasma colloid osmotic
-bowman capsule hydrostatic pressure
45
Glomerular capillary blood pressure
Out of capillary
-55 mmHg
-aff vs eff
-along entire capillary length
46
Plasma colloid osmotic
Into capillary
-30 mmHG
-high because of more water filtered
47
Bowman’s capsule hydrostatic pressure
Into outside of capillary
-balance
-15 mmHg
48
Calculation of pressures in glomerular filtration
55 - (30 + 15)
55 - 45
49
Favours filtration
Glomerular capillary blood pressure
-55 mmhg going OUT
50
Opposes filtration (two)
-plasma colloid 30
-bowman’s capsule hydrostatic 15
51
Net filtration pressure
-the difference between opposing and favouring
Favour the filtration
-10 mmHg
52
Blood pressure of glomerular capillary depends on
Resistance to blood flow by aff and eff arteriole s
53
Glomerular capillary blood pressure definition
-fluid pressure exerted by blood in glomerular capillaries
-major force producing glomerular filtration
54
Plasma colloid osmotic pressure is caused by
Unequal distribution of plasma proteins across glomerular membrane
-opposes filtration
55
Bowman’s capsule hydrostatic pressure def
-pressure entered by fluid in initial part of tubule
-push fluid out of bowman’s capsule
56
Glomerular filtration rate depends on
Net filtration pressure
57
Pathological influences on plasma colloid osmotic pressure
-severely burned patient has a greater GFR
-dehydrating diarrhea lower GFR
58
Pathological influences on bowman’s capsule hydrostatic pressure
Obstructions lower GFR
-kidney stones
59
What can be controlled to adjust GFR to suit the body’s needs
Glomerular capillary blood pressure
60
What are constant pressures of the body
Plasma colloid osmotic pressure and bowman’s capsule hydrostatic pressure
61
Two major control mechanisms on glomerular capillary blood pressure to alter GFR
-autoregulation
-extrinsic sympathetic control
62
Autoregulation
Aimed at preventing spontaneous changes
-myogenic
-tubuloglomerular feedback
63
Extrinsic sympathetic control
Aimed at long term regulation of arterial blood pressure
-sympathetic ns input to aff arteriols
-barreceptor reflexc
64
Spontaneous changes in GFR are prevented by
Intrinsic regulatory mechanisms
-autoregulation
65
Increase of BP
Increase of GFR
66
Decrease of BP
Decrease of GFR
67
Autoregulation works by changing the
Diameter for afferent arteriole
-then changing bp
68
Vasoconstriction of aff arteriole
Dec glomerular capillary bp and net filtration
Dec GFR
69
Vasodilation of aff arteriole
Inc glomerular capillary bp, net filtration pressure
In GFR
70
Myogenic mechanism
Vascular smooth muscle
-stretch and contract
Less stretch, causes relaxation
71
Tubuloglomerular feedback
Involves juxtaglomerular apparatus
-salt delivery to macula dense regulates ATP release
-degrades to adenosine
-adenosine constricted aff arteriole
72
Autoregulation by tubuloglomerular feedback
Increase in salt increases ATP
-aff constriction
-dec blood flow
73
Inc salt is due to
Increased GFR
74
Dec blood flow
Dec GFR
75
Autoregulation s prevents
Unintentional shifts in GFR
76
Increase in BP does what to GFR
Does not increase GFR
77
Low BP does not result in
Excess waste products
78
Extrinsic sympathetic control aimed at
Aimed at long term regulation of arterial blood pressure
79
Extrinsic control is a
Deliberate change mediated by sympathetic ns input to aff arteriole
80
Decrease in arterial blood pressure is detected by
Aortic arch and carotid sinus baroreceptors
81
What are the short term adjustments that can be made in response to low arterial blood pressure
Inc of cardiac output and TPR
82
Long term adjustment for Dec arterial blood pressure
Lowered GFR, urine volume, conservation of fluid and salt
83
Where does filtration take place
Glomerulus
84
Where does reabsorption take place
-proximal tubule
-loop of henle
-distal tubule
-collection duct
85
Where does secretion take place
-proximal tubule
-loop of henle
-distal tubule
-collecting duct
86
Lumen to blood
Reabsorption
87
Blood to lumen
Secretion
88
Tubular reabsorption
-transfer of substances from tubular lumen into Peritubular capillaries
-selective and variable
-transepithelial transport (five barriers)
89
The order of tubular reabsorption
-Tubular fluid into luminal membrane
-pass through cytosol
-cross basolateral membrane
-through interstitial fluid and capillary wall
90
Tubular fluid is the same concentration as in plasma except for
PROTEINS
91
Waste material remains in
Tubule
92
Passive reabsorption
-no energy needed
-down electrochemical/osmotic gradients
93
Active reabsorption
-requires energy
-against electrochemical gradient
94
Percentage of Na reabsorbed: proximal tubule
67
95
Percentage of Na reabsorbed: ascending limb—> loop of henle
25
96
Percentage of Na reabsorbed: distal and collecting tubules
8
97
Role of Na reabsorption: proximal tubule
Reabsorbs: glucose, amino acids, H2O, Cl and urea
98
Role of Na reabsorption: ascending limb of the loop of henle
Kidneys ability to produce urine of varying concentrations
99
Role of Na reabsorption: distal and collecting tubules
-hormonal control
-regulates ECF volume
100
What is found on basolateral membrane and is essential for Na reabsorption
Na and K, ATPase pump
101
What happens to water when sodium is reabsorbded by osmosis
Water follows direction of sodium
102
Sodium reabsorption effects
-blood volume
-blood pressure
103
Why is Na reabsorption so important
Volume and pressure
104
If you control Na (and Cl) you control..
ECF and water volume
105
If you control ECF water volume you control…
Blood volume
106
If you control blood volume you control…
BP control
107
What increases blood volume
-passive bulk flow of fluid from IF into plasma
-salt and water retention
108
___ is the most abundant cation in the filtrate
Na
109
___ reabsorption is almost always active transport
Na
110
Function of Na pump
Generates and electrochemical gradient that couples to passive entrance of other substances
-glucose, amino acids
111
Fine tuning of Na reabsorption takes place in
Distal tubule
112
If there is too much Na then..
Less reabsorbed
-excreted in urine
113
If too little Na
Then more is reabsorbed
114
Na load reflects ___ volume
ECF
115
ECF volume changes
Affect BP
116
RAAS
Renin angiostensin aldosterone system
117
Renin angiostensin aldosterone system
Important for Na regulation
-renin release
-control volume ECF
118
Liver releases
Angiotensinogen
119
Kidney releases
Renin
120
What two hormones combine to activate angiotensin 1
Renin and angiotensinogen
121
Angiotensin activates
Angiotensin 2
122
Angiotensin II activates
Aldosterone
123
Aldosterone
Stimulates kidney to increase Na reabsorption
124
Function of RAAS
Inc Na absorption, promotes water retention
-stimulate thirst
-stimulate vasopressin secretion
125
Aldosterone
Acts on last portion of distal convoluted tubules and collecting ducts
-Na channels
-more Na/K ATPase pumps
126
Low ECF volume and low BP causes
More renin released
127
More renin released causes
More aldosterone
128
More Aldosterone causes
More Na reabsorption
129
More Na reabsorption causes
Greater volume in ECF
130
High ECF volume causes
Less renin released
131
Less renin released causes
Less aldosterone
132
Less aldosterone causes
Less Na reabsorption
133
Less Na reabsorption causes
More body volume in urine
134
ANP- atrial natriuretic peptide
Inhibits Na reabsorption
-secreted by atria
135
Inhibiting Na reabsorption opposes
Aldosterone effects
136
ANP is secreted by atria in response to
-stretching due to Na retention
-expansion of ECF volume
-inc in arterial pressure
137
How are glucose and amino acids reabsorbed
By sodium dependent
-secondary active transport
138
How is electrolytes such as Ca reabsorbed
Cl follows passively
139
80 percent of water reabsorbed is
Uncontrolled
140
What places in the urinary system is water reabsorbed
-proximal tubule 65
-loop of henle 15
-distal portion of nephron
141
20 percent of water reabsorbed is
Controlled
142
Where is water reabsorption controlled
When in control of hormone vasopressin
-distal portion
143
Water follows
Na
144
When water is reabsorpted in the proximal tubule and loop of henle it is what?
NOT subject to regulation
145
Aquaporins
How water is reabsorbed
146
Bulk flow in water reabsorption is enhanced by …
Is enhanced by inc plasma colloid osmotic pressure in the peritubular capillaries
147
Waste products become more ___ as water is reabsorbed
Concentrated as water is reabsorbed
148
Urea
Waste product from the breakdown of protein
149
Tubular secretion
Moving from peritubular capillaries into the tubular lumen
-kidney tubules selectively add
150
H+ secretory system
Important in regulating acid base balance
151
Where is H+ secreted
Proximal, distal and collecting tubules
152
K+ secretory system
Keeps plasma K concentration at appropriate level
-to maintain normal membrane excitability in muscles and nerves
All filtered K is reabsorbed
153
Where does K+ tubular secretion take place
Distal and collecting tubules
-control of aldosterone
154
Organic irons secretory system
Efficient elimination of foreign organic compounds from the body
155
where are organic ions secreted
Only in proximal tubules
156
Na K pump
-moves Na out of the cell into lateral space
-transports K from lateral space into tubular cells
157
Control of K secretion
Aldosterone
-if there is an inc of K, then Aldosterone will inc to promote secretion of excess K
158
Aldosterone can be stimulated by
Two separate pathways
159
Inc aldosterone leads to
Promotes Na reabsorption and K secretion
160
K+ secretion in basolateral membrane vs luminal membrane
-basolateral membrane: K+ is recycled
-luminal membrane: K+ secretion
161
Basolateral membrane is located
Proximal tubule and loop of henle
162
Luminal membrane is found
Distal portions
163
If aldosterone pathway activated by decreased Na+ could cause
Deficiency in K+
164
Two organic ion secretion proximal tubule (2)
-anionic transporter
-cationic transporter
165
Endogenous compounds
-NE, histamine, prostaglandins
166
Exogenous compounds
-drugs, chemicals
-converted by liver enzymes to anionic form
167
Depending on the body’s state of hydrations the kidneys
Secrete urine of varying concentrations
168
Vertical osmotic gradient
Formed by accumulation of solutes, primarily NaCl and urea
-allows water reabsorption and concentrated urine production
169
Too much water (<300) in the ECF establishes
A hypotonic ECF
170
A water deficient ECF (>300) establishes
A hypertonic ECF
171
Medullary vertical osmotic gradient is established by
Countercurrent multiplication
172
Concentration of urine ___ as you go down the descending limb
-increases
-as water leaves
173
Concentration of urine ___ as you go up the ascending limb
Decreases
-NaCl reabsorption only (leaving)
174
Water moves in the distal convoluted tubule only if
There is vasopressin available
175
Descending limb is
Highly permeable to water but not sodium
176
Ascending limb
Actively transports NaCl out of the tubular lumen into the surrounding interstitial fluid
-impermeable to water
177
Secretion of vasopressin increases
Permeability of tubule cells to water
178
Vasopressin action
-activates cyclic AMP
-inc permeability to H2O by inserting water channels
179
Vasopressin is produced in
The hypothalamus
-released from the post pituitary
180
Dehydration and concentration levels
Concentration may be up to 1200 mOsm/L as it leaves collecting tubule
-since H2O is conserved for body
181
Water excess and concentration
Large volume of dilute urine, no collecting tubule H2O is reabsorbed in distal portion of nephron
-excess H2O is eliminated
182
Vasopressin increases during
A water deficit
-less urine produced
183
Vasopressin decreases during
An excess of water
-more urine is produced
184
Osmotic diuresis
Large volume of urine
-inc excretion of water and solute
185
Diabetes mellitus
High filtered load of glucose, that exceeds reabsorption capacity
-glucose in urine
186
Water diuresis
Inc urine with no or little increased solute
187
Excretion of large quantities of Na+ is always accompanied by
Excretion of large amounts of water
188
Excretion of large amounts of water does not
Always mean excretion of Na+
189
Proximal tubule
-Na reabsorption uncontrolled
-H2O is passive
-reabsorption of glucose, amino acids, Cl, H2O, urea
190
Loop of henle
-Na+ reabsorption is uncontrolled (establishes the medullary interstitial vertical osmotic gradient)
-H2O reabsorption is passive
191
Distal and collecting tubules
-Na reabsorption variable and subjective to aldosterone control (important in regulating ECF volume and bp)
-H2O reabsorption not linked to solute reabsorption
192
Control of Na reabsorption is important for
Regulating ECF volume and long term control of blood pressure
193
Internal urethral sphincter
Smooth muscle
-relaxed bladder causes closure
194
External urethral sphincter
Skeletal muscle
-under voluntary control
