Unit 2- Urinary System Part 2 Flashcards
Urinary System (170 cards)
1
Q
What are the three main processes in renal physiology?
A
The three main processes in renal physiology are:
1. Glomerular Filtration
2. Tubular Reabsorption
3. Tubular Secretion
2
Q
What happens during glomerular filtration?
A
In the glomerulus, blood plasma and dissolved substances (smaller than most proteins) are filtered into the glomerular capsule.
3
Q
What occurs during tubular reabsorption?
A
Along the renal tubule and collecting duct, water, ions, and other substances are reabsorbed from the renal tubule lumen into the peritubular capillaries, ultimately returning them to the blood.
4
Q
What is the process of tubular secretion?
A
Along the renal tubule and collecting duct, substances such as waste, drugs, and excess ions are secreted from the peritubular capillaries into the renal tubule, eventually making their way into the urine.
5
Q
What does urine contain?
A
Urine contains secreted substances.
6
Q
What does blood contain after tubular reabsorption?
A
Blood contains reabsorbed substances.
7
Q
What are the components of glomerular filtration?
A
- Fenestration (pore) of glomerular endothelial cell
- Basal lamina of glomerulus
- Slit membrane between pedicles
8
Q
What is the role of the fenestration (pores) in glomerular endothelial cells during filtration?
A
The fenestrations prevent the filtration of blood cells but allow all components of blood plasma to pass through.
9
Q
What is the function of the basal lamina of the glomerulus?
A
The basal lamina prevents the filtration of larger proteins.
10
Q
What is the function of the slit membrane between pedicels in the glomerulus?
A
The slit membrane between pedicels prevents the filtration of medium-sized proteins.
11
Q
Why is the volume of fluid filtered by the renal corpuscle much greater than other capillaries?
A
It is due to:
- A large surface area
- A thin and porous filtration membrane
- High glomerular blood pressure
12
Q
Where is the glomerular filtration taking place?
A
The actual filtration process occurs at the glomerular capillaries within the renal corpuscle (glomerulus + Bowman’s capsule).
13
Q
Describe the volume of fluid filtered by the renal corpuscle compared to other capillaries.
A
Volume of fluid filtered by the renal corpuscle is much greater than other capillaries.
14
Q
The surface area available for filtration in the glomerulus is regulated by?
A
The surface area available for filtration in the glomerulus is regulated by mesangial cells.
15
Q
What are the mesangial cells and what do they do?
A
- Relaxed mesangial cells allow for maximal surface area and filtration.
- Contracted mesangial cells reduce surface area and filtration.
16
Q
What is the thickness of the filtration membrane in the glomerulus?
A
The filtration membrane is 0.1 mm thick and 50 times leakier than normal capillaries, due to large pores.
17
Q
Why is the glomerular blood pressure high?
A
The efferent arteriole is smaller than the afferent arteriole, creating higher pressure within the glomerulus.
18
Q
What makes up the net filtration pressure (NFP)?
A
- Glomerular blood hydrostatic pressure (GBHP)
- Capsular hydrostatic pressure (CHP)
- Blood colloid osmotic pressure (BCOP)
19
Q
What is Glomerular Blood Hydrostatic Pressure (GBHP)?
A
GBHP is the primary force responsible for the formation of filtrate. It pushes water and solutes through the filtration membrane.
20
Q
What is the glomerular blood hydrostatic pressure?
A
55 mmHg
21
Q
What is Capsular Hydrostatic Pressure (CHP)?
A
CHP is the back pressure exerted by the fluid already in the capsular space.
22
Q
Does the Capsular Hydrostatic Pressure (CHP) aid in filtration or oppose it?
A
It opposes filtration.
23
Q
What is the value of Capsular Hydrostatic Pressure (CHP)?
A
The value of Capsular Hydrostatic Pressure is 15 mmHg.
24
Q
What is Blood Colloid Osmotic Pressure (BCOP)?
A
BCOP is the pressure caused by the presence of proteins (mainly albumin) in the blood that cannot pass through the filtration membrane.
25
How does Blood Colloid Osmotic Pressure (BCOP) affect filtration?
BCOP tends to pull water back into the bloodstream from the filtrate, opposing filtration.
26
What is the value of Blood Colloid Osmotic Pressure (BCOP)?
The value of BCOP is 30 mmHg.
27
What is Net Filtration Pressure (NFP)?
Net Filtration Pressure (NFP) is the difference between the glomerular blood hydrostatic pressure (GBHP) and the sum of capsular hydrostatic pressure (CHP) and blood colloid osmotic pressure (BCOP), driving the filtration process in the kidneys.
28
How is Net Filtration Pressure (NFP) calculated?
NFP is calculated using the formula:
NFP = GBHP - CHP - BCOP
29
What is the NFP value when GBHP = 55 mmHg, CHP = 15 mmHg, and BCOP = 30 mmHg?
NFP = 55 - 15 - 30 = 10 mmHg
30
What happens to filtration if Glomerular Blood Hydrostatic Pressure (GBHP) drops below 45 mmHg?
If GBHP falls below 45 mmHg, no filtration occurs.
31
How does dilation of the afferent arteriole affect Net Filtration Pressure (NFP)?
Dilation of the afferent arteriole increases NFP, leading to greater filtration.
32
How does constriction of the efferent arteriole affect Net Filtration Pressure (NFP)?
Constriction of the efferent arteriole increases NFP, leading to greater filtration.
33
What is Glomerular Filtration Rate (GFR)?
GFR is the amount of filtrate formed by both kidneys each minute.
34
What does the glomerular filtration rate measure?
It measures how well the kidneys are functioning.
35
What is the average GFR for a male?
The average GFR for a male is 125 mL/min.
36
What is the average GFR for a female?
The average GFR for a female is 105 mL/min.
37
The Glomerular Filtration Rate (GFR) cannot be directly measured, but what can we do instead?
GFR cannot be directly measured, but it can be estimated using eGFR (estimated GFR).
38
What is an eGFR?
Blood test to measure creatinine level.
39
What factors are used to calculate eGFR?
eGFR is calculated based on the following factors:
- Age
- Gender
- Race (Black or Other)
40
How does GFR change with age?
GFR decreases with age (even in people without kidney disease).
41
How is Glomerular Filtration Rate (GFR) related to Net Filtration Pressure (NFP)?
GFR is directly related to NFP (Net Filtration Pressure).
42
What is the GFR/ glomerular filtration rate (GFR) directly related to?
GFR is directly related to the NFP. Higher NFP leads to higher GFR.
43
What are the two main ways GFR is regulated?
GFR is regulated by:
1. Adjusting the blood flow into and out of the glomerulus.
2. Altering the glomerular capillary surface area available for filtration.
44
Homeostasis of body fluids requires a constant _________
Homeostasis of body fluids requires a constant GFR.
45
Why is a constant GFR important for homeostasis?
A constant GFR is crucial for homeostasis to ensure proper fluid balance, waste removal, and nutrient retention.
46
What happens if GFR is too high?
If GFR is too high, needed substances may be lost in the urine, leading to insufficient reabsorption.
47
What happens if GFR is too low?
Waste products may not be excreted.
48
What are the three main mechanisms that control Glomerular Filtration Rate (GFR)?
The three main mechanisms that control GFR are:
1. Renal Autoregulation
2. Neural Regulation
3. Hormonal Regulation
49
How do all mechanisms regulating GFR work?
All mechanisms regulate GFR by:
- Adjusting the blood flow into or out of the glomerulus.
- Altering the glomerular capillary surface area available for filtration.
50
What is the role of renal autoregulation in controlling GFR?
Renal autoregulation helps maintain normal blood flow and GFR even during activities like exercise, ensuring GFR stays stable.
51
What happens to the GFR when the mean arterial blood pressure is anywhere between 80 and 180 mmHg?
GFR is nearly constant.
52
What is the range of mean arterial blood pressure (MAP) within which GFR remains constant?
GFR is nearly constant when the mean arterial blood pressure (MAP) is between 80 and 180 mmHg.
53
What are the mechanisms involved in renal autoregulation?
The two mechanisms of renal autoregulation are:
- Myogenic Mechanism
- Tubuloglomerular Feedback
54
How is renal autoregulation affected by chronic kidney disease?
Renal autoregulation is disrupted in cases of chronic kidney disease, leading to impaired regulation of GFR.
55
What is the Myogenic Mechanism in renal autoregulation?
The Myogenic Mechanism normalizes GFR within seconds by:
- If blood pressure rises, stretch receptors trigger smooth muscle cells to constrict the afferent arterioles.
- If blood pressure drops, the opposite occurs, leading to dilation of the afferent arterioles.
56
How quickly does the Myogenic Mechanism adjust GFR?
The Myogenic Mechanism normalizes GFR within seconds.
57
How quickly does Tubuloglomerular Feedback operate compared to the Myogenic Mechanism?
Tubuloglomerular Feedback operates much slower than the Myogenic Mechanism.
58
What is Tubuloglomerular Feedback in renal autoregulation?
Tubuloglomerular Feedback detects increased sodium, chloride, and water levels (indicating reduced reabsorption time) and causes afferent arteriole constriction.
59
How quickly does the Myogenic Mechanism normalize GFR?
The Myogenic Mechanism normalizes GFR within seconds.
60
What is Tubuloglomerular Feedback in renal autoregulation?
Tubuloglomerular Feedback detects increased sodium, chloride, and water levels (indicating reduced reabsorption time) and causes afferent arteriole constriction by inhibiting the release of nitric oxide (which causes vasodilation) from cells in the juxtaglomerular apparatus.
61
How does Tubuloglomerular Feedback affect the afferent arterioles?
Tubuloglomerular Feedback causes constriction of the afferent arterioles when there is an increase in sodium, chloride, and water levels in the filtrate.
62
What is the overall effect of Tubuloglomerular Feedback?
By lowering GFR, the kidneys allow more time for reabsorption of sodium, chloride, and water, helping to maintain electrolyte balance and prevent excessive fluid loss.
63
What part of the nervous system regulates GFR?
The Sympathetic Autonomic Nervous System (ANS).
64
What does the sympathetic autonomic nervous system do?
The Sympathetic Autonomic Nervous System (ANS) supplies nerves to the kidneys and plays a role in regulating GFR.
65
At rest, what is the role of the sympathetic nervous system on GFR?
At rest, the sympathetic nervous system does not significantly control GFR because renal autoregulation is the dominant mechanism.
66
What happens when the sympathetic nervous system is activated?
Sympathetic nerve stimulation causes vasoconstriction of both the afferent and efferent arterioles, reducing renal blood flow and GFR.
67
How does sympathetic stimulation affect GFR during conditions like hemorrhage or severe dehydration?
During blood loss (hemorrhage) or dehydration, sympathetic stimulation causes constriction of both afferent and efferent arterioles, which decreases renal blood flow and GFR.
68
What are the effects of decreased GFR during sympathetic stimulation?
Decreased GFR leads to reduced urine output (helps conserve water) and increased blood flow to vital organs like the heart and brain.
69
In how many minutes has more fluid entered the PCT than the body's total blood volume?
In 45 minutes, more fluid has entered the PCT than the body's total blood volume.
70
What happens to most of the filtrate in the kidneys?
Most of the filtrate is reabsorbed from the tubules back into the bloodstream.
71
What is the process called when most of the filtrate is reabsorbed from the tubules back into the bloodstream?
This process is called Tubular Reabsorption.
72
What substances are reabsorbed during tubular reabsorption?
The substances reabsorbed during tubular reabsorption include water, glucose, proteins, urea, and ions (such as Na⁺, Cl⁻, Ca²⁺, K⁺).
73
What are the types of transport mechanisms involved in tubular reabsorption?
The types of transport mechanisms involved are Passive Transport and Active Transport.
74
What is passive transport?
Passive transport does not require energy.
75
What is active transport?
Active transport requires energy.
76
What percentage of water is reabsorbed in the kidneys?
99% of water is reabsorbed in the kidneys.
77
How is water reabsorbed in the kidneys?
Water reabsorption is driven by solute reabsorption.
78
How does water reabsorption occur in the kidneys?
Water reabsorption is driven by solute reabsorption and occurs via osmosis, which is a form of passive transport.
79
What are the two types of water reabsorption in the kidneys?
The two types of water reabsorption are Obligatory Water Reabsorption (90%) and Facultative Water Reabsorption (10%).
80
Where does obligatory water reabsorption occur and what percentage of water does it account for?
Obligatory water reabsorption accounts for 90% of water reabsorption and occurs in the PCT and the descending Loop of Henle.
81
What is facultative water reabsorption capable of doing?
Facultative water reabsorption is capable of adapting to the body's needs and accounts for 10% of water reabsorption.
82
How is facultative water reabsorption regulated?
It is regulated by Antidiuretic Hormone (ADH).
83
How does ADH regulate facultative water reabsorption?
ADH (antidiuretic hormone) regulates facultative water reabsorption by increasing the permeability of the renal collecting ducts to water, allowing more water to be reabsorbed back into the bloodstream in response to dehydration or high plasma osmolarity.
84
Where does facultative water reabsorption occur?
Facultative water reabsorption occurs in the DCT and collecting ducts.
85
What is the role of principal cells in the DCT?
Principal cells in the DCT have receptors for ADH and help control facultative water reabsorption.
86
What is tubular secretion?
Tubular secretion is the movement of substances from the capillaries surrounding the nephron into the filtrate.
87
Where does tubular secretion occur in the nephron?
Tubular secretion occurs in areas other than the filtration membrane, specifically in the Proximal convoluted tubule, Distal convoluted tubule, and Collecting ducts.
88
How does tubular secretion occur?
Tubular secretion occurs by active transport.
89
What role does tubular secretion play in pH regulation?
Tubular secretion helps control pH by secreting hydrogen (H⁺) and ammonium ions (NH₄⁺) to decrease acidity in the body and conserving bicarbonate (HCO₃⁻), which acts as a buffer to maintain a stable pH.
90
How much water is filtered, reabsorbed, and secreted per day?
Filtered (enters glomerular capsule) = 180 L, Reabsorbed (returned to blood) = 178-179 L, Secreted (to become urine) = 1-2 L.
91
How much glucose should be secreted in urine?
0g.
92
What does glucose being secreted in urine indicate?
The presence of glucose in urine, a condition known as glucosuria, typically indicates that blood glucose levels are elevated beyond the renal threshold for reabsorption, often associated with conditions causing impaired glucose metabolism.
93
Where does the majority of water get reabsorbed?
The majority of water gets reabsorbed in the PCT.
94
What occurs in the PCT?
Reabsorption and secretion.
95
What is reabsorbed in the Proximal Convoluted Tubule (PCT)?
In the PCT, the following substances are reabsorbed: Water (65%), Almost 100% of glucose and amino acids.
96
What is the role of the Na⁺-H⁺ antiporter in the PCT?
The Na⁺-H⁺ antiporter promotes the absorption of Na⁺ and the secretion of H⁺ in the PCT.
97
What percentage of water is reabsorbed in the Loop of Henle?
15%.
98
What substances are reabsorbed in the Loop of Henle?
In the Loop of Henle, the following substances are reabsorbed: Sodium (Na⁺), Potassium (K⁺), Chloride (Cl⁻), Calcium (Ca²⁺), Magnesium (Mg²⁺), Water (15%).
99
What is the permeability of the descending limb of the Loop of Henle?
The descending limb of the Loop of Henle is impermeable to solutes but permeable to water.
100
What is the permeability of the ascending limb of the Loop of Henle?
The ascending limb of the Loop of Henle is impermeable to water but permeable to sodium (Na⁺) and chloride (Cl⁻) ions.
101
What are the two portions of the ascending limb of the Loop of Henle?
The ascending limb has two portions: Thin portion and Thick portion.
102
What is countercurrent multiplication in the Loop of Henle?
Countercurrent multiplication refers to the process by which the descending and ascending limbs of the Loop of Henle work in tandem to create an osmotic gradient, allowing for the reabsorption of water and solutes, essential for concentrating urine.
103
By the end of the Distal Convoluted Tubule (DCT), what percentage of water and solutes have been reabsorbed?
By the end of the DCT, 95% of water and solutes have been reabsorbed.
104
What are the cells in the DCT?
Principal cells and Intercalated cells.
105
What are principal cells in the DCT?
Principal cells in the DCT contain receptors for ADH (Antidiuretic Hormone) and aldosterone, which help control facultative water reabsorption.
106
What role do principal cells play in facultative water reabsorption?
Principal cells regulate facultative water reabsorption based on the body's hydration needs, controlled by ADH and aldosterone.
107
What are intercalated cells in the DCT?
Intercalated cells are specialized cells in the DCT that help maintain blood pH homeostasis by secreting H⁺ (acid) or reabsorbing HCO₃⁻ (bicarbonate).
108
How do intercalated cells maintain blood pH?
Intercalated cells regulate blood pH by secreting hydrogen ions (H⁺) to decrease acidity or by reabsorbing bicarbonate ions (HCO₃⁻) to help buffer and raise pH.
109
What happens when blood pressure drops?
When blood pressure drops, the Renin-Angiotensin-Aldosterone System (RAAS) is activated to help increase blood pressure and ADH/Anti-diuretic hormone is released.
110
Where is renin released from when blood pressure drops?
Renin is released from the kidneys when blood pressure drops.
111
What does renin do in the Renin-Angiotensin-Aldosterone System?
Renin activates Angiotensin I, which is an inactive form of the hormone.
112
How is Angiotensin I converted into its active form, Angiotensin II?
Angiotensin I is converted into Angiotensin II by the enzyme Angiotensin-converting enzyme (ACE).
113
What effect does Angiotensin II have on blood pressure?
Angiotensin II is a potent vasoconstrictor, meaning it causes the constriction of arterioles, which increases blood pressure.
114
What other action does Angiotensin II trigger besides vasoconstriction?
Angiotensin II also triggers the adrenal glands to release Aldosterone.
115
What does aldosterone do?
Aldosterone increases blood pressure.
116
How does Aldosterone increase blood pressure?
Aldosterone promotes the reabsorption of sodium in the kidneys, which leads to water retention, increasing blood volume and ultimately raising blood pressure.
117
What happens when blood pressure drops in relation to Antidiuretic Hormone (ADH)?
When blood pressure drops, the posterior pituitary gland releases ADH.
118
What is the function of Antidiuretic Hormone (ADH) in the kidneys?
ADH promotes facultative water reabsorption in the kidneys, which means water is reabsorbed back into the bloodstream.
119
How does ADH affect blood pressure?
By promoting water reabsorption, water retention increases ADH helps to increase blood volume, which in turn increases blood pressure.
120
What is the important hormone that functions when blood pressure rises because of increased volume?
Atrial natriuretic peptide (ANP).
121
What triggers the release of Atrial Natriuretic Peptide (ANP)?
ANP is released from the heart when it is stretched, which happens when there is too much blood volume.
122
What effect does Atrial Natriuretic Peptide (ANP) have on the afferent arteriole?
ANP causes the afferent arteriole to dilate, or get bigger.
123
How does the dilation of the afferent arteriole affect glomerular filtration rate (GFR)?
Dilation of the afferent arteriole increases GFR, allowing more filtrate to be formed.
124
How does Atrial Natriuretic Peptide (ANP) affect blood pressure?
ANP decreases blood pressure by increasing GFR and promoting the excretion of sodium and water, reducing blood volume.
125
Where are the ureters located in relation to the peritoneum?
The ureters are retroperitoneal (located behind the peritoneum).
126
What is the anatomical position of the ureters in relation to the psoas muscle?
The ureters are anterior to the psoas muscle.
127
How long are the ureters?
The ureters are approximately 10 to 12 inches long.
128
How does urine move through the ureters?
Peristalsis moves urine through the ureters, with gravity also helping.
129
Where is the most anterior part of the ureter located?
The middle part of the ureter is the most anterior.
130
How do the ureters enter the urinary bladder?
As the ureters approach the bladder, they curve medially and pass through the posterior wall of the bladder at an oblique angle, ending at the trigone.
131
What are the ureteral junctions?
The ureteral junctions are UPJ (ureteropelvic junction) - where the ureter connects to the renal pelvis and UVJ (ureterovesical junction) - where the ureter connects to the urinary bladder.
132
What does an RPO 30-degree oblique best demonstrate?
The right ureteropelvic junction (UP junction).
133
What does an RPO 30-degree oblique best demonstrate regarding the kidneys?
The left kidney parallel to the image receptor (IR).
134
What is the UVJ?
The UVJ (ureterovesical junction) is where the ureter connects to the urinary bladder.
## Footnote
There is no anatomic valve at this junction.
135
How does an RPO 30-degree oblique position affect the right kidney?
It demonstrates the right kidney in profile.
136
What does an RPO 45-degree oblique best demonstrate?
The left ureterovesical (UV) junction.
137
What best demonstrates the right ureteropelvic junction (UP junction)?
RPO 30-degree oblique position.
138
What best demonstrates the left kidney parallel to the image receptor (IR)?
RPO 30-degree oblique position.
139
What best demonstrates the right kidney in profile?
RPO 30-degree oblique position.
140
What best demonstrates the left ureterovesical (UV) junction?
RPO 45-degree oblique position.
141
What is the function of the bladder?
The bladder is a temporary storage for urine, with a capacity of 700 to 800 mL.
142
Where is the bladder located in relation to the symphysis?
The bladder is posterior to the symphysis pubis.
143
How does the bladder change shape as it fills with urine?
When empty, the bladder looks like a deflated balloon; as it fills, it becomes round and then pear-shaped when very full.
144
What is the Trigone of the bladder?
The Trigone is a triangular area at the base of the bladder, defined by:
1. 2 ureteral openings (where the ureters enter the bladder)
2. 1 internal urethral orifice (where urine exits the bladder)
3. It has a smooth appearance compared to the rest of the bladder.
145
What is the surface texture of the rest of the bladder (besides the trigone)?
The rest of the bladder has rugae, which are folds that allow for expansion as the bladder fills.
146
Where is the bladder located in relation to the rectum in males?
In males, the bladder is located directly anterior to the rectum.
147
Where is the bladder located in relation to the vagina in females?
In females, the bladder is located anterior to the vagina.
148
Where is the bladder located in relation to the uterus in females?
In females, the bladder is located inferior to the uterus.
149
How long is the urethra in males?
The urethra in males is approximately 20 cm long.
150
What are the 3 parts of the male urethra?
The male urethra consists of 3 parts:
1. Prostatic (passes through the prostate)
2. Membranous (short segment between the prostate and the penis)
3. Spongy (also called the penile urethra, passes through the penis)
151
What role does the male urethra serve?
The male urethra serves a dual role: it carries urine and sperm.
152
How long is the urethra in females?
The urethra in females is approximately 4 cm long.
153
What is the direction of the female urethra?
The female urethra is directed inferiorly and anteriorly.
154
What are the types of renal autoregulation of glomerular filtration rate?
1. Myogenic mechanism
2. Tubuloglomerular feedback
3. Neural regulation
155
What are the hormone regulation of glomerular filtration rate?
1. Angiotensin II
2. Atrial natriuretic peptide (ANP)
156
What is the effect of the myogenic mechanism on GFR?
Decrease.
157
What is the effect of tubuloglomerular feedback on GFR?
Decrease.
158
What is the effect of neural regulation on GFR?
Decrease.
159
What is the effect of angiotensin II on GFR?
Decrease.
160
What is the effect of atrial natriuretic peptide (ANP) on GFR?
Increase.
161
Which regulation of glomerular filtration rate (GFR) is referred to by increased stretching of smooth muscle fibers in afferent arteriole walls due to increased blood pressure?
Myogenic mechanism.
162
Which regulation of glomerular filtration rate (GFR) is referred to by rapid delivery of Na+ and Cl- to the macula densa due to high systemic blood pressure?
Tubuloglomerular feedback.
163
Which regulation of glomerular filtration rate (GFR) is referred to by increased activity level of renal sympathetic nerves releasing norepinephrine?
Neural regulation.
164
Which regulation of glomerular filtration rate (GFR) is referred to by decreased blood volume or blood pressure stimulating the production of angiotensin II?
Angiotensin II.
165
Which regulation of glomerular filtration rate (GFR) is referred to by stretching of atria of heart stimulating secretion of atrial natriuretic peptide?
Atrial natriuretic peptide.
166
What is the mechanism and site of action of the myogenic mechanism?
Stretched smooth muscle fibers contract, thereby narrowing lumen of afferent arterioles.
167
What is the mechanism and site of action of tubuloglomerular feedback?
Decreased release of nitric oxide (NO) by juxtaglomerular apparatus causes constriction of afferent arteriole.
168
What is the mechanism and site of action of neural regulation?
Constriction of afferent arterioles through activation of alpha receptors and increased release of renin.
169
What is the mechanism and site of action of angiotensin II?
Constriction of afferent and efferent arterioles.
170
What is the mechanism and site of action of atrial natriuretic peptide (ANP)?
Relaxation of mesangial cells in glomerulus increases capillary surface area available for filtration.
