1 Flashcards
(166 cards)
1
Q
What is the organ called that forms urine?
A
Kidneys
2
Q
What are the accessory structures in the urinary system that store and transport urine?
A
Ureters, Urethra, & the Urinary Bladder
3
Q
What is the structure called that water is reabsorbed through and moves across in the tubular epithelial cells?
A
- Aquaporins
4
Q
Describe the passive rebasorption of Water.
A
- Water is reabsorbed passively down its osmotic gradient, which is primarily established by the active transport of sodium
5
Q
How is chloride rebasorbed across the proximal tubule?
A
- Chloride moves across the tight junctions of these tubules
6
Q
Describe the passive rebasorption of chloride.
A
- The electrochemical gradient for chloride is already established by the active transport of sodium
7
Q
What is the passive reabsorption of solutes such as chloride, water, and urea dependent on?
A
- It is dependent on sodium reabsorption
8
Q
What is the term that refers to the coconcentration of glucose (or any other substance) in the filtrate that causes the transport maximum to be reached ? And, what happens once it is reached?
A
- Renal threshold
- Once it is reached, glucose will begin to be excreted in the urine
9
Q
What is the term referred to when transport proteins are saturated and operating at their maximum speeds?
A
- Maximum rate of transport
10
Q
Describe the process of glucose reabsorption and how it is relevant to sodium reabsorption
A
- On the apical membrane, glucose moves across by cotransport with sodium through a secondary transport protein
- On the basolateral membrane, glucose moves across using a facilitated diffusion carrier protein
11
Q
What is ANP and how does it influence sodium reabsorption in the distal tubule? Also, how does it differ from aldosterone?
A
- ANP is a hormone released from specialized cardiac atrial muscle cells in response to stretching.
- ANP decreases Na⁺ reabsorption by decreasing the number of Na⁺ channels in the apical membrane of the principal cells of the distal tubule
• ANP also inhibits the secretion of renin and aldosterone,
• ANP inhibits the contraction of smooth muscle cells in the afferent arteriole,
• & ANP inhibits the activity of the sympathetic nervous system.
12
Q
List the 3 inputs that stimulate granular cells (of the juxtaglomerular apparatus) to secrete renin
A
- By the decreases in pressure in the afferent arterioles
- By paracrine messengers released from macula densa cells in response to decreased salt concentration in the filtrate
- By increased sympathetic nervous system activity (baroreceptor reflex)
13
Q
Which system regulates aldosterone secretion?
A
- The Renin - Angiotensin-Aldosterone System (RAAS)
14
Q
What is aldosterone and how does it increase sodium reabsorption in the distal tubule?
A
- A steroid hormone secreted from the adrenal cortex, which increases Na⁺ reabsorption by:
• (1) Increasing the number of Na⁺ channels in the apical membrane
• (2) Increasing the number of Na⁺ / K⁺ -ATPase in the basolateral membrane
15
Q
List the hormones that regulate sodium reabsorption in the distal tubule
A
- Aldosterone & Arterial natriuretic peptide (ANP)
16
Q
Describe the process of sodium reabsorption in the Distal tubule? Including both the Apical and basolateral membranes
A
- On the Apical membrane, Sodium moves across by cotransport with chloride (Cl-) through a secondary active transport protein or through sodium channels.
- On the Basolateral membrane, Sodium moves across by a primary active transport protein, the Na+/K+-ATPase
17
Q
Describe the process of sodium reabsorption in the proximal tubule? Including both the Apical and basolateral membranes
A
- On the apical membrane, Sodium moves across by cotransport or by countertransport through secondary active transport proteins.
- On the basolateral membrane, Sodium then moves across by a primary active transport protein, the Na+/K+-ATPase
18
Q
Why is sodium reabsorption in the proximal tubule important?
A
- Because it is important for the reabsorption of other solutes, such as glucose, amino acids, water, chloride (Cl⁻), hydrogen ions (H⁺), and urea
19
Q
Where is the majority of sodium (67%) reabsorbed? Where is the rest of the sodium reabsorbed (25%)? And, where is the remaining sodium reabsorbed (8%)?
A
- Proximal tubule (67%)
- Loop of Henle (25%)
- Distal tubule (8%)
20
Q
What is hyponatremia?
A
- It is a lower than normal plasma concentration of Na⁺, and is also accompanied by low plasma volume and decreased blood pressure
21
Q
What is hypernatremia?
A
- It is a higher than normal plasma concentration of Na⁺, and is also accompanied by water retention and an increased blood pressure
22
Q
Why is the homeostatic maintenance of Sodium important?
A
- Important to achieve normal osmotic pressure and for the functioning of excitable cells
23
Q
What is the primary solute in the ECF?
A
Sodium
24
Q
What are the components of the reabsorption barrier in tubular reabsorption?
A
- Tubular epithelial cells (With apical and basolateral membranes), basement membrane, peritubular space, and peritubular capillary endothelial cells
25
Why is tubular reabsorption a highly selective process?
- Because most solutes require the presence of a transport protein to facilitate movement across the reabsorption barrier.
26
Where does most reabsorption occur, and is unregulated?
- The proximal tubule
27
On the topic of tubular reabsorption, describe the reabsorption concentration concept
- With the exception of the plasma proteins, all solutes are in the same concentration in the glomerular filtrate as in the plasma
28
What is Tubular reabsorption?
- It is the movement of solutes and water from the tubules, back into the plasma in the peritubular capillaries
29
How does the sympathetic nervous system extrinsically regulate GFR?
- Through the baroreceptor reflex (Involved in the short- and long- term regulation of MAP)
- And through the mesangial cells ( Which are modified smooth muscle cells that surround the glomerular capillaries, and upon SNS innervation, they decrease the surface area available for filtration)
30
How are the extrinsic mechanisms of regulating GFR different from the intrinsic ones? And what is the goal of the extrinsic mechanisms of regulating GFR?
- Extrinsic mechanisms can override intrinsic ones, allowing for changes to GFR even when MAP is within the range of 80-180 mm Hg and is subjected to intrinsic regulation
- Goal is to maintain MAP, through the SNS
31
Describe Tubuloglomerular feedback intrinsic regulation of GFR, and its response to changes in MAP?
- Intrinsic response of the macula densa cells of the juxtaglomerular apparatus (distal tubule) in response to an increase in the salt concentration of the fluid in the filtrate.
- In an increase in MAP, and increase in salt concentrations, Macula densa secrete adenosine (paracrine chemical messenger), causing neighbouring afferent arterioles to vasoconstrict
- In a decrease in MAP, results in less adenosine secretion by macula densa cells, thus less vasoconstriction or vasodilation of afferent arterioles
32
Describe Myogenic intrinsic regulation of GFR, and its response to changes in MAP?
- Is an intrinsic response to a stretching of the smooth muscles in the walls of the afferent arteriole.
- In an increase in MAP, the afferent arterioles stretch, causing vasoconstriction, increasing resistance, and decreasing GC hydrostatic pressure, thus decreasing GFR
- Opposite sequence goes for a decrease in MAP
33
What are the intrinsic mechanisms for the regulation of GFR? And, their function
- Myogenic regulation & Tubuloglomerular feedback
| - They function to allow for GFR to remain constant with changes in MAP over the range of 80-180 mm Hg
34
List some examples of unregulated pathological changes that affect GFR?
- Severely burned patients (lose protein-rich plasma, decrease GC oncotic pressure, & increasing GFR)
- Dehydration diarrhea patient (increase in plasma-protein, increase GC oncotic pressure, & decreasing GFR)
- Glomerular capillary damage ( protein filters into bowman's capsule, increasing BC oncotic pressure, & increasing GFR)
- Kidney stones or an enlarged prostate ( Increasing BC hydrostatic pressure, decreasing GFR)
35
What are the unregulated pathological changes that affect GFR?
- Includes changes in GC oncotic pressure and BC oncotic & hydrostatic pressures
36
What is the regulated variable that affects GFR?
- The glomerular capillary hydrostatic pressure
| - Which occurs in response to an increase in MAP (GFR increases as well)
37
Why is it important to regulate GFR?
- Because small increases in GFR result in large increases in the volume of fluid filtered and excreted
38
What is the filtration fraction?
- It is the fraction of plasma that enters the Bowman's capsule as filtrate during glomerular filtration -> on average 20% of plasma enters Bowman's capsule as filtrate
39
How is the filtration coefficient determined?
- by the glomerular surface area available for filtration & the glomerular membrane permeability
40
What are the 2 variables that GFR depends on?
- Net glomerular filtration pressure & the filtration coefficient (Kf)
41
What is the Glomerular filtration rate (GFR)
- Is it the rate of filtration through the glomerular capillaries
42
What is the net glomerular filtration pressure? And, how is it calculated?
- It is the forces that exist across the walls of glomerular capillaries
- It is calculated by totalling the starling forces favouring filtration and subtracting them by the starling forces favouring absorption across the glomerular capillaries
43
Describe the Bowman's Capsule hydrostatic pressure (Pbc). And answer whether it favours filtration or absorption across the glomerular capillaries
- It is the pressure exerted by the filtrate in the bowman's capsule -> 15 mm Hg
- It favours absorption across the glomerular capillaries
44
Describe the Bowman's Capsule oncotic pressure (πBC). And answer whether it favours filtration or absorption across the glomerular capillaries
- It results from proteins present in the bowman's capsule -> 0 mm Hg under normal healthy conditions
- It favours filtration across the glomerular capillaries
45
Describe the Glomerular capillary oncotic pressure (πGC). And answer whether it favours filtration or absorption across the glomerular capillaries
- It results from proteins present in the glomerular capillaries - > 29 mm Hg
- It favours absorption across the glomerular capillaries
46
Describe the Glomerular capillary hydrostatic pressure (Pgc). And answer whether it favours filtration or absorption across the glomerular capillaries
- It is the blood pressure exerted on the glomerular capillaries -> at 60 mm Hg
- It favours filtration across the glomerular capillaries
47
List the 4 starling forces involved in glomerular filtration
- Glomerular capillary oncotic pressure & Glomerular capillary hydrostatic pressure
- Bowman's capsule oncotic pressure & Bowman's capsule hydrostatic pressure
48
What is the pathway for the glomerular filtration process? (step by step)
- Glomerular filtration occurs through the glomerular membrane, by moving solutes and fluid through the fenestrations in the capillary endothelial cells
- Then across the basement membrane
- And finally, through the filtration slit pores in the tubule epithelial cells (podocytes)
49
What is the glomerular filtration process?
- It is the mechanism of action where protein-free plasma filters through the glomerular capillaries to the Bowman's capsule
50
Describe Tubular secretion in its role in urine formation?
- Is the selective transfer of substances from the peritubular capillaries to the tubular lumen
51
Describe Tubular reabsorption in its role in urine formation?
- As filtrate flows through the tubules, substances of value are returned to the peritubular capillaries' plasma
52
Describe glomerular filtration in its role in urine formation?
- 1st step in urine formation, occurs in the renal corpuscle
- Where 20% of the blood entering the glomerulus via the afferent arterioles filters into the Bowman's capsule and becomes filtrate
53
Which renal processes are involved in the formation of urine?
- Glomerular filtration, Tubular reabsorption, & Tubular secretion
54
Describe Juxtamedullary nephrons, and list their location. What is the % of nephrons that are of this type? What is their function?
- 15-20% of nephrons are juxtamedullary, and they have long loops of Henle located deep into the medulla.
- They also play an important role in establishing the medullary vertical osmotic gradient (allowing for water reabsorption)
55
Describe cortical nephrons, and list their location
- Most nephrons are cortical nephrons (80-85%)
| - They are located in the renal cortex
56
What are the 2 types of nephrons called? And, how are they distinguished?
- They are the cortical and juxtamedullary nephrons
| - They are distinguished based on their anatomical locations
57
What structure do the Granular cells of the juxtaglomerular apparatus belong to? And what is their function?
- Surround the afferent arterioles
| - They secrete the enzyme renin, which functions to regulate blood volume and blood pressure
58
What structure do the macula densa cells of the juxtaglomerular apparatus belong to? And what is its function?
- Belong to the epithelial cells of the distal tubule
| - Function in the detection of salt concentrations in the filtrate
59
What is the Juxtaglomerular Apparatus in the nephron?
- It is the region where the distal tubule and the afferent arteriole meet, leading into the glomerulus
60
Describe the Collecting duct in the tubular component of the nephrons?
- Distal tubule finally empties the filtrate here.
| - The filtrate leaves the collecting ducts as urine, as its emptied into the minor calyx
61
What is the structure called that the distal tubule collects the filtrate from? And, where is the distal tubule located in the nephron?
- Following the loop of Henle, which lies entirely in the renal cortex
62
Describe the Loop of Henle in the Tubular component of the nephrons? What is the structure called that it collects the filtrate from? And, where is it's loops located
- Following the proximal tubule, forming a U-shape, with ascending and descending loops, that dip into the renal medulla and rise into the renal cortex
63
Describe the Proximal tubule in the tubular component of the nephrons?
- Following Bowman's capsule, filtered fluid enters here.
| - Is it located in the renal cortex
64
Describe the Bowman's capsule in the tubular component of the nephrons?
- Tubular component begins here, following glomerular filtration, it collects the filtrate from the glomerular capillaries
65
What is the function of the tubular component of the nephron?
- It forms the urine within the nephron
66
Describe the Venules in the vascular component of the nephrons?
- Peritubular capillaries rejoin to form venules, which exit the kidneys as the renal vein
67
Describe the peritubular capillaries in the vascular component of the nephrons. What are the functions of the peritubular capillaries? And, from what structure do they arise?
- Subdivision of efferent arterioles, which supply the renal tissue with blood.
- Also important in the exchange between the tubular system and the blood during conversion of filtered fluid into urine
68
Describe the efferent arterioles in the vascular component of the nephrons. What do they form in the renal cortex and medulla?
- Carry the remaining blood from the glomerulus, which forms the peritubular capillaries in the renal cortex, or the vasa recta in the renal medulla
69
Describe the filtrate in the vascular component of the nephrons
- The end-product of glomerular filtration, and is drained in the tubular component of the nephron
70
Describe the structure and function of the glomerulus in the vascular component of the nephrons
- They are a ball-like tuft of capillaries, through which glomerular filtration takes place
71
Describe the structure and function of the afferent arterioles in the vascular component of the nephrons
- They are a subdivision of the renal artery, which delivers blood directly to the glomerulus for filtration
72
What is the function of the vascular component of the nephron?
- It contains the blood within the nephron
73
What are the 2 components of a nephron called?
- A vascular and a tubular component
74
What are nephrons? How many of them are there in a single kidney? And, where are they arranged within the kidneys?
- Are the functional unit of the kidneys
- Approx. 1 million nephrons per kidney
- Nephrons are arranged within the renal cortex and renal medulla
75
From the renal medulla, what is the path that urine follows as it exits the kidneys?
From the renal medulla, urine drains into the minor calyx, then the major calyx, then into the renal pelvis, and finally leaving the kidney through the ureter
76
Where in the kidneys is the renal medulla located, and what is it composed of?
- Renal medulla is in the inner layer, composed of renal pyramids
77
Where in the kidney is the Renal cortex located?
- In the outer layer of the kidneys
78
Structure and location of the kidneys
- Bean-shaped organ
| - Located at the back of the abdominal cavity on each side of the vertebral column
79
What are the Kidney's physiological functions?
- Secretion of Erythropoietin (RBCs synthesis)
- Production & Secretion of Renin (fluid balance)
- Activating Vitamin D3 to calcitriol (calcium & phosphate balance)
- Gluconeogenisis (synthesis of glucose)
80
As a result of regulating the plasma composition, the Urinary system/Kidneys thus influence what else?
- The stability of the ECF
- Electrolyte composition
- Osmolarity
81
How does the urinary system handle other metrics within the body by regulating plasma composition?
Through the regulation of plasma composition:
- It regulates the concentration of ions & waste products in the blood
- It regulates blood volume control
- It regulates pH balance of the blood
82
How is chloride rebasorbed across the proximal
83
What is the strucutre called that water is reabsorbed through and moves across in the tubular epithelial cells ?
- Aquaporins
84
What occurs to the urethral sphincter control as it begins to show signs of aging?
- It decreases in control, resulting in more frequent urination, or a delay in the sensation of the need to urinate
85
What occurs to the urinary bladder as it begins to show signs of aging?
- It exhibits an overall decrease in size, a decrease in muscle tone in the bladder, and urethral sphincter control decreases
86
What occurs to nephrons as they begin to show signs of aging? Such as hormonal responses & GFR factors.
- They decrease in number, contributing to a decrease in the GFR, a decrease in responsiveness to hormonal regulation by aldosterone, atrial natriuretic peptide (ANP), and vasopressin -> resulting in a decrease in the ability to control blood volume and blood pressure.
87
What occurs to the kidneys as it begins to show signs of aging? In terms of blood flow & nephron count
- It begins to exhibit an overall decrease in size, a decrease in blood flow, and a decrease in the number of functional nephrons.
88
When does the urinary system begin to show signs of aging?
- About 30 years of age and onwards
89
What is the developmental complication that results from the duplication of the ureter?
- Duplicated (bifid) ureter
90
What is the developmental complication that refers to the development of extra kidneys, resulting from ureteric bud duplication?
- Supernumerary kidney
91
What is the developmental complication that refers to when 2 kidneys have fused during the migration process, halting the migration process?
- Horseshow Kidney
92
What is the developmental complication that refers to the failure of the kidney to migrate toward the top of the abdominal cavity?
Pelvic kindney, and is asymptomatic
93
What is the developmental complication that refers to the failure of the kidney to develop and results from the failure of the ureteric bud and metanephric mesoderm to merge? And how is it asymptomatic?
- Renal agenesis, and is asymptomatic if it occurs unilaterally
94
What occurs to the kidneys during prenatal development? And, where do they finally migrate to in the abdominal cavity?
- They continue to grow in size, develop complexity, and migrate to their final adult location in the superior lumbar portion of the abdominal cavity.
95
In prenatal development, what is the structure called that gives rise to the nephrons of the kidney?
- The metanephric mesoderm
96
In prenatal development, what is the structure called that gives rise to the ureters, renal pelvis, calyces, and collecting ducts?
- Ureteric bud
97
Describe metanephros based on their order, composition, location, function, and the period of time that they are developed
- Metanephros is the third set, composed of 2 metanephroi, begins developing from the caudal (tail) end of the mesonephric duct in the 5th week of prenatal development
- They will form the functional adult kidney, taking over urine production in the 10th week, as mesonephros degenerate
98
Describe mesonephros based on their order, composition, location, function, and the period of time that they are developed in
- Mesonephros is the second set, composed of 2 mesonephroi, that exist in the thoracic and lumbar region between the 4th and 10th weeks of prenatal development
- They are capable of forming urine, which drains into the developing bladder
99
Describe pronephros based on their order, composition, location, function, and the period of time that they are developed in.
- Pronephros is the first set, composed of 2 pronephroi, and is present in the cervical region during the 4th week of prenatal development
- No known function
100
What are the 3 sets of embryonic excretory organs called?
- Pronephros, mesonephros, and metanephros
101
Where is the stretch reflex of micturition located? And, is it a voluntary or an involuntary action?
- Is located in the wall of the bladder, which is involuntarily controlled as an infant and young child, but can be voluntarily controlled with experience
102
Which autonomic nervous system controls micturition? And, which structures does it innervate?
- The PNS, innervating the internal urethral sphincter & the external urethral sphincter
103
Where is urine formed? And where does it drain into? What is the path of urine following said draining?
- Urine is formed in the renal tubules of the nephrons
| - Urine is drained into the renal pelvis before moving through the ureters and into the urinary bladder
104
What is the process of urination called?
- Micturition
105
What is the clinical term that refers to a deficiency in vasopressin secretion from the posterior pituitary gland? And, what are the clinical symptoms?
- Diabetes Insipidus
| - Symptoms include: Polyuria (excessive urination) and polydipsia (excessive fluid intake)
106
List the possible variables that vasopressin responds to, and in turn, is released because of
* An increase in osmolarity of the ECF
* A decrease to Mean Arterial Pressure (MAP)
* A decrease in Blood Volume
107
Where is vasopressin released from?
- Released from the neurosecretory cells that originate in the hypothalamus and terminate in the posterior pituitary gland
108
What is the mechanism of action of vasopressin in the collecting ducts & distal tubule, to increase aquaporin-2 channels?
- Vasopressin binds to its receptors on the basolateral membrane of distal and collecting tubule cells. This binding activates the cyclic AMP second-messenger system which increases the insertion of water channels (Aquaporin-2 channels)
109
In the process of water reabsorption in the collecting ducts, what occurs in the presence of vasopressin?
- Thus the presence of Aquaporin-2 channels, the collecting duct is permeable to water, and water reabsorption occurs
110
In the process of water reabsorption in the collecting ducts, what occurs in the absence of vasopressin?
- Thus the absence of Aquaporin-2 channels, the collecting duct is impermeable to water, and no reabsorption occurs
111
Which Aquaporin (water channels) are dependent upon the hormone vasopressin, and are located on the apical membrane of the collecting ducts tubular epithelial ?
- Aquaporin-2
112
Which Aquaporin (water channels) are independent and always present on the basolateral membrane of the collecting ducts tubular epithelial ?
- Aquaporin-3
113
What is the water reabsorption in the collecting ducts dependent on?
- Its dependent on the osmotic gradient established by the countercurrent system and the permeability of the epithelium to water
114
In juxtamedullary nephrons, which limp of the loop of Henle is impermeable to water, and permeable to ions?
- The ascending limp
115
In juxtamedullary nephrons, which limp of the loop of Henle is permeable to water, and impermeable to ions?
- The descending limp
116
Which system establishes and regulates the vertical osmotic gradient? And, what structure is the said system formed by?
- The medullary countercurrent system (multiplier) & its formed by the loop of Henle in the juxtamedullary nephrons
117
The osmolarity of the interstitial fluid is higher in the ...?
- In the renal medulla, near the renal pelvis
118
The osmolarity of the intersitiail fluid is lower in the ...?
- Renal cortex, where the osmolarity is isotonic
119
Describe the vertical osmotic gradient in the renal medulla
- It is where the osmolarity of the interstitial fluid in the medulla varies with depth
120
Where is the rest of the water reabsorbed? Is that reabsorption accomplished in a regulated or unregulated manner? What is the percentage of water rebasorbed in this structure? And, how does it get rebasorbed ?
- In a regulated manner, 20% of water is reabsrobed in the collecting ducts.
- Involving vasopressin & the medullary countercurrent system (multiplier)
121
Where is the majority of water reabsorbed? and is that reabsorption accomplished in a regulated or unregulated manner? What is the percentage of water rebasorbed in this structure? And, how does it get rebasorbed ?
- In an unregulated manner, 80% of water is reabsrobed in the proximal tubule
- By passively using its osmotic gradient, established by the active transport of sodium (Na⁺)
122
What does the renal handling of water regulate?
- It regulates the ECF's osmolarity
123
What is the term that refers to the process of water diffusing down it concentration gradient?
- Osmosis
124
What is the term that refers to an osmolarity of more than 300 mOsm/L
- Hypertonic conditions
125
What is the term that refers to an osmolarity of less than 300 mOsm/L
- Hypotonic conditions
126
What is the osmolarity of the ECF dependent on? And, what is the measurement in milliosmoles/L of its isotonic state?
- The ECF is dependent on the concentration of water
| - With an isotonic state of 300 mOsm/L
127
What is the plasma clearance of Para-aminohippuric acid (PAH) (mL/min)? And, what is it equal to?
- 625 mL/min = to the average renal plasma flow rate.
128
Describe the properties of the organic anion Para-aminohippuric acid (PAH).
- Can be administered clinically
| - PAH is fully filtered across the glomerular capillaries and it also not reabsorbed but is fully secreted.
129
How can the rate of plasma flow into the glomerular capillaries also be measure?
- By measuring the Plasma clearance rate
130
What is the plasma concentration of creatine?
- 140 mL/min
131
What is creatine? And, what are its properties that make it unique at measuring GFR?
- Creatine is the end-product of muscle metabolism
- Its a more convenient way of measuring GFR, it is freely filtered across the glomerular capillaries and is also not reabsorbed, but a small amount of it is secreted.
132
What is the plasma concentration of Inulin?
-125 mL/min
133
What is inulin? And, what makes it a unique molecule at measuring GFR?
- Inulin is a harmless carbohydrate derived from Jerusalem Artichokes
- It freely filtered across the glomerular capillaries, and Inulin is not reabsorbed or secreted
134
How is GFR determined by inulin?
- By measuring the plasma clearance of inulin
135
How is the plasma clearance of solutes calculated?
- Plasma clearance = Excretion rate of the solute / Plasma concentration of the solute
136
What is the term that is equal to the volume of plasma cleared of a particular solute per minute
- The plasma clearance of solutes
137
Can the plasma clearance of solutes determine the renal handling?
- Yes
138
What would happen if the amount of a solute secreted per min is less than the amount filtered per min?
- Results in the solute being reabsorbed
139
How is the renal handeling of a solute determined?
- By comparing the amount of solute excreted to the amount of solute filtered
140
What is the net balance of the renal processes of glomerular filtration, tubular reabsorption, and tubular secretion?
- The processes of excretion
141
What increases Aldosterone secretion?
- Increased concentration of plasma potassium
142
How does aldosterone increase potassium secretion in the distal tubule?
- By inserting additional potassium channels in the apical membrane & increasing the number of Na⁺/ K⁺-ATPase Primary Active transport proteins in the basolateral membrane
143
Which hormone regulates the secretion of potassium in the distal tubule?
- Aldosterone
144
Describe the process of potassium secretion in the distal tubule
- In the basolateral membrane, potassium Na⁺/ K⁺-ATPase Primary Active transport protein pumps potassium into the cell
- In the apical membrane, potassium moves down its electrochemical gradient through potassium channels
145
How is potassium secreted across the basolateral membrane in the proximal tubule?
- Via Na⁺/ K⁺-ATPase Primary Active transport protein
146
List the 2 ways that potassium is reabsorbed in the proximal tubule
- Through the tubular tight junctions
| - Or through basolateral potassium channels
147
What is the term that refers to low plasma concentration of potassium, resulting in cardiac arrhythmias?
- Hypokalemia
148
What is the term that refers to a high plasma concentration of potassium, resulting in cardiac arrhythmias ?
- Hyperkalemia
149
Why is the homeostatic maintenance of Potassium (K⁺) important?
- For the functioning of excitable cells
150
How are organic anion & cation transported?
- Through organic anion-selective or organic cation- selective transport proteins
151
List the foreign compounds included in the organic anion & cation group
- Pesticides
- Non-steriodal anti-inflammatory drugs
- Penicillin
152
List the waste products included in the organic anion & cation group
- Histamine
| - Norepinephrine
153
Why is the secretion & regulation of hydrogen ions important?
- Important for the acid-base balance
154
List the solutes that rely on tubular secretion
- Hydrogen ions
- Organic anions & cations
- Potassium
155
Are the transport mechanism for tubular secretion any different from tubular reabsorption?
- No, they are the same, but move in the opposite direction
156
List the barrier for tubular secretion, and are they any different from tubular reabsorption?
- No, they are the same, including: the pertibular capillary endothelial cells, the pertiubular space, the basement membrane,& the tubular epithelial cells
157
Describe the renal process of tubular secretion
- It is the process of moving solutes from the peritubular capillaries into the tubules
158
What is the percentage of urea that is rebasorbed?
- 50% of urea is actually reabsorbed, with the remainder being excreted
159
Describe the passive/free diffusion of Urea. Which molecule establishes its concentration gradient?
- In the proximal tubule, the reabsorption of water establishes a concentration gradient favouring the reabsorption of urea
- Urea freely diffuses across the epithelial cell membrane
160
Which structure is water rebasorbed in an regulated manner? And, what is the percentage of water rebasorption in that same structure?
- 20% of water is reabsorbed in the collecting ducts
161
Which structure is water rebasorbed in an unregulated manner? And, what is the percentage of water rebasorption in that same structure?
- 80% of water is reabsorbed in the proximal tubules
162
What is the strucutre called that water is reabsorbed through and moves across in the tubular epithelial cells ?
- Aquaporins (water channels)
163
What is the plasma clearance of solutes ?
- It is equal to
164
Where is vasopressin released from?
- Released from the neurosecretory cells that originate in the hypothalamus and terminate in the posterior pituitary gland
165
List the possible reasons that release vasopressi
166
List the possible reasons that release vasopressi
