Test 4 - Unit 6 & 7 Flashcards
1
Q
If clearance of a substance is greater than GFR, the substance is ______.
A
Net secreted by the kidney
If a substance was net reabsorbed by the kidney, the plasma clearance would be lower than GFR.
If a substance is only filtered, then the clearance would equal GFR.
2
Q
The renal corpuscle is the site where __________.
- glucose reabsorption occurs
- plasma is filtered from the glomerulus into Bowman’s capsule
- sodium ions are reabsorbed
- the steep medullary osmotic gradient is established
A
Plasma is filtered from the glomerulus into Bowman’s capsule
3
Q
Glucose reabsorption from the renal filtrate is due to __________.
- osmosis and simple diffusion along the distal tubule
- Sequential active transport and facilitated diffusion by the cells of the proximal tubule
- Osmotic pressure in the golmerular capillaries
- Active transport along the descending loop of Henle
A
Sequential active transport and facilitated diffusion by the cells of the proximal tubule
4
Q
Which of the following would not result in an increase in GFR?
- increased glomerular pressure
- increased resistance in the efferent arteriole
- increased resistance in the afferent arteriole
- relaxation of mesangial cells
A
increased resistance in the afferent arteriole
5
Q
Poisoning the Na-K-ATPase in the proximal tubule would likely __________.
A
decrease the amount of glucose reabsorption in this segment
6
Q
In kidney renal tubules, all of the following substances normally are excreted into urine as it forms except __________.
- potassium ions
- glucose
- hydrogen ions
A
glucose
As long as an individual has a normal plasma glucose concentration, 100% of the glucose in the filtrate is reabsorbed. However, potassium and hydrogen ions are excreted in the urine in order to regulate blood pH and plasma potassium concentrations. The hydrogen ions are secreted from the proximal and distal convoluted tubule as well as the collecting duct. Potassium ions are secreted from the distal convoluted tubule and the collecting duct.
7
Q
In and around the urinary bladder, skeletal muscle can be found in the __________.
- external urethral sphincter
- internal urethral sphincter
- detrusor muscle
- ureters
A
External urethral sphincter
8
Q
Urine is carried from the collecting duct to what structure?
- renal pelvis
- loop of henle
- ureter
- urethra
A
Renal pelvis
9
Q
The nephron is the functional unit of the kidney because __________.
- the nephron consists of vascular parts and tubular parts
- there are a million nephrons per kidney
- the nephron is essentially continuous with the external environment
- the nephron filters the plasma, reabsorbs critical molecules, and excretes the rest
A
the nephron filters the plasma, reabsorbs critical molecules, and excretes the rest
10
Q
Which part of the nephron always has low permeability to water, regardless of hormone levels?
- collecting duct
- proximal tubule
- ascending loop of henle
- descending loop of henle
A
Ascending loop of henle
11
Q
Secretion differs from filtration in that __________.
A
secretion is selective because it is carrier-mediated
12
Q
Factors that favor filtration at the glomerulus include ________
- the concentration of proteins in the bowman’s space
- capillary blood pressure and the concentration of proteins in the bowman’s capsule
- capillary blood pressure
- concentration of proteins in the plasma
- capillary blood pressure and the concentration of proteins in the plasma
A
capillary blood pressure and the concentration of proteins in the bowman’s capsule
13
Q
Tubular reabsorption __________.
A
permits reclamation of filtered items from the plasma, occurs in the loop of Henle, and is responsible for the movement of amino acids, CA2+, Cl- and water at the proximal convoluted tubule
14
Q
In a normal kidney in a healthy individual, glucose __________.
- is freely filtered at the glomerulus
- is excreted in the urine
- moves by simple diffusion across the membranes of the proximal tubule
- is actively transported in the distal tubule
A
is freely filtered at the glomerulus
15
Q
Where is renal filtrate formed in the kidney’s outer shell, which is also called the
A
renal cortex
16
Q
The ability of the nephron to filter substances based on size and charge is not due to the __________.
- capillary endothelium
- basla lamina
- epithelium of the bowman’s capsule
- hydrostatic pressure
A
hydrostatic pressure
17
Q
If a person with a normal body fluid osmolarity drinks a large quantity of water, which of the following would occur if the kidneys could not excrete any of the water?
- Decreased plasma osmolarity
- Cell shrinkage
- Hypervolemia and cell shrinkage
- Hypervolemia
- Hypervolemia and decreased plasma osmolarity
A
Hypervolemia and decreased plasma osmolarity
18
Q
An ACE (angiotensin converting enzyme) inhibitor would be used to treat __________.
- Hypertension since ACE inhibition will result in decreased secretion of anti-diuretic hormone and aldosterone
- Hypertension since ACE inhibition will decrease the rate of urine production
- Hypotension since ACE inhibition will result in increased secretion of anti-diuretic hormone and aldosterone
- Hypotension since ACE inhibition will decrease the rate of glomerular filtration
A
Hypertension since ACE inhibition will result in decreased secretion of anti-diuretic hormone and aldosterone
19
Q
People suffering from central diabetes insipidus (a disorder of the hypothalamus or pituitary gland) may have increased __________.
- Urine volume
- Urine osmolarity
- Plasma osmolarity
- Plasma osmolarity and urine volume
- Urine volume and ADH levels
- ADH levels
A
Plasma osmolarity and urine volume
20
Q
The effects of ANG II on the central nervous system
- Increase activity of the respiratory control center
- Increase thirst, increase cardiac output, and cause peripheral vasoconstriction
- Inhibit secretion of ADH from the posterior pituitary gland
- Act on the medulla oblongata to decrease blood pressure
A
Increase thirst, increase cardiac output, and cause peripheral vasoconstriction
21
Q
A vasopressin receptor antagonist would __________.
- Cause vasoconstriction and increased blood pressure
- Prevent membrane recycling in collecting duct cells
- Increase peripheral resistance
- Cause aquaporins to be inserted into the apical membranes of collecting duct cells
A
Prevent membrane recycling in collecting duct cells
22
Q
The organ(s) that regulate water loss to maintain water balance is (are) the
- Lungs, skin, and kidneys
- Kidneys
- Lungs, and kidneys
- Liver
- Lungs
- Skin
A
Kidneys
23
Q
The signals controlling ADH release come from _______.
- The macula densa
- Osmoreceptors in the hypothalamus
- Arterial baroreceptors
- All answers are correct
A
All answers
24
Q
Moderate changes in blood pressure (mean arterial pressure not less than 80 mmHg or greater than 180 mmHg) generally do not affect the glomerular filtration rate due to which known local control processes within the kidney?
- Tubule-glomerular feedback
- The myogenic response
- The myogenic response and tubule-glomerular feedback
- Release of renin by the granular cells
- Release of ADH from the adrenal cortex
A
The myogenic response and tubule-glomerular feedback
25
Filtrate leaving the loop of Henle is __________ in volume and __________ to the fluid entering the loop.
- Lower; iso-osmotic
- Lower; hypo-osmotic
- Lower; hyperosmotic
- Higher; hypo-osmotic
lower; hypo-osmotic
26
Which of the following hormones will directly act on the collecting duct of the kidney to enhance the reabsorption of water?
- ADH
- Aldosterone
- ANP
- Renin
ADH
27
When mean arterial pressure increases, which of the following may increase in response?
- Water reabsorption
- GFR and ADH levels
- Urine volume
- ADH levels
- GFR and urine volume
- GFR
-GFR and urine volume
28
An osmotic gradient develops in the renal medulla because various parts of the loop of Henle differ from each other in which of the following characteristics?
- Active transport of solutes
- All answers
- Permeability to water
- Direction of fluid movement
All
29
Put the following events in the correct order:
a) Angiotensin I is converted to angiotensin II.
b) Renin is secreted by the granular cells.
c) Aldosterone is released from the adrenal glands.
d) Renin converts angiotensinogen into angiotensin I.
e) Cells in the macula densa detect a decrease in the flow of fluid (or ion concentration) in the distal tubule.
e, b, d, a, c
30
When insufficient water intake leads to dehydration, compensatory mechanisms to preserve plasma volume and homeostatic osmolarity include __________.
- Increasing the rate of glomerular filtration
- Increasing the amount of water that is reabsorbed from the filtrate in the collecting duct
- Increasing the amount of water excreted
- Reducing the concentration of sodium ions in the excreted urine
increasing the amount of water that is reabsorbed from the filtrate in the collecting duct
31
The movement of water across the late distal tubule and collecting duct is __________.
- Passive, through channels called aquaporins, and from plasma to tubule lumen
- From plasma to tubule lumen
- Passive, through channels called aquaporins, and driven by the medullary osmotic gradient
- Passive
- Through aquaporins
- Driven by the medullary osmotic gradient
Passive, through channels called aquaporins, and driven by the medullary osmotic gradient
32
Angiotensin II leads to an alteration in kidney function by __________.
- Reducing water appetite and reducing the water permeability of the collecting duct
- Increasing water reabsorption along the proximal tubule and increasing potassium reabsorption along the distal tubule
- Increasing water reabsorption from the collecting ducts and increasing sodium reabsorption along the distal tubules
- Decreasing sodium reabsorption along the descending loop of henle and increasing the water permeability of the ascending loop of henle
Increasing water reabsorption from the collecting ducts and increasing sodium reabsorption along the distal tubules
33
In the absence of ADH, which of the following will decrease?
- The medullary osmotic gradient
- Aquaporin synthesis
- Urine osmolarity, aquaporin synthesis, and the medullary osmotic gradient
- Urine volume
- Urine osmolarity
- Urine osmolarity and aquaporin synthesis
Urine osmolarity and aquaporin synthesis
34
Angiotensin II leads to an alteration in kidney function by __________.
- Reducing water appetite and reducing the water permeability of the collecting duct
- Increasing water reabsorption along the proximal tubule and increasing potassium reabsorption along the distal tubule
- Increasing water reabsorption from the collecting ducts and increasing sodium reabsorption along the distal tubules
- Decreasing sodium reabsorption along the descending loop of henle and increasing the water permeability of the ascending loop of henle
Increasing water reabsorption from the collecting ducts and increasing sodium reabsorption along the distal tubules
35
ANG II stimulates the ________
- Release of aldosterone and release of renin
- Release of aldosterone
- Vasodilation of arterioles
- Release of aldosterone and release of ADH
- Release of ADH
- Release of renin
Release of aldosterone and release of ADH
36
When mean arterial pressure decreases, which of the following may increase in response?
- Urine volume
- ADH levels
- ADH levels and water reabsorption
- Water reabsorption
- GFR
- GFR and urine volume
ADH levels and water reabsorption
37
The primary function of the vasa recta is to
- Promote sodium and water excretion in the nephron
- Fine-tune water reabsorption in order to maintain plasma volume
- Maintain the medullary concentration gradient
- Establish the medullary concentration gradient
Maintain the medullary concentration gradient
38
Which of the following is not true of thirst?
- Thirst can actually increase plasma volume if it leads to ingestion of fluid
- Thirst is a physiological mechanism that maintains fluid and electrolyte balance
- Angiotensin II stimulates thirst
- High osmolarity stimulates thirst
Thirst is a physiological mechanism that maintains fluid and electrolyte balance
39
If a human drinks 200 ml of seawater, how will the body correct for the increase in plasma osmolarity?
- By decreasing the release of vasopressin
- By increasing the release of aldosterone
- By increasing the release of vasopressin
- Be decreasing the release of ANP
By increasing the release of vasopressin
40
Which of the following is not true of thirst?
- Thirst is a physiological mechanism that maintains fluid and electrolyte balance.
- High osmolarity stimulates thirst.
- Angiotensin II stimulates thirst
- Thirst can actually increase plasma volume if it leads to ingestion of fluid.
Thirst is a physiological mechanism that maintains fluid and electrolyte balance.
41
Hemorrhage would tend to increase the secretion of which of the following?
- Aldosterone
- ADH
- ANP, Aldosterone, and erythropoietin
- Erythropoietin
- ADH, aldosterone, and erythropoietin
- ANP
ADH, aldosterone, and EPO
42
Describe which parts of the airway have airway circular smooth muscle.
Airway circular smooth muscle is typically found in the bronchioles where it is important in determining resistance to airflow
- high resistance = bronchoconstriction, where ACSM is contracted
- low resistance = bronchodilation, where ACSM is relaxed.
43
Describe where gas exchange occurs in the airway.
Alveoli, which are clustered at the ends of terminal bronchioles, are the site of gas exchange.
More specifically gas exchange occurs in Type 1 alveoli cells
44
Distinguish between Type I and Type II alveolar cells.
Type 1 - very large and thin they are the main site of gas exchange
Type 2 - Secrete surfactant which reduces surface tension of alveoli and makes it easier to breathe
45
Describe the function of the ciliary escalator.
To sweep mucous and trapped materials upwards towards the pharynx where they can be swallowed and enter the stomach
46
Draw the relationship between atmospheric pressure, alveolar pressure and intrapleural pressure on a graph of pressure as a function of time for inspiration and expiration.
See notes
47
Explain how skeletal muscles are used to change the alveolar pressure.
Skeletal muscles contracting and relaxing compress and enlarge the thoracic space, thus increasing or decreasing pressure in the alveolar space.
48
Define pneumothorax.
The pleural membrane surrounds the lungs, which encloses a fluid-filled space called the pleural space. The pleural space (the area between the outside of the lung and the pleural membrane) is normally at a lower pressure than the alveolar space, which keeps the lungs expanded.
A pneumothorax, or a punctured lung, occurs when the pleural membrane is punctured and the intrapleural, alveolar, and atmospheric pressures are equalized. (Palv=Patm=Pip)
49
List the factors that affect the state of airway circular smooth muscle and explain what factors determine their activity level.
Bronchodilation - decreased resistance = increased airflow
-Caused by:
1. Increased epinephrine at Beta adrenergic receptors &
2. Increased carbon dioxide in the alveolar air
Bronchoconstriction (increased calcium entry & increased myosin kinase activity) - increased resistance = decreased airflow
-Caused by:
1. Parasympathetic stimulation
2. Eicosanoids
3. Decreased carbon dioxide in the alveolar air
4. Histamine
50
Explain the difference between paracrine control of airway circular smooth muscle and vascular circular smooth muscle in both the systemic and pulmonary arterioles.
1
51
Explain why alveolar airflow and blood flow to alveoli are matched.
Ventilation and alveolar blood flow are matched to maximize diffusion of oxygen into the blood.
52
Describe (or draw) the pathway that oxygen follows starting from the alveoli and ending up in a working cell. Include partial pressures of oxygen in the atmosphere, alveoli, arterial blood, cells and venous blood.
The concentration of O2 in the atmosphere is 155mmHg and the concentration of O2 in the alveolus is 100mmHg. This causes O2 to diffuse into the alveoli. Then O2 diffuses from the alveoli into the arterial blood until it reaches equilibrium. The concentration of O2 in a working cell is about 40 mmHg, so O2 diffuses into a working cell until it reaches equilibrium.
53
List factors that affect the partial pressure of oxygen in the blood.
1
54
Be able to draw the oxygen-hemoglobin saturation curve and describe factors that affect the affinity of hemoglobin for oxygen.
Decreased hemoglobin affinity:
-Decreased pH, high blood temp, high CO2, high 2-3-DPG (all characteristics of a working cell)
Increased hemoglobin affinity:
-Increased pH, decreased temp, decreased CO2, decreased 2-3-DPG.
55
Describe the 3 ways that carbon dioxide is transported in the blood.
7% is dissolved in the plasma
23% bound to hemoglobin
70% as bicarbonate (HCO3-)
56
Describe the relationship between partial pressure of carbon dioxide in the blood and pH using the law of mass action.
CO2+H20 H2CO3 H+ + HCO3-
If we increase the amount of CO2 in the blood we increase the amount of H+ thus making the plasma more acidic called respiratory acidosis. If we lose too much CO2, by for example, hyperventilating, then we lost H+ and the plasma becomes too alkaline, called respiratory alkalosis.
57
Explain how ventilation rate is controlled.
Normal breathing rhythm determined by a cluster of neurons in the brain called the central pattern generator
Central pattern generator controlled by 3 different things:
- Emotions and voluntary control
- Central chemoreceptors in CNS that respond to CO2 and pH....ex- no matter how long you try to hold your breath for your central and peripheral chemoreceptors will override voluntary control
- Peripheral chemoreceptors in aortic arch and carotid artery that respond to H+, pH and O2. ~only under extreme circumstances of hypoxia will a decrease P O2 lead to an increase in respiration rate.
58
Explain how prolonged exposure to high altitude causes pulmonary edema, respiratory alkalosis and an elevated hematocrit.
Respiratory alkalosis occurs as a result of hyperventilation, when alveolar ventilation increases without a matching increase in metabolic CO2 production. Consequently plasma PCO2 falls making the blood more alkaline. (decreased PCO2, increased pH, Decreased HCO3)
The Kidneys work to fix this problem by reabsorbing H+ into the blood causing pH to lower.
Decreased O2 availability at high altitudes causes EPO to be secreted by the kidney, which binds to receptors on bone marrow to increase red blood cell production. This increase in RBC's causes an increase in hematocrit.
59
Describe the four main functions of the renal system: 1) homeostatic control of ECF volume and ionic composition, 2) excretion, 3) as an endocrine gland and 4) organ of gluconeogenesis.
1. The kidneys regulate the composition of plasma with respect to sodium, potassium, calcium, HCO3, chloride, and H+. The fact that they can regulate hydrogen and bicarbonate ions means that they also play a role in regulating plasma pH.
2. The kidneys remove metabolic waste products and foreign substances, such as drugs and environmental toxins from the blood. Ex- urea from protein metabolism, bilirubin.
3. Kidney cells synthesize EPO (a hormone) which regulates red blood cell synthesis. They also secrete renin, which regulated the production of hormones involved in sodium balance and blood pressure. Finally renal enzymes help convert vitamin D3 into a hormone that regulates Calcium balance.
4. The kidneys play a minor role in making new glucose during times of fasting - most is done in the liver.
60
Explain where and how filtration occurs in the nephron
Filtration occurs in the renal corpuscle which consists of the glomerular capillaries surrounded by the Bowman's capsule. Hydrostatic pressure is generated by the heart which pumps blood into the aorta, then to the renal artery and then to the afferent arteriole. Blood "arrives" from the afferent arteriole and then moves into the glomerular capillaries, where fluid is squeezed out into the Bowman's capsule. Blood exits via the efferent arteriole where it moves to peritubular capillaries. Peritubular capillaries are draped along the nephron so when nutrients are reabsorbed by the kidneys they are picked up by this blood.
61
Distinguish between renal autoregulation, and adjustment of GFR to correct for large changes in MAP.
Tubuloglomerular feedback or renal autoregulation is a process that maintains constant glomerular filtration despite small fluctuations in MAP.
62
Be able to draw a diagram of the nephron and label the following: each region of the nepthron, the renal medulla, cortex and salt gradient, areas of high, low and hormonally regulated permeability to water, the renal portal system, the afferent and efferent arterioles, the vasa recta, “always-on” sodium pumps, glucose transporters, hormonally-regulated sodium pumps. ADH receptors, osmolarity of the filtrate in each region of the nephron.
see notes
63
Explain how EPI/NE affect water conservation by the kidney
1
64
Describe the response of the kidney to acidosis and alkalosis
Acidosis = blood pH of the plasma is too low
If an increase in respiration rate does not restore plasma pH to normal then the kidneys can add bicarbonate back to the blood or excrete more H+ (a long term response). Excretion of H+ is coupled with absorption of K+. The consequence of this is that long term, uncontrolled acidosis could lead to hyperkalemia.
Alkalosis: the pH of the plasma is too high
Over the long term, kidneys can reabsorb H+ from the filtrate (coupled with a LOSS of K+) or excrete more bicarbonate from the blood to the filtrate. A long term consequence would be hypokalemia.
65
Describe the response of the kidney to hyperkalemia.
Increased potassium in the plasma cause a sensor in the adrenal cortex to produce more aldosterone which increases the excretion of K+ (couple with a retention of Na+) in the distal tubule.
66
Relate hyper- and hypokalemia to the function of excitable cells.
Hyperkalemia:
-resting membrane potentials are less negative
-cells depolarize more easily
-can lead to heart arrhythmias
Hypokalemia:
-resting membrane potentials are more negative
-cells are less excitable
-leads to failure of skeletal and cardiac muscle
67
Explain the relationship between acid/base balance and potassium balance.
1
68
Describe the response of the kidney to disturbances in calcium balance.
Decreased calcium in the plasma cause parathyroid hormone to be released.
Parathyroid hormone stimulates:
-increased calcium reabsorption from the distal tubule of the nephron
-increased osteoclast activity to "dissolve" bone.
-increased activity of calcitriol to stimulate absorption of dietary calcium from the small intestine
****caclitriol is the active form of vitamn D. It is a steroid and the conversion from vitamin D occurs in the kidneys
69
The affinity of hemoglobin for oxygen _____ as the pH of blood ____
- increases; decreases
- decreases; decreases
- decreases; increases
- doesnt change; increases
- doesnt change; decreases
decreases; decreases
70
Which of the following best describes the affinity of hemoglobin (Hb) to bind to oxygen?
- The affinity that hemoglobin has to oxygen never changes
- The higher the affinity, the less likely it will be that oxygen binds to hemoglobin
- Affinity only changes at high altitude
- The higher the partial pressure or carbon dioxide, the higher the affinity of Hb for oxygen
- The higher the affinity the more likely it will be that oxygen binds to hemoglobin
The higher the affinity, the more likely it will be that oxygen binds to hemoglobin
71
Low PO2 in the blood causes the release of EPO from the _____ which has receptors in the _______.
- Bone marrow, liver
- Bone marrow; kidney
- Heart; spleen
- Adrenal cortex; bone marrow
- Kidney; bone marrow
Kidney; bone marrow
72
Hypoventilation due to an obstructed airway increases the amount of _____ in the blood, thus ____ plasma pH
- CO2; decreasing
- O2; increasing
- CO2; increasing
- O2; decreasing
- CO2; not changing
CO2; decreasing
73
Of the factors that influence diffusion of respiratory gases, the most variable in a healthy individual, and therefore, the most important factor to consider is the:
- Membrane thickness
- Diffusion distance
- Membrane lipid comp
- Membrane surface area
- Gas concentration gradient
Gas concentration gradient
74
The process of inhalation occurs when ______ and the diaphragm is _______
- Palv> Patm, relaxed
- Palv< Patm, contracted
- Palv< Patm, contracted
- Palv
Palv
75
Pulmonary arterioles are most likely to dilate when:
- A sympathetic activity is high
- Histamine levels are low
- Levels of O2 increase in the alveoli
- O2 levels decrease in the alveoli
- pH decreases in the pulmonary capillaries
Levels of O2 increase in the alveoli
76
Filtered glucose enters cells lining the lumen of the ____ by the process of _____ and then glucose exits from these cells by the process of ______, moving toward the blood
- Distal, facilitated diffusion, secondary active transport
- Distal; facilitated diffusion; simple diffusion
- Proximal tubules; secondary active transport; facilitated diffusion
- Collecting duct; simple diffusion, facilitated diffusion
Proximal tubule, secondary active transport, facilitated diffusion
77
More urine than normal might be a product of:
- Protein levels in the blood being too high
- ANG II levels in the blood that are elevated
- Blood glucose levels abnormally low
- There is an increased sympathetic activity
- Glucose transporters in the proximal tubule are saturated
Glucose transporters in the proximal tubule saturate
78
Dilation of the afferent renal arterioles occurs _____, resulting in _____ urine output
- When nitric oxide levels are low; decreased
- With sympathetic activation during vigorous exercise; decreased
- When atrial stretch; increased
- When ANP is secreted; decreased
- When ADH levels are elevated; increased
When atrial stretch; increased
79
Hypokalemia is a condition where ______ levels are abnormally low in the blood, resulting in excitable cells that depolarize ______.
- Potassium; more easily
- Calcium; less easily
- Sodium; more easily
- Calcium; more easily
- Potassium; less easily
Potassium; less easily
80
Diameter of the bronchioles is mainly controlled by _____ in the alveoli and bronchioles during expiration
CO2
81
What causes bronchodilaiton?
Increased bad stuff - dilate to get rid of it faster
82
The diameter of the pulmonary arterioles is controlled by ______ in the alveoli
O2
83
Decreased O2 in the pulmonary arterioles causes what
Vasoconstriction
| "only send blood where it is needed"
84
Diameter of the systemic arterioles is controlled equally by ____ and _____
CO2 and O2
85
Decreased O2 or Increased CO2 causes what in systemic arterioles
Vasodilation
| "working tissues need more blood to get rid of the bad stuff and bring in the good stuff"
86
Describe the factors that affect glomerular filtration rate.
GFR = amount of filtrate formed per unit time
- Relaxed vascular circular smooth muscle of the afferent arteriole (dilation) leads to increased hydrostatic pressure in the glomerular capillaries thus increasing GFR and urine output
- Contracted vascular circular smooth muscle of the afferent arteriole (constriction) leads to decreased hydrostatic pressure in the glomerular capillaries thus causing a decrease in GFR and urine output.
87
Vasodilators that cause an increase in GFR
Increased atrial stretch causes an increase in ANP resulting in vasodilation causing an increase in GFR and an increase in urine output resulting in decreased blood volume and lower MAP.
Other vascular circular smooth muscle vasodilators:
-Increased conc of bad stuff (CO2 etc)
-Decreased conc of good stuff (O2 etc)
-Sympathetic activation of beta-adrenergic receptors on blood vessels
-Increased ANP
-Increased NO
-Histamine
88
Vasoconstrictors that cause a decrease in GFR
Increased ADH (due to decreased MAP or high plasma osmolarity)
Increased ANG II ( from low renal blood pressure - RAAS)
Increased sympathetic output at alpha-adrenergic receptors
all cause GFR to decrease resulting in decreased MAP which would require water conservation.
89
Explain how ADH affects water conservation by the kidney
ADH is a posterior pituitary gland hormone it causes the body to retain water. When ADH acts on target cells the collecting duct epithelium becomes more permeable to water, because aquaporins are inserted into the membrane.
-a lot of ADH results in very concentrated urine and without ADH the collecting duct is very impermeable to water
90
Explain how Aldosterone affects water conservation by the kidney
- Up regulates sodium pumping causing sodium pumps to pump faster and causes more of them to be inserted into the plasma membrane of the distal tubule. Water thus follows the sodium solute out
- Aldosterone is released at the end of the RAAS pathway in response to low blood pressure
91
Explain how Aldosterone affects water conservation by the kidney
- Up regulates sodium pumping causing sodium pumps to pump faster and causes more of them to be inserted into the plasma membrane of the distal tubule. Water thus follows the sodium solute out
- Aldosterone is released at the end of the RAAS pathway in response to low blood pressure
