What is the range of urine osmolarity that can be excreted?
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50 – 1200 mOsM.
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What is the range of urine osmolarity that can be excreted?
50 – 1200 mOsM.
What does the mug represent in the fluid balance analogy?
The body.
What is the primary function of the kidneys in fluid balance?
To conserve volume and recycle fluid.
What happens to the Glomerular Filtration Rate (GFR) if body fluid volume falls too low?
GFR stops.
What must be true to maintain a constant volume of water in the body?
Intake must equal output.
What is the driving force for water reabsorption throughout the nephrons?
Osmotic gradient between the tubular lumen and surrounding interstitial fluid.
What is the role of type B intercalated cells in the collecting duct during alkalosis?
They secrete HCO3- and reabsorb H+.
What are the four parameters that homeostatic control mechanisms aim to maintain?
Fluid volume, osmolarity, concentration of individual ions, and pH.
How does the cardiovascular system contribute to fluid balance?
By regulating blood volume and pressure.
What is osmolarity?
The concentration of solutes in the blood.
What contributes to daily water gain besides drinking?
Food and metabolic production.
In which course will the detailed mechanism of sodium balance be covered?
BIOL 3503.
What is the mechanism of water balance?
It involves the regulation of water intake and output to maintain homeostasis.
What is the total daily water output for an average person?
2.5 L/day.
What enzyme is found in high concentration in the cytoplasm of type A intercalated cells?
Carbonic anhydrase (CA).
What role does the kidneys play in response to salt ingestion?
The kidneys adjust sodium and water reabsorption to maintain balance.
What is the normal plasma pH range?
7.38 – 7.42.
What behavioral response is triggered by changes in blood pressure?
Thirst causes water intake.
What is the role of H+ secretion in the proximal tubule?
It helps maintain pH homeostasis by combining with filtered HCO3- to form CO2.
How does blood pressure influence vasopressin secretion?
Low blood pressure stimulates vasopressin release to increase blood volume.
What is the initial concentration of the medullary interstitial fluid?
300 mOsm.
Where does urine osmolarity depend on reabsorption?
In the collecting duct.
What is the primary function of the urinary system?
To maintain fluid and electrolyte balance.
What is the vertical osmotic gradient?
A difference in osmolarity that allows for water reabsorption in the kidneys.
What role does the renin-angiotensin system play in fluid balance?
It helps regulate blood volume and osmolarity.
What is pH homeostasis?
It is the regulation of the acidity or alkalinity of body fluids to maintain a stable pH level.
What are some examples of other electrolytes the body may intake?
K+, H+, Ca2+, HCO3-.
How does H+ secretion in type A intercalated cells differ from that in the proximal tubule?
It involves H+-K+-ATPase in type A intercalated cells.
What is acidosis?
A condition where pH is too low.
What role does aldosterone play in potassium balance?
Aldosterone plays a critical role in potassium homeostasis.
What is the concept of balance in fluid and electrolyte regulation?
It refers to maintaining stable levels of fluids and electrolytes in the body.
What is the daily water intake for an average person?
2.2 L/day.
What receptors are involved in detecting changes in blood volume and pressure?
Volume receptors in the atria, and carotid and aortic baroreceptors.
What is insensible water loss?
Water loss that occurs without conscious awareness, estimated at 0.9 L/day.
How does HCO3- exit type A intercalated cells?
Through the HCO3--Cl- antiporter to the interstitial space.
What hormone acts on principal cells in the distal tubule and cortical collecting duct?
Aldosterone.
What is the equation that represents fluid and electrolyte balance in the body?
Input + production = utilization + output.
What role does the medullary vertical osmotic gradient play in the kidneys?
It enables the kidneys to produce urine of varying concentration (100 - 1200 mOSm).
What are the avenues for water loss in the body?
Urine, lungs, feces, and skin.
How does aldosterone affect potassium ions?
It facilitates renal excretion of potassium ions.
What type of antiporter is involved in the function of type B intercalated cells?
HCO3- - Cl- antiporter.
What is the mechanism of ion balance?
It involves the regulation of ion concentrations in the body fluids to ensure proper physiological function.
What is the task of the body regarding electrolytes?
Maintain balance by excreting what comes in if the body does not need it.
How do collecting ducts utilize the vertical osmotic gradient?
They use it to concentrate urine.
What is salt appetite?
A behavior that leads people to seek and ingest salt (NaCl).
How does blood supply reach the renal medulla?
Via the vasa recta.
What is the pathway of the vasa recta?
It descends from the cortex to the medulla and loops back up to the cortex.
What happens to intracellular proteins when there is a change in intracellular pH?
They can become denatured, affecting enzymes and membrane channels.
What metabolic process produces lactic acid?
Anaerobic respiration.
What is the outcome of NH4+ secretion?
NH4+ is secreted and excreted, contributing to acid-base balance.
What is the primary focus of fluid and electrolyte balance?
The integrated control of blood volume and osmolarity.
What are the other routes for excreting water and ions besides the kidneys?
Feces, sweat, and lungs.
How does the body regulate sodium levels after salt ingestion?
Through hormonal mechanisms, including aldosterone secretion.
What two processes establish the medullary vertical osmotic gradient?
Countercurrent multiplication and urea recycling.
What is the permeability characteristic of the proximal cortical collecting duct?
It is permeable to water.
What promotes salt and water excretion in the body?
Natriuretic peptide.
What causes the release of Natriuretic peptides?
Increased blood volume leading to increased atrial stretch.
What is the characteristic of the ascending limb in countercurrent multiplication?
It is water impermeable and has active Na+ transport.
What are the effects of acidosis on neurons?
Neurons become less excitable, leading to CNS depression.
What role do buffers play in pH homeostasis?
They moderate changes in pH by combining with or releasing H+.
What is the relationship between renin and blood pressure?
Decreased renin leads to decreased blood pressure.
What type of fluid is produced in the ascending limb of the Loop of Henle?
Hyposmotic fluid.
What functions are influenced by Ca2+?
Exocytosis, muscle contraction, and other cellular functions.
What stimulates salt appetite?
Low sodium levels stimulate salt appetite.
What is the primary route for water loss and removal of many ions?
The kidneys.
What is the primary homeostatic response to salt ingestion?
The body increases thirst and promotes water retention.
What reaction does carbonic anhydrase (CA) facilitate in type A intercalated cells?
It converts CO2 and water to H+ and HCO3-.
What is the entire functional organization that involves the vertical osmotic gradient called?
Medullary countercurrent system.
Can the kidneys replace lost fluid volume?
No, they cannot replenish lost water.
How is regulated water reabsorption related to urine volume?
It determines the volume loss in the urine.
What are the permeability characteristics of the vasa recta?
It is permeable to water and solutes.
What happens to solutes and water during the descent of the vasa recta?
Solutes are reabsorbed from the medullary interstitium and water is removed.
What is produced during aerobic respiration that affects acid-base balance?
CO2.
What is the role of the adrenal cortex in fluid balance?
It releases aldosterone, which regulates sodium balance.
What happens to neurons during alkalosis?
They become hyperexcitable, leading to sensory changes and sustained contractions.
What behavioral mechanism helps replace fluid loss?
Drinking replaces fluid loss.
What is the average daily intake of fluid for the body?
Approximately 2 liters.
What role do type A intercalated cells play in the collecting duct during acidosis?
They secrete H+ and reabsorb HCO3-.
What is the function of the vasa recta in relation to the vertical osmotic gradient?
They preserve/maintain the vertical osmotic gradient while providing blood to the renal medulla.
What role do the kidneys play in fluid balance?
They excrete salts and water in urine and conserve water to minimize further volume loss.
How does the cardiovascular system respond to changes in blood pressure?
Through cardiac output and vasodilation or vasoconstriction.
How does increased osmolarity affect vasopressin release?
It stimulates the release of vasopressin to conserve water.
What role does blood volume play in vasopressin release?
Decreased blood volume triggers vasopressin release to retain water.
What happens to concentrated urea in the distal collecting duct?
It moves into the renal interstitium and can be recycled.
How is permeability to water and solutes regulated in the nephron?
By hormones.
What can result from severe CNS depression due to acidosis?
Cease of respiratory center function and death.
What are some buffers found in urine?
Phosphates and ammonia.
What substances are excreted due to increased blood volume?
NaCl (sodium chloride) and H2O (water).
How does renal regulation manage pH disturbances?
By directly excreting or reabsorbing H+ and indirectly changing the excretion or reabsorption of HCO3-.
What is the role of the collecting duct in urine concentration?
It allows variable reabsorption of water, influenced by hormones.
What role do collecting ducts play in fluid and electrolyte balance?
They utilize the vertical osmotic gradient.
How does the vertical osmotic gradient affect water balance?
It facilitates the reabsorption of water from the collecting ducts.
How much water is lost through urine daily?
1.5 L/day.
What is the main goal of maintaining fluid and electrolyte balance?
To maintain homeostasis.
What effect does increased salt intake have on blood volume?
It can lead to increased blood volume and blood pressure.
What are the main buffers in extracellular fluid?
HCO3- (bicarbonate).
What are the two main compartments of body fluid volume?
Extracellular fluid (ECF) and intracellular fluid (ICF).
What happens to CO2 in the proximal tubule cells?
CO2 diffuses into the cell and combines with water to form H+ and HCO3-.
How does increased blood volume affect GFR?
It increases GFR (glomerular filtration rate).
What happens when fluid is taken away from the mug?
Fluid loss from the handle is turned off to prevent additional fluid loss (concentrated urine is produced).
What is the osmolarity of isosmotic fluid in the proximal tubule?
300 mOsM.
What is the primary function of aldosterone in the kidneys?
To facilitate the reabsorption of sodium and potassium secretion.
Which systems are involved in the regulation of blood volume and osmolarity?
Cardiovascular, renal, and hypothalamic systems.
How much NaCl does the body typically intake daily?
6 - 15 grams.
What triggers homeostatic reflexes related to fluid and electrolyte balance?
Changes in blood volume and blood pressure.
What behavioral mechanism helps to replace water loss?
Thirst.
What is the role of the vasa recta in the kidney?
To preserve the vertical osmotic gradient while providing blood to the renal medulla.
What is the normal pH range of plasma?
7.38 - 7.42.
How does extracellular pH relate to intracellular pH?
Extracellular pH usually reflects intracellular pH.
What is a source of acid input in the body?
Diet (e.g., fatty acids, amino acids).
What is the function of glutamine in the renal process?
Glutamine is metabolized to ammonium ion (NH4+) and HCO3-.
What happens to vasopressin levels when blood volume increases?
Vasopressin levels decrease.
What type of fluid is reabsorbed in the distal nephron?
Variable reabsorption of water and solutes.
What happens during hypoventilation?
It lowers pH by increasing CO2, which combines with H2O to produce H+ and HCO3-.
How is permeability to water and solutes regulated in the kidneys?
By hormones.
What are some examples of inputs that can affect H+ levels?
Fatty acids, amino acids, CO2, lactic acid, and ketoacids.
What are the primary excretion routes for maintaining fluid and electrolyte balance?
The kidneys and lungs.
How does the polarity of type B intercalated cells differ from type A cells?
Type B cells have reversed polarity, meaning the same transport systems occur on opposite sides of the cells.
Which type of nephrons establish the vertical osmotic gradient?
Juxtamedullary nephrons (loop of Henle).
How do the lungs contribute to fluid and electrolyte balance?
They lose water and help remove H+ and HCO3- by breathing out CO2.
What is vasopressin?
A hormone that regulates water balance in the body.
What factors can affect the release of vasopressin?
Osmolarity, blood volume, and blood pressure.
What happens to urea concentration in the proximal cortical collecting duct when water moves out?
The concentration of urea increases in the duct.
What is the permeability characteristic of the distal collecting duct?
It is permeable to urea.
What is the effect of increased blood volume on blood pressure?
It decreases blood pressure.
What occurs when extra fluid is added to the mug?
Excess fluid drains out of the handle (excreted in urine).
Why is the function of the vasa recta important?
It prevents washing away of the concentration gradient in the kidney.
What is the significance of reabsorbing HCO3-?
Reabsorbing HCO3- is crucial for maintaining acid-base balance in the body.
What is the final outcome of the countercurrent multiplication process?
The final vertical osmotic gradient is established.
What buffers are found in extracellular fluid?
HCO3-.
What is the significance of thirst in fluid balance after salt ingestion?
Thirst stimulates water intake to dilute excess sodium.
What role do proteins and hemoglobin play in the body?
They act as buffers in cells.
What is the systemic response to changes in blood pressure?
It involves a stimulus, receptor, effector, and tissue response.
How does vasopressin affect the collecting duct?
It increases the permeability of the collecting duct to urea.
How does the ascending limb establish a 200-mOsm gradient?
By pumping out NaCl to the interstitium.
What is alkalosis?
A condition where pH is too high.
What dietary sources contribute to base input in the body?
Fruits and vegetables.
How does Na+ affect the body?
It influences extracellular fluid volume and osmolarity, affecting cell volume.
What two processes establish the medullary vertical osmotic gradient?
Countercurrent multiplication and urea recycling.
What is the characteristic of the descending limb in countercurrent multiplication?
It is water permeable and has no active Na+ pump.
What creates hyposmotic fluid in the nephron?
Removal of solute in the thick ascending limb.
What occurs during the ascent of the vasa recta?
Solutes diffuse back to the interstitium and water moves back into the capillaries.
What is a consequence of diabetes related to acid-base balance?
Production of ketoacids.
What is the osmolarity of urine typically excreted?
300 mOsM.
What is the response time for renal regulation of pH?
It is the slowest response.
How do H+ and HCO3– affect the body?
They alter pH balance.
What happens to isosmotic fluid leaving the proximal tubule?
It becomes progressively more concentrated in the descending limb.
What does the hollow handle represent in the fluid balance analogy?
The kidney.
What hormone makes the collecting duct permeable to water?
Vasopressin.
What is the range of urine osmolarity that can be excreted?
50 – 1200 mOsM.
What occurs after the 300 mOsm fluid enters from the proximal tubule?
The ascending limb pump and descending limb passive fluxes reestablish the 200-mOsm gradient.
What can sustained contractions during alkalosis lead to?
Paralysis of respiratory muscles and death.
What buffers are present in cells?
Proteins, hemoglobin, and phosphates.
What is the normal range for plasma pH?
7.38 – 7.42.
What transporters are involved in H+ and HCO3- handling in the proximal tubule?
Na+-H+ antiport and HCO3--Na+ symporter.
Why is water and ion balance important?
It is crucial for maintaining extracellular fluid volume and osmolarity, which affect cell volume.
What buffers are found in urine?
Phosphates and ammonia.
What happens to water in the descending limb during countercurrent multiplication?
Water diffuses from the descending limb into the interstitial fluid.
What happens to fluid in the descending limb of the Loop of Henle?
Water is reabsorbed, resulting in progressively more concentrated fluid.
What percentage of pH disturbance is managed by ventilation?
75%.
What are the two pathways involved in H+ secretion and HCO3- reabsorption?
Pathway A (steps 1-5) and Pathway B (steps 6-7).
What systems are involved in maintaining water and ion balance?
The respiratory and cardiovascular systems, along with renal and behavioral responses.
What is the role of K+ in the body?
It affects cardiac and muscle function.
What occurs in the distal tubule regarding ion and water reabsorption?
Ions are reabsorbed but no water.
What is mass balance in the context of fluid and electrolyte balance?
The body must maintain a balance of fluids and electrolytes to function properly.
