minor term - nieren. 85 good questions, nicely answered!

Q: What are the primary functions of the kidneys?

Osmoregulation : Maintains volume and composition of extracellular fluid. Hormone Production : Produces renin and EPO. Waste Excretion : Eliminates nitrogen waste.

Q: How do different animals excrete nitrogenous wastes?

Aquatic Animals/Bony Fishes : Excrete ammonia. Mammals/Amphibians/Sharks : Excrete urea. Reptiles/Birds/Insects/Land Snails : Excrete uric acid.

Q: What terms are used for kidney structures in the provided context?

Cortex : schors Medulla : merg Renal pelvis : nierbekken

Q: Describe the nephron and its function in kidneys.

Functional units of the kidneys. Run through both cortex and medulla . Each kidney contains approximately 1 million nephrons. 1 long tube with twists/loops and contains glomerulus .

Q: What structures does Bowman's capsule connect to within the nephron?

Bowman's capsule connects to: - Proximal tubule - Loop of Henle - Distal tubule - Collecting duct - Renal pelvis Small molecules move freely between glomerulus and Bowman's capsule .

Q: Describe the urine formation starting from the filtrate in the kidneys.

About 180 L of filtrate is formed daily. Approximately 1600 L of blood flows through kidneys daily. 99% of filtrate reabsorbed leaving 1.5 liters of urine .

Q: What are the key functions of the proximal tubule in urine formation?

Reabsorption of ions, water, nutrients (glucose, amino acids). Water follows by osmosis. pH regulation : H+ transported into lumen, HCO3- reabsorbed . Concentration increases farther into the proximal tubule .

What are the primary functions of the kidneys?

Osmoregulation: Maintains volume and composition of extracellular fluid.
Hormone Production: Produces renin and EPO.
Waste Excretion: Eliminates nitrogen waste.

How do different animals excrete nitrogenous wastes?

Aquatic Animals/Bony Fishes: Excrete ammonia.
Mammals/Amphibians/Sharks: Excrete urea.
Reptiles/Birds/Insects/Land Snails: Excrete uric acid.

What is nitrogen waste and how is it processed in the body?

Breakdown of proteins and nucleic acids creates ammonia, which is very toxic.
Conversion to less toxic substances: urea.
Combining ammonia with CO2 results in low toxicity but requires energy.

Describe the structure and function of the kidneys.

Two kidneys, each about 10 cm.
Urine travels via ureter to urinary bladder.
Urine exits body through urethra.
Structures: cortex, medulla, renal pelvis.
Blood supply: renal artery; drainage: renal vein.
Fluid reabsorbed into blood, exiting through renal vein.

How does urine travel from the kidneys to exit the body?

Urine is transported from the kidneys via the ureter to the urinary bladder.
Urine exits the body through the urethra.
Key terms: urineleider (ureter), plasbuis (urethra).

What terms are used for kidney structures in the provided context?

Cortex: schors
Medulla: merg
Renal pelvis: nierbekken

Describe the nephron and its function in kidneys.

Functional units of the kidneys.
Run through both cortex and medulla.
Each kidney contains approximately 1 million nephrons.
1 long tube with twists/loops and contains glomerulus.

What structures does Bowman's capsule connect to within the nephron?

Bowman's capsule connects to:
- Proximal tubule
- Loop of Henle
- Distal tubule
- Collecting duct
- Renal pelvis
Small molecules move freely between glomerulus and Bowman's capsule.

Describe the urine formation starting from the filtrate in the kidneys.

About 180 L of filtrate is formed daily.
Approximately 1600 L of blood flows through kidneys daily.
99% of filtrate reabsorbed leaving 1.5 liters of urine.

What are the key functions of the proximal tubule in urine formation?

Reabsorption of ions, water, nutrients (glucose, amino acids).
Water follows by osmosis.
pH regulation: H+ transported into lumen, HCO3- reabsorbed.
Concentration increases farther into the proximal tubule.

What factors influence the excretion of toxins from the liver?

Size of substance: no filtration by glomeruli
Water/fat solubility: reabsorption by kidney/blood
Saturation of toxin excretion pathways
Functionality of renal mitochondria (ATP)

Describe the role of the descending limb of the loop of Henle.

Reduces filtrate volume further
Contains aquaporins: no channels for NaCl or small molecules
Increasing osmolarity: cortex to medulla
Water leaves filtrate: concentration increases

What processes occur in the ascending limb of the loop of Henle?

No aquaporins
NaCl exits filtrate (passive then active)
Active transport: requires ATP, maintains fluid osmolarity
Lower osmolarity at the bottom of descending limb

What is the function of the distal tubule in the kidney?

- Regulates concentration of NaCl and K+ ions

What is the role of the collecting duct in urine formation?

Filtrate becomes urine.
Controls urine concentration via hormonal regulation.
Concentrated urine: water reabsorbed, impermeable to salts.
Diluted urine: salts actively uptaken, no water follows.
Aquaporins presence is hormonally regulated.

How do hormones affect urine concentration?

Adjust urine concentration based on water/salt balance and urea production.
Antidiuretic hormones (ADH) regulate osmolarity.
Renin-Angiotensin-Aldosterone System (RAAS) regulates blood volume and pressure.

What is the function of Anti-diuretic hormone (ADH)?

Also known as vasopressin.
Produced by the pituitary gland.
Binds to collecting duct receptors.
Incorporates aquaporins, promoting water reuptake.
Reduces urine volume for homeostasis.

What are the characteristics of Diabetes insipidus?

Mutations or disturbances in ADH receptors.
Leads to high urine production.
Results in high water intake (5-15 liters per day).

What effect does alcohol intake have on ADH production?

Inhibits ADH production.
Leads to decreased water reabsorption.
Results in higher urine volume and increased dehydration risk.

What triggers the release of ADH in response to an increase in blood osmolarity?

Osmoreceptors in the hypothalamus detect increased blood osmolarity.
This triggers the release of ADH from the pituitary gland.
ADH increases water reabsorption in the collecting ducts.
This helps prevent further osmolarity increase.

How does the RAAS respond to a decrease in blood volume and pressure?

RAAS increases water and Na+ reuptake.
Juxtaglomerular apparatus (JGA) detects pressure drop.
JGA surrounds small arteries to the glomerulus.
Pressure drop triggers renin release.

Outline the process from renin release to aldosterone's effect.

Renin converts angiotensinogen to angiotensin II.
Angiotensin II causes vasoconstriction.
Angiotensin II stimulates aldosterone release from adrenal glands.
Aldosterone increases Na+ and water uptake in distal tubules.

What are the key functions and characteristics of Glomerular Filtration Rate (GFR)?

120 ml/min: Average rate.
Filters all extracellular fluid every hour.
Diseases impact water/salt balance and waste removal.
No symptoms until 80-90% loss of nephrons.
2-4% have one kidney.

How is renal function analyzed biochemically?

Clearance: Evaluates excretion.
Plasma creatinine: Monitors kidney function.
Estimated GFR (eGFR): Assesses filtration.
Glomerular integrity: Determines kidney health.

What does clearance involve in the context of renal function?

Excretion measurement: In urine of filtered substances.
Not excreted/metabolized by renal tubules.
Blood volume clearance occurs in one minute.

Why is inulin not used in routine tests, and what alternative is usually measured?

Inulin needs to be injected; this limits its use in routine tests.
Creatinine in urine and plasma is commonly measured.
Creatinine is:
- A muscle breakdown product.
- Produced consistently daily.

Explain the formula for creatinine clearance and its approximate value.

Formula: \( \text{Clearance} = \frac{U}{S} \times V \)
\( U \): Urine creatinine (mg/dL)
\( S \): Serum creatinine (mg/dL)
\( V \): Urine volume (mL or dL)
Approximate creatinine clearance: 120 mL/min

Describe the relationship between estimated GFR and plasma creatinine.

Estimated GFR is linked to plasma creatinine concentration.
A 50% decrease in GFR doubles plasma creatinine if production is stable.
Higher plasma creatinine indicates lower GFR.

What is RER and how is it calculated?

RER stands for renal excretion rate.
Calculated as: RER = CLr Cp.
CLr: renal plasma clearance (volume of plasma cleared of toxin).
Cp: plasma concentration.

What factors influence renal clearance of toxins?

Depends on GFR and tubular secretion.
Tubular secretion described by: CLTs = Tm/(Kt + Cp)
Tm: maximum transport capacity.
Kt: Michaelis-Menten constant.
Cp: plasma concentration.

What factors affect glomerular filtration?

- Influenced by:

Molecular size
Molecular charge
Protein binding
Renal blood flow
Age and renal disease

What influences drug secretion in the proximal tubule?

- Proximal tubule secretion influenced by:

Protein binding
Renal blood flow
Competition between substrates
Concentration of the drug

What are some markers and causes of glomerular injury?

Markers:
- Collagen IV
- Cystatin C
- Total protein
Causes:
- Thrombotic microangiopathy
- Calcineurin inhibitors
- Clopidogrel
- Cocaine
- Minocycline
- Quinine

What markers and causes are associated with distal tubule injury?

Markers:
- Clusterin
- H-FABP
- NGAL
- Osteopontin
- π-GST
Causes:
- Amphotericin B
- Calcineurin inhibitors
- Lithium
- Sulfonamide

What are the causes and markers for Hemodynamic alteration?

Causes:
- ACE-I, ARB
- Amphotericin B
- Calcineurin inhibitors
- Diuretics
- NSAIDs
- Radiocontrast agents
Markers: None mentioned specifically

What are the functions of the kidneys?

The kidneys perform essential functions:

Osmoregulation: Maintain volume and composition of extracellular fluid.
Hormone production: Produce hormones like renin and epo.
Waste excretion: Remove nitrogen waste.

What are the nitrogenous waste products of different animal groups?

Aquatic animals, bony fishes: Ammonia (NH₃)
Mammals, amphibians, some bony fishes: Urea (CO(NH₂)₂)
Reptiles, birds, insects, land snails: Uric acid

What happens during the breakdown of proteins and nucleic acids in terms of nitrogen waste?

Breakdown produces ammonia (NH₃), highly toxic.
Ammonium (NH₄⁺) may disrupt oxidative phosphorylation.
Conversion to less toxic urea.
Ammonia combines with CO₂, reducing toxicity but consuming energy.

What are the main characteristics and functions of the kidneys?

Two kidneys, each about 10 cm.
Urine passes via ureter (Dutch: urineleider) to the bladder.
Urine exits through urethra (Dutch: plasbuis).
Diagram shows renal structures.

What are the main components and functions of the kidney?

Kidney components: cortex (schors) and medulla (merg).
Renal artery: supplies blood.
Renal vein: drains blood.
Fluid is reabsorbed, exits via renal vein.
Urine collected in renal pelvis (nierbekken).

What are the four important processes highlighted in the diagram related to the excretory system?

Filtration:
- Occurs in the capillary
- Forms filtrate
Reabsorption:
- Occurs in the excretory tubule
- Moves filtrate components back to blood
Secretion:
- Transfer of wastes to the tubule
Excretion:
- Releases urine from the body

What is involved in the filtration process in excretion?

Filtration is driven by blood pressure.
Small molecules like water, salts, sugar, amino acids, and nitrogen waste pass through the endothelial membrane.
These form the filtrate.

Describe the reabsorption process in excretion.

Reabsorption involves active transport.
Useful molecules like sugar, salts, vitamins, hormones, and amino acids are reabsorbed.
This preserves essential nutrients.

What occurs during the secretion process in excretion?

Secretion excretes non-essential molecules.
Waste products actively removed in filtrate.
Helps manage body waste efficiently.

What are nephrons, and where are they located in the kidney?

Functional units of the kidney.
Run through both the cortex and medulla of the kidney.
Each kidney contains approximately 1 million nephrons.

What are the types of nephrons and their locations in the kidney?

Cortical nephron
- Located in the renal cortex
Juxtamedullary nephron
- Extends into the renal medulla
Both connect to the collecting duct heading to the renal pelvis

What structures are involved in the filtrate and blood flow in a nephron?

Afferent arteriole from renal artery
Glomerulus
Bowman’s capsule and proximal tubule
Efferent arteriole from glomerulus
Descending and ascending limbs of the Loop of Henle
Vasa recta, distal tubule, and collecting duct

Describe the path of blood and filtrate flow in a nephron.

Blood enters via the afferent arteriole
Passes through glomerulus into Bowman’s capsule
Flows to proximal tubule
Moves along descending and ascending limbs of the Loop of Henle
Continues to distal tubule and collecting duct
Exits through renal vein branches and vasa recta

What are the main structural components of a nephron?

Nephron: long tube with twists/loops, contains glomerulus
Bowman's capsule surrounds glomerulus
Sequential pathway:

1. Proximal tubule

Loop of Henle
Distal tubule
Collecting duct
Renal pelvis

How do small molecules behave between the glomerulus and Bowman's capsule in the nephron?

Small molecules like salts, sugar, and amino acids move freely.
Initial concentration is equal between blood and filtrate.
Allows efficient filtering in the kidneys.

What is the daily blood flow and filtrate formation in the kidneys?

1600 L of blood flows daily through the kidneys.
About 180 L of filtrate is formed.
99% is reabsorbed, leaving 1.5 liters of urine.

What processes occur in the proximal tubule from filtrate to urine?

Reabsorption of ions, water, glucose, and amino acids
Osmosis causes water to follow (pre-urine is hypotonic)
pH regulation: H⁺ transported into lumen, HCO₃⁻ reabsorbed
Filtrate becomes more concentrated farther into the tubule

What processes occur in the proximal tubule during kidney filtration?

Active Transport: NaCl, Nutrients, HCO₃⁻, K⁺
Passive Transport: H₂O
Additional Substances: H⁺ and NH₃ are involved.

What happens in the loop of Henle during urine formation?

Descending Limb: Passive transport of H₂O
Ascending Limb: Active transport of NaCl
Regions: Outer medulla and inner medulla involved

What activities occur in the distal tubule?

Active Transport: NaCl, HCO₃⁻, K⁺
Passive Transport: H₂O
Other Actions: H⁺ secretion

Describe the processes in the collecting duct of the nephron.

Active Transport: NaCl
Passive Transport: Urea, H₂O
Involved regions: Inner and outer medulla

What is the role of transporters in the kidney proximal tubules regarding the excretion of toxins?

Transporters in kidney proximal tubules actively excrete liver-originating toxins.
Includes OAT4, OCTN1, OCTN2, and ENT1.
MRP2, MRP4, PEPT1, and PEPT2 also play roles.
Regulatory DDI guidance transporters include OATP, OCT2, and OAT1.

What are the functions of the distal tubule in the kidney?

Regulation of NaCl concentration
Control of K⁺ ions
pH regulation

What role does the collecting duct play in urine concentration and aquaporin regulation?

Filtrate turns into urine.
Hormonal control affects urine concentration.
Aquaporins enable water reabsorption in concentrated urine.
Diluted urine absorbs salts; no water follows.
Hormones regulate aquaporin presence.

What factors influence the concentration of urine and which endocrine systems are involved?

Urine concentration depends on water and salt balance, and urea production rate.
Endocrine systems involved:

1. Antidiuretic hormone (ADH) ➔ Regulates osmolarity.
2. Renin-Angiotensin-Aldosterone System (RAAS) ➔ Regulates blood volume and pressure.

What is Anti-Diuretic Hormone (ADH) and where is it produced?

ADH is also known as vasopressin.
It is produced by the pituitary gland.
The Dutch term for the pituitary gland is "hypofyse."

What are the functions and characteristics of Anti-Diuretic Hormone (ADH)?

Also called: Vasopressin
Produced by: Pituitary glands (Dutch: hypofyse)
Binds to: Receptors on the collecting duct
Role with aquaporins: Increases incorporation
Effect on urine: More aquaporins reduce urine volume
Maintains: Homeostasis

What triggers the release of ADH in the body?

Osmoreceptors in the hypothalamus trigger ADH release.
Increases in blood osmolarity stimulate hypothalamus.
Thirst mechanism is activated.
ADH is released by the pituitary gland.
Response includes increased permeability in the collecting duct for water reabsorption.

How does the body maintain homeostasis of blood osmolarity?

Blood osmolarity homeostasis is at 300 mOsm/L.
Increased osmolarity causes ADH release, increasing water reabsorption.
Permeability of the distal tubule and collecting duct rises.
Drinking water helps reduce blood osmolarity.
Negative feedback restores osmolarity.

What is the function of the Renin Angiotensin Aldosterone System (RAAS)?

RAAS responds to decreased blood volume and pressure.
Increases water and Na⁺ reuptake for compensation.
Juxtaglomerular apparatus (JGA) surrounds arteries.
JGA detects blood pressure drop, triggering renin release.

What is the function of Renin in the RAAS?

Renin converts angiotensinogen (from the liver) into angiotensin II.
This process occurs through a variety of intermediate steps.

How does Angiotensin II affect the body?

Angiotensin II causes vasoconstriction.
It stimulates aldosterone release from the adrenal gland (Dutch: bijnier).

What role does Aldosterone play in RAAS?

- Aldosterone increases Na⁺ and water uptake in the distal tubule.

What role does the juxtaglomerular apparatus (JGA) play in blood pressure regulation?

The JGA detects low blood volume or pressure.
It releases renin.
Renin converts angiotensinogen to angiotensin I.
Angiotensin I becomes angiotensin II via ACE.
Angiotensin II helps restore homeostasis.

What does the feedback circuit involving ACE inhibitors regulate?

Stimulus: Low blood volume or pressure
Liver: Releases angiotensinogen
Enzyme: Renin converts angiotensinogen to angiotensin I
ACE: Converts angiotensin I to angiotensin II
Effect:
- Angiotensin II causes adrenal gland to release aldosterone
- Function: Increases Na⁺ and H₂O reabsorption
- Arterioles constrict
Outcome: Restores blood pressure and volume

What is the role of the glomerular filtration rate (GFR) in kidney function?

GFR is 120 ml/min.
Filters all extracellular fluid every hour.
Kidney disease affects water/salt balance, blood pH, waste removal.
No symptoms up to 80-90% nephron loss.
2-4% of people have 1 kidney.

What are the components of biochemical analysis of renal function?

Clearance: Measures kidney's ability to remove substances from the blood.
Plasma creatinine: Indicates kidney health.
Estimated GFR (eGFR): Assesses filtration rate.
Determination of glomerular integrity: Evaluates glomerular condition.

What is clearance in the context of renal function?

Measures excretion in urine of substances fully filtered by glomeruli.
Substance is not actively excreted, absorbed, or metabolized by renal tubules.
Volume of blood from which substance is removed per minute is called clearance.

Why is inulin not useful in routine tests, and what is typically measured instead?

Inulin requires injection, limiting its routine test usefulness.
Typically, creatinine is measured in urine and plasma.
Creatinine is a muscle breakdown product.
It’s produced at a relatively constant daily rate.

How is creatinine clearance calculated and what is its average rate?

Formula: Creatinine clearance uncorrected = U/SxV/T
- U: Urine creatinine (mg/dL)
- S: Serum creatinine (mg/dL)
- V: Urine volume (mL)
- T: Collection time (minutes)
Average Rate: Approximately 120 mL/min

What is the relationship between GFR and plasma creatinine concentration?

Creatinine: Approximate relationship with GFR and plasma creatinine concentration.
Decreasing GFR by 50% increases plasma creatinine to twice normal if creatinine production is constant.

What is the formula for renal clearance of toxins and the meaning of its components?

RER = CL_R × C_p
RER: Renal excretion rate (amount of toxin excreted per unit time)
CL_R: Renal plasma clearance (volume cleared per unit time)
C_p: Plasma concentration

What is the formula for renal clearance of toxins and what does it mean if a toxin is excreted only by filtration?

Renal Excretion Rate (RER): \( RER = CL_R \times C_p \)
If a toxin is excreted only by filtration:
- Renal Clearance (\( CL_R \)) equals Glomerular Filtration Rate (GFR).

What factors affect renal clearance of toxins besides GFR?

Renal clearance is also influenced by tubular secretion.
CL_TS denotes the clearance through tubular secretion.
T_m is the maximum transport capacity (amount of toxin per time).
K_T is the Michaelis-Menten constant.
C_p stands for plasma concentration.

What does the Michaelis-Menten graph illustrate?

The curve shows enzyme kinetics.
V is the maximum reaction rate.
K_m represents the substrate concentration at half V.
The reaction rate v approaches V asymptotically.

What processes are involved in renal clearance of toxins?

Glomerular filtration: Removes substances from blood.
Tubular secretion: Adds additional toxins to urine from blood.

These processes collectively enhance toxin elimination from the body.

What factors influence glomerular filtration rate (GFR)?

Molecule size: Anything larger than 30 Angstrom is not filtered.
Molecule charge: Negatively charged molecules are repelled.
Protein binding: Only the free fraction is filtered.
Renal blood flow and age and renal disease.

Describe the factors affecting drug secretion in the proximal tubule.

Protein binding: Only the free fraction is available for uptake.
Renal blood flow.
Competition between substrates for the same transporter.
Concentration of the drug; transporters are saturable.

How does drug reabsorption occur and what factors influence it?

Occurs either actively or passively in distal tubule and collecting duct.
Passive diffusion:
- Follows concentration gradient.
- Influenced by urine flow.
- Affected by non-ionised drug fraction and urine pH.
Active transport resembles natural substrates.

What is necessary for dose adjustment in renal impairment?

Assess degree of impairment.
Alter regular dose and dosing frequency.
Monitor plasma drug levels for drugs with a narrow therapeutic index.

Minor term - nieren

85 important questions on Minor term - nieren