Urinary system - structure and glomerular filtration

What is the primary function of the kidneys?

Maintain water balance in the body.

How do kidneys help maintain osmolarity?

By regulating water balance in body fluids.

What is the role of erythropoietin?

Stimulates the production of red blood cells.

What does renin do?

Regulates salt balance in the body.

What is the active form of vitamin D produced by the kidneys?

Calcitriol.

What is a nephron?

The functional unit of the kidney, approximately 1 million per kidney.

What is the role of the glomerulus?

Filtration of blood to form urine.

What is tubular reabsorption?

Selective movement of filtered substances back into the blood.

What does tubular secretion involve?

Movement of nonfiltered substances from blood into the tubular lumen.

What percentage of plasma entering the glomerulus is filtered?

20%.

What is net filtration pressure (NFP)?

The pressure responsible for filtrate production.

What is hydrostatic pressure of blood (HPB) in mm Hg?

55 mm Hg.

What opposes filtration in the Bowman’s capsule?

Hydrostatic pressure and osmotic pressure.

What is the effect of arterial vasoconstriction on GFR?

Decreases GFR.

What happens to GFR if blood pressure increases?

GFR increases.

What do juxtaglomerular cells do?

They release renin when blood pressure is low.

What does myogenic mechanism involve?

Vasoconstriction or vasodilation of the afferent arteriole based on blood pressure.

What happens during tubuloglomerular feedback with high BP?

Increased vasoconstriction of the afferent arteriole decreases GFR.

What do macula densa cells monitor?

The flow and concentration of filtrate.

What does the renin-angiotensin-aldosterone system help regulate?

Blood pressure and fluid balance.

How does aldosterone affect kidney function?

Increases sodium reabsorption which raises blood volume and pressure.

What forces favor glomerular filtration?

Glomerular capillary blood pressure.

What pressure opposes glomerular filtration?

Plasma-colloid osmotic pressure and Bowman's capsule hydrostatic pressure.

What is the normal range for net filtration pressure?

Approximately 10 mm Hg.

How does increased blood pressure affect NFP?

Increases NFP.

What is the primary function of the distal convoluted tubule?

Fine-tuning of reabsorption and secretion.

What happens if the GFR is too high?

Needed substances cannot be reabsorbed and are lost in urine.

What effect does renal autoregulation have on GFR?

Helps maintain stable GFR despite fluctuations in systemic blood pressure.

What mechanism uses changes in blood pressure to adjust kidney function?

Myogenic mechanism.

What occurs during slow filtrate flow in the tubuloglomerular feedback loop?

Decreased GFR.

What is reabsorbed in the proximal tubule?

Sodium, glucose, amino acids, vitamins, water, and urea.

How does the Na+-K+ Pump function in the proximal tubule?

It helps in reabsorption by creating a sodium gradient.

What happens to water during reabsorption in the proximal tubule?

Water is reabsorbed through osmosis.

What is the role of interstitial fluid in nephron function?

Facilitates the movement of reabsorbed substances back into the blood.

What substances are secreted into the tubular lumen?

H+ ions and organic ions.

What does a rise in capillary blood pressure indicate in patients?

Possible kidney issues related to filtration.

What are the three basic processes that create urine?

Glomerular filtration, tubular reabsorption, tubular secretion.

What is the consequence of decreased NFP?

Reduces glomerular filtration rate.

Where does the filtration of blood occur in the kidney?

In the glomerulus.

What is the average percentage of plasma not filtered from the glomerulus?

80%.

What is the main effect of angiotensin II?

Increases blood pressure via vasoconstriction.

What pressure is measured in the Bowman's capsule?

Hydrostatic pressure.

Which structure stores urine before it is expelled from the body?

Renal pelvis.

What is the role of collecting ducts in the nephron?

Concentrates urine by reabsorbing water.

What type of epithelium is the glomerular capillary wall?

Fenestrated epithelium.

What hormone triggers water reabsorption in the kidneys?

Antidiuretic hormone (ADH).

How is glucose reabsorbed in the nephron?

By secondary active transport with sodium.

What effect does vasodilation of the afferent arteriole have?

Increases blood flow and GFR.

What do peritubular capillaries surround?

The nephron tubule.

How is osmotic pressure created in the kidneys?

Through the concentration of proteins in the blood.

What indicates a high osmolarity in the filtrate?

High sodium or solute concentration.

What role do podocytes play in the nephron?

They form part of the filtration barrier in the glomerulus.

What happens if there is a block in the renal pelvis?

It affects the hydrostatic pressure and filtration processes.

What effect does decreased blood flow to the kidneys have?

Decreases glomerular filtration rate.

What is the significance of large pores in glomerular capillaries?

They increase permeability to water and solutes.

How is urea transported across the nephron?

By diffusion from the filtrate to the interstitial fluid.

What happens to potassium ions in the nephron?

They are secreted into the tubular fluid.

What factor influences glomerular filtration rate the most?

Glomerular capillary blood pressure.

What occurs in the renal corpuscle?

Initial blood filtration occurs here.

What effect does renal perfusion pressure have?

It influences the rate of filtration in the glomerulus.

What structure helps regulate GFR via feedback?

Juxtaglomerular apparatus.

How does the nephron adapt to low blood pressure?

By releasing renin and inducing vasoconstriction.

What happens during hyponatremia concerning kidney function?

May lead to increased excretion and dehydration.

What is the key player in the regulation of fluid balance?

Kidneys.

What is the first site of blood filtration in the nephron?

The glomerulus.

What happens in the minor calyx?

Collects urine from the renal papilla.

What do nephron loops (descending and ascending limbs) primarily handle?

Concentration and dilution of urine.

What regulates sodium reabsorption in the distal convoluted tubule?

Aldosterone.

What is the significance of the renal medulla?

It contains structures that are involved in urine concentration.

How do tubular cells adapt to their function?

By having microvilli to increase surface area for absorption.

What triggers the release of renin by juxtaglomerular cells?

Decreased blood pressure.

What is the role of the renal cortex?

Contains renal corpuscles and proximal tubules for filtration and reabsorption.

What does the term 'fenestrated' refer to concerning capillaries?

Having small pores that allow passage of certain substances.

What is the function of the efferent arteriole?

Carries filtered blood away from the glomerulus.

What role do hormones play in kidney function?

Regulate hydration and electrolyte balance.

What is an effect of kidney disease on urine output?

Can lead to either increased or decreased urine output depending on the condition.

What structural feature enhances the reabsorption capacity of renal tubules?

Microvilli.

In what part of the nephron is the majority of water reabsorbed?

The proximal convoluted tubule.

What happens to calcium levels in response to parathyroid hormone?

Increases reabsorption in the kidneys.

What does the term 'glomerular ultrafiltrate' refer to?

Fluid that is filtered from the blood into Bowman’s capsule.

What is the nephron composed of?

Renal corpuscle and renal tubule.

How does the kidney respond to dehydration?

By reabsorbing more water and concentrating urine.

What is a common cause of decreased GFR?

Renal artery stenosis or decreased blood flow.

What process allows for the regulation of urine concentration?

Counter-current multiplication.

What is the function of the renal pelvis?

Collects urine before it moves to the ureter.

What is the relationship between blood volume and blood pressure?

Higher blood volume leads to increased blood pressure.

Which cells in the kidney are responsible for sensing changes in filtrate flow?

Macula densa cells.

What does high levels of albumin in urine indicate?

Possible damage to the glomerular filtration barrier.

How does the kidney handle excess electrolytes?

By excreting them in the urine.

What is the main driving force for glomerular filtration?

Hydrostatic pressure.

What hormone decreases renal blood flow?

Angiotensin II.

What occurs during dehydration at the nephron level?

Increased reabsorption of water.

What structural changes occur in response to volume overload?

Increased glomerular filtration area.

What is the physiological importance of the vasa recta?

Maintains the osmotic gradient in the kidney.

How do kidneys adjust electrolyte levels in the body?

Through selective reabsorption and secretion.

What term describes the pressure in the glomerular capillaries that drives filtration?

Hydrostatic pressure.

What can result if the GP during GFR is too low?

Inefficient filtration and increased retention of waste products.

What happens pharmacologically during renal impairment?

Medications may not be excreted effectively, requiring dosage adjustments.