Kidney Function and Nephron Structure

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Questions and Answers

What effect does an increase in Bowman’s Capsule Hydrostatic Pressure have on GFR?

It has no effect on GFR.

It increases renal blood flow.

It decreases GFR by opposing filtration. (correct)

It causes GFR to increase significantly.

If the Glomerular Capillary Colloid Osmotic Pressure increases, what will likely happen to the glomerular filtration rate?

GFR will decrease as fluid is pulled back into the capillaries. (correct)

GFR will fluctuate randomly.

GFR will increase due to more fluid filtration.

GFR will remain the same.

How does Net Filtration Pressure (NFP) correlate to Glomerular Filtration Rate (GFR)?

GFR is unaffected by changes in NFP.

GFR and NFP are inversely related.

GFR decreases as NFP increases.

GFR increases when NFP increases. (correct)

What primarily determines the balance of pressures that affect Net Filtration Pressure?

Hydrostatic and osmotic pressures across glomerular capillaries. Signup and view all the answers

Which of the following factors would likely result in an increased GFR?

Decreased efferent arteriole resistance. Signup and view all the answers

What does a decrease in renal blood flow suggest about the pressures in the glomeruli?

Glomerular capillary hydrostatic pressure may decrease. Signup and view all the answers

Which pressure typically opposes the filtration process at the glomerulus?

Bowman's capsule hydrostatic pressure. Signup and view all the answers

What condition would likely result from an increase in glomerular capillary hydrostatic pressure?

Increased GFR. Signup and view all the answers

What is the primary consequence of decreased Net Filtration Pressure?

Decreased Glomerular Filtration Rate. Signup and view all the answers

What effect does constricting the efferent arteriole while keeping the afferent arteriole unchanged have on GFR?

Decreases GFR due to reduced outflow resistance. Signup and view all the answers

Which statement correctly describes the relationship between hydrostatic pressure and colloid osmotic pressure in the context of ultrafiltration in the glomerulus?

Hydrostatic pressure must exceed colloid osmotic pressure for ultrafiltration to occur. Signup and view all the answers

What is the primary effect of dilation of both the afferent and efferent arterioles on GFR?

The GFR decreases due to decreased glomerular pressure. Signup and view all the answers

Which of the following correctly explains the concept of Net Filtration Pressure (NFP)?

NFP calculates the difference between glomerular hydrostatic pressure and the sum of influences from colloid osmotic pressure and capsular hydrostatic pressure. Signup and view all the answers

How does constricting both the afferent and efferent arterioles influence renal blood flow (RBF)?

Decreases RBF due to reduced blood flow into the glomerulus. Signup and view all the answers

What physiological mechanism triggers the micturition reflex when the bladder is full?

Stretch receptors stimulate parasympathetic activity causing bladder contraction. Signup and view all the answers

Which outcome is most likely when the afferent arteriole is dilated while the efferent arteriole remains unchanged?

Increased GFR due to higher glomerular capillary pressure. Signup and view all the answers

What is the primary driving force for the filtration of blood through the glomerulus?

Glomerular hydrostatic pressure. Signup and view all the answers

What does an increase in colloid osmotic pressure in the peritubular capillaries indicate?

Increased driving force for reabsorption of water into capillaries. Signup and view all the answers

How does sympathetic activity affect the bladder during the filling phase?

Promotes bladder relaxation to increase its capacity. Signup and view all the answers

Which statement best describes the role of the glomerular filtration rate (GFR) in kidney function?

GFR measures the amount of blood filtered by the kidneys per minute. Signup and view all the answers

What primarily influences net filtration pressure (NFP) in the glomerulus?

The balance between oncotic pressure and hydrostatic pressure. Signup and view all the answers

Which statement correctly differentiates afferent and efferent arterioles?

Efferent arterioles bring blood away from the glomerulus, while afferent arterioles bring blood to the glomerulus. Signup and view all the answers

How does glomerular capillary pressure affect renal blood flow?

Increased capillary pressure enhances renal blood flow. Signup and view all the answers

Which nephron type is primarily involved in maintaining the vertical osmotic gradient?

Juxtamedullary nephrons, because of their long loops of Henle. Signup and view all the answers

What is the primary function of the peritubular capillaries?

They facilitate the exchange of nutrients and waste products between blood and the nephron. Signup and view all the answers

Which pathway correctly describes blood flow through the renal vasculature?

Heart → Renal Artery → Afferent Arteriole → Glomerulus → Efferent Arteriole. Signup and view all the answers

Which of the following conditions would likely decrease renal blood flow (RBF)?

Increased vascular resistance due to vasoconstriction. Signup and view all the answers

What is the primary function of the loop of Henle within the nephron?

Reabsorption of water and salts to concentrate urine. Signup and view all the answers

Study Notes

Kidney Function

Kidneys filter blood, retaining beneficial substances and eliminating waste products as urine.
Blood enters the kidney through the renal artery, passes through various vessels, and leaves through the renal vein.
The kidney is structurally divided into the cortex and medulla.
The medulla contains pyramids, where urine is collected in minor and major calices and drained into the pelvis, then the ureter.

The Nephron

The nephron is the functional unit of the kidney, consisting of a filtering glomerulus and a tubule system.
The glomerulus and tubule system are surrounded by capillaries.
The vascular components of the nephron are the afferent arteriole, efferent arteriole, glomerulus, peritubular capillaries, and vasa recta.
The tubular components of the nephron are the Bowman's capsule, proximal tubules, loop of Henle, distal tubules, and collecting ducts.

Types of Nephrons

There are two types of nephrons: superficial (cortical) nephrons and juxtamedullary nephrons.
Cortical nephrons are more numerous, accounting for about 85%, while juxtamedullary nephrons make up the remaining 15%.
Juxtamedullary nephrons have long loops of Henle surrounded by vasa recta.
Superficial nephrons have short loops of Henle surrounded by peritubular capillaries.
Both types of nephrons contribute to reabsorption and secretion.
However, juxtamedullary nephrons also contribute to the vertical osmotic gradient.

Blood Pathway through the Kidney

The blood flow through the kidney: Heart - Aorta - Renal Artery - Segmental Artery - Lobar Artery - Arcuate Artery - Interlobular Artery - Afferent Arteriole - Glomerulus - Efferent Arteriole - Peritubular Capillaries - Interlobular Vein - Arcuate Vein - Interlobar Vein - Renal Vein - Inferior Vena Cava - Heart.

Tubular Reabsorption and Secretion

Tubular Reabsorption: selective transfer of specific substances from the filtrate back into the blood of the peritubular capillaries.
Tubular Secretion: selective transfer of substances from the peritubular capillary blood into the tubular lumen.

Micturition Reflex

The micturition reflex involves temporary urine storage in the bladder and its subsequent emptying.
It involves bladder contraction and the opening of both the internal and external urethral sphincters.
The bladder wall is composed of detrusor smooth muscle.
The internal sphincter is made of smooth muscle and is involuntary.
The external sphincter is skeletal muscle and is voluntarily controlled.
Sympathetic activity relaxes the bladder, allowing it to fill.
Parasympathetic activity, triggered by stretch receptors, contracts the smooth muscle in the bladder and opens the internal sphincter.

Glomerulus

Glomerular filtration rate (GFR) is determined by the balance of pressures across the glomerular capillaries.
Hydrostatic pressure is the force exerted by the blood on the glomerular capillary wall, pushing fluid and solutes out.
Colloid osmotic pressure is the pressure generated by proteins in the blood, pulling water back into the capillaries.

Factors Affecting GFR

Afferent arteriole constriction: Reduces blood flow into the glomerulus, decreasing glomerular pressure, leading to decreased GFR.
Efferent arteriole constriction: Increases resistance to blood leaving the glomerulus, raising glomerular pressure, potentially increasing GFR.
Afferent arteriole dilation: Increases blood flow into the glomerulus, raising glomerular pressure, increasing GFR.
Efferent arteriole dilation: Decreases resistance to blood leaving the glomerulus, lowering glomerular pressure, potentially decreasing GFR.

Net Filtration Pressure (NFP)

NFP is the pressure driving fluid and solutes from the blood in the glomerulus into Bowman’s capsule.
NFP is determined by the balance of:
- Glomerular Capillary Hydrostatic Pressure (PGC)
- Bowman's Capsule Hydrostatic Pressure (PBC)
- Glomerular Capillary Colloid Osmotic Pressure (πGC)

GFR and NFP

Increased NFP leads to an increase in GFR.
Decreased NFP leads to a decrease in GFR.

Maintaining Glomerular Blood Pressure

The kidney carefully regulates blood pressure across the glomerulus to maintain a constant GFR.

Chapter 14: Renal

The kidneys play a crucial role in maintaining the balance of electrolytes and fluid in the body.
They also excrete waste products and help regulate blood pressure.

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Description

This quiz covers the essential functions of the kidneys and the detailed structure of nephrons, the functional units of the kidneys. Topics include the renal artery and vein, and the types and components of nephrons, highlighting their roles in blood filtration and urine formation.