Nephron Functions and Physiology Quiz

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Questions and Answers

What distinguishes the ascending limbs of juxtamedullary nephrons from those of other nephrons?

They consist only of thick segments.

They consist of both thin and thick segments. (correct)

They consist only of thin segments.

They are located exclusively in the renal cortex.

Which type of nephrons primarily receive blood supply from vasa recta?

Juxtamedullary nephrons (correct)

Superficial nephrons

Short-loop nephrons

Cortical nephrons

What is the primary function of collecting ducts in the nephron?

To filter blood from the renal arteries.

To secrete uric acid into the filtrate.

To reabsorb all nutrients back into the blood.

To drain urine into the minor calyces. (correct)

In which part of the cortex do the renal corpuscles of juxtamedullary nephrons primarily reside?

Close to the medulla. Signup and view all the answers

How do short-loop nephrons receive their blood supply?

From peritubular capillaries that arise from efferent arterioles. Signup and view all the answers

What is the primary function of the renal corpuscle?

Filtration of blood Signup and view all the answers

What is the net filtration pressure in the renal corpuscle?

10 mmHg Signup and view all the answers

Which of the following substances is fully filtered but not reabsorbed?

Creatinine Signup and view all the answers

How much water is typically returned to the blood from glomerular filtrate in a day?

178-179 L Signup and view all the answers

What effect does angiotensin II have on glomerular filtration rate (GFR)?

Reduces GFR by vasoconstricting arterioles Signup and view all the answers

What is the typical amount of glucose reabsorbed from glomerular filtrate daily?

162 g Signup and view all the answers

Which substance is actively reabsorbed in the nephron?

Glucose Signup and view all the answers

What is the total amount of filtrate produced from plasma daily?

180 L Signup and view all the answers

Which hormone is responsible for increasing the water permeability of principal cells in the kidney?

Antidiuretic hormone (ADH) Signup and view all the answers

What effect does parathyroid hormone (PTH) have on phosphate reabsorption in the kidney?

PTH inhibits phosphate reabsorption. Signup and view all the answers

Which hormone is primarily released in response to low blood flow?

Antidiuretic hormone (ADH) Signup and view all the answers

Which of the following hormones does NOT help maintain systemic blood pressure?

Parathyroid hormone (PTH) Signup and view all the answers

What is the primary action of angiotensin II in relation to blood pressure?

Increase peripheral resistance. Signup and view all the answers

Which hormone is released from the heart and causes an increase in sodium excretion?

Atrial natriuretic peptide (ANP) Signup and view all the answers

How does aldosterone affect sodium levels in the body?

It increases sodium reabsorption. Signup and view all the answers

Where is antidiuretic hormone (ADH) produced?

Posterior pituitary Signup and view all the answers

What is the primary function of the kidneys?

Removal of toxins and metabolic wastes Signup and view all the answers

Where are the kidneys located in the body?

Along the back body wall below the diaphragm Signup and view all the answers

What type of nephrons make up the majority of nephrons in the kidneys?

Cortical nephrons Signup and view all the answers

Which hormone produced by the kidneys regulates blood pressure?

Renin Signup and view all the answers

What is the role of the renal corpuscle in the nephron?

Initial filtering component Signup and view all the answers

Approximately how much of cardiac output do the renal arteries deliver to the kidneys each minute?

1/4 Signup and view all the answers

What is the primary functional unit of the kidney?

Nephron Signup and view all the answers

Which process is NOT part of renal physiology?

Hormonal digestion Signup and view all the answers

What is the significance of the short loops of Henle in cortical nephrons?

They penetrate only a small way into the medulla Signup and view all the answers

Which of the following is NOT a function of the kidneys?

Digestion of food Signup and view all the answers

What triggers the release of atrial natriuretic peptide (ANP)?

A sudden large increase in blood pressure Signup and view all the answers

What effect does ANP have on the glomerulus?

Increases the surface area for filtration Signup and view all the answers

Which of the following correctly describes paracellular reabsorption?

Movement of substances between cells Signup and view all the answers

What role do the sodium-potassium pumps play in the reabsorption process?

Maintaining sodium gradients for reabsorption Signup and view all the answers

How is bicarbonate (HCO3) reabsorbed in the proximal convoluted tubule?

Via carbonic anhydrase reactions Signup and view all the answers

Which part of the nephron is primarily responsible for reabsorbing a significant portion of filtered Na+ and K+?

Thick ascending limb Signup and view all the answers

Which of the following hormones is NOT mentioned as affecting renal tubule reabsorption?

Insulin Signup and view all the answers

In the proximal convoluted tubule, how does glucose enter the tubule cell?

By Na+ coupled transport Signup and view all the answers

What percentage of filtered water is reabsorbed in the thick ascending limb of the loop of Henle?

15% Signup and view all the answers

What is the primary method of reabsorption in the later sections of the proximal convoluted tubule?

Passive reabsorption Signup and view all the answers

How does the thick ascending limb of the Loop of Henle handle calcium and magnesium?

It has a variable absorption rate Signup and view all the answers

Which of the following substances undergoes significant reabsorption in the proximal convoluted tubule?

Amino acids Signup and view all the answers

Which mechanism does the nephron employ to help maintain electrolyte balance?

Hormonal regulation of reabsorption Signup and view all the answers

What occurs during the secretion of potassium (K+) in the distal convoluted tubule?

K+ is secreted in exchange for Na+ Signup and view all the answers

Study Notes

MPharm Programme Renal - PHA115

The lecture is part of the MPharm Programme, specifically focusing on the renal system.
The course code is PHA115.
The presenter is Dr Praveen Bhugra.
The university is Sunderland.

Learning Objectives

Students will be able to describe the organs and function of the urinary system briefly.
Detailed knowledge of kidney anatomy, including location, internal and external structure, blood and nerve supply, and function, will be acquired.
The structure of the nephron and its blood supply, along with its function, will be understood.
The lecture will delve into renal physiology, including urine formation, glomerular filtration, tubular reabsorption, tubular secretion, hormonal regulation, and homeostasis.

Urinary System

The kidneys produce urine and help regulate bodily fluids.
The ureters transport urine to the bladder.
The urinary bladder acts as a reservoir for urine.
The urethra carries urine to the exterior.

Urinary System (Specific Organs)

Kidneys: paired, bean-shaped organs located along the back body wall, below the diaphragm, and adjacent to the vertebral column.
Right kidney is slightly lower than the left due to the liver's position.
Other Organs: ureters, urinary bladder, urethra are listed and their general functions are detailed.

Structure of Kidney

The kidney comprises renal cortex, renal medulla, renal columns, renal pyramids, renal papilla, and renal capsule.
The image shows the path of urine drainage, including minor and major calyxes, renal artery, renal pelvis, renal vein, ureter, and urinary bladder.

Blood and Nerve Supply

~1200 ml of cardiac output is delivered to the kidneys every minute via renal arteries.
Arterial and venous blood flow through similar pathways.
The nerve supply to the kidneys is via sympathetic fibers of the renal plexus.

Blood Supply of Kidney

The detailed blood supply of the kidney is described, highlighting the renal artery, segmental arteries, interlobar arteries, arcuate arteries, cortical radiate arteries, afferent arterioles, glomerulus, efferent arterioles, peritubular capillaries, vasa recta, arcuate veins, interlobar veins, cortical radiate veins, and renal vein.

Renal Blood Supply

The detailed pathway of blood flow from aorta to the peritubular capillaries and vasa recta, detailing renal artery, segmental artery, interlobar artery, arcuate artery, cortical radiate artery, afferent arteriole, glomerulus (capillaries), efferent arteriole, peritubular capillaries and vasa recta, interlobar vein, arcuate vein, cortical radiate vein, and renal vein.

Functions of the Kidney

The kidney removes toxins, metabolic wastes, and excess ions from the blood.
It regulates blood volume, chemical composition, and pH.
Gluconeogenesis occurs during prolonged fasting.
Endocrine functions include renin regulation of blood pressure and kidney function, erythropoietin regulation of RBC production, and vitamin D activation.

Functions of the Kidney (Calcium Homeostasis)

The kidney regulates calcium and phosphate levels involving calcitriol, phosphate excretion, bone resorption, serum phosphate, and parathyroid hormone (PTH).
The details of the regulation are shown in an image.

Nephron

Nephrons are the structural and functional units of the kidney, responsible for forming urine.
Approximately one million nephrons exist per kidney.
Each nephron consists of a renal corpuscle (initial filtering component) and a renal tubule extending from the renal corpuscle.
Detailed illustrations displayed show components of the nephron, like glomerular capsule, glomerulus, proximal convoluted tubule, loop of Henle, and distal convoluted tubule.
Differences between cortical and juxtamedullary nephrons are described.

Nephrons (Cortical and Juxtamedullary)

Cortical nephrons make up about 80-85% of the nephrons, with short loops of Henle and renal corpuscles located in the outer cortex.
Juxtamedullary nephrons constitute the remaining 15-20%, situated deeper in the cortex near the medulla, with long loops of Henle extending deep into the medulla.
Blood supply for each type differs slightly.

Nephrons (Collecting Duct)

Distal convoluted tubules of multiple nephrons empty into a single collecting duct.
These collecting ducts merge to create several hundred large papillary ducts, which drain into the minor calyces, major calyces, renal pelvis, and ureters.

Functions of the Nephron

The process of filtering, reabsorbing, and secreting substances is described.
These steps involve filtration from blood (plasma) into nephron, tubular reabsorption (fluid back into blood), and tubular secretion (from blood into fluid).
Images illustrate these steps and their location within the nephron.

Renal Corpuscle

The glomerular (Bowman's capsule), including its parietal and visceral layers, glomerulus (capillaries), mesangial cells, and their location relative to afferent and efferent arterioles, are described.

Glomerular Filtration

Components of the filtration membrane are described, including the capillary endothelium, basement membrane, and foot processes of podocytes.
The process of blood filtration is described and visualized to filter substances into the filtrate.
Data on filtration rates and amounts of various substances (water, proteins, glucose, urea, creatinine) filtered, reabsorbed, and excreted by the kidneys is presented in tabular format.

Glomerular Filtration Regulation

The role of two hormones, angiotensin II, and the atrial natriuretic peptide (ANP) in regulating glomerular filtration rate (GFR) are detailed.
ANP actions are presented, which include relaxation of the glomerulus and increasing the filtration surface area.

Reabsorption Routes

Detailed description of transcellular and paracellular pathways for reabsorption.
Components like tight junctions and the basal membrane are described.
Active and passive transport mechanisms involved in reabsorption are detailed.

Reabsorption in PCT and Other Tubular Segments

Different substances' reabsorption occurs in distinct ways.
The proximal convoluted tubule (PCT) reabsorbs water, Na+, various ions, amino acids, glucose through various symporters and channels.
The thick ascending limb of the Loop of Henle regulates Na+, Cl-, and K+.

Reabsorption in Distal Convoluted Tubule and Collecting Duct

Reabsorption of Na+ and secretion of K+ is described and related to principal cells.
How this process is regulated by hormones is included

Hormones and Homeostasis

Multiple hormones that impact sodium, chloride, calcium, water reabsorption and potassium secretion in the tubules are detailed.
These hormones are crucial for maintaining homeostasis of blood flow, blood pressure, and volume.
The actions of antidiuretic hormone (ADH), aldosterone, atrial natriuretic peptide (ANP). and parathyroid hormone (PTH) are detailed.
This section presents a flowchart of how hormones regulate systemic blood pressure and the associated changes in GFR, using dehydration, blood volume decrease, and blood pressure decrease as triggers.

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Description

Test your knowledge on the functions and anatomy of nephrons, focusing on the distinctions between juxtamedullary and cortical nephrons. This quiz covers key concepts such as blood supply, filtration rates, and the roles of various nephron components. Perfect for students of renal physiology and advanced biology!