Kidney Function and Nephrons Overview

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Questions and Answers

What is the primary function of the kidneys in regulating blood composition?

Regulation through excretion and osmoregulation (correct)

Excretion of water only

Production of hormones exclusively

Filtration of nutrients

Which hormone is secreted by the kidneys to help control red blood cell formation?

Renin

Calcitriol

Insulin

Erythropoietin (correct)

What is the role of renin in the kidneys?

Catalyzes sugar metabolism

Facilitates nutrient absorption

Regulates blood pressure and volume (correct)

Increases urine production

What do dipstick tests measure in relation to kidney function?

Proteinuria and microalbuminuria Signup and view all the answers

How does creatinine help estimate Glomerular Filtration Rate (GFR)?

It is freely filtered and not reabsorbed Signup and view all the answers

What is urea a by-product of?

Protein metabolism Signup and view all the answers

What is the primary component of the renal corpuscle?

Glomerulus Signup and view all the answers

In what way does urine specific gravity relate to kidney function?

Assesses kidney's ability to concentrate urine Signup and view all the answers

What does renal clearance measure?

The volume of plasma completely cleared of a substance each minute Signup and view all the answers

What occurs to functional nephrons as people age?

They decline by 30 - 40% between ages 25 and 85 Signup and view all the answers

Which diagnostic method is used to visualize kidney structures like renal calyces and bladder?

Excretory urography Signup and view all the answers

Which of the following can lead to renal activity reduction?

Diabetes and atherosclerosis Signup and view all the answers

What happens to the glomerular filtration rate (GFR) with aging?

It reduces Signup and view all the answers

What is a common consequence of uremia?

Increased potassium and hydrogen levels in the blood Signup and view all the answers

Which diagnostic imaging technique is least likely to be used for direct visualization of the urinary system?

Radionuclide imaging Signup and view all the answers

What effect does aging have on the body's total water content?

It gradually decreases Signup and view all the answers

Study Notes

Kidney Function and Regulation

Kidneys regulate blood composition and volume via excretion and osmoregulation, maintaining homeostasis.
Excretion removes metabolic waste products; osmoregulation balances water and salt.
Kidney functions include regulating fluid volume, composition, and pH; removing metabolic waste; controlling red blood cell production (erythropoietin); regulating blood pressure and volume (renin); and activating vitamin D for calcium absorption.

Nephrons: Functional Units of the Kidney

Nephrons are the functional units of the kidneys.
The renal corpuscle comprises a glomerulus (capillaries) enclosed in Bowman's capsule.
Blood enters via the afferent arteriole, flows through glomerular capillaries, and exits through the efferent arteriole to peritubular capillaries.
Fluid and substances filter from blood into Bowman's space within Bowman's capsule.

Diagnostic Tests for Kidney Function

Urine analysis (pH, electrolytes, metabolic byproducts) assesses kidney function.
Urine specific gravity measures urine concentration ability.
Proteinuria/microalbuminuria tests detect abnormal glomerular filtration or tubule reabsorption.
Serum creatinine, a muscle metabolism byproduct, is a common GFR (glomerular filtration rate) indicator (freely filtered, not reabsorbed, not secreted).
BUN (blood urea nitrogen), a liver protein metabolism byproduct, is related to GFR but also affected by protein intake, bleeding, and hydration.

Visualizing Kidney Structures

Visual inspection/tests
Cystoscopy and ureteroscopy visualize urethra, bladder, and ureters.
Ultrasound assesses kidney size.
Radioisotope imaging evaluates kidney structures.
Radiological methods (excretory urography) examine renal calyces, pelvis, ureters, and bladder.
CT scans, MRI, and renal angiography provide further diagnostics.

Renal Clearance

Renal clearance measures plasma volume cleared of a substance per minute.
Clearance depends on filtration, reabsorption, and secretion of a substance in the renal tubules.
Clearance rates vary by substance, always measured in plasma volume per unit time. Calculated by urine concentration multiplied by urine flow rate, divided by plasma concentration of the substance

Aging and the Urinary System

Kidney function declines with age.
Functional nephrons decrease by 30-40% between ages 25 and 85.
Glomerular filtration rate diminishes.
Water and sodium reabsorption reduces; potassium excretion increases.
Micturition reflex issues can arise.
Total body water content and mineral content decrease.
Increased incidence of disorders affecting other major systems.

Kidney Dysfunction

Reduced renal activity can result from glomerulonephritis, diabetes, atherosclerosis, or kidney stones and cause:
- High blood pressure
- High blood potassium and hydrogen levels
- Uremia (urea in the blood)
Patients with uremia may require dialysis.

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Description

Explore the vital roles of kidneys in regulating blood composition and homeostasis through excretion and osmoregulation. This quiz delves into the structure and function of nephrons, the kidney's functional units, and essential diagnostic tests for kidney health.