Chapter 5 · Question 18
Describe the structure and functioning of nephrons.
Q18
Describe the structure and functioning of nephrons.
Answer Revealed
Direct Answer:
Nephrons are the filtering units of the kidney. Each nephron has a Bowman's capsule, glomerulus, and a long tubule. They filter blood, reabsorb useful substances, and produce urine.
Simple Explanation
Nephrons are tiny filters inside our kidneys. Blood enters the nephron, wastes and extra water are filtered out, and the clean blood goes back. The filtered waste becomes urine.
Exam-Ready Structure
Structure of nephron: Each kidney contains about one million nephrons. A nephron consists of: 1. Bowman's capsule — A cup-shaped structure at the beginning of the nephron that encloses the glomerulus. 2. Glomerulus — A knot of capillaries where blood is filtered under pressure. 3. Renal tubule — A long, coiled tube divided into proximal convoluted tubule, loop of Henle, and distal convoluted tubule. 4. Collecting duct — Where several nephrons deposit urine, which then flows to the ureter. Functioning: Blood enters the glomerulus under high pressure. Water, glucose, amino acids, urea, and salts are filtered into the Bowman's capsule (ultrafiltration). As this filtrate passes through the tubule, useful substances like glucose, amino acids, most water, and some salts are selectively reabsorbed back into the blood capillaries around the tubule. Remaining waste (urine) contains urea, excess water, and excess salts, which travels through the collecting duct to the ureter and is stored in the urinary bladder.
Key Points
- Nephrons are the filtering units of kidneys
- Glomerulus filters blood under pressure
- Useful substances are reabsorbed in the tubule
- Urine contains urea, excess water, and salts
Common Mistakes
- Saying filtration happens in the tubule instead of the glomerulus
- Forgetting that glucose is fully reabsorbed in a healthy kidney
Relevant Maps and Figures
Structure of a Nephron
figure
Use the nephron figure to show where filtration begins and where useful substances are reabsorbed.
It is the main structure-function anchor for the kidney answer.
This nephron diagram is the main visual anchor for filtration, selective reabsorption, and the route from Bowman's capsule to urine formation.
Answer Sources
- Figure 5.14 structure of a nephronfigure | Science | Life Processes | Nephron structure and selective reabsorption | Pages 19