2i-Excretion Flashcards
Q: What is excretion, and why is it important?
A: Excretion is the removal of metabolic waste products from the body. It is essential to prevent toxic buildup, maintain homeostasis, and ensure proper cell function.
What are the main excretory organs in humans and their functions?A:
Lungs: Remove carbon dioxide produced during respiration.
Kidneys: Filter blood to remove urea, excess water, and salts, forming urine.
Skin: Removes excess water, urea, and salts through sweat.
How do the kidneys function in excretion?
The kidneys filter blood through three main processes:
The kidneys filter blood through three main processes:
Ultrafiltration: Blood is filtered under high pressure in the glomerulus, removing water, glucose, urea, and salts into the Bowman’s capsule.
Selective Reabsorption: Useful substances like glucose, amino acids, and some water are reabsorbed in the nephron.
Formation of Urine: Excess water, urea, and salts form urine, which is collected in the bladder and excreted via the urethra.
How does the body maintain water balance through the kidneys?A:
The hormone ADH (antidiuretic hormone) regulates water reabsorption in the kidneys:
When dehydrated: More ADH is released, increasing water reabsorption and producing concentrated urine.
When overhydrated: Less ADH is released, reducing water reabsorption and producing dilute urine.
Practical: Investigating the Composition of Urine
Testing for Glucose in Urine:
Method: Add Benedict’s solution to a urine sample and heat.
Positive Result: Brick-red color indicates glucose (possible diabetes).
Negative Result: No color change (solution remains blue).
Practical: Investigating the Composition of Urine
Testing for Protein in Urine:
Testing for Protein in Urine:
Method: Add Biuret solution to a urine sample.
Positive Result: Purple color indicates protein (possible kidney damage).
Negative Result: No color change (solution remains blue).
