Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
The lungs, liver, and skin also play significant roles in the elimination of excretory wastes besides the kidneys.
Lungs: Responsible for the removal of large amounts of (approximately ) and significant quantities of in the form of vapor.
Liver: The largest gland in the body. It secretes bile containing substances like bilirubin, biliverdin, cholesterol, degraded steroid hormones, vitamins, and drugs. Most of these are excreted via digestive wastes.
Skin (Sweat Glands): Produce sweat, a watery fluid containing , small amounts of urea, and lactic acid. Its primary function is thermoregulation (cooling), but it also aids in excretion.
Skin (Sebaceous Glands): Eliminate substances like sterols, hydrocarbons, and waxes through sebum, which provides a protective oily covering for the skin.
Saliva: Small amounts of nitrogenous wastes can also be eliminated through salivary secretions.
📐Formulae
💡Examples
Problem 1:
Calculate the total volume of excreted by the lungs in based on the average physiological rate.
Solution:
Total volume .
Explanation:
Since the lungs remove at a rate of every minute, multiplying by the minutes in an hour gives the hourly excretion volume.
Problem 2:
Which substances are primarily eliminated by the liver through bile, and how are they finally removed from the body?
Solution:
The liver eliminates bilirubin, biliverdin, cholesterol, degraded steroid hormones, vitamins, and drugs. They are removed through digestive wastes (feces).
Explanation:
These metabolic byproducts and toxins are processed by hepatocytes, secreted into the bile duct, stored in the gallbladder, and released into the small intestine to be expelled with undigested food.