Human circulatory, nervous, digestive, and respiratory system biology.
Test your knowledge with these top questions!
What is an enlarged thyroid gland that causes a visible neck swelling called?
A goiter often develops from iodine deficiency, as the thyroid enlarges while straining to capture more iodine.
Which exercise most directly strengthens the human abdominal muscles?
Sit-ups curl the trunk against gravity, repeatedly shortening the rectus abdominis.
About what is the usual comfortable capacity of an adult human bladder?
Stretch sensors start signaling before the bladder is full, so an early urge can often be delayed voluntarily.
What does the calorie count on a food label measure?
The listed calories apply to one serving; eating two servings doubles the energy total.
Which change during gentle walking can speed lactate transport away from hard-working muscles?
Active recovery can move lactate into circulation, where the heart and other tissues can use it as fuel.
How many kidneys does a typical healthy human adult have?
The pair of bean-shaped organs sits toward the back of the abdomen, below the rib cage.
Which organ breaks down most of the alcohol in human blood?
Liver enzymes convert alcohol into acetaldehyde, then into acetate the body can clear more easily.
Which blood pressure reading is considered healthy for most adults?
The top number measures pressure during beats and the bottom measures pressure between beats.
Which skin pigment increases to produce a suntan?
Melanocytes make melanin, which absorbs ultraviolet light and helps shield deeper skin cells.
Which blood components does the human spleen hold in reserve to help with clotting?
An enlarged spleen can trap extra platelets, reducing the number available in circulating blood.