Which of the following are structures that rely on capillaries for exchange or movement of small molecules?
1 teeth, aorta, ureter
2 cartilage, epidermis, larynx
3 nephron, villi, alveoli
4 leukocytes, atrium, bronchi
answer #2
whoops 3 i meant
The correct answer is 3. Nephron, villi, and alveoli are structures that rely on capillaries for the exchange or movement of small molecules.
To arrive at this answer, we need to understand the function of capillaries. Capillaries are tiny blood vessels that connect the arteries and veins. They are responsible for the exchange of nutrients, oxygen, and waste products between the blood and surrounding tissues. Capillaries have extremely thin walls that allow for the diffusion of small molecules.
Now let's look at each option:
1. Teeth, aorta, ureter: Teeth are structures in the mouth used for chewing, and they do not rely on capillaries for the exchange of small molecules. The aorta is a large artery that carries blood away from the heart and does not exchange small molecules. The ureter is a tube that transports urine from the kidney to the bladder and also does not rely on capillaries for exchange.
2. Cartilage, epidermis, larynx: While these structures have important roles in the body, they do not rely on capillaries for the exchange or movement of small molecules. Cartilage is a type of connective tissue, the epidermis is the outer layer of the skin, and the larynx is a part of the respiratory system. None of them have a direct connection to capillaries for molecular exchange.
3. Nephron, villi, alveoli: These structures are directly involved in the exchange or movement of small molecules and rely on capillaries for this purpose.
- Nephron: The nephron is the functional unit of the kidney. It filters waste products and excess water from the blood and reabsorbs necessary substances. This filtration and reabsorption process occurs in the glomerulus, a network of capillaries in the nephron.
- Villi: Villi are tiny finger-like projections found in the small intestine. They increase the surface area for the absorption of nutrients from digested food. Each villus contains capillaries that transport the absorbed nutrients into the bloodstream.
- Alveoli: Alveoli are small air sacs in the lungs, where the exchange of oxygen and carbon dioxide occurs during respiration. The walls of the alveoli are surrounded by capillaries, allowing for the exchange of gases.
Therefore, the correct answer is option 3: nephron, villi, and alveoli.