| Questions | 5 |
| Topics | Capillaries, Cytoplasm, Exoskeleton, Fiber, Heart |
Capillaries are small thin-walled vessels that permit the exchange of oxygen, carbon dioxide, nutrients, and waste between blood and the body's cells. This process of exchange is called diffusion.
The nucleus of a eukaryotic cell contains the genetic material of the cell and is surrounded by cytoplasm which contains many organelles. These include:
| Organelle | Function |
|---|---|
| ribosomes | produce proteins |
| mitochondria | produce energy |
| endoplasmic reticulum | helps synthesize proteins and fats |
| Golgi apparatus | prepare proteins for use |
| lysosomes | help the cell manage waste |
| centrosomes | guide cell reproduction |
An exoskeleton (external skeleton) is common in arthropods like insects, spiders, and crustaceans.
Fiber provides bulk to help the large intestine carry away waste. Good sources of fiber are leafy vegetables, beans, potatoes, fruits, and whole grains.
The heart is the organ that drives the circulatory system. In humans, it consists of four chambers with two that collect blood called atria and two that pump blood called ventricles. The heart's valves prevent blood pumped out of the ventricles from flowing back into the heart.