How organ systems work together to keep us alive
The digestive system breaks food into simple substances the body can absorb. Digestion starts in the mouth with saliva, continues in the stomach with acid and enzymes, and is completed in the small intestine, where finger-like villi absorb nutrients into blood. The large intestine absorbs water. The respiratory system brings in oxygen: air passes through the nose and windpipe into the lungs, where tiny air sacs exchange oxygen and carbon dioxide with the blood.
The circulatory system includes the heart, blood and blood vessels. Arteries carry blood away from the heart, veins return it, and capillaries connect them. The heart has four chambers and beats about 70 to 80 times a minute in an adult at rest. The excretory system removes waste: the kidneys filter blood and make urine, which is stored in the bladder. The skeletal and muscular systems support and move the body, while the nervous system controls everything. All these systems depend on each other.
Why it matters
Understanding body systems explains why exercise strengthens the heart and lungs, why smoking damages breathing, and why drinking enough water helps the kidneys. Doctors check pulse and blood pressure to see how the circulatory system is working. Blood donation saves lives. These ideas are built upon in life processes in Class 10.
Key terms
- Villi
- Tiny finger-like projections in the small intestine that absorb digested food.
- Artery
- A blood vessel that carries blood away from the heart.
- Kidney
- An organ that filters waste from the blood and produces urine.
- Pulse
- The regular throbbing felt in arteries as the heart pumps blood.