"Working Together In Interactions."
This system delivers oxygen and nutrients while removing waste products, making it a key partner of the respiratory and digestive systems.
What is the circulatory system?
This muscular organ pumps blood through the body, keeping oxygen and nutrients flowing.
What is the heart?
This hormone triggers major changes during puberty in males, including muscle growth and voice deepening.
What is testosterone?
This muscular tube moves food from your mouth to your stomach, making sure gravity isn’t required for swallowing.
What is the esophagus?
This part of the body controls all organ systems and occasionally makes you say embarrassing things before thinking.
What is the brain?
Without this system’s electrical signals, none of your other organ systems would know what to do.
What is the nervous system?
When you get a cut, these cell fragments rush to the site to form a clot and stop bleeding.
What are platelets?
This structure provides nutrients and oxygen to a growing fetus during pregnancy.
What is the placenta?
This organ’s acid and enzymes break down your food, but don’t worry—it has a mucus layer to keep from digesting itself.
What is the stomach?
Your spinal cord is full of these pathways that carry messages between your brain and the rest of your body.
What are nerves?
Your bones are more than just support! This system works closely with the muscular system to allow movement.
What is the skeletal system?
Unlike arteries, these vessels carry blood back toward the heart, often using valves to prevent backflow.
What are veins?
While most cells in the human body contain 46 chromosomes, reproductive cells only have half. This process ensures that offspring inherit the right number of chromosomes from their parents.
What is meiosis?
The liver produces this greenish substance that helps break down fats.
What is bile?
The nervous system has two main parts: but this system that handles everything outside the brain and spinal cord.
What is the peripheral nervous system?
The endocrine system sends chemical messages using these molecules, which regulate metabolism, growth, and more.
What are hormones?
This component of blood carries oxygen thanks to hemoglobin.
What are red blood cells?
In males, this reproductive structure is located outside the body rather than internally, keeping cells at an optimal temperature for survival.
What are the testes?
This enzyme in saliva starts breaking down carbohydrates while you’re still chewing—so digestion begins before food even hits your stomach.
What is amylase?
These insulating structures wrap around neurons to speed up electrical signals.
What are myelin sheaths?
The lymphatic system helps this other system defend against pathogens, keeping you healthy.
What is the immune system?
The circulatory system and respiratory system work together, exchanging gases in these tiny air sacs of the lungs.
What are alveoli?
This specialized cell is formed when two gametes merge, marking the beginning of a new organism’s development.
What is a zygote?
This organ is multitasking—it filters toxins, stores energy, and even helps with digestion.
What is the liver?
Your body's fastest reflexes bypass the brain entirely, sending signals straight to this central nervous system highway instead.
What is the spinal cord?