The circulatory system is responsible for the transportation of substances such as oxygen, nutrients, hormones, and waste products throughout the body. There are two main types of circulatory systems found in animals: open circulatory system and closed circulatory system. Here's how they differ:
1. Open Circulatory System:
- Found in certain invertebrates such as insects, mollusks, and arthropods.
- Blood or a fluid called hemolymph is pumped by a heart into interconnected sinuses and cavities called hemocoels.
- Hemolymph directly bathes the organs and tissues, facilitating the exchange of nutrients, gases, and waste products.
- Hemolymph also functions in the immune response and plays a role in the body's defense mechanisms.
- Hemolymph is not enclosed within blood vessels but flows freely throughout the body cavity.
- The flow of hemolymph is relatively slower compared to the closed circulatory system.
- The pressure of the circulating fluid is low, limiting the efficiency of nutrient and oxygen delivery to tissues.
2. Closed Circulatory System:
- Found in many vertebrates, including humans, as well as some advanced invertebrates like cephalopods (e.g., squids, octopuses).
- Blood is contained within a closed network of blood vessels, including arteries, veins, and capillaries.
- The heart pumps blood under pressure, which facilitates the efficient transport of substances.
- The blood is divided into oxygen-rich (oxygenated) and oxygen-poor (deoxygenated) components.
- Oxygen-rich blood is pumped from the heart to the body tissues through arteries, while oxygen-poor blood returns to the heart through veins.
- Capillaries, the smallest blood vessels, allow for the exchange of nutrients, gases, and waste products between the blood and tissues.
- The closed circulatory system enables more precise control over blood flow and distribution of substances to specific tissues.
- This system allows for rapid delivery of oxygen and nutrients and more effective removal of waste products.
- The blood pressure is higher, providing a faster and more efficient transport system.
In summary, the main distinction between open and closed circulatory systems lies in the organization of blood flow and the presence or absence of blood vessels. Open circulatory systems lack dedicated blood vessels and use hemolymph that directly bathes the organs, while closed circulatory systems have a closed network of blood vessels that transport blood pumped by the heart. Closed circulatory systems offer greater efficiency in delivering oxygen, nutrients, and waste removal due to the higher pressure and precise control of blood flow.