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Most animals use the circulatory system to move blood around the body. Water, nutrients, and gases are diffused in certain primitive species. However, complex organisms rely on the circulatory system to transfer gases, nutrients, and waste. Open (where blood mixes with interstitial fluid) or closed circulatory systems (separated from the interstitial fluid). Although all animals have closed circulatory systems, evolutionary adaptations and anatomical variances cause major differences in heart and blood circulation structure. Fish have a two-chambered heart that only circulates one way. Blood mixing and double circulation are possible in Amphibians’ three-chambered hearts. Non-avian reptiles’ blood is rarely mingled, hence they have double circulation. Mammalian and avian hearts have four chambers and no blood mixing.
Circulatory Fluids
The two most vital body fluids in the human body are blood and lymph. Blood is made up of platelets, plasma, and white blood cells. Lymph is a clear liquid that circulates within lymphatic vessels.
The various types of bodily fluids include the following:
Blood
The major components of blood are as follows:
- Plasma: Plasma is the blood’s liquid component. It is a viscous fluid composed of 55% blood, 90% water, and 8% proteins. Plasma is primarily composed of albumin. Additionally, immunoglobulins and clotting factors are proteins.
- Red Blood Cells: Red blood cells make up 40% of the blood. RBCs contain the protein haemoglobin, which gives blood its red colour.
- White Blood Cells: White blood cells are extremely rare. The ratio of WBC to RBC is 1:600. They primarily serve to protect the body from infection. Numerous WBCs pass through vessel walls and into adjacent tissues. Platelets: These are a smaller type of blood cell than red blood cells. Platelets aid in blood clotting at the site of a wound.
Lymph
Lymph is a colourless fluid that circulates throughout the interstitial tissues. It is carried by the lymphatic system. It is defined as blood devoid of RBCs. This fluid facilitates the exchange of nutrients, hormones, and gases. It is composed of lymphocytes, which play a critical role in the body’s immune responses.
Circulatory System Types
There are two types of circulatory systems:
- Circulatory system that is open
- Circulatory system that is closed
Blood circulates freely throughout the body cavity, rather than in closed vessels. This is a system that is frequently found in insects.
Closed Circulatory System- Under sufficiently high pressure, blood flows through closed tube-like vessels. This system is present in every vertebrate.
Circulation of blood in the human body
The circulatory system feeds and oxygenates all cells (cardiovascular system). It contains the heart and vessels. The circulatory system is also discussed, including the heart and its blood vessels. Blood is returned to the heart via veins. The vascular system is like a tree: the main artery (aorta) has enormous branches. The smallest arteries constitute the capillary network.
The human body has two blood circulation systems: The systemic circulation nourishes organs, tissues, and cells. That’s where fresh oxygen goes. Blood emits CO₂.
During rest, blood flows from the atria (top two chambers) into the ventricles (lower two chambers), which expand. During the ejection phase, both ventricles push blood into the major arteries.
The left ventricle delivers oxygen-rich blood to the main artery via the left atrium (aorta). Blood travels from the major artery to the capillary network via smaller arteries. The blood trades oxygen, nutrients, and waste products for CO₂. The oxygen-depleted blood is gathered in veins and delivered to the right atrium and ventricle.
The pulmonary circulation originates here: Deoxygenated blood is pumped into the pulmonary artery, which branches into smaller arteries and capillaries. A fine capillary network surrounds the pulmonary vesicles (grape-like air sacs at the end of the airways). In the pulmonary vesicles, carbon dioxide from the blood is expelled into the air and new oxygen is absorbed. When we exhale, It includes the heart and blood vessels.
Equation of blood flow
Then, a relative relationship between vascular flow, pressure difference, and resistance (i.e., the basic flow equation) can be described as follows: Flow equals resistances due to pressure differences. Alternatively, Q = P R.
Conclusion
The heart is a large muscular organ that continually pushes oxygen-rich blood to the brain and extremities and transports oxygen-depleted blood from the brain and extremities to the lungs for oxygenation. The right atrium receives blood from the body, passes through the right ventricle, and is pushed into the pulmonary arteries of the lungs. After absorbing oxygen, the blood returns to the heart via the pulmonary veins into the left atrium, the left ventricle, and the aorta to the body’s tissues.
