The Circulatory system
In the body of larger and intricate animals, there is very little exposed surface to volume ratio.
The majority of the cells are not exposed to the external environment directly and it becomes extremely difficult to transport materials by simple diffusion.
Complex animals have evolved transport systems in the form of a blood vascular system or circulatory system.
- 1) Properties of Circulatory System
- 2) Open and Closed Circulatory System
- 3) Circulatory system of Vertebrates
- 4) Evolution of vertebrate heart
- 5) Heart of Birds and Mammals – Double Circuit Heart
- 6) FAQs about the Circulatory System
- 7) Conclusion – Unveiling the Wonders of the Circulatory System:
- 8) You may also like to learn:
Properties of Circulatory System
A circulatory system represents a quick mass flow of materials from one part of the body to the other, where diffusion would be too sluggish.
There are three characteristics of a circulatory system.
- (A) A circulatory fluid – the blood.
- (B) A contractile pumping device – which might be the modified capillary or a heart.
- (C) Tubes/ Vessels, which can transport the circulatory fluid (blood) to and from cells of the body These tubes are the blood vessels. Materials should be exchanged in between the circulatory fluid and other body cells.
Open and Closed Circulatory System
The circulatory systems of animals are divided into two primary types:
- a) Open circulatory system: It is observed in animals belonging to Phylum Arthropoda (crustaceans, spiders, insects) and Phylum Mollusca (snails and clams) and a group of protochordates, the tunicates.
- b) closed circulatory system: It is observed in animals belonging to annelids, cephalopod molluscs (squids and octopus), echinoderms, and vertebrates.
Circulatory system of Vertebrates
The elements of the vertebrate blood vascular system are the common circulatory system-blood, heart, blood vessels (arteries, capillaries, and veins). All vertebrates have actually closed circulatory system. In addition, there is a lymphatic system which likewise assists in transportation.
The heart pumps the blood to different parts of the body through the aorta and arteries. Arteries break into the fine capillaries, the blood vessels. These join to form veins that bring blood back to the heart. The capillaries are sites where the exchange of materials between blood and body tissues takes place.
Evolution of vertebrate heart
Heart of Fish– Single Circuit Heart
The heart of fishes has sinus venosus, an atrium, a ventricle, and bulbus arteriosus or conus arteriosus. Sinus venosus gets deoxygenated blood from the body, and after that blood is passed to the atrium, which on contraction passes it to the ventricle. ventricle has a thick muscular wall. When the muscles of the ventricle contract, they push the blood through the conus arteriosus or bulbous arteriosus (proximal swollen part of the ventral aorta).
Therefore, the heart of fishes works as a single circuit heart. The blood streams in one direction only, from sinus venosus to atrium then to ventricle and to ventral aorta by means of bulbus arteriosus or conus arteriosus to the gills and then to the body. The blood goes back to the heart in the sinus venosus. The oxygenated blood is supplied from the dorsal aorta through coronary arteries, to the heart and is carried back by coronary veins from the heart.
Heart of Amphibians
In amphibians, the heart is 3 chambered with regard to auricles and ventricles. There are two auricles and one ventricle. In addition, sinus venosus and truncus arteriosus are also present. Sinus venosus receives de-oxygenated blood from 2 exceptional vena cava (Perceval) and one inferior vena cava (portocaval) from different parts of the body. This blood passes to the ideal auricle.
The oxygenated blood from the lungs is poured via lung veins into the left auricle. Both auricles contract all at once and blood is passed into the ventricle. There is a total mixing of oxygenated and deoxygenated blood in the ventricle. When the ventricle contracts, it pushes blood through truncus arteriosus, to two carotids, 2 systemics, and two pulmocutaneous arches.
Heart of Reptiles– Double Circuit Heart
The heart of reptiles and all other amniotes practically works as 4 chambered heart. There are 2 auricles in the heart of reptiles. The reptiles have actually incompletely separated ventricle; but in crocodiles, the interventricular septum is total and the heart is four-chambered. In all reptiles, the left and right systemic arches carry oxygenated blood and occur from a region of the ventricle called cavum venosum – into which the left ventricle directs its blood.
The deoxygenated blood from the best atrium is directed towards the entrance of the pulmonary trunk which is also located or begins with a pocket the cavum pulmonale, on the right side of the ventricle- in the animals (reptiles) which do not have actually totally divided ventricle. Although the two systemic arches start from the ventricle individually, they are likewise adjoined at their base by an opening.
Heart of Birds and Mammals – Double Circuit Heart
In birds and mammals, the heart is 4 – chambered, and oxygenated and deoxygenated blood does not mix at all. The pulmonary trunk emerges from the best ventricle and causes the lungs. The aortic trunk emerges from the left ventricle and causes carotid and systemic arches. The left systemic disappears in birds and best systemic, the majority of it, disappears in mammals.
In reptiles, birds, and mammals, as a result of these modifications, all blood returning to the best side of the heart passes to the lungs. After oxygenation, blood returns to left atrium from the lungs using lung veins. The left atrium passes this blood to the left ventricle – which on contraction pumps it to different parts of the body, and once again blood goes back to the right atrium.
Lung flow is by pulmonary arch bring deoxygenated blood from the right ventricle of the heart to lungs, and the blood returns to the left atrium after oxygenation via pulmonary veins. Also, the systemic arch distributes blood to different parts of the body, and then the blood from the body returns to the heart, in the best atrium via Perceval and postcaval. This is a systemic flow. So, the hearts of amphibians, reptiles, birds, and mammals have both lung and systemic blood circulation.
FAQs about the Circulatory System
- What is the Circulatory System?
- The circulatory system is a transport system in larger animals, facilitating the rapid flow of materials throughout the body, particularly where simple diffusion would be too slow.
- What are the key components of the Circulatory System?
- The essential components include:
- (A) Circulatory fluid: blood
- (B) Contractile pumping device: heart
- (C) Vessels/tubes: blood vessels (arteries, capillaries, veins)
- The essential components include:
- How is the Circulatory System classified based on structure?
- The two main types are:
- a) Open circulatory system (found in arthropods and mollusks)
- b) Closed circulatory system (found in annelids, cephalopod mollusks, echinoderms, and vertebrates)
- The two main types are:
- What are the elements of the Vertebrate Blood Vascular System?
- The vertebrate blood vascular system comprises blood, heart, and blood vessels (arteries, capillaries, veins), with additional support from the lymphatic system.
- How does the Evolution of the Vertebrate Heart progress?
- It evolves from a single circuit heart in fish to a three-chambered heart in amphibians, a partially separated ventricle in reptiles, and finally, a four-chambered heart in birds and mammals.
- Describe the Heart of Fish and its Function.
- The fish heart operates as a single circuit heart, with the blood flowing from the sinus venosus to the atrium, then to the ventricle and out to the gills. Oxygenated blood is then distributed to the body.
- What distinguishes the Heart of Amphibians?
- Amphibians have a three-chambered heart with two auricles and one ventricle. There is mixing of oxygenated and deoxygenated blood in the ventricle.
- How does the Heart of Reptiles function?
- The reptile heart is mostly a four-chambered heart, with incompletely separated ventricles. Oxygenated and deoxygenated blood is partially separated, improving efficiency.
- Explain the Heart Structure in Birds and Mammals.
- Birds and mammals have a four-chambered heart where oxygenated and deoxygenated blood does not mix. This separation enhances oxygen supply to the body.
- What is the significance of Lung and Systemic Circulation?
- Lung circulation involves blood flow to and from the lungs for oxygenation, while systemic circulation distributes oxygenated blood to different body parts. Both are vital for maintaining oxygen levels.
- How is Blood circulated in Birds and Mammals?
- Blood is pumped from the right ventricle to the lungs via the pulmonary trunk, and from the left ventricle, it is sent to the body through the aorta. The oxygenated blood returns to the left atrium via pulmonary veins.
- Why is a Closed Circulatory System advantageous?
- A closed circulatory system ensures efficient and rapid transport of materials, preventing reliance on slow diffusion, which is crucial in larger and complex animal bodies.
- Do all Vertebrates have a Closed Circulatory System?
- Yes, all vertebrates possess a closed circulatory system, including fish, amphibians, reptiles, birds, and mammals.
- What role does the Lymphatic System play in circulation?
- The lymphatic system supports circulation by assisting in the transport of fluids and aiding in the immune response.
- Why is the Evolution of the Vertebrate Heart considered adaptive?
- The evolutionary progression of the vertebrate heart reflects adaptations that improve the efficiency of oxygen transport, allowing animals to thrive in various environments.
Multiple Choice Questions
Open circulatory system is present in phylum
- A) Arthropods
- B) Mollusca
- C) Both A & B
- D) Chordata
Ans: C
Valves are not present in
- A) Arteries
- B) Veins
- C) Lymphatic ducts
- D) All
Ans: A
Echocardiogram is
- A)Recording
- B) Machine
- C) Process
- D) All
Ans: A
Systolic pressure in normal individuals is:
- A) 60mm of Hg
- B) 120mm of Hg
- C) 30 mm of Hg
- D) 80mm of Hg
Ans: B
One complete heart cycle lasts for about:
- A) 8 sec
- B) 10 sec
- C) 0.12 sec
- D) 0.6 sec
Ans: A
Conclusion – Unveiling the Wonders of the Circulatory System:
The circulatory system, an intricate network coursing through the bodies of larger animals, is a marvel of biological engineering. Its existence is indispensable, addressing the challenge posed by limited surface-to-volume ratios in complex organisms. In essence, the system serves as a sophisticated transport mechanism, overcoming the limitations of simple diffusion.Key properties define the efficiency of the circulatory system, embodying a swift mass flow of materials between body parts, where traditional diffusion would prove sluggish. This intricate system comprises three fundamental components:
- (A) Circulatory fluid – Blood: The lifeblood that carries essential substances.
- (B) Contractile Pumping Device: A dynamic force, be it a modified capillary or the remarkable heart.
- (C) Tubes/Vessels: The intricate network of blood vessels facilitating material exchange between the circulatory fluid and body cells.
The animal kingdom showcases two primary circulatory systems: the open circulatory system found in arthropods and mollusks, and the closed circulatory system prevalent in annelids, cephalopod mollusks, echinoderms, and vertebrates. Vertebrates, in particular, boast a closed circulatory system, complemented by the lymphatic system, contributing to seamless transportation within the body.
As we journey through the evolution of the vertebrate heart, we encounter fascinating adaptations. Fishes, with their single-circuit heart, guide blood through a precise route, efficiently serving their needs. Amphibians introduce a three-chambered heart, and reptiles elevate the sophistication with a double-circuit heart. Birds and mammals, the epitome of circulatory efficiency, exhibit a four-chambered heart, segregating oxygenated and deoxygenated blood for optimal systemic and lung circulation.
In these diverse hearts, from the piscine beats to the avian symphony, a symphony of life unfolds. Each adaptation, from the single circuit to the double circuit, reflects nature’s ingenuity in optimizing oxygen transport. Whether swimming through the depths, leaping between water and land, or soaring through the skies, the circulatory system ensures vitality and sustenance.
In essence, the circulatory system exemplifies biological brilliance, seamlessly integrating form and function. From the pulsating heart to the intricate network of vessels, it orchestrates a ballet of life, ensuring the ebb and flow that sustains the myriad complexities of the animal kingdom. Truly, the circulatory system stands as a testament to the intricate beauty woven into the fabric of life.