Body Fluids and Circulation (VSAQs)
Zoology-2 | Unit-2A: Body Fluids and Circulation – VSAQs:
Welcome to VSAQs in Unit-2A: Body Fluids and Circulation. This page includes the most important FAQs from previous exams. Each answer is presented in the exam format to help you prepare effectively and aim for top marks in your final exams.
VSAQ-1: Write the Differences Between ‘Open’ and ‘Closed’ Systems of Circulation
In a closed system of circulation, like the one found in humans and other vertebrates, the blood flows exclusively through a network of vessels, including tiny capillaries that connect arteries and veins. This system keeps the blood contained, moving it in a continuous loop through the heart and vessels, which allows for more efficient transport of oxygen and nutrients.
On the other hand, an open system of circulation, seen in creatures like leeches and many arthropods, is more like a partially open reservoir. Here, blood flows into open spaces or sinuses rather than through a closed network of vessels. This type of system is simpler but less efficient in transporting blood throughout the body. The blood directly bathes the organs, which can limit the speed and efficiency of nutrient and gas exchange.
VSAQ-2: Sino-Atrial Node Is Called the Pacemaker of Our Heart. Why?
The sino-atrial (SA) node, often called the heart’s pacemaker, is crucial for keeping our heartbeats steady. Situated in the right atrium of the heart, this small cluster of cells generates electrical impulses that kickstart each heartbeat. Imagine the SA node as the conductor of an orchestra, ensuring that all parts of the heart beat in harmony. These electrical signals make the heart muscles contract in a well-coordinated rhythm, pumping blood throughout the body at a steady pace.
VSAQ-3: Name the Valves That Guard the Left and Right Atrioventricular Apertures in Man
In the human heart, the left atrioventricular aperture is guarded by the bicuspid valve (also known as the mitral valve), while the right atrioventricular aperture is protected by the tricuspid valve. These valves act like gatekeepers, ensuring that blood flows in the correct direction and doesn’t leak back into the atria when the ventricles contract.
VSAQ-4: Why Are the Arteries More Elastic Than the Veins?
Arteries need to be more elastic than veins because they face higher pressure from the blood being pumped directly from the heart. Think of arteries as stretchable balloons that expand and contract with each heartbeat. This elasticity helps them handle the surge of blood and maintain blood pressure. Veins, however, carry blood back to the heart under much lower pressure and do not require the same level of elasticity. Their job is more about smooth, steady transport rather than handling high-pressure surges.
VSAQ-5: Define Cardiac Cycle and Cardiac Output
The cardiac cycle refers to the complete sequence of events that occurs during one heartbeat. It includes the contraction phase (systole) and relaxation phase (diastole) of the heart chambers, along with the opening and closing of the heart valves. This cycle ensures that blood flows smoothly through the heart and into the rest of the body.
Cardiac output is the total amount of blood the left ventricle pumps out in one minute. It’s measured in milliliters per minute (mL/min) and is an indicator of how efficiently the heart is working. Cardiac output is determined by two factors: the heart rate (how many times the heart beats per minute) and stroke volume (the amount of blood pumped with each beat).
VSAQ-6: What Is Meant by Double Circulation? What Is the Significance?
Double circulation is a system where blood passes through the heart twice during one complete trip around the body. This process includes two separate circuits: pulmonary circulation, which takes deoxygenated blood from the heart to the lungs to receive oxygen, and systemic circulation, which sends oxygen-rich blood from the heart to the rest of the body. This separation ensures that oxygenated and deoxygenated blood do not mix, which is crucial for efficiently meeting the body’s high metabolic demands. This system enhances the efficiency of oxygen transport and helps maintain proper blood pressure and flow throughout the body.