6 Most VSAQ’s of Body Fluids and Circulation Chapter in Inter 2nd Year Zoology (TS/AP)

2 Marks

VSAQ-1 : Write the differences between ‘open’ and ‘closed’ systems of circulation.

The differences between ‘open’ and ‘closed’ systems of circulation are as follows

  1. Open System of Circulation:
    • Blood flows through vessels and sinuses, and it lacks capillaries.
    • Found in organisms like leeches, arthropods, mollusks, echinoderms, and ascidians.
  2. Closed System of Circulation:
    • Blood flows through blood vessels and includes capillaries.
    • Found in organisms like annelids, cephalopods, cephalochordates, and vertebrates.

VSAQ-2 : Sino-atrial node is called the pacemaker of our heart. Why?

The sino-atrial (SA) node is called the pacemaker of the heart because it generates the electrical impulses that initiate and control the heart’s rhythm. Located in the right atrium, the SA node sends out electrical signals that cause the heart muscles to contract in a coordinated manner, pumping blood effectively. This automatic and rhythmic activity ensures the heart beats regularly and at the right pace, making the SA node the natural regulator of the heart’s rhythm.

VSAQ-3 : Name the valves that guard the left and right atrioventricular apertures in man.

The valves that guard the left atrioventricular aperture are the bicuspid (mitral) valve, while the right atrioventricular aperture is guarded by the tricuspid valve in humans.

VSAQ-4 : Why the arteries are more elastic than the veins?

The arteries are more elastic than the veins because arteries need to withstand and accommodate the high-pressure surges of blood that are ejected directly from the heart during each heartbeat. This elasticity allows arteries to expand when blood is pumped into them and then contract to help propel the blood forward. Veins, on the other hand, transport blood back to the heart under lower pressure and do not need the same level of elasticity as arteries.

VSAQ-5 : Define cardiac cycle and cardiac output.

Cardiac cycle is defined as the sequence of events that occur during one complete heartbeat. It includes the contraction (systole) and relaxation (diastole) of the atria and ventricles, along with the opening and closing of the heart valves, to ensure the flow of blood in a coordinated manner through the heart.

Cardiac output is the amount of blood ejected by the left ventricle of the heart in one minute. It is typically measured in milliliters per minute (mL/min) and is an important parameter in assessing the heart’s efficiency in pumping blood throughout the body. Cardiac output depends on both the heart rate (number of heartbeats per minute) and stroke volume (the amount of blood ejected with each heartbeat).

VSAQ-6 : What is meant by double circulation? What is the significance?

Double circulation is a circulatory system where the blood passes through the heart twice in a complete circuit of the body. It consists of two loops: pulmonary circulation and systemic circulation. Pulmonary circulation takes blood from the heart to the lungs for oxygenation, while systemic circulation distributes oxygen-rich blood to the rest of the body. This separation ensures efficient oxygen supply to body tissues and prevents the mixing of oxygenated and deoxygenated blood, making it essential for organisms with high metabolic demands.