The smallest blood vessel in the body is:
As capillaries are the connecting link between arteries and veins as well as site of exchange of materials they are the smallest blood vessels.
Arteries carry oxygenated blood except :
It is the only exception. Pulmonary vein is the only vein to carry oxygenated blood.
Four chambered heart is found in :
Other reptiles do not have a complete 4 chambered heart. But in crocodile the 4 chambers are well developed and distinct.
The average life span of red blood corpuscles is about
The superior and inferior vena cavas ( pre and post cavals) are the great veins which empty blood in the right auricle. Superior vena cava is the veins of the head, neck, and chest all drain into the superior vena cava, which goes to the heart. Inferior vena cava is much longer than the superior vena cava and returns the blood from the parts of the body below the diaphragm. It begins in the lower abdomen with the Union of the two common iliac veins.
Mitral valve in mammals guards the opening between :
Valves are the membranous structure that prevents the backflow of the blood. The left atrioventricular valve is the bicuspid valve, but it is usually referred to as the " Mitral - valve " . It has two rather heavy cusps, that permit blood to flow freely from the left atrium into the left ventricle. However, the cusps close when the left ventricle begins to contract ; this prevents blood from returning to the left atrium and ensures the forward flow of blood into the aorta.
Tricuspid valve is present between :
The tricuspid valve, or right atrioventricular valve, is on the right dorsal side of the mammalian heart, between the right atrium and the right ventricle. The function of the valve is to prevent back flow of blood from the right ventricle into the right atrium.
Which of the following has the thickest walls ?
The two lower chambers are the ventricles, which have thick walls and force blood out of the heart by way of arteries The left ventricle has the thickest walls because it is the major pumping chamber of the heart.
The pacemaker of heart is :
The SA node is the heart's natural pacemaker. The SA node consists of a cluster of cells that are situated in the upper part of the wall of the right atrium (the right upper chamber of the heart). The electrical impulses are generated there. The SA node is also called the sinus node.
Why is blood that flows from the lungs to the heart bright red rather than dark red?
The heart pumps blood to your lungs to pick up oxygen. The oxygen-rich blood is then pumped out to your body through your arteries. It's bright red at this point. From your arteries, the blood flows through tiny blood vessels called capillaries, where it gives up its oxygen to the body's tissues.
The impulse of heartbeat originates from :
SA node (sinoatrial node) – known as the heart's natural pacemaker. The impulse starts in a small bundle of specialized cells located in the right atrium, called the SA node. The electrical activity spreads through the walls of the atria and causes them to contract. This forces blood into the ventricles.
The heart of a healthy man beats normally per minute:
Systole causes :
Systole causes the exit of blood from ventricles. It is the contraction phase of the cardiac cycle (contrast with diastole) that results in the ejection of blood into an adjacent chamber or vessel.
Typical 'lubb-dupp' sounds heard during heartbeat are due to :
It is caused by the closure of bicuspid and tricuspid valves. Called dupp, it is higher pitch and occurs at the beginning of ventricular diastole and is caused by the closure of the semilunar valves. Ventricular systole occurs between the first and second heart sounds.
The instrument used to hear heart sound is :
The stethoscope is an acoustic medical device for auscultation, or listening to the internal sounds of an animal or human body. It typically has a small disc-shaped resonator that is placed against the chest, and two tubes connected to earpieces. It is often used to listen to lung and heart sounds.
In adult man, normal BP is :
Blood pressure numbers of less than 120/80 mm Hg are considered within the normal range. If your results fall into this category, stick with heart-healthy habits like following a balanced diet and getting regular exercise.
The instrument by which BP of man is determined :
Blood pressure is measured with a simple device called a sphygmomanometer. This device usually has an inflatable arm cuff attached to a machine or gauge that displays the pressure in millimeters of mercury (mm Hg).
Blood pressure is expressed as "systolic over diastolic"; for example, "120 over 80" (written as 120/80). Systolic is the pressure when your heart beats, and diastolic is when your heart rests between beats.
William Harvey is known for discovery of :
William Harvey is known for the discovery of blood circulation. He was the first person to correctly describe blood’s circulation in the body. He showed that arteries and veins form a complete circuit. The circuit starts at the heart and leads back to the heart. So, the correct answer is option A.
Mammals are said to have double circulation. It means :
The majority of mammals (including humans) utilize a double circulatory system. This means we have two loops in our body in which blood circulates. One is oxygenated, meaning oxygen rich, and the other is deoxygenated, which means it has little to no oxygen, but a lot of carbon dioxide.
Double circulatory systems are important because they ensure that we are giving our tissues and muscles blood full of oxygen, instead of a mixture of oxygenated and deoxygenated blood. While it may take a bit more energy than a single circulatory system, this system is much more efficient!
In mammals, veins differs from arteries in having :
Veins have thin Walls as compared to arteries and are superficially located. They carry deoxygenated blood towards the heart and have valves which prevent blood from going forward. Arteries are elastic and thick because they need to transport high pressure blood while in veins blood flows in low pressure.
Oxygenated blood returns from lungs to the heart through :
The pulmonary circulation is the portion of the circulatory system which carries deoxygenated blood away from the right ventricle of the heart, to the lungs, and returns oxygenated blood to the left atrium and ventricle of the heart. The term pulmonary circulation is readily paired and contrasted with the systemic circulation. The vessels of the pulmonary circulation are the pulmonary arteries and the pulmonary veins.
How many molecules of O2 can associate with a molecule of haemoglobin in man ?
The hemoglobin molecule has four binding sites for oxygen molecules: the iron atoms in the four heme groups. Thus, each Hb tetramer can bind four oxygen molecules. From the molecular weight of Hb, one can calculate that 1 g of Hb can combine with 1.39 ml of oxygen.
Haemoglobin shows maximum affinity with
Hemoglobin in humans has a very high affinity for carbon monoxide, forming carboxyhemoglobin which is a very bright red in color. Carbon monoxide is thus problematic for humans because it has affinity higher than that of oxygen.
The greatest affinity for haemoglobin is shown by CO.
Hence (c) is the correct answer.
In which form, CO2 is carried by blood :-
About 10% of total carbon dioxide is carried by the blood in the dissolved state as carbonic acid (CO2 + H2O – H2CO3) but 80% of CO2 as Sodium bicarbonate in the plasma and as potassium bicarbonate in the plasma and as potassium bicarbonate in the corpuscles and the remaining 10% as carbamino-hemoglobin (a loose compound formed by CO2 + hemoglobin).
Amount of oxygen which is transported by one gram of haemoglobin is :-
Haemoglobin has an oxygen-binding capacity of 1.34 mL O2 per gram, which increases the total blood oxygen capacity seventy-fold compared to dissolved oxygen in blood. The mammalian hemoglobin molecule can bind (carry) up to four oxygen molecules.
Mountain sickness result due to :-