Lesson Circulation

Question 1.
Explain the structure and function of the human heart.

Answer:
The human heart is a muscular organ located in the chest cavity. It is divided into four chambers:
.Right atrium and right ventricle (carry deoxygenated blood).
.Left atrium and left ventricle (carry oxygenated blood).
The heart functions as a double pump:
.The right side pumps deoxygenated blood to the lungs for oxygenation (pulmonary circulation).
.The left side pumps oxygenated blood to the rest of the body (systemic circulation).
Valves (like tricuspid, bicuspid, and semilunar valves) prevent the backflow of blood.

Question 2.
What is double circulation? Why is it important in humans?

Answer:
Double circulation refers to the circulation of blood in two separate loops:
1.Pulmonary circulation: Blood flows from the heart to the lungs and back.
2.Systemic circulation: Blood flows from the heart to the body and back.
Importance:
.Ensures separation of oxygenated and deoxygenated blood.
.Maintains efficient oxygen and nutrient supply to the body.

Question 3.
Define blood pressure. What are systolic and diastolic pressures?

Answer:
Blood pressure is the force exerted by blood on the walls of blood vessels.
.Systolic pressure: The pressure during heart contraction (normal value ~120 mmHg).
.Diastolic pressure: The pressure during heart relaxation (normal value ~80 mmHg).
Normal blood pressure is written as 120/80 mmHg.

Question 4.
Differentiate between arteries and veins.

Answer:
Arteries:
Arteries are the blood vessels that transfer oxygenated blood from the heart to various organs.
The exception is the pulmonary artery that carries deoxygenated blood from the heart to the lungs.
Veins:
Veins are the blood vessels that carry deoxygenated blood from various organs to the heart.
The exception is the pulmonary vein that carries oxygenated blood from the lungs back to the heart.

Question 5.
What is the role of platelets in blood circulation?

Answer:
Platelets are small, disk-shaped blood components. Their role includes:
.Helping in blood clotting to prevent excessive bleeding.
.Sealing wounds by forming clots at injury sites.

Question 6.
What is lymph? How does it help in circulation?

Answer:
Lymph is a colorless fluid that forms from interstitial fluid. It contains white blood cells.
Functions:
.Transports nutrients and hormones.
.Removes waste and toxins from tissues.
.Helps in immunity by transporting white blood cells.

Question 7.
Draw and label the structure of the human heart.

Question 8.
Describe the process of blood circulation in humans.

Answer:
.Pulmonary circulation:
1.Deoxygenated blood enters the right atrium from the body via the vena cava.
2.It flows into the right ventricle and is pumped to the lungs through the pulmonary artery.
3.In the lungs, blood gets oxygenated.
.Systemic circulation:
1.Oxygenated blood returns to the left atrium via the pulmonary veins.
2.It enters the left ventricle and is pumped to the body through the aorta.
This ensures the continuous supply of oxygen and nutrients to tissues.

Question 9.
Why do veins have valves but arteries do not?

Answer:
.Veins carry blood back to the heart at lower pressure and against gravity. Valves prevent the backflow of blood.
.Arteries carry blood under high pressure, so valves are not needed.

Question 10.
What happens to the circulation system when there is a blockage in the coronary artery?

Answer:
A blockage in the coronary artery restricts blood flow to the heart muscles. This leads to:
.Reduced oxygen supply to the heart.
.Chest pain (angina).
.If untreated, it can cause a heart attack (myocardial infarction).

Question 11.
What are the components of blood?

Answer:
The components of blood are:
1.Plasma: The liquid portion that carries nutrients, hormones, and waste products.
2.Red Blood Cells (RBCs): Contain hemoglobin and transport oxygen.
3.White Blood Cells (WBCs): Fight infections and provide immunity.
4.Platelets: Help in blood clotting.

Question 12.
What are the functions of blood?

Answer:
The functions of blood include:
.Transporting oxygen and nutrients to cells.
.Removing carbon dioxide and waste from cells.
.Protecting the body from infections through WBCs.
.Regulating body temperature and maintaining pH balance.
.Clotting blood to prevent excessive bleeding.

Question 13.
Describe the cardiac cycle.

Answer:
The cardiac cycle is the sequence of events in one complete heartbeat. It has three phases:
1.Atrial systole: The atria contract, pushing blood into the ventricles.
2.Ventricular systole: The ventricles contract, pumping blood to the lungs and body.
3.Diastole: The heart relaxes, and the chambers refill with blood.
The entire cycle lasts about 0.8 seconds.

Question 14.
What are capillaries? What is their function?

Answer:
Capillaries are tiny blood vessels that connect arteries to veins.
Functions:
.Exchange oxygen, carbon dioxide, nutrients, and waste between blood and tissues.
.Facilitate diffusion due to their thin walls (one-cell thickness).

Question 15.
What is the difference between pulmonary and systemic circulation?

Answer:
Pulmonary and systemic circulation:
The circulation in animals is divided into two circuits, and blood is circulated twice through the heart, called double circulation.
The two forms of circulation that occur in a double circulation system are pulmonary and systematic circulation.
Systemic circulation transports oxygenated blood from the heart throughout the body.
pulmonary circulation brings deoxygenated blood back to the heart.

Question 16.
What are the types of blood groups in humans?

Answer:
The four main blood groups are:
1.A
2.B
3.AB (universal recipient)
4.O (universal donor)
These are classified based on the presence of antigens (A or B) on the surface of RBCs and antibodies in the plasma.

Question 17.
What is meant by heartbeat, and what regulates it?

Answer:
A heartbeat is the rhythmic contraction and relaxation of the heart muscles. It is regulated by:
.Sinoatrial (SA) node: The natural pacemaker of the heart.
.Nervous system: The medulla oblongata adjusts the heart rate based on the body’s needs.
Normal heartbeat: 72 beats per minute in adults.

Question 18.
Why is the wall of the left ventricle thicker than the right ventricle?

Answer:
The left ventricle pumps blood to the entire body (systemic circulation), requiring higher pressure. Hence, it has a thicker muscular wall.
In contrast, the right ventricle pumps blood to the lungs (pulmonary circulation), requiring less force.

Question 19.
What is anemia, and how does it affect circulation?

Answer:
Anemia is a condition in which there is a deficiency of red blood cells or hemoglobin.
Effects on circulation:
.Reduced oxygen transport to tissues.
.Symptoms include fatigue, shortness of breath, and pale skin.

Question 20.
What are the major blood vessels connected to the heart?

Answer:
1.Aorta: Carries oxygenated blood from the left ventricle to the body.
2.Pulmonary artery: Carries deoxygenated blood from the right ventricle to the lungs.
3.Pulmonary veins: Bring oxygenated blood from the lungs to the left atrium.
4.Vena cava: Brings deoxygenated blood from the body to the right atrium.

Question 21.
What is the function of hemoglobin in blood?

Answer:
Hemoglobin is a protein in red blood cells that binds with oxygen.
Functions:
.Transports oxygen from the lungs to tissues.
.Carries carbon dioxide from tissues to the lungs for exhalation.

Question 22.
What are heart valves? Name them.

Answer:
Heart valves ensure unidirectional blood flow and prevent backflow.
The four valves are:
1.Tricuspid valve (between right atrium and right ventricle).
2.Bicuspid (mitral) valve (between left atrium and left ventricle).
3.Pulmonary valve (between right ventricle and pulmonary artery).
4.Aortic valve (between left ventricle and aorta).

Question 23.
What is coronary circulation?

Answer:
Coronary circulation is the flow of blood to and from the heart’s own tissues.
.Coronary arteries supply oxygenated blood to the heart muscles.
.Coronary veins remove deoxygenated blood from the heart muscles.
Blockage in coronary arteries can lead to a heart attack.

Question 24.
Why is blood called a connective tissue?

Answer:
Blood is called a connective tissue because:
.It connects different parts of the body by transporting nutrients, oxygen, and waste.
.It contains cells suspended in plasma, similar to the extracellular matrix in connective tissues.

Question 25.
What is a pulse? How is it related to the heartbeat?

Answer:
A pulse is the rhythmic expansion and contraction of arteries due to blood flow during a heartbeat.
.Pulse rate is equal to the heartbeat rate.
.It can be felt at arteries close to the skin, like the wrist or neck.