The Circulatory system

Question 1

Name certain fluids in our body

Answer 1

• Blood
• Tissue fluid
• Lymph

Question 2

What are the functions of Blood?

Answer 2

1] TRANSPORT
- Transport of digested food
- Transport of oxygen
- Transport of carbon dioxide
- Transport of excretory material
- Distribution of hormones
- Distribution of heat
2] PROTECTION
- Blood forms clot to prevent further loss of blood and entry of disease causing germs.
- Its white blood corpuscles protect the body from diseases.
- Produces Antitoxins and Antibodies which neutralise the poisonous substances.

Question 3

What is Plasma ?

Answer 3

The plasma is a light yellow colored, alkaline liquid.
It has about 90% of water, 7% of proteins, 1% of inorganic salts and other substances in traces.The plasma from which the protein fibrinogen is removed is called serum.

Question 4

What are red blood cells?

Answer 4

• They are minute disc like structures that are flat in the center and curved on the edges.
• The small size and concavities provide a large surface area helping in efficient absorbing of oxygen.

Question 5

What is Haemoglobin ?

Answer 5

• It is the effective chemical constituent of RBCs.
• Present in the stroma.
• Formed of an iron containing part and a protein.
• Has ability to combine with oxygen readily and form oxyhaemoglobin.

Question 6

What are White blood cells?

Answer 6

Leukocytes have a nucleus and are absent in haemoglobin. Most are amoeboid and can produce pseudopodia which helps them squeeze through the walls of the capillaries into the tissues.

Question 7

Mention the functions of Leukocytes.

Answer 7

1] Phagocytosis
This is a process in which most WBCs and particularly the neutrophils engulf particle like solid substances, especially bacteria
2] Inflammation
Occurs due to the reaction to tissues to injury and to localized invasion of germs.
3] Formation of antibodies
The WBCs produce antibodies which kill or neutralise the germs, or the poisons from them.

Question 8

What are Blood Platelets?

Answer 8

• Minute oval or round structures, non nucleated, floating in the blood. The platelets are derived from some giant cells called megakaryocytes in a manner that each one is completely surrounded with membrane.

Question 9

How are Platelets useful in clotting of blood ?

Answer 9

In blood coagulation, platelets play certain role -
~ The injured tissue cells and platelets disintegrate at the sight found to release thromboplastin(thrombokinase)
~ Thromboplastin with the help of calcium ions converts inactive prothrombin into active thrombin.
~ Thrombin in the presence of calcium ions converts converts soluble fibrinogen into insoluble fibrin which forms a mesh or a network at the sight.
~ The blood cells traps in this network shrink and squize the plasma to leave behind a solid mass known as clot.

Question 10

What are Arteries and veins?

Answer 10

1] ARTERIES
- Arteries are vessels which carry blood away from heart
- Have thick walls to withstand the pressure of blood
- Pale in color
- Values are absent
- Deep position in body
- Arteries break into branches called capillaries.
2] VEINS
- Veins are the vessels that carry blood towards heart.
- Veins are thin walled
- Dark in color as color of blood is seen through walls
- Valves are present to prevent back flow of blood.
- Normally superficial in position
- Veins are formed by joining the capillaries.

Question 11

Explain the structure of Heart

Answer 11

• It is right in center between the two lungs and above the diaphragm.
• It is protected by a double walled membranous covering called pericardium which contains lubricating pericardial fluid which reduces friction due to heartbeats.
• contains 4 chambers
• The upper two are auricles and lower two are ventricles.
• The auricles have thinner walls because their major function is to to receive blood
• The ventricles have thicker muscular walls as they have to pump blood to a long distances.

Question 12

Name and state the functions of blood vessels entering/leaving the heart.

Answer 12

1] Blood vessels entering the heart
• Anterior Vena Cava - brings deoxygenated blood from the anterior/upper regions of the body including head, chest and arms.
• Posterior Vena Cava - brings from the posterior/lower region of the body including abdomen and legs.
2] Blood vessels leaving the heart
• Pulmonary Artery - arises from the right ventricle and carries deoxygenated blood to the lungs for oxygenation.
• Aorta - arises from left ventricle and carries oxygenated blood to supply it to all parts of the body.
• Coronary Artery - arise from the base of aorta and supply blood to the the heart muscles.

Question 13

Name the Valves in the heart and state the functions.

Answer 13

• Tricuspid valve - Also called right atrio-ventricular valve. Located between the right auricle and the right ventricle. it has 3 flaps.
• Bicuspid valve - also called left atrio-ventricular valve. Located in a similar way on the left side of the heart. It has 2 cusps.
• Pulmonary semilunar valves - located at the opening of the right ventricle into the pulmonary artery.
• Aortic semilunar valves - located at the point of origin of aorta from the left ventricle.