These MP Board Class 11th Biology Notes for Chapter 18 Body Fluids and Circulation help students to get a brief overview of all the concepts.

MP Board Class 11th Biology Notes Chapter 18 Body Fluids and Circulation

→ The heart of a bird is proportionately larger than that of any other vertebrate.

→ In mammals, sinus venosus is absent.

→ The tissues of heart itself receive blood through the small coronary arteries.

→ In heart block transmission of the impulse through the heart is blocked at critical points in the conductive system. One of the most common of these points is between the auricles and the ventricles. This condition is called auriculoventricular block. It usually indicates myocardial infection, arteriosclerosis, rheumatic heart disease, etc.

MP Board Class 11th Biology Notes Chapter 18 Body Fluids and Circulation

→ Puffiness or oedema of tissue is caused by the increased capillary pressure; increased per-meability of the capillary wall or decreased rate of return of lymph due to increased pressure in the veins.

→ In adult human male, the heart is about 0-43% of the body weight and in female about 0-4%; but in active mammals like the deer or greyhound, the heart is about 1 % of the body weight.

→ Rate of heartbeat in elephant is about 25 times per minute.

→ Pulsating hearts are simply blood vessels with a relatively heavy muscular layer which contracts in peristaltic waves thus pushing the blood through blood vascular system. Such vessels have valves as found in many forms of annelids.

→ Neurogenic heart is found in most of the arthropods.

→ Inferior vena cava is the largest vein in human body.

→ Aorta is the largest artery of human body.

→ The pacemaker is the specialized region which initiates and sets pace to the contraction of the heart. There are two pacemakers, S.A. node and A.V. node in the heart of higher vertebrates.

MP Board Class 11th Biology Notes Chapter 18 Body Fluids and Circulation

→ The heart of vertebrates is described as myogenic in which the contractions are started from within the muscles of heart.

→ The heart of invertebrates is described as neurogenic because the contractions of the heart are initiated by a nerve impulse.

→ The human heart beats about 72 times per minute.

→ The blood circulation in humans was discovered by William Harvey. He is regarded as the Father of Physiology.

→ The circulatory system in vertebrates is derived from embryonic mesoderm.

→ When the heart muscles are deprived of oxygen and nutrients due to the formation of clot, hardening, degenerative changes in the coronary arteries, the heart does not receive enough blood. This damage to the heart is known as heart attack or coronary thrombosis.

→ Tricuspid valve is found in the opening of right atrium.

→ In closed circulatory system, blood flows in closed vessels and never comes in the direct contact with the tissues.

→ Hypotension is a condition with low blood pressure than normal.

→ Hypertension is a condition with high blood pressure than normal.

→ Stethoscope is an instrument used to listen to heart and lung sounds.

→ The circulation of blood from the heart to the body (except lungs) and back is called systemic circulation or body circulation.

MP Board Class 11th Biology Notes Chapter 18 Body Fluids and Circulation

→ The circulation of blood from the heart to the lungs back is called pulmonary circulation.

→ Systole is a phase of heart when the heart muscle is contracted and blood is being pumped into the arteries.

→ In earthworms, haemoglobin is dissolved in plasma.

→ The blood pressure of a normal healthy man is 120/80 mm Hg.

→ Bicuspid valve is located in between left auricle and left ventricle.

→ The relaxation of heart, during which blood comes in the heart, is called diastole.

Largest sized heart is found in blue-whale.