Blood: A special connective tissue that circulates in principal vascular system of man and other vertebrates consisting of fluid matrix, plasma and formed elements.
Plasma : The liquid part of blood or lymph which is straw coloured, viscous fluid and contains about 90-92% of water and 6-8% proteins.
Lymph : A clear yellowish, slightly alkaline, coagulable fluid, containing white blood cells in a liquid resembling blood plasma.
Hear Beat : The rhythmic contraction and relaxation of the heart, which includes one systole (contraction phase) and one diastole (relaxation phase) of the heart. Heart beat count of healthy person is 72 times per minute.
Cardiac output : The amount of blood pumped by heart per minute is called cardiac or heart output. The value of cardiac output of a normal personis about 72×70
= 5040 mL or about 5L per minute.
Electrocardiograph : (ECG) The machine used to record electrocardiogram.
Electrocardigoram ECG : The graphic record of the electric current produced by the excitation of the cardiac muscles. It is composed of a ‘P’ wave, ‘QRS’ wave (complex) and ‘T’ wave (Refer fig. 18.3, page 286 (for a standard ECG) (NCERT class XI - Biology)
Human Blood Corpuscles
| Name and Number/ Percentage | Structure | Life Span and Formation | Function |
| (A) Erythrocytes RBCs - 4.5 to 5.5 | Yellow colour Circular, biconcave | Formed from birth onwards by | Transport of oxygen and some amount |
| million per cubic | denucleated, elastic, | bone marrow | of carbon |
| milimetre of blood | lack of cell organelles | Life - 120 days | dioxide. |
| like ER, ribosomes, | |||
| mitochondria etc. |
Lymph
The colouless mobile fluid connective tissue drains into the lymspatic capillaries from the intercellular spaces.
Composition :
It is composed of fluid matrix, plasma, white blood corpuscles or leucocytes.
Functions :
- It drains excess tissue fluid from extra celluar spaces back into the blood.
- It contain lymphocytes and antibodies.
- It transport digested fats.
Human Heart
It is the mesodirmally derived organ situated in thoracic cavity in between the two lungs. Protected by pericardium.
Four chambers - two (left and right) atria, and two ventricles (left and right)
Inner- artrial septum separates the two atria and inter ventricular septum separates th two ventricles, while the atria & ventricles are separated by atrio- ventricular septum.
The valves between right atrium and right ventricle is tricuspid while between left atrium and ventricle is bicuspid or mitral value.
The openings of the right and the left ventricles into the pulmonary artery and the aorta are guarded by semilunar values.
The values allow the flow of blood only in one direction, i.e., from atria to ventricles and from ventricles to pulmonary artery or aorta.
Blood Clotting
Blood Groups
Rh (Rhesus) System :
Discovered by Landsteiner and wiener in 1940. The antigen found on the surface of RBCs. The presence of this antigen is termed as Rh - positive (Rh+) and its absence as (Rh–)
SAN (Sino - artrial node) : A patch of tissues present in the right upper corner of the right atrium.
AVN (Atrio Ventricular Node) : A mass of tissues seen in the lower left corner of the right atrium close to the atrio-ventricular septum.
Heart Valves
Tricuspid Valve : The valves formed of three musclar flaps or cups, which guard the opeing between the right atrium and the right ventricle.
Bicuspid Valve (Mirtral Valve) :
The valves which guard the opeing between the left atrium and the left ventricle, made up of two flaps.
Semilunar Valves : The valves present at the opeing of the right and the left ventricles and allow the entry of blood into pulmonary artery and the aorta respectively.
Reading of ECG : ‘P’ Wave represents the electrical excitation (or depolarisation)
of the atria and leads to the contraction of both the atria.
‘ORS’ complex : represents the depolarisation of the ventricles, which imitiates the ventricular contraction
‘T’ Wave : represents the return of the ventricles from excited to normal state
(repolarisation). The end of T-wave marks the end of sytole.
Double circulation : The passage of same blood twice throught heart in order to complete one cycle. eg.
- The blood pumped by the right ventricle (dioxygenated blood) is trans ported through pulmonary artery to lungs where CO2 is exchanged with O2 through diffusion and returns back to the heart through pulmonary vein.
- The oxygenated blood from left ventricle is trans ported through aorta to different body parts (cells and tissues) where O2 is exchanged with CO2 through deffusion and then returned back to the heart through vena-cava.
Disorders of circulatory System
Hypertension (High Blood Pressure) : It results from narrowing of arterial lumen and reduced elasticity of arterial walls in old age. It can cause rupturing of capillaries. It is a silent killer.
Coronary Artery Disease : (CAD) Atherosclerosis The supply of the blood to heart muscles is affected. It is caused by deposits of ca, fat, cholesterol and fibrous tissues to make the lumen of arteries narrower.
Angina Pectoris : Caused due to arteriosclerosis, when no enought oxygen is reaching the heart muscle due to which the perosn experiences acute chest paind.
Heart attack : Caused when the heart muscle is suddenly damaged by an inadequate blood supply.
Cardiac arrest : The state in which the heart stops beating.
Arteriosclerosis : The state of hardening of arteries and arterioles due to thickening of the fibrous tissue and consequent loss of elasticity. It Causes hypertension.
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