CLASS 11TH BIOLOGY CHAPTER- 18 BODY FLUIDS AND CIRCULATION NCERT QUICK REVISION NOTES FOR NEET AND CBSE EXAM
BODY FLUIDS AND CIRCULATION
Diagrammatic presentation of a standard ECG.
¶ It is the mesodermally derived organ situated in thoracic cavity in between the two lungs. Protected by a double membrane covering called Pericardium.
¶ 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 conta (only lymbphocytes) ins 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.
¶ Serum: Blood plasma from which fibrinogen and other clotting factory have been removed.
¶ Heart 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 person is about 72 × 70=5040 mL or about 5L per minutes.
¶ Electrocardiograph: (ECG) the machine used to record electrocardiogram. Electrocardiogram 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.
¶ Blood Pressure-The resistance offered by the lumen of the artery to the flow of Blood.
¶ Cardiac Cycle: The rhythmic contraction and dilation of different parts of heart in one beat. Hypertension: The condition when blood pressure is higher than normal
(120/80 mmHg).
Systole: Contraction of heart muscles.
Diastole: Relaxation of heart muscles.
LYMPH
The colourless mobile fluid connective tissue drains into the lymphatic capillaries from the intercellular spaces. It is formed by squeezing of blood through capillaries, within tissues. Its flow is unidirectional i.e., from tissues to heart.
Composition:
It is composed of fluid matrix, plasma, white blood corpuscles or leucocytes.
Functions:
(i) It drains excess tissue from extra cellular spaces back into the blood.
(ii) It contain lymphocytes and antibodies.
(iii) It transport digested fats.
¶ Four chambers-two (left and right) atria, and two ventricels (left and right)
¶ Inner-artrial septum separates the two atria and inter ventricular septum separates the two ventricles, while the atria and ventricles are separated by atrioventricular septum.
¶ The valves between right atrium and right ventricle is tricuspid while between left atrium and ventricle is bicuspid or mitral value.
¶ The opening of the right and the left ventricles into the pulmonary artery and the aorta are guarded by semilunar values.
¶ The value allow the flow of blood only in one direction, i.e., from atria to ventricles and from ventricles to pulmonary artery or aorta.
FUNCTIONS OF BLOOD
Transport, of food, respiratory gases (O₂ and CO₂), hormones, metabolic intermediates, waste products, supply of raw materials, regulation of water balance,
regulation of pH and body temperature, and provides immunity.
Blood clotting
BIPOD GROUPS
RH (RHESUS) GROUP:
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-). It plays a crucial role in childs birth born out of a marriage between Rh- woman and Rh+ man, causing to produce anti Rh antibodies.
→SAN (Sino-artrial node): A patch of tissues present in the right upper corner of the right atrium, acts are pacemaker due to having a unique property of self exitation.
→AVN (Atrio Ventricular Node): A mass of tissues seen in the lower left corner of the right atrium close to the atrio-ventricular septum. Fresh wave of contraction generated here, passes over both the ventricles simultaneously along the bundle of his.
HEART VALVES
Tricuspid Valve: The valves formed of three muscular flaps or cups, which guard the opening between the right atrium and the right ventricle.
BICUSPID VALVE (MITRAL VALVE) :
The valves which guard the opening between the left atrium and the left ventricle, made up of two flaps.
¶ Semilunar Valves: The valves present at the opening 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.
¶ 'QRS' complex : represents the depolarisation of the ventricles, which initiates 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 through heart in order to complete one cycle. eg.
(i) The blood pumped by the right ventricle (deoxygenated blood) is transported through pulmonary artery to lungs where CO2 is exchanged with O2 through diffusion and returns back to the heart through pulmonary vein. It is called pulmonary circulation.
(ii) The oxygenated blood from left ventricle is transported through aorta to different body parts (cells and tissues) where O2 is exchanged with CO2 through diffusion and then returned back to the heart through vena-cava. It is called systemic circulation.
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 Calcium, fat, cholesterol and fibrous tissues to make the lumen of arteries narrower.
¶ Angina Pectoris: Caused due to arteriosclerosis, when no enough oxygen is reaching the heart muscle due to which the person experiences acute chest pain.
¶ 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 herding of arteries and arterioles due to thickening of the fibrous tissue and consequent loss of elasticity. It causes hypertension.
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