Welcome student, today we will mention Class 11 Biology Ch 18 Body, Fluids and Circulation Important points to remember, it will cover the whole NCERT, and best for revision, and prepared by the masters of their field. 

Class 11 Biology Ch 18 Body, Fluids and Circulation Important points to remembered

Points To Remember:-

Blood : A special connective tissue that circulates in principal vascular system of man and other vertebrates consisting of fluid matrix, plasma and formed 

elements (Blood = Plasma + All blood cells).

Plasma : (Blood – All blood cells = Plasma) The liquid part of blood which is straw coloured, viscous fluid and contains about 90-92% of water and 6-8% 

proteins.

Lymph : A clear yellowish, slightly alkaline, coagulable tissue fluid, 

containing white blood cells (Only lymphocytes), a liquid resembling blood 

plasma.

Serum : Blood plasma from which fibrinogen and other clotting factors 

have been removed. [Plasma– (fibrinogen & other clotting factor)] = blood serum.

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.

Stroke Volume : The volume of blood pumped out by the heart during a 

systole. It is approximately 70 ml.

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. 

Cardiac Cycle : The rhythmic contraction and dilation of different parts of 

heart in one beat.

Systole : Contraction of heart muscles.

Diastole : Relaxation of heart muscles

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TYPES OF BLOOD CELLS THEIR NUMBER, STRUCTURE & FUNCTIONS

Blood Pressure—The resistance offered by the lumen of the artery to the

flow of Blood.

Hypertension : The condition when blood pressure is higher than normal

(120/80 mmHg)

Electrocardiograph : (ECG) the machine used to record electrocardiogram.

Electrocardiogram ECG : The print out of pattern of heart beat taken on

a graph paper from Electrocardiograph. (ECG machine)

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 having only lymphocytes

of white blood corpuscles or leucocytes.

Functions : (i) It drains excess of tissue fluid from extra cellular spaces

back into the blood.

(ii) It contain lymphocytes and antibodies.

(iii) It transport digested fats.

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Blood Clotting : Coagulation of Blood : (Cascade process)

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 Groups : 

Based on presence of Antigens and Antibodies in blood.

Rh (Rhesus) Group :

• Rh positive (Rh + ve) – Rh antigen similar one present in rhesus monkey.

Observed on the surface of RBCs (nearly 80% of humans)

• Rh negative (Rh–ve) – those in whom this antigen is absent.

• Compatibility is crucial during transfusion and pregnancy as if Rh -ve person

exposed to Rh +ve blood forms specific antibodies against Rh antigens.

 Rh incompatibility in pregnancey

 

→ SAN (Sino-atrial node) : A patch of tissues present in the right upper corner of the right atrium, acts as pacemaker due to having a unique property of  self excitation.

→ 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.

Human Heart 

•  It is the mesodermally derived organ situated in thoracic cavity in between 
• the two lungs. Protected by a double membrane covering called Pericardium.
•  Four chambers–two (left and right) atria, and two ventricles (left and right)
•  Inter-atrial 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 left ventricle is bicuspid or mitral value. 
•  The opening of the right ventricle into the pulmonary artery and the opening 
• of left ventricle in to aorta are guarded by semilunar values.
• The valves allow the flow of blood only in one direction, i.e., from atria to
• ventricles and from ventricles to pulmonary artery or aorta.

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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.

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.

Standard ECG and 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

CARDIAC CYCLE : The rhythmic contraction and dilation of different parts of heart in one beat.

Systole : contraction of heart muscles.

Diastole : relaxation of heart muscles.

 

■ Joint diastole :-All chambers of heart in relaxed state.

 • Tricuspid and bicuspid valves– open

 • Blood from pulmonary vein and vena cava flows into left and right atrium respectively.

■ Atrial systole :- contraction of atrias

 • SAN generates action potential to stimulate atrias to contract simultaneously

 • Blood flows to respective ventricles

■ Ventricular systole : contraction of ventricles

 • AV node and AV bundle conduct the wave of contraction to the

 ventricles via bundle of HIS.

 • Ventricles contract as a closed chamber (as AV valves and

 semilunar valves are close).

 • Pressure of blood opens the semilunar valves and blood flows to

 respective arteries.

■ Joint diastole : Relaxation of all chambers.

HEART SOUNDS

• Closure of bicuspid and tricuspid valves produces first heart sound

 ‘lub’

• Closure of semilunar valves produces second heart sound ‘dub’

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 hardening of arteries and arterioles due to thickening of the fibrous tissue and consequent loss of elasticity. It causes hypertension.

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