Chapter-18
Body Fluids and Circulation
- Points to Remember
- Blood : A special connective tissue that circulates in principal vasucular 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 alkalline, 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 sercum.
- 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 appoximately 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 x 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 Heat Muscles.
- Diastole : Relaxation of Heat Muscles.
TYPES OF BLOOD CELLS THEIR NUMBERM STRUCTURE & FUNCTIONS
- Blood Pressure - The resistance offere by the lumen of the artery to the flow of Blood.
- Hypertension : The Conditions 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 heat beat taken on a graph paper from Electrocardiograph. (ECG machine)
Lymph :
- The colourless mobile fluid connective tissue drains into the lymphatic capillaries from the intercelluar spaces. It is formed by squeezing of blood through capillaries, within tissues. Its flow is undidirectional 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 trasport digested fats.
- Blood Clotting : Coagulation of Blood : (Cascade Process)
Functions of Blood :
- Transport, of food, respiratory gases (O2 CO2), hormones, metabolic intermediates, waste products, supply of raw materials, regulation of water balance, regulation pf 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.
- Compatiblity is crucial during transfusion and pregnancy as if Rh-ve person exposed to Rh+ve blood forms specific antibodies aganiest Rh antigens. Rh incompatiblity in pregnancy
- → 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 conrner of the right atrium close to the atrio-venticular septum. Fresh wave of contraction generated here, passes over both the venticles 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 values 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.
Human Valves :
- Tricuspid Valve : The valves formed of three muscular flaps or cups, which guard the opening between the right atrium and the right ventricl.
- Bicuspid Valve (Mitral Valve) : The valves which guard the opening 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 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 teh 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 heat 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 repective ventricle
- ■ Ventricular systole : contraction of ventricles
- ● AV node and AV bundle conduct the wave of contraction to the ventricles contract as 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 arteial 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 musucles is affected. It is "caused by deposits of Calucium, 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 musucle due to which the person experieces acute chest pain.
- Heat attack : Caused when the heart musucle 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.
