Heart
Heart is a pumping system which circulates blood throughout the body. It has four sections. The upper two sections are called auricle. The lower two parts are called right and left ventricle. Left and right portion are separated and are not connected internally. Blood containing oxygen enters the left auricle from pulmonary vain. This blood goes to the left ventricle through bicuspid valve. Blood from left ventricle is pumped be Aorta. Thus the pure blood is in the left ventricle and left auricle. By venacava impure blood comes to the right auricle and sent to ventricle through tricuspid valve. The pulmonary artery takes the impure blood from the right ventricle to lungs. In the state of rest the heart beat rest of and adult is 70 times per minute. The sino-auricular node in the heart is called pace maker or pace setter.
Working mechanism of Heart :
The heart beat start from sino-auricular node. The oxygenated blood comes to the left auricle of heat from pulmonary vein. At this time the left auricle stays in the relaxed state. When the left ventricle contracts then the blood is pumped to different parts of the arteries.
When the right auricle is in the relaxed state then impure blood comes through venacava. When right auricle contracts then blood comes to pulmonary artery. Compared to auricle, ventricle is thick and more muscular become ventricle takes blood to deferent parts of body.
The valves between auricle and ventricle prevent the flow of blood in the reverse direction.
Double Circulation of blood in human
1) Pulmonary circulation
In this circulation impure blood comes to lungs from right ventricle through pulmonary artery and pure blood comes from lungs to heart through pulmonary vein.
2) Systemic Circulation
In this circulation, blood from left ventricle goes to aorta and pure blood is circulated to the entire body.
|
The pressure against blood vessel walls is called blood pressure. This pressure is high in artery as compared to vein. The blood pressure inside artery during contraction of ventricle is called Systolic pressure and pressure inside artery during relaxation of ventricle is called Diastolic pressure. The normal Systolic pressure is 120 mm of Hg and normal Diastolic pressure is 80 mm Hg. Blood pressure is measured by sphygmomanometer. High blood pressure is at also called hypertension. Its reason is contraction of arteries which resists many cause bursting of arteries and internal bleeding. |
Lymph :
A liquid other than blood helping in circulation is Lymph. Lymph is a colourless fluid connecting tissue. Plasma, protein and blood corpuscles enter in yhe intercellular space through pores of cell walls and from Lymph.
Lymph reaches to lymph cells from the intercellular space. They join together to form a large lymph vessel. This lymph vessel opens into a large vein. The fat absorbedby small intestine is circulated by lymph.
Function of Lymph :
1) This protect body by killing harmful bacteria.
2) Absorbs the digested fat and takes it to various parts of the body.
3) It helps in healing wounds helps in filtration of blood.
Difference between Blood and Lymph :
|
Sl. No. |
Lymph |
Blood |
|
1 |
It is a colourless connecting tissue. |
This is a dark red colour fluid. |
|
2 |
RBC absent. |
RBC present. |
|
3 |
Amount of excretory meterial is more. |
Amount of excretory meterial is less. |
|
4 |
The amount of protein is less. |
The amount of protein is more. |
|
5 |
The amount of CO2 is more. |
The amount of CO2 is less. |
Disease Related
to Heart
|
Sl. No. |
Name of Disease |
Symptoms |
Reason |
|
1 |
Hypertension |
Blood pressure |
Obsity, Smoking, Mental
tention |
|
2 |
Heart Block |
Stopping of blood
circulation |
Narrowing and hardening of artery
wall |
|
3 |
Rheumatic heart disease |
Weakening of heart and
functioning of value |
Pneumonia and bacterial
Infections |
|
4 |
Pericarditis |
Increase in the size of
heart |
Bacterial Infections |
Coagulation of Blood :
To prevent blood flow to the torn, wounded part of body , coagulates. This prevents excess flow of blood. The blood coagulates in the following steps.
1) Formation of thromboplastin : By injury or cut the blood platelets come in contact with air and liberated a material called thromboplastin.
2) Formation of thrombin : Thromboplastin combines with calcium ions and converts prothrombin to thrombin.
3) Formation of Fibrin and Fibrin Filaments : Thrombin converts the protein fibrinogen of blood to fibrin. This fibrin combines with blood corpuscles to make blood clots.
Contact
Blood platelets ----------------------￫ Thromboplastin
With air
Thromboplastin
Prothombin ---------------------------￫ Thrombin (active)
(inactive) Ca++
Thrombin + Fibrinogen (Soluble protein) ---------------￫ Fibrin (Insoluble protein)
Fibrin + Blood cells -------------￫ Blood clot
Blood Groups :
Landstiner discovered the blood group in human beings. Antigen is is found in the red blood corpuscles of blood and antibody in plasma. On its basis the blood group has been classified in four groups.
|
Sl. No. |
Blood Group |
Antigen (RBC) |
Antibody (Plasma) |
|
1 |
A |
A |
b |
|
2 |
B |
B |
a |
|
3 |
AB |
A and B |
- |
|
4 |
O |
- |
a and b |
Blood Transfusion :
Transfusions of blood from a healthy person to any other person is called blood transfusion. The person donating blood is called donor and one accepting blood is called recipient. The blood group “AB” is called Universal recipient and the blood group “O” is called universal donor. During blood transfusion there should not be agglutination because sticking of blood corpuscles can tear the blood vessels and may cause death also.
Blood
Recipient
|
Blood donor |
Antibody b of group
A |
Antibody a for
group B |
Antibody ab of
group is absent |
Antibody ab of
group O |
|
Group A (Antigen A) |
|
|
||
|
Group B (Antigen B) |
|
|
||
|
Group AB (Antigen AB) |
|
|
||
|
Group O (No Antigen) |
|
✔️ |
✔️ |
✖️ |
- ✖️ - Indicates no agglutination
- ✔️ - Indicates agglutination
Rh factor :
Landsteiner and Weiner discovered this factor in Rhesus monkey. The persons having this factor are called Rh+ and those with this facror absent are caller Rh- . If father is Rh+ and mother is Rh- then foetus in the womb forms Rh blood corpuscles in mother uterus which may cause foetal death. This is called erythro blastosis foetalis.
Blood Bank :
Due to non supply of blood during accident and other blood related diseases million of people lose their lives. In hospitals doctors preserve blood at low temperature. Such places of blood storage are called Blood Bank. Blood Bank is important for supplying blood during emergency. By blood donation more blood can be stored in the blood banks and can be used during urgent need or emergency. Each person should donate blood and also inspire others to do so.
Written by : Jayanta Kumar Meher (BSc, BEd)
0 Comments