The group of organs though which blood circulatesthough out the body is called thebloodcirculatory system.
The main components of the system are:
-Blood vessels.
-Blood.
-Heart.

Blood is a red-colored viscous and complex tissuefluid made up of plasma (55%) and blood corpuscles.
Any 3 properties of blood are:
-It is red,viscous, and complexfluidconnective tissue.
-Its salty in taste and slightly alkaline in nature.
-The specific gravity of blood is 1.05 to 1.06.
Its functions are:
-Transport respiratory gas.
-Transport of nutrients.
-Transport of waste products.
-Transport of body secretions.
-Regulation of body temperature.
-Water balance.

The transparent clear yellowish liquid that forms 55%of blood volume and contains about 90%of water, 8%proteins and 2% other dissolved substances calledplasma.
The functions are:
-It transport digestedfood to different parts of thebody.
-It transport wastematerials.
-It regulatesthe body temperature.
-It transports hormone secreted by endocrine glands.
-Fibrinogenpresent in plasma helps in blood clotting.

Erythrocytesare red colored, biconcaveand enucleateddisk like structures present in the plasma (RBCs).
Its functions are:
- It transport oxygen from lungs to other tissues and CO2 from other tissues to lungs.
- It maintain the viscosity of blood and ion-balance.
The larger and irregular cells having a nucleus is called leucocytes (WBCs).They are capable of amoeboid movement.
Its functions are:
- It helps in destroying solid substances.
- It fights against germ and destroy the damaged...

Platelets arecolorless, round, non-nucleated, cytoplasmicfragmented formed from giant cells of the bone marrow.
Its functions are:
-It plays an important role in the coagulation orclotting of blood.
-It release a chemical calledthromboplastin.

Valves are the switch found in heart and differentblood vessels that regulate the flow of blood withinthe heart and itspassage.
The valves found in human body are:
-Tricuspidvalve
-Mitral valve
-Aortic valve
-Pulmonary valve

Blood vessels are the muscular tubes or pipes throughwhich blood flows in the different parts of the body.
Its importanceare:
-It forms the system or channel for the bloodcirculation.
-It suppliesnutrients, oxygen and other necessary substance to differentparts of the body.
- It helps to supply back the different waste bodiesfrom the diff. parts of body to specific organs.

The circulation of blood from the left ventricle to theright ventricle of the heart via body tissuesis calledsystemic circulation.
The circulation in which blood travels twice throughthe heart in one complete cycle in the body is calleddouble circulation.

The circulation of blood from the right ventricle ofthe heart to the left auricle via lungs is calledpulmonary circulation.

a. RBC and WBC.

b. WBC and Platelets.

Blood pressure is the force with which bloods pushesagainst the walls of the arteries.
The normal blood pressure of a healthy young adult is120/80 mmHg.

The pressure of the blood inside the arteries ishighest which is called systole.
The pressure of the blood inside the arteries iscomparatively less, which is calleddiastole.

We all know, WBCs protect the body from the attack of diseases causing germs and other harmful foreign materials. As a result, WBCs are called soldiers of the body.

We all know, the blood flow with low pressure in veinsbut flows with high pressure in arteries. So, to preventthe backward flow of blood in veins, valves arepresent. But no valves are required in arteries. So that, valvesare present in veins but not in arteries.

We all know ventricle pumps out the large amountof blood to different parts of the body and lungs. So,it requires greater force for this action which isprovided by thick wall. But auricle receives blood fromlungs and different parts of body for which no great force isrequired. So, wall of ventricle is thicker than thatof auricles.

We all know, left ventricle pumps large amount of bloodto various parts of body through aorta. For this, it requiresgreater force which provided by its thick wall. Butright ventricle supplies blood onlytowards lungs. Forwhich, leas force is required. So, the wall of leftventricle is more muscular than that of right one.

Arterial pulse is the systemic contraction of the heartthat can be felt as a jerk in certain arteries whichare superficial in position.

The continuous rhythmic beat throughout life which is produced due to the contraction and relaxation of heart muscles is called heart beat.

The factors affecting rate of heart beat are:
-Fear
-Physical exercises.
- Fever.
-Tension.
-Emotion.

Thegroupof organs which work together for thecirculation of blood throughout the body is calledblood circulatory system. In the human body, a rapidsupplyof oxygen, nutrients, hormones, etc. to varioustissues and deposal of waste products is an essentialrequirement. As circulatory system in human body isresponsible for transporting variousmaterials inside thebody with the help of blood. Therefore, this is the imp.of blood circulation in human body.

Any five causes of high blood pressure are:
-Smoking and alcoholism.
-Lack of physical exercise.
-Genetic causes.
-Consumption of spicy and salty foods.
-Hypertension.

Any four preventive measures of high blood pressure are:
-Avoidthe consumption of cold drinks.
-Smoking & alcoholism should be avoided.
-Regular physical exercise should be done.
-Avoid the consumption of fatty, oily and spicy food.

Diabetes is a disease which is caused due to increasein the sugarlevel in blood
Its symptoms are:
-Frequent urination.
-Excessive thrust & hunger.
-Tiredness.
-Delay in wound healing.
-Blurred vision.
Its preventive measures are:
-Obesity should be reduced.
-Balanced diet should be taken.
-Hypertensionshould be reduced.
-Regular physical exercise.
-Avoid smoking and alcoholism.

Uric acid is a compound of carbon and nitrogen with theformulaeC₅H₄N4O₃.
Its causes are:
-Consumption of spicy & salty foods.
-Consumption of fatty red meat, sea food, pulses, etc.
Its effects are:
-It can lead to gout diabetes, kidney stone, etc.
-It causes swelling of the skin and joints of thelegs with burning sensation.

- WBCs:
-It forms antibodies.
-It defend body from various diseases.

- Plasma:
-It transport digestivefood.
-It regulates body temperature.

- RBCs:
-They transport oxygen and CO₂.
-They maintain viscosity of blood and ion-balance.

- Platelets:
-It helps in clotting of blood.
-It release chemical called thromboplastin.