Circulatory System Class 10 Notes Science

Transportation in Human Beings The Heart - Life Processes, Class 10, Science

CIRCULATORY SYSTEM

Circulation :

The process of transporting the absorbed food, water and waste products from one place to another in the body is called circulation.

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Circulatory system : There are two types of circulatory system found in the animals :-

(i) Open Circulatory System : In this type of circulatory system, the main blood vessels arising from heart and pour the blood into tissue spaces (sinuses).  e.g. Arthropoda (Cockroach), Echinodermata 

(ii) Closed Circulatory System : In this type of circulatory system the blood remains only in the blood vessels and carried to various organ through vessels and capillaries.  e.g. Human beings, Annelida (Earthworm), some molluscs 

In human beings, the circulatory (transport) system is divided into two system :

(i) Blood Circulatory System (ii) Lymphatic System

(a) Blood (a) Lymph

(b) Blood vessels (b) Lymph vessels

(c) Heart (c) Lymph nodes

Blood circulatory system 

q Blood 

Blood is an important fluid conducting tissue, which transport the materials to different body parts.

u Composition of Blood : 

Liquid part (Matrix) Blood plasma

Solid part Blood corpuscles (RBC, WBC and Platelets)

Plasma : 

It composes 55% of blood.

The plasma has 90-92% water and remaining 8% -10% are other materials.

The plasma is a faint yellow viscous fluid.

Plasma contains some soluble proteins (serum albumin, serum globulins, prothrombin and fibrinogen), inorganic salts, food materials, waste products, dissolved gases, anticoagulants and antibodies.

Function of Plasma :

(i) Transportation of nutrients, respiratory gases, excretion of wastes and hormones of endocrine glands.

(iii) Prothrombin and fibrinogen plasma proteins help in blood clotting at injuries.

(iv) Globulins of blood plasma act as antibodies and provide immunity (disease resistance) to body.

(v) Plasma also help in transportation of minerals like iron, copper etc.

q Blood Corpuscles :

They form 45% part of blood

u Erythrocytes or Red Blood Corpuscles (RBC)

u Leucocytes or White Blood Corpuscles (WBC)

u Platelets or Thrombocytes

Functions of Blood :

1. Transporation of oxygen from lungs to tissues.

2. Transporation of carbon dioxide from the tissues to the lungs.

3. Transporation of excretory material from the tissues to the kidneys : Some of the chemical activities in the body form nitrogenous end products, like urea, that are poisonous. These substances diffuse into the capillaries and are carried by plasma. When they eventually reach the kidneys, a large proportion of them is removed and excreted.

4. Transporation of digested food from the small intestine to the tissue.

5. Distribution of hormones and enzymes.

6. Formation of clots to prevent blood loss.

7. Distribution of heat and temperature control : Muscular and chemical activities release heat. The heat so produced locally is distributed all around the body by the blood and in this way an even temperature is maintained in all body regions.

8. Preventation of infection and wound healing : WBCs in the blood help in wound healing. Bacteria are destroyed by the WBCs before they can enter the general circulation. Also, the WBCs provide defence to the body against disease germs and foreign substances.

Haemopoiesis  : The process of formation of blood is called hoemopoiesis. This process occurs in red bone marrow and lymphoid tissues (spleen, thymus and lymphatic nodes)

Study of blood - Haematology

Blood by weight - 7 to 8% of body weight

Blood by volume - 5-6 litres in male and 4-5 litres in female

Process of RBC formation - Erythropoiesis.

Decrease in RBC count - Anaemia

Number of RBC count increases at high altitude, this condition known as polycythemia

Blood red in colour due to red coloured respiratory pigment haemoglobin is present in RBC .

Iron (Ferrous ion Fe⁺² )element found in Haem component of haemoglobin (Hb).

Leukemia  Abnormal increase in TLC (Total Leucocyte Count) . It is also called blood cancer.

On the basis of nucleus and nature of cytoplasm WBCs are of following types :-

(i) Agranulocytes :- (a) Monocytes (b) Lymphocytes

(ii) Granulocytes :- (a) Acidophils (b) Basophils (c) Neutrophils

Maintenence by platelets

When we are injured and start bleeding. Naturally the loss of blood from the system has to be minimised. In addition, leakage would lead to a loss of pressure which would reduce the efficiency of the pumping system. To avoid this, the blood has platelet cells which circulate around the body and plug these leaks by helping to clot the blood at these points of injury.

Blood Clotting 

Blood flows from cut or wound but after sometimes it stops automatically. It is called clotting of blood.

Mechanism of blood clotting :- (Enzyme Cascade theory)

Proposed by Macfarlane and Co-workers

According to this theory, there are 3 steps of blood clotting.

Step 1 :- Injured tissues and Damaged platelets release

Thomboplastin + Ca⁺² Thrombokinase (An enzyme)

Step 2 :- Prothrombin (soluble plasma protein)  Thrombin (An active enzyme)

Step 3 :- Fibrinogen (soluble plasma protein) Fibrin fibres + blood corpuscles ® Blood clot

Serum is blood plasma from which fibrinogen, the blood clotting protein, has been removed.

13 clotting factors are helpful in blood clotting.

Clotting factor → Fibrinogen

Clotting factor I → Prothrombin

Clotting factor II → Thromboplastin

Clotting factor IV → Calcium

Vitamin-K is necessary for the synthesis of clotting factor in liver.

In human, three types of blood vessels are present.

1. Arteries : The vessels which carry blood from heart to various organs of the body.

2. Veins : They collect the blood from different parts of the body and pour it into the heart.

3. Capillaries : These are smallest blood vessels and one-cell thick.

The major differences between various blood vessels have been given in Table.

Heart

Size 5 × 3.5 inches  Colour Pink

Shape Conical  Weight  300 gm.

• Position : It is situated in thoracic cavity, between the lungs slightly on the ventral surface.

• Its triangular, superior-broad portion is tilted slightly towards right (dorsal) side, its lower narrow portion is tilted

towards left side.

• Heart is enclosed from all the sides by an envelope of two membranes called pericardial membranes (pericardium).

• The narrow space in between these two membranes is called pericardial cavity. A fluid is present in this cavity, called pericardial fluid.

• Pericardial fluid prevents the heart from external jerks.

• It reduces the friction during contraction.

• The human heart is divisible into four chambers.

• The upper two chambers are auricles (atria) while the lower two chambers are called ventricles.

• In between the auricles and ventricles, a clear groove is present which is known as coronary sulcus. 

q External structure of Heart :

• Auricular part of heart is smaller and its walls are thin.

• It is divided into right and left auricles, by a groove called inter-auricular sulcus.

• Ventricular part is broad and muscular.

• Ventricles have thicker wall than auricles.

• The groove which divides the two ventricles is termed as inter-ventricular sulcus.

Heart : External Structure Heart : Internal Structure

q Internal structure of Heart : 

• Partition between right and left auricle is known as inter-auricular septum while partition between the two ventricles is known as inter- 

ventricular septum.

• Partition between auricles and ventricles is known as auriculo-ventricular septum.

(A) Right Auricle (Atrium) :

• The right auricle has the openings of the superior vena cava, inferior vena cava and coronary sinus.

• Deoxygenated blood from the veins of the head, neck and upper limbs enters the right auricle by superior vena cava and from the rest of the body and lower limbs by the inferior vena cava.

• The coronary sinus, which drains deoxygenated blood from the heart muscle.

• From the right auricle blood passes into the right ventricle through a tricuspid valve, (so called because it has three cusps.)

(B) Rigth Ventricle :

• Blood leaves the right ventricle through the pulmonary artery. It is guarded by semilunar valve.

• This artery further divides into right and left pulmonary arteries entering into the two lungs where they further branch into pulmonary capillaries.

(C) Left Auricle (Atrium) :

• This chamber receives four pulmonary veins, two from each lung from where they bring oxygenated blood.

• The left auricle empties its blood into the left ventricle through a mitral or bicuspid valve. 

(D) Left Ventricle :

• Blood leaves the left ventricle by the large, main artery of the body called the aorta.

• The opening from the left ventricle into the aorta is guarded by aortic semilunar valve.

• Just beyond these, a pair of coronary arteries are present which supply blood to heart muscles.

• This blood is brought back to heart by coronary veins which join to form coronary sinus.

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Haversian valve _ Present on the opening of superior vena cava (SVC)

Eustachian valve _ Present on the opening of inferior vena cava (IVC)

Thebesian valve _ Present at the opening of coronary sinus.

Columnae carnae _ Finger like projection from ventricle inner walls.

Papillary muscles _ Present at the tip of columnal carnae.

Chorda tendinae _ Arise from papillary muscles and keep the valves in proper position.

Musculi pectinati _ Transverse muscular ridges present on auricles' inner walls.
.

Working of the heart 

• The heart of the human works like a pump.

• Pure oxygenated blood enters the left auricle from lungs through pulmonary veins.

• The deoxygenated blood from various part of the body enters right auricle through veins and capillaries.

• The two auricles contract simultaneously so the oxygenated blood from left auricle to left ventricle and deoxygenated blood from right auricle is pumped into right ventricle.

• Now both the ventricles contract simultaneously so the pressure is created on the blood and the valves between auricle and ventricle close and the blood does not go back into auricle.

• Due to this pressure, aorta valve opens and the blood comes in aorta, from here, blood is sent to different parts of the body with the help of various arteries.

• By the contraction of right ventricle, blood reaches the lungs through pulmonary arteries where it gets reoxygenated.

Heart beat 

• Rhythmic contraction and expansion of heart is called heart beat. Contraction and expansion occurs separately in atria and ventricles.

• The Sinu-Atrial node (SA node) found in the wall of the right atrium, is responsible to initiate and maintain the heart beat by generating impulses.

• SA node is also known as "Pacemaker" of heart. In some heart patients, the heart does not beat normally. The muscle cells stop functioning. In such patients, a machine called pace maker is inserted in the patient's heart, so that heart beats normally.

• Heart beat in human, 72 times in one minute.

• Each heart beat has two components, systole and diastole. Systole represents contraction while diastole represents expansion or distension of heart chambers.

• Tachycardia :- It is the condition where heart beat (rate) exceeds 90 per minute for an average adult man.

• Bradycardia :- It is the condition where heart beat falls below 60 per minute for an average adult man.

• Cardiac Cycle :- The sequence of events which takes place during the completion of one heart beat.

Pulse

• A wave of distension passes along the arteries following each ventricular systole. This wave of distension is called arterial pulse.

• It is generally felt by placing fingers over the radial artery at the wrist.

• The pulse rate is same as heart beat rate.

Heart-Sound

• I^st Sound - This is a contraction sound which denotes the beginning of ventricle-contraction. It arises due to closing of mitral valve and the tricuspid valve. It is weak and appears in the form of " Lubb " (L - U - B - B)

• II^nd Sound - This is a diastolic sound which denotes the beginning of ventricular diastole. This arises due to the closing of the semi-lunar valves and is heard in the form of " Dup".

• These "Lubb" and "Dup" sounds of the heart can be heard with the help of an instrument called " Stethoscope." 

Electrocardiogram (ECG)

• The functioning of heart can be graphically recorded by an instrument called electrocardiograph.

• The heart muscles generate electric currents whichbring about heart beats. The electrical changes during heart beat can be graphically recorded by placing electrodes on thechest above the heart and connecting the electrodes to a sensitive galvanometer with a recording device.

• The graphic recording is called an electrocardiogram (ECG.)

• It was first of all recorded by " Waller"

• "Einthovan" is known as the Father of Electro Cardio Graphy.

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What is Blood Pressure and Lymphatic System - Life Processes, Class 10, Science

blood pressure

• Definition :  Blood pressure is the pressure exerted by the flowing blood on the wall of blood vessel.

• Types : Blood pressure is of two types.

(i) Systolic blood pressure (ii) Diastolic blood pressure

Characters Systolic blood pressure Diastolic blood pressure 

1. Definition Blood pressure at the time of Blood pressure at the time of maximum

maximum contraction of ventricles. relaxation of ventricles.

2. Value 120 mm Hg. 80 mm Hg.

• Hypertension : - A persistent increase in blood pressure is called hypertension or high blood pressure.

It is caused by narrowing of arterial lumen and reduced elasticity of arterial walls.

• The instrument by which we can measure B.P. is called "sphygmomanometer".

• In man B.P. is measured in the branchial artery of arm.

• Normal B.P. of a healthy person is 120/80 mm Hg.  
 

Double circulation 

In double circulation, the blood passes twice through the heart to supply once to the body.

(i) Systemic circulation : 

In this, blood completes its circulation from left ventricle to right auricle through the body organs.
(systemic organs)

(ii) Pulmonary circulation : 

In this, blood completes its circulation from right ventricle to left auricle through the lungs.

The right portion of heart is known as pulmonary heart and it have deoxygenated blood. The left portion of heart is known as systemic heart and it have oxygenated blood.

The separation of the right side and the left side of the heart is useful to keep oxygenated and de-oxygenated blood from mixing.

Such separation allows a highly efficient supply of oxygen to the body. This is useful is animals that have high energy needs (e.g. birds and mammals) which constantly use energy to maintains their body temperature. In animals that doe not use energy for this purpose, the body temperature depends on the temperature of environment. (e.g. fishes, frogs)

Single circulation : 

In this, the blood passes once through the heart to supply once to the body.

It is found in fishes which have two-chambered heart one auricle and one ventricle. The heart receives only deoxygenated blood, which is first pumped to the gills for oxygenation and then oxygenated blood is supplied to rest of the body parts by various arteries.

Lymphatic system 

It consists of lymph, lymphatic capillaries, lymph vessels, lymph nodes and lymphoid organs (spleen thymus and tonsils).

Lymph : When blood flows into thin capaillaries some amount of plasma filters out of thin capillaries. This fluid is called interstital fluid or tissue fluid  or lymph. Lymph is also called extracellular fluid. It is colourless and contains lymphocyte cells. Unlike blood, lymph does not contain red blood corpuscles, but contains less plasma protein. Lymph flows only in one direction, that is from tissues to heart.

The functions of lymph are as under :

u It transports fatty acids and glycerols from small intestine to blood.

u Lymphocytes present in it which destroy harmful pathogens.

u It drains excess tissue fluid from intercellular spaces back into the blood.

u Lymph nodes localize the infection and prevent it from spreading to other body parts.

Circulatory diseases 

• Thrombosis :- Thrombosis is the formation of a small blood clot or thrombus inside a blood vessel. A blood clot, or any other solid particle floating in the blood stream is known as an embolism.

• Hardening of the arteries : As people get older the leastic and muscle layers of their arteries are gradually replaced by inelastic fibrous tissue. The artery walls become stiff and hard, a condition known as hardening of the arteries, or arteriosclerosis. This condition reduces the flow of blood.

• Atheroma :- Blood flow along an artery is sometimes slowed or stopped altogether by a layer of fatty substance called cholesterol, stuck to the artery walls. This type of blockage is called an atheroma. Arteriosclerosis and atheroma are very dangerous when they occur in the heart or brain.

• Heart attacks (heart failures) :- A heart attack, or heart failure, is the sudden slowing or stoppage of the heart beat. A heart attack occurs when a coronary artery is blocked by a thrombosis or atheroma. Coronary arteries supply heart muscle with food and oxygen. Consequently, when a coronary artery is blocked, a section of heart muscle stops working and eventually dies. If the whole heart is affected, death is instantaneous.

• Angina pectoris :- If one or both of the coronary arteries is partly blocked due to atheroma, heart muscle is unable to work properly during exercise. This causes pains in the chest known as angina pectoris.

• Stroke :- A stroke, or cerebral thrombosis, is a blood clot in the brain. The blood clot suddenly blocks an artery inside the brain causing the region served by this vessel to stop working, and dies. The results of a stroke depend on the area of the brain affected. Muscles may be paralysed, and speech or memory affected. Death occurs if the brain damage is extensive.

• Prevention of circulatory diseases :- Studies have shown that these diseases occur far less often among people :-

1. Who never smoke cigarettes.

2. Who take regular exercise (walking, cycling, swimming, active sports, etc.)

3. Who never drink alcohol or drink only moderate amounts.

4. Who eat balanced meals.

5. Who have seven or eight hours sleep a night.