The formal charge over an atom of a polyatomic molecule or ion is the difference between the valence electron of that atom in the elemental state and the number of electrons assigned to that atom in Lewis structure.

Mathematically, it can be expressed by following formula:

F.C. = [Total no. of valence e^– in free state] – [total no. of e^– assigned in Lewis structure] F.C. = [Total no. of valence e^– in free state] – [total no. of non-bonding pair e^– (lone pair)] – 1/2 [total no. of bonding e^–]

The factor of ½ is attached to the no. of bonding e^– because bonding e^– is shared between two atoms.

Olympic flag was created in 1913 by Baronde Coubertin. It was first inaugurated in Paris in June 1914. Olympic flag is made of white silk and contains five interlocking rings/circles in five colours representing five continents of the world namely America, Europe, Australia, Asia and Africa. The five rings have different colours namely yellow, green red blue and black. The interlocking of the ring circle symbolizes co-cooperation and friendship.

Cockroaches are pests inhabiting the unhygienic and damp places. They are dark brown in colour belonging to the phylum Arthropoda, the Blattidae family, and class Insecta.

Cockroaches have 13 chambered hearts. 3 chambers are present in the thorax and 10 in the abdomen.

• The sequential event in the heart which is cyclically repeated is called the cardiac cycle and it consists of systole and diastole of both the atria and ventricles.
• Duration of a cardiac cycle is 0.8 seconds.
• During a cardiac cycle, each ventricle pumps out approximately 70 mL of blood which is called the stroke volume.
• The stroke volume multiplied by the heart rate gives the cardiac output.
• Cardiac output can be defined as the volume of blood pumped out by each ventricle per minute and averages 5000 mL or 5 litres in a healthy individual.
• As the tricuspid and bicuspid valves are open, blood from the pulmonary veins and vena cava flows into the left and the right ventricle respectively through the left and right atria and the semilunar valves are closed at this stage.
• The SAN now generates an action potential which stimulates both the atria to undergo a simultaneous contraction – the atrial systole.
• The action potential is conducted to the ventricular side by the AVN and AV bundle from where the bundle of HIS transmits it through the entire ventricular musculature, which causes the ventricular muscles to contract, (ventricular systole), the atria undergoes relaxation (diastole), coinciding with the ventricular systole.
• Ventricular systole increases the ventricular pressure causing the closure of tricuspid and bicuspid valves.
• As the ventricular pressure increases further, the semilunar valves guarding the pulmonary artery (right side) and the aorta (left side) are forced open, allowing the blood in the ventricles to flow through these vessels into the circulatory pathways.
• The ventricles now relax (ventricular diastole) and the ventricular pressure falls causing the closure of semilunar valves which prevents the backflow of blood into the ventricles.
• As the ventricular pressure declines further, the tricuspid and bicuspid valves are pushed open by the pressure in the atria exerted by the blood which was being emptied into them by the veins and the blood now once again moves freely to the ventricles, leading the ventricles and atria again in a relaxed (joint diastole) state.
• Again, the SAN generates a new action potential and the events are repeated.
• During each cardiac cycle two prominent sounds are produced which can be easily heard through a stethoscope.
• The first heart sound (lub) is associated with the closure of the tricuspid and bicuspid valves, whereas the second heart sound (dub) is associated with the closure of the semilunar valves.

The double circulation of blood includes:
(i) Systematic Circulation
(ii) Pulmonary Circulation

Systematic Circulation

• Systemic circulation transfers oxygenated blood from left ventricles to capillaries in the tissue.
• The oxygen-rich blood is passed to the aorta for distribution into various body sections.
• The veins and venules later absorb the deoxygenated blood which is rich in carbon dioxide from different parts of the body.
• The deoxygenated blood is transferred back to the superior vena cava, then on to the right atrium.
• The right atrium transports blood to the right ventricle for pulmonary circulation, after receiving the deoxygenated blood.

Pulmonary Circulation

• The distribution of blood starts in the pulmonary circulation from the right atrium to the left atrium.
• The pulmonary artery receives the blood from the right ventricle and carries to the lungs for oxygenation.
• When the oxygenated blood is pumped back to the left atrium via the pulmonary vein, that is brought to the left ventricles, after the purification process.

It is necessary for a human being to separate oxygenated and de-oxygenated blood because this makes their circulatory system more efficient and helps in maintaining constant body temperature.

• High Blood Pressure: 

  The pressure which is created by the blood flow on the wall of blood vessels. In humans, the normal range of blood pressure is 120/80. In this range, 120 is the systolic blood pressure and 80 is the diastolic blood pressure.

  Systolic blood pressure – It is defined as the pressure that is created in the arteries when blood flows through arteries to the rest of the body when the heartbeats.

• Coronary Artery Disease (CAD)Coronary artery disease is also termed as atherosclerosis. Coronary Artery Disease is the disease which is caused by the deposition of waxy substances in the blood vessels which supplies the blood to the heart muscle and this deposition leads to the blockage of the blood flow. The examples of waxy substances are fat, cholesterol and fibrous tissues. As a result, it may also cause a heart attack.

• Angina

  Angina is the condition in which chest pain occurs if the heart receives insufficient oxygen and nutrients through the blood vessels. Angina could be caused by the different risk factors. These factors are as follows:

• Smoking.
• Age factor (More than 40 age).
• Hypertension.
• Obesity.
• Physical inactivity.

The P wave indicates atrial depolarization. The P wave occurs when the sinus node, also known as the sinoatrial node, creates an action potential that depolarizes the atria. The P wave should be upright in lead II if the action potential is originating from the SA node. ECG – A Pictorial Primer. Atrial and ventricular depolarization and repolarization are represented on the ECG as a series of waves: the P wave followed by the QRS complex and the T wave. The first deflection is the P wave associated with right and left atrial depolarization. ... The second wave is the QRS complex.

Heartbeat is triggered by electrical impulses which is induced by a specific pathway. The SA node known as sinoatrial node is the heart’s natural pacemaker. This impulse begins in this small bundle of specialized cells which is located in the right atrium. The electrical impulse spreads through the walls of the atria and it causes contraction. Contraction sends the blood into the ventricles.

The heart performs the following important functions:

• The primary function of the heart is to pump blood throughout the body.
• It supplies oxygen and nutrients to the tissues and removes carbon dioxide and wastes from the blood.
• It also helps to maintain adequate blood pressure throughout the body.

Structure of Human Heart

• The heart is a muscular organ covered by a double membrane called pericardium.
• The pericardial fluid of the pericardium lubricates the heart.
• The heart is divided into four chambers — two upper atria and two lower ventricles.
• The inter-atrial septum separates the two atria and the inter-ventricular septum separates the two ventricles.
• The atrium and the ventricle of each side are separated by the atrioventricular septum.
• Superior and inferior vena cavae open into the right atrium.
• The right ventricle opens into the pulmonary artery.
• Four pulmonary veins open into the left atrium.
• The left ventricle opens into the aorta.
• The opening between the right atrium and right ventricle is guarded by the tricuspid valve.
• The opening between the left atrium and left ventricle is guarded by the bicuspid (mitral) valve.
• The opening of the right ventricle into the pulmonary artery and the opening of the left ventricle into the aorta is guarded by the semilunar valves.

• Two blood groupings are done
• ABO and
• Rh

ABO grouping

• ABO grouping is based on the presence or absence of two surface antigen on the RBCs namely A and B.
• The plasma of different individuals contains two natural antibodies.
• The distribution of antigens and antibodies in the four groups of blood, A, B, AB and O.
• The blood of a donor has to be carefully matched with the blood of a recipient before any blood transfusion to avoid severe problems of clumping, which leads to destruction of RBC.
• Group ‘O’ blood can be donated to persons with any other blood group and hence ‘O’ group individuals are called ‘universal donors’.
• Persons with ‘AB’ group can accept blood from persons with AB as well as the other groups of blood, and such persons are called ‘universal recipients’.

Rh grouping

• The Rh antigen similar to one present in Rhesus monkeys is also observed on the surface of RBCs of majority of humans, hence the antigen is known as Rh antigen.
• The individuals having Rh antigen are called Rh positive (Rh+ve) and those in whom this antigen is absent are called Rh negative (Rh-ve).
• An Rh-ve person, if exposed to Rh+ve blood, will form specific antibodies against the Rh antigens, and hence Rh group should also be matched before transfusions.
• A special case of Rh incompatibility has been observed between the Rh-ve blood of a pregnant mother with Rh+ve blood of the foetus , which leads to a disease known as erythroblastosis foetalis.
• Rh antigens of the foetus do not get exposed to the Rh-ve blood of the mother in the first pregnancy as the two bloods are well separated by the placenta, during the delivery of the first child, maternal blood may get exposed to small amounts of the Rh+ve blood from the foetus and the mother starts preparing antibodies against Rh in her blood.
• In case of subsequent pregnancies, the Rh antibodies from the mother (Rh-ve) can leak into the blood of the foetus (Rh+ve) and destroy the foetal RBCs, which cause severe anaemia and jaundice to the baby leading to a condition known erythroblastosis foetalis.
• Erythroblastosis foetalis can be avoided by administering anti-Rh antibodies to the mother immediately after the delivery of the first child.

• Blood coagulation or clotting is the mechanism to prevent excessive loss of blood from the body.
• Reddish brown scum formed at the site of a cut is due to clot formed mainly of a network of threads called fibrins in which dead and damaged formed elements of blood are trapped.
• Fibrins are formed by the conversion of inactive fibrinogens in the plasma by the enzyme thrombin.
• Thrombins are formed from another inactive substance present in the plasma called prothrombin by an enzyme complex known as thrombokinase.
• Calcium ions play a very important role in clotting.

Blood is a fluid connective tissue that consists of plasma, blood cells and platelets. It circulates throughout our body delivering oxygen and nutrients to various cells and tissues. It makes up 8% of our body weight. An average adult possesses around 5-6 litres of blood.

Plasma

The liquid state of blood can be contributed to plasma as it makes up  ~55% of blood. It is pale yellow in colour and when separated, it consists of salts, nutrients, water and enzymes. Blood plasma also contains important proteins and other components necessary for overall health. Hence, blood plasma transfusions are given to patients with liver failure and life-threatening injuries.

Red Blood Cells (RBC)

Red blood cells consist of Haemoglobin, a protein. They are produced by the bone marrow to primarily carry oxygen to the body and carbon dioxide away from it.

White Blood Cells (WBC)

White blood cells are responsible for fighting foreign pathogens (such as bacteria, viruses, fungi) that enter our body. They circulate throughout our body and originate from the bone marrow.

Platelets

Tiny disc-shaped cells that help regulate blood flow when any part of the body is damaged, thereby aiding in fast recovery through clotting of blood.

The Virashaiva movement began in Karnataka in the mid-twelfth century. It was initiated by Basavanna and his companions like Allama Prabhu and Akkamahadevi. This movement strongly argued for the equality of all human beings, It was against Brahmanical ideas about caste and the treatment of women.