Page 408 - General Knowledge

GENERAL KNOWLEDGE 2019

 Air pressure in lungs decreases and rushes into the lungs.
 Expiration – Breathing out of air.
 Relaxion of muscles of ribs and diaphragm takes place.

 Diaphragm becomes dome-shaped.
 In humans, breathing rate is 18-20 breaths per minutes.
Anaerobic respiration
 Respiration takes place in the absence of oxygen.
 Found in endo-parasites like roundworm.
 Respiratory substances are incompletely oxidized.
Internal Respiration
 Food is broken down to release energy.
 Transportation of oxygen takes place.
 Transportation of 10-20% carbon dioxide takes place by haemoglobin of blood.
 400 ml water is lost through breathing every day.
Circulatory System
 Supplies useful material and removes waste from body cells.
 Consists of heart, blood vessels and blood.
Heart
 Thick, muscular, contractile, automatic pumping organ of blood vascular system.
 Auricles – Chamber which receives the blood from body tissues.
 Ventricles – Chambers of heart which pump blood to body tissues.

 Pericardium – Thin two layered sac around the heart.
 Filled with watery fluid called pericardial fluid.
 A new born baby‘s average heart weight is about 20 g.
 Average weight of heart in men – 280 – 340 g and women – 230- 280 g.
 The normal rate of heartbeat at rest is about 70-72 times per minute.
 For new born baby – heart beat rate – 130 times per minute.
Blood
 Fluid connective tissue is composed of blood corpuscles, plasma and platelets.
 Alkaline nature – pH 7.4
 Volume in an adult – 5.8 L
 Fibrinogen changes into fibrin by thrombin during blood clotting.
 Female haemoglobin level – 13.5 – 14.5 %

 Male haemoglobin level – 14.5 – 15.5 %
 Haemoglobin level is highest in the foetus.
Blood vessels
 Consists of three types.
 Arteries, Veins and Capillaries.
Arteries
 Thick walled blood vessels.
 Deep seated in the body, no valves in them.
 Carries oxygenated blood.
 Except the pulmonary artery, it carries deoxygenated blood.
 Blood flows at high pressure and high speed.

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