AP Inter 2nd Year Zoology Notes Chapter 2(a) Body Fluids and Circulation

Students can go through AP Inter 2nd Year Zoology Notes Lesson 2(a) Body Fluids and Circulation will help students in revising the entire concepts quickly.

AP Inter 2nd Year Zoology Notes Lesson 2(a) Body Fluids and Circulation

→ The circulatory system is an organ system that passes nutrients, gases, hormones etc., to and from cells in the body to supply nutrients, fight against diseases, stabilize body temperature and pH and to maintain homeostasis.

→ The human cardiovascular system is described as a closed, two cycle system namely pulmonary and systemic circulation system.

→ In pulmonary circulation deoxygenated blood Is pumped away from the heart via pulmonary artery to the lungs and returned, Oxygenated blood to the heat via the pulmonary vein.

→ In systemic circulation oxygenated blood pumped away from the heart to the rest of the body and returns deoxygenated blood back to the heart.

→ Blood is the most commonly used circulatory fluid by most of the higher organisms, including the humans.

→ In addition to blood another fluid, lymph also helps in transport of certain substances.

AP Inter 2nd Year Zoology Notes Chapter 2(a) Body Fluids and Circulation Notes

→ Lymphatic system is an open circulatory system.

→ The thoracic duct of the lymphatic system is the largest lymphatic vessel.

→ Spleen is the largest lymphatic organ and it also acts as reservoir of RBC.

→ Spleen also acts as haemopoietic organ until the fifth month of the gestation.

→ Human heart has four chambers, with two smaller upper chambers called atria and two larger lower chambers called ventricles.

→ Atria are thin walled blood receiving chambers.

→ Ventricles are thick walled blood pumping chambers.

→ Sino atrial node (SAN) has the ability to generate other potential without any external stimuli, hence called pacemaker.

→ The cardiac cycle consists of three phases namely atrial systole, ventricular systole and cardiac diastole.

→ The human heart beats 72 times per minute normally. Hence the duration of a cardiac cycle is about 0.8 sec.

AP Inter 2nd Year Zoology Notes Chapter 2(a) Body Fluids and Circulation Notes

→ Each ventricle pumps out 5 litres of blood per minute.

→ Thyroxine, epinephrine and nor ephinephrine increases the heart rate and cardiac output.

→ The blood pressure at rest is 120 mm Hg (systolic)/ 80 mm Hg (diastolic).

→ High blood pressure leads to heart diseases and also affects vital organs such as the brain and kidneys.

→ Blood pressure 140/90 mm Hg is considered as hypertension.

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