UNIT 4 - HUMAN HEART
The human heart is an organ that pumps blood throughout the body via the circulatory system, supplying oxygen and nutrients to the tissues and removing carbon dioxide and other wastes. It is located in the centerof the chest, usually pointing slightly left. The tissues of the body need a constant supply of nutrition in order to be active. If the heart is not able to supply blood to the organs and tissues, they will die. It is generally observed that if heart is taken out of the body, it still keeps on beating. This indicates that it has its own generating system and rhythm.The human heart has four chambers. The different parts of human heart are shown in the diagram.
The outer wall of the heart consists of three layers – the outermost wall (epicardium), the middle layer (myocardium), the inner wall (endocardium). The tricuspid valve and the mitral valve make up the atrioventricular (AV) valves, which connect the atria and the ventricles. Valves prevent back flow keeping the blood flowing in one direction through the heart. The pulmonary semi-lunar valve separates the right ventricle from the pulmonary artery and the aortic valves separates the left ventricle from the aorta. The heart circulates blood through two pathways: the pulmonary circuit (deoxygenated blood) and the systemic circuit (oxygenated blood). Blockage of any of the arteries can cause heart attack or damage to the muscle of the heart. The heart contains electrical pacemaker cells which cause it to contract producing a heartbeat. The heart rate is the number of times the heart beats per minute.
Q1. Under what condition, pacemaker is implanted and why?
Q 2. How many chambers are present in the heart of a frog?
(a) 2 chambers (b) 3 chambers (c) 4 chambers (d) 5 chambers
Q 3. Which of the following has thickest walls?
(a) Right ventricle (b) Left ventricle (c) Right atrium (d) Left atrium
Q 4. Encircle Yes or No for each statement -
(a)The blood vessels that carry blood to and from the body tissues form the pulmonary circulation. Yes/ No
(b) The myocardium is the thickest layer in the walls of the heart. Yes/No
Q 5.How many valves are there in the heart? Name them:
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Answer:
Q.2.
(b) three
Q.3.
(b) left ventricle
Q.4.(a) yes
(b) yes
Q.5.There are four valves in heart
(1) Tricuspid valve
(2) pulmonary valve
(3) mitral valve
(4) aortic valve.
Explanation:
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