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Summary The Heart, Lungs and the Circulatory System

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Module
Science

Institution
GCSE

A summary on the functions of the circulatory system and your heart and lungs with habits that pose dangers to them and how they work. It also has a few study tips to help you study.

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Uploaded on August 10, 2023
Number of pages 7
Written in 2023/2024
Type Summary

Institution GCSE
Education GCSE
Module Science
School year 1

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The Heart, Lungs and the Circulatory System

GCSE Biology: Study Guide - The Heart

1. Overview of the Heart:

● The heart is a muscular organ responsible for pumping blood throughout the
body.
● It is located slightly left of the centre of the chest and is protected by the
ribcage.

2. Structure of the Heart:

a. Chambers of the Heart: - The heart has four chambers: two atria (upper
chambers) and two ventricles (lower chambers). - The right atrium receives
deoxygenated blood from the body, while the left atrium receives oxygenated blood
from the lungs. - The right ventricle pumps deoxygenated blood to the lungs, and the
left ventricle pumps oxygenated blood to the rest of the body.

b. Valves of the Heart: - The heart has four valves: tricuspid valve (between right
atrium and right ventricle), pulmonary valve (between right ventricle and pulmonary
artery), mitral (bicuspid) valve (between left atrium and left ventricle), and aortic
valve (between left ventricle and aorta). - Valves prevent the backflow of blood and
ensure unidirectional blood flow.

3. Circulation of Blood:

a. Pulmonary Circulation: - Deoxygenated blood from the body enters the right
atrium and then passes through the tricuspid valve into the right ventricle. - The right
ventricle pumps blood through the pulmonary valve into the pulmonary artery, which
carries blood to the lungs. - In the lungs, blood picks up oxygen and releases carbon
dioxide. Oxygenated blood returns to the heart through the pulmonary veins, entering
the left atrium.

b. Systemic Circulation: - Oxygenated blood from the left atrium passes through the
mitral valve into the left ventricle. - The left ventricle pumps blood through the aortic
valve into the aorta, which distributes oxygenated blood to the rest of the body. -
Deoxygenated blood returns to the heart through the superior and inferior vena cava,
entering the right atrium.

, 4. Cardiac Cycle:

● The cardiac cycle consists of systole (contraction) and diastole (relaxation) of
the heart chambers.
● Systole: Ventricles contract, pushing blood into the pulmonary artery and
aorta. Atria relaxes.
● Diastole: Atria contract, filling the ventricles with blood. Ventricles relax.

5. Heartbeat and Electrical Conduction:

● The heartbeat is controlled by electrical signals generated by the sinoatrial
(SA) node, the natural pacemaker of the heart.
● The electrical signals spread through the atria, causing them to contract. The
signals then pass through the atrioventricular (AV) node and bundle of His,
reaching the ventricles and causing them to contract.

6. Factors Affecting Heart Health:

a. Diet and Lifestyle: - A balanced diet and regular exercise support heart health. -
Avoiding excessive intake of saturated fats, salt, and sugar can reduce the risk of
heart disease.

b. Smoking and Alcohol: - Smoking damages blood vessels and increases the risk of
heart disease. - Excessive alcohol consumption can also contribute to heart
problems.

c. Hypertension (High Blood Pressure) and Stress: - High blood pressure can strain
the heart and increase the risk of heart disease. - Chronic stress can impact heart
health.

7. Common Heart Disorders: a. Coronary Artery Disease (CAD):

- Narrowing of coronary arteries due to plaque buildup, leading to reduced blood flow
to the heart muscle. b. Heart Attack (Myocardial Infarction): - Blockage of blood flow
to a portion of the heart muscle, leading to tissue damage.

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