Heart & Circulatory System

Quick revise

The heart is a four-chambered muscular pump which pumps blood round the circulatory system.

The right side of the heart pumps de-oxygenated blood to the lungs to pick up oxygen.

The left side of the heart pumps the oxygenated blood from the lungs around the rest of the body.

Circulatory System

  • 1. Deoxygenated blood enters through the vena cava into the right atrium
  • 2. It’s then pumped through a valve into the right ventricle chamber
  • 3. And then up through the pulmonary valve into the pulmonary artery towards the lungs
  • 4. Oxygenated blood enters through the pulmonary veins into the left atrium
  • 5. It’s then pumped through a valve into the left ventricle
  • 6. And then through the aortic valve and out of the aorta to the rest of the body

This video explains how the heart works

How the Blood is transported

Blood Transport

Arteries (thick walled muscular tubes) carry blood away from the heart at high pressure in thick walled lumen

Capillaries (very narrow tubes) have thin walls to allow glucose and oxygen to diffuse through

Veins (thin walled tubes) carry low pressure blood back to the heart. Veins have thinner walls and valves to prevent backflow of blood

This video overviews the heart and explains how blood is transported around the body

Heart Disease

Blood vessels called the coronary arteries supply blood to the heart muscles. If they become blocked, a heart attack can happen.

A heart attack can happen after a sequence of events,

  1. fatty deposits build up in the coronary arteries
  2. a blood clot can form on a fatty deposit
  3. the blood clot can block a coronary artery
  4. some heart muscle cells do not get the oxygen and nutrients they need
  5. these cells start to die.

In the UK about 300,000 people have a heart attack every year.

Factors for Heart Disease

The risk of developing heart disease is increased by several factors, including:

  • smoking
  • high blood pressure
  • high levels of salt in the diet
  • high levels of saturated fat in the diet.

High levels of salt in the diet can lead to increased blood pressure. High levels of saturated fats in the diet lead to a build of cholesterol in the arteries, causing a plaque and narrowing of the arteries.

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