© Folens 2009 FOR EDEXCEL 1.2.2 A healthy, active lifestyle and your cardiovascular system Blood...

© Folens 2009FOR EDEXCEL 1.2.2 A healthy, active lifestyle and your cardiovascular system

Blood vessels 1

Blood vessels


What you will learn about in this topic:

1. What blood vessels are and what they do

2. Arteries

3. Veins

4. Capillaries

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Blood vessels 3

Learning objectives

By the end of this presentation you should be able to:

•Understand the different types of blood vessel

•Describe how blood vessels work

•Explain the effects of exercise and inactivity on blood vessels


Task 1

Starting and finishing with the right ventricle, put the following in the correct order to describe blood flow around the body:

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• Left ventricle

• Right atrium

• Aorta

• Pulmonary vein

• Pulmonary artery

• Vena cava

• The lungs

• The body

• Left atrium


Task 1 answers

Right ventricle

• Pulmonary artery

• The lungs

• Pulmonary vein

• Left atrium

• Left ventricle

• Aorta

• The body

• Vena cava

• Right atrium

Right ventricle

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Superior vena cava

Right atrium

Tricuspid value

Septum

Right ventricle

Aorta

Pulmonary artery

Pulmonary veins

Left atrium

Semi-lunar valve

Mitral value

Left ventricle

Recap of the heart:


Recap of the circulatory system:

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The blood vessels

There are three main types of blood vessel:

• Arteries

• Veins

• Capillaries

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Arteries

Arteries carry oxygenated blood from the heart to the rest of the body (apart from the pulmonary artery where deoxygenated blood goes to the lungs).

The longest artery in the body is the aorta.

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An artery:


Smaller arteries branch off the aorta, they then divide into smaller arterioles and then into even smaller capillaries.

The outer layer of an artery is tough and fibrous, the inner liner is elastic. The blood stretches the walls, the walls contract and force the blood along.

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Arteries have small passageways for blood (internal lumen – the open space inside a blood vessel that blood travels through).

Blood in the arteries is bright red due to the presence of oxygen (apart from in the pulmonary artery).

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Veins

Veins carry deoxygenated blood from the body to the lungs (apart from the pulmonary veins where oxygenated blood travels from the lungs to the heart).

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A vein:

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Veins have a large lumen and the blood flows slower, at a lower pressure. Veins have much thinner walls than arteries.

Blood in the veins is dark red due to the presence of carbon dioxide and the lack of oxygen (apart from in the pulmonary veins).

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Veins contain valves to stop the blood from flowing backwards and pooling, avoiding problems like varicose veins.

Veins eventually split into venules and then into capillaries.

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Capillaries

Capillaries are microscopic blood vessels, much thinner than a human hair; most let only a single blood cell through at a time.

They are found in the muscles and lungs.

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Gas exchange takes place through the walls of the capillaries. Oxygen and nutrients are passed into tissues and carbon dioxide and waste products pass from the tissues into the blood.

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At the end of the capillaries blood flows back into veins and returns to the heart via the vena cava at a very low pressure.

There are over 100,000 km of capillaries in the body.

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Task 2

List as many differences and similarities between arteries, veins and capillaries as you can.

For example, the arteries carry oxygenated blood as do the veins whereas the capillaries carry both oxygenated and deoxygenated blood.

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Effects of inactivity

Oxygen is not exchanged as easily between muscles during inactivity due to the cooler blood vessel and blood temperature.

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Inactivity can lead to storing energy around the body as fat. Storing fat, like cholesterol, in the blood vessels reduces the space for the blood to flow through them, which raises blood pressure.

This can put great stress on the heart and blood vessels and can lead to problems such as a heart attack.

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Effects of exercise onblood vessels

When blood in the veins flows close to the working muscles, the ‘skeletal pump’ effect helps move blood around the body.

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The blood vessels increase in size to allow more blood to flow to the working muscles.

An increase in blood temperature helps blood to flow better.

Oxygen is exchanged with the muscles more easily when blood is warm.

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Exam questions1. Which of the following best describes a vein?A. Works at lower pressure than other blood

vessels, has semi-permeable walls

B. Has valves, works under high pressure, transports oxygenated blood

C. Walls are thin, has valves, works at a low pressure, transports deoxygenated blood

D. Transports deoxygenated blood, divides into arterioles, walls are one cell thick


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What you have learntin this topic:

1. What blood vessels are and what they do

2. Arteries

3. Veins

4. Capillaries


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Learning objectives

You should now be able to:

•Understand the different types of blood vessel

•Describe how blood vessels work

•Explain the effects of exercise and inactivity on blood vessels

© Folens 2009 FOR EDEXCEL 1.2.2 A healthy, active lifestyle and your cardiovascular system Blood...

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