Blood vessels 1 Blood vessels

What you will learn about Blood vessels 2 What you will learn about in this topic: What blood vessels are and what they do Arteries Veins Capillaries

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

Blood vessels 4 Task 1 Starting and finishing with the right ventricle, put the following in the correct order to describe blood flow around the body: 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 Blood vessels 5 Task 1 answers Right ventricle Pulmonary artery The lungs Pulmonary vein Left atrium Left ventricle Aorta The body Vena cava Right atrium

Recap of the heart: Blood vessels 6 Aorta Superior vena cava Pulmonary artery Pulmonary veins Left atrium Semi-lunar valve Right atrium Mitral value Tricuspid value Septum Left ventricle Right ventricle

Recap of the circulatory system: Blood vessels 7 Recap of the circulatory system:

The blood vessels There are three main types of blood vessel: Arteries Veins Capillaries

Blood vessels 9 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.

Blood vessels 10 An artery:

Blood vessels 11 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.

Blood vessels 12 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).

Blood vessels 13 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).

Blood vessels 14 A vein:

Blood vessels 15 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).

Veins eventually split into venules and then into capillaries. Blood vessels 16 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.

Blood vessels 17 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.

Blood vessels 18

Blood vessels 19 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.

There are over 100,000 km of capillaries in the body. Blood vessels 20 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.

Blood vessels 21 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. Teacher’s notes Similarities – they both carry blood. Differences – arteries are less elastic than veins. The walls of the arteries are thick and the capillaries are thin, sometimes only one cell thick. Arteries rely on pressure from the heart’s pump action to pump blood, veins use gravity and valves to move the blood through them.

Blood vessels 22 Effects of inactivity Oxygen is not exchanged as easily between muscles during inactivity due to the cooler blood vessel and blood temperature. Source: New England journal of Medicine 22

Blood vessels 23 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.

Effects of exercise on blood vessels When blood in the veins flows close to the working muscles, the ‘skeletal pump’ effect helps move blood around the body. 24

An increase in blood temperature helps blood to flow better. Blood vessels 25 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.

Exam questions 1. Which of the following best describes a vein? Blood vessels 26 Exam questions 1. Which of the following best describes a vein? Works at lower pressure than other blood vessels, has semi-permeable walls Has valves, works under high pressure, transports oxygenated blood Walls are thin, has valves, works at a low pressure, transports deoxygenated blood Transports deoxygenated blood, divides into arterioles, walls are one cell thick Teacher’s notes Correct answer is 1C.

What you have learnt in this topic: Blood vessels 27 What you have learnt in this topic: What blood vessels are and what they do Arteries Veins Capillaries

Learning objectives You should now be able to: Blood vessels 28 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