1.Circulatory system: functions and elements. The functions of the circulatory system are:

1. to provide body tissues with oxygenated blood and nutrients. 2. to remove waste products and carbon dioxide. 3. to distribute heat.

The endocrine system, which secretes hormones directly into the circulation, and the immune system, which defends the body against disease, use the blood as their means of transportation. The blood circulatory system consists of blood vessels (arteries, veins and capillar-ies) and the heart. The arteries are tubes with thick, elastic, muscular walls. They branch along their length, becoming thinner and narrower as they subdivide, and finally becoming capillaries, which are very small. Capillaries run through the tis-sues and then join up to form the smallest veins. These combine into larger veins, which have valves to control the direction of flow. The largest veins empty into the heart, a muscular bag with four chambers that pumps blood into the arteries with each beat. Exercise 1.

1. Explain in a short sentence the main function of the circulatory system. 2. What type of substances are transported by the circulatory system? 3. What other body systems do you think are connected with the circulatory

system? 4. What organs make up the circulatory system?

How well proceed:

2.Heart. The heart is the only muscular organ that never stops working. It is divided into four parts called chambers. The two upper chambers are called atria. They are joined to two lower chambers, called ventricles. The valves between the chambers keep the blood flowing in the right direction. The valves have flaps called cusps. As blood flows through the valves, it forces cusps to open. They then shut, to stop blood from flowing back. Thus, the blood always moves from the atria to the ventricles. There are valves between the ventricles and the arter-ies that keep the blood always moving from ventricles to arteries.

Activity: Lets make a heart. You need for this activity:

Red pencil (it represents oxygenated blood) Blue pencil (it represents non-oxygenated blood) Yellow pencil (for the valves) Glue Scissors A photocopy of the next page A sheet of paper of your notebook

Step 1 Colour the white spaces on the right side of the heart in blue and the white spaces on the left side of the heart in red. Cut out the heart and add glue all over the back and stick it in the middle of a page of your notebook. Step 2 Colour parts 2 and 3 red. Cut out and glue only a small part of the back of the ar-rowed ends and stick on top of the appropriate numbers. Part 2 brings oxygenated blood from the lungs to the heart and part 3 is carrying oxygenated blood from the heart to the body. Step 3 Colour parts 4, 5 and 6 blue. Cut out and glue only a small part at the back of the arrowed ends and stick over the appropriate numbers. Parts 4 and 5 are bringing the used blood to the lungs from the body and part 6 takes the used blood to the lungs to be re-supplied with oxygen. Notice blood on the left side of the heart does not mix with blood from the right side. Step 4 Colour parts 7 and 8 yellow. Cut them out and then cut along the dotted lines. Paste the arrowed edges and stick on to the cut along the line with the appropriate number. Try to stick these valves so that they can open and close. Part 9 Cut around the shape of the heart and sticking tab and fix so that the heart is com-pletely covered. Finally, label the following in the diagram:

Right atrium Left atrium Left ventricle Pulmonary vein Right ventricle Vena cava Aorta Tricuspid valve Pulmonary artery Mitral valve

Exercise 2. Complete the following diagram, that shows the structure of the heart, with the words in the box. Left atrium Aorta Vena cava Pulmonary artery

Right ventricle Pulmonary veins Left ventricle Right atrium

Identify the three types of valves in the right side of the heart above: 1. Tricuspid valve is between right atrium and right ventricle. 2. Mitral valve is between left atrium and left ventricle. 3. Semilunar valves are between ventricles and arteries.

Exercise 3. Show with arrows the direction in which blood moves into the heart. Use red arrows for oxygenated blood and blue ones for non-oxygenated blood. Exercise 4. Copy and complete the following paragraphs using the words below- you can use some words more than once. _______________ blood from the body travels to the heart in the _________________. The blood enters the right ________ and then flows into the right ________ through the open ________ valve. The ____________ valve opens and blood is forced out of the heart. The blood flows along the pulmonary __________ to the lungs where it gets rid of ____________________ and picks up oxygen. The __________ blood from the lungs returns to the heart in the pulmonary ____________.

Vena cava Semilunar Ventricle Atrium Deoxygenated Tricuspid

Artery Oxygenated Veins Carbon dioxide

The blood enters the ____________ atrium and then flows down into the ____________ ventricle through the open ____________ valve. The very muscular ____________ ventricle contracts, the ____________ valve closes, the ____________ valve opens and blood is forced out of the heart. The blood leaves at high pressure in the biggest artery called the ____________ and is pumped all around the body.

Aorta Left Mitral Semilunar

3.Blood vessels. We have a closed circulatory system, that is, the blood flows around the body to all cells through blood vessels. These blood vessels are the arteries, the veins and the capillaries. The following diagrams show the cross sections of these blood ves-sels. Notice the differences between them. These differences are related to their jobs. Pay particular attention to the artery and vein. Both possess the same three layers, but the relative thickness of the layers is different. In addition, the veins have valves along their length that arteries dont. Exercise 5.

1. Define the three types of blood vessels including their functions. a. Arteries are blood vessels that transport __________ from the ________

to the ________ . b. Veins are blood vessels that ____________________________________ c. Capillaries __________________________________________________

2. Whats the reason for the veins possessing valves? 3. Why is the wall of the capillaries very thin and permeable? 4. Explain what happens if you cut an artery, a vein or a capillary.

5. Look at the photograph of a transverse section through an artery and a vein and identify which is the vein and which is the artery. Explain your choice. 6. Label the diagram. Give two differences in the composition of blood at A and C.

4.Blood circulation. We have a double circulatory apparatus. It means that blood passes through the heart twice during one complete circulation of the body. First, blood is pumped from the right side of the heart through the pulmonary ar-tery to the lungs, where it picks up fresh oxygen and releases carbon dioxide. Then it returns to the left side of the heart through the pulmonary veins. This part is known as pulmonary circulation. Then, blood is pumped from the left side of the heart through the aorta to the rest of the body to carry the oxygen. In the way to the organs blood releases oxygen and nutritional substances and collects the carbon dioxide and other waste prod-ucts. Finally, the blood returns to the right side of the heart through the two vena cava to begin the cycle again. This part is known as systemic circulation.

Exercise 6. 1. Why do you think the wall of the left ventricle is thicker than the wall of

the right ventricle? 2. Why do scientists say the heart is a double pump? 3. Is it correct to define the arteries as blood vessels that transport oxygen-

rich blood? Explain your answer.

5.Blood. As well as carrying substances around the body, blood helps to kill germs, heal wounds and control body temperature. Blood is made of three types of cells floating in a liquid called plasma. The average adult has about 5-6 litres of blood. Plasma: This is a pale yellow liquid in which the cells float. It dissolves and

transports carbon dioxide, waste products, digested food and hormones. It is 55% of blood composition.

Red blood cells: They are disc-shaped cells which contain a red pigment called

haemoglobin. They combine with oxygen to form oxyhaemoglobin which car-ries oxygen from the lungs to the cells. Red blood cells are very numerous and they represent 45.55% of blood composition. They are produced in the bone marrow at a rate of two million per second.

White blood cells: They are larger than red ones. They fight against germs that enter the blood. There are different types of white blood cells. As red ones they are produced in the bone marrow.

Platelets: They are tiny fragments of giant cells located in the bone marrow.

They help to stop the bleeding if a blood vessel is cut.

Exercise 7. Complete the table.

Exercise 8. Identify the three types of blood cells in the following photomicrograph.

Blood component Function

Plasma

Red blood cells

White blood cells

Platelets

Final task. Work in groups and make a PowerPoint presentation about the most important cir-culatory diseases. Include the cause, organs that are affected, main symptoms and healthy habits to prevent them. Here is a list of the most important circulatory diseases:

Anaemia Arteriosclerosis / Hypercholesterolemia Haemophilia Coronary heart disease (angina) / Heart attack Aneurysm Arrhythmia Hypertension Thrombosis Phlebitis

Glossary Aorta: the main artery of the body. Artery: blood vessel that carries the blood from the heart to the organs. Beat: every contraction and relaxation of the heart. Bleed: to lose blood. Blood: the red liquid that is sent around the body by the heart. Blood vessel: any of the tubes through which blood flows in the body. Bone marrow: soft tissue containing a lot of fat in the centre of a bone. Capillary: a very thin blood vessel that connects arteries and veins. Cross section: something that has been cut in half so that you can see inside. Cusp: a sharp point or apex. Deoxygenated: without oxygen. Disease: an illness caused by infection or a failure of health. Flap: a piece of tissue partly separated from the surrounding tissue. Flow: to move in one direction (gases, liquids or electricity). Germ: a very small organism that causes disease. Haemoglobin: a substance in red blood cells which combines with and car-

ries oxygen around the body, and gives blood its red colour. Heart: the organ that sends the blood around the body. Heat: the quality of being hot or warm. Means of transportation: a vehicle, such as buses or trains, for getting from

one place to another. Notice: to see something or someone.

Oxygenated: with oxygen. Pigment: a substance that gives something a particular colour. Plasma: the liquid part of the blood. Platelet: a very small cell in the blood that stops bleeding caused by an injury. Pressure: the force applied to a unit area of surface. Provide: to give someone something that they need. Pump: to cause liquids or gases to move from one place to another. Red blood cell: any of the cells that carry oxygen around the body. Remove: to take someone or something away from somewhere. Secrete: to produce and release a liquid. Thin / narrow: much longer than wider. Tissue: a group of connected cells in an animal or plant that are similar and

have the same function. Valve: a structure which opens and closes to control the flow of liquids or gas-

es. Vein: blood vessel that carries the blood from the body to the heart. Vena cava: one of the two very large veins through which blood returns to the

heart. White blood cell: a cell in the blood that fights against infection.

Manuel Jess Rosa Rasco IES RAFAEL REYES

CARTAYA (HUELVA)