3
3.2 Listening
male and female. There are other systems that you may be less familiar with, too: the endocrine system, which is responsible for the production of hormones to regulate the body; the lymphatic and immune system, which creates cells to fight against disease; and the integumentary system, which is the skin and structures derived from it. Those, then, are the 11 systems I referred to at the start of the lecture. Now to the skeletal system. Most of you will be
familiar with the arrangement of bones within the human skeleton. Believe it or not, bone is a living tissue which is constantly being renewed and reshaped, with new bone being built up while old bone is broken down. The structure of bone is made up of around 25% water, 25% collagen and 50% crystallized mineral salts. The mineral salts give bone its hardness, and the collagen fibres give it flexibility. Bones can be divided into four types. Short bones
are nearly equal in length and width. Most ankle and wrist bones are short bones. Long bones have a greater length than their width. They include those in the thigh, leg and arm. Flat bones are thin in shape, and these include the breastbone, ribs and shoulder blades. Irregular bones have shapes which do not fall into the other categories and include bones in the face and the vertebrae of the backbone.
D Set for individual work and pairwork checking.
17
Play Part 3. Tell students to take notes. Allow students to compare their features. Don’t confi rm the answers at this stage.
Answers
1. Elicit various options and accept any reasonable methods of note-taking.
Explain that a table can be a useful way to write notes in this context.
2. Elicit key points from the students, and build up the table below, sharing it visually.
17 Part 3
The cardiovascular system is made up of three components: blood, the heart and the blood vessels. The function of the system is to transport blood throughout the body, with the heart acting as the pump for circulation. Blood is essential for the functioning of the body. It
transports oxygen from the lungs to the cells throughout the body and takes carbon dioxide from the cells to the lungs. It also carries nutrients and hormones. Blood is also important in regulating body temperature. Blood is made up of plasma, red and white blood cells, and platelets. Red blood cells are responsible for transporting the oxygen from the lungs to cells throughout the body. There are about 250 million red blood cells in a drop of blood. White blood cells protect the body against disease, forming a first line of defence against infection. The ratio of red blood cells to white blood cells is around 700 to 1. Platelets are the component of blood which helps to stop bleeding when blood vessels are damaged. There are between 500,000 and 2 million platelets in each drop of blood. The heart is the mechanism by which the blood is
pumped through the body. It beats about 100,000 times each day, pumping more than 14,000 litres of blood. The left side of the heart pumps blood through the blood vessels. The right side pumps blood through the lungs to collect oxygen and discharge carbon dioxide. As you can see from Slide 4, the heart is composed of four chambers: the right and left atria and the left and right ventricles.
56
blood
essential for functioning of body
transports oxygen from lungs to cells and carbon dioxide from cells to lungs regulates body temperature
made up of: • plasma • red blood cells – transport oxygen • white blood cells – protect against disease • platelets – stop bleeding
heart
pumps 14,000 litres of blood round body per day
left side: pumps blood through blood vessels
right side: pumps blood to lungs composed of four chambers has its own blood supply
blood vessels
three types: • arteries – carry blood to tissues
• capillaries – arteries divide into capillaries, they allow exchange of nutrients and body waste between cells and blood
• veins – transport blood back to the heart
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