a Healthy CIrCulatORy SYStEM

Refresh What happens when you cut your skin?

21 The circulatory system

The circulatory system is a network of blood vessels filled with blood pumped by the heart. It moves nutrients, water and oxygen around the body to all the cells, tissues and organs. It also transports waste. There are two circuits that blood follows in the circulatory system. The pulmonary circuit starts at the heart. (1) Blood high in carbon dioxide and waste substances is pumped from the heart to the lungs. In the capillaries in the alveoli, it deposits carbon dioxide and collects oxygen.

(2) Oxygenated blood travels back to the heart. It is pumped into the systemic circuit.

(3) It goes to the organs, tissues and cells in the body through arteries and capillaries. (4) Blood delivers oxygen and collects carbon dioxide and returns to the heart through veins.

Veins carry deoxygenated blood back to the heart. Capillaries exchange substances between the cells and the blood.

Heart Arteries transport oxygenated blood to the rest of the body.

• Draw the circulatory system on a piece of card. Use bottle lids, containers, pipe cleaners and strings to recreate the journey that blood makes.

The heart

The heart is a muscle and pumps blood around our body. The heart contracts and, as the blood moves, it produces a beat. This is your heartbeat, or pulse.

Each heartbeat involves two movements: diastole and systole. In diastole, the heart fills with blood. In systole, the heart contracts and blood leaves the heart.

The blood

Blood is the fluid that circulates around the body through the blood vessels. It collects oxygen and nutrients and transports them to all the cells in the body and it removes carbon dioxide and waste substances.

Blood has got plasma, a liquid made of water and other substances, such as salts, nutrients and cellular waste. It has got three types of cells: red blood cells, white blood cells and platelets.

1 Answer the questions in your notebook.

a) What is the heartbeat?

b) What happens during diastole?

c) What happens during systole?

d) What is plasma?

• Press two fingers to the side of your neck or your wrist to find your pulse. For 15 seconds, count how many times your heart beats. Now do twenty jumping jacks and count your heart beats again. Do you notice anything different?

Refresh How does your body eliminate waste?

23 The excretory system and the urinary system

Excretion is the process of eliminating waste from our body. Waste is all the substances that our body does not need and that can be harmful for our health if they accumulate inside the body.

The excretory system is formed by the urinary system and the sweat glands. The urinary system consists of the following organs: a) This is where urine is kept until it leaves the body. b) This organ extracts waste from the blood. c) This is the tube that takes urine outside the body. d) This tube connects the kidneys to the bladder.

• Kidneys: there are two kidneys. They have got an outer layer that filters blood plasma. They are formed by tubes that extract waste from the blood and turn it into urine.

• Ureters: are tubes that connect the kidneys to the bladder. They are made of muscle tissue that contracts to move the urine along.

• Bladder: this is an organ that stores the urine until it is expelled. It sends a signal to the nervous system when it is full.

• Urethra: the tube that connects the bladder with outside the body so that urine can be released.

1 Write the correct organ for each definition.

• Create Make a mockup of the urinary system using recycled materials. Label its parts.

The sweat glands

The skin contains sweat glands, which are organs that produce a waste substance called sweat. These glands are all over the skin, but they are more abundant in some areas, such as the palms of the hands, under the arms, the groin and the face.

The main purpose of sweat is to help regulate our body temperature. However, it also plays a role in excretion.

Blood capillaries take blood to the sweat glands, where waste and water are extracted. The combination of these two substances in the glands makes sweat. Filtered blood returns to the blood capillaries and sweat leaves our bodies through the pores in the skin.

Blood vessels a) Lungs c) Bladder e) Alveoli b) Intestine d) Skin f) Kidneys

2 What role do sweat glands play in excretion?

3 Discuss how kidneys and sweat glands perform their function. Are they similar or different? Why?

4 Find and write the function of these organs in the process of excretion.

1 thInk!

Malnutrition is one of the biggest problems in the world. Look at the following picture. Does it show a child with signs of malnutrition? Discuss with a classmate.

2 Read the following definitions of malnutrition according to the WHO (World Health Organisation). Use them to write your own definition of what malnutrition is.

Malnutrition refers to deficiencies or excesses in nutrient intake or imbalance of essential nutrients and energy.

Malnutrition means ‘poor nutrition’ and can refer to undernutrition (not getting enough nutrients) and overnutrition (getting more nutrients than needed).

Malnutrition comes from a deficiency or excess in the intake of calories and nutrients or when these nutrients are of bad quality and rich in fats and sugars.

3 a) Heart disease b) A lack of energy c) A headache d) Type 2 diabetes e) Anaemia f) The flu g) Eye infections aCt!

In small groups analyse the malnutrition definitions that you wrote. What conclusions can you make? Talk and share your ideas with the rest of the class.

4 The problem with malnutrition is the consequences it has got on people’s health. Look at the list of health problems and do some research to find out which ones are directly caused by a bad diet.

5 Your class is going to organise a campaign to promote the importance of a healthy diet containing the right amount of nutrients in young children. What do you need to consider? Look at the list, choose and add what you think is important.

• Type of shop

• Where they live

• Quality of nutrients

• Food wheel

Year 6 will create healthy meals for Year 1. There is a prize for the emptiest plates at the end!

We will never get year 1 to eat a full plate of fruit or vegetables.

Look what I’ve got! Rainbow kebabs! Strawberry, orange, pineapple, kiwi, blueberry and grape!

All your plates are empty! How did you do it?

That’s cheating!

Only a little. Who wants one?

Who wants to try my game? Guess the vegetable while wearing a blindfold!

Easy. I promised them a desert if they ate their vegetables.

1 Why do you think the students are worried about getting year 1 to eat a plate of fruit or vegetables?

2 Why is the first snack called ‘rainbow kebabs’?

3 Which body part and which sense do the children use to guess the fruit or vegetable?