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Learn about your Digestive System

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Presentation on theme: "Learn about your Digestive System"— Presentation transcript:

1 Learn about your Digestive System

2 The Digestive System Feeding is the process of introducing foodstuffs into your body. Nutrition is the transformation of food so it can be used by the body. The energy obtained from food is necessary for development, growth and activity. Nutrition is possible because of the joint action of the digestive, respiratory, circulatory and excretory systems.

3 How Digestion Begins As food passes through the digestive system, it is broken down into simple substances that our bodies are able to use. The digestive process starts in the mouth and is set in motion by the teeth, the tongue, and saliva. The sharp-edged teeth chop and tear the food, while the premolars and molars, which have flatter surfaces, grind it up. This is the process of mastication, or chewing. Incisor Canine Premolar Molar

4 The Tongue The tongue is the most muscular organ in the body. It can carry out any kind of movement. It pushes the food and places it between our teeth. The 1 to 2 litres of saliva secreted daily by the salivary glands helps to dissolve the food and make it easier to swallow. While the saliva lubricates the food, some of the special proteins it contains start to act on the starch.

5 Swallowing In the digestive process, there are two phases: the mechanical phase and the chemical phase. The mechanical phase is carried out in the mouth by the teeth and in digestive tract by the muscles that move the bolus of the food along. The chemical phase is the transformation carried out by the different digestive juices. The first of these to have affect is the saliva. Swallowing is a total mechanical process that consist of a series of movements which propel the bolus toward the stomach.

6 The Stomach The stomach has two muscles that control the food that enters it and that leaves it. The stomach is made up of three layers. The most important layer is the internal layer arranged in numerous folds which contains the glands that secrets gastric juices. The middle muscular layer of the stomach helps to breaks the food to a small mass.

7 The Small Intestine The small intestine is more than 20 feet (7 meters) long. It is divided into three parts. These are called the duodenum, the jejunum and the ileum. In the first part the duodenum secretions are produced by the liver and by the pancreas. Digestion occurs here. Next the food reaches the jejunum and the ileum, where the process of digestion ends. The food has now been broken down into small particles that are ready to pass into the bloodstream through small finger-like projections (called villi) which line the ileum.

8 The Large Intestine The waste products that have neither been digested nor absorbed make up the faeces. The function of the large intestine is basically to absorb water to maintain the consistency of the faeces. For the faeces to pass easily through the large intestine and out of the anus it is important to eat a lot of fibre. This helps the food move along the gut and adds bulk to the faeces. It prevents constipation and keep the colon (part of the large intestine) healthy.

9 The End This was done by Bernice Gauci and Vanessa Zerafa

10 Rebecca Bonnici & Donna Micallef
Monocots & dicots Rebecca Bonnici & Donna Micallef

11 Differences Between Monocots & Dicots
Embryo: Monocots have one cotyledon while Dicots have two cotyledons Leaf venation: Monocots have parallel veins while dicots have web-like veins Roots: Monocots have a fibrous root system while Dicots have taproots Stems: Monocots have vascular bundles scattered while dicots have vascular bundles in a ring Flowers: Monocots have floral parts usually in groups of three and dicots have floral parts usually in groups of four

12 Monocot Seedling Leaf Monocots: have only one seedling leaf (cotyledon) and usually have scattered vascular bundles, parallel veined leaves and flower parts in multiple of three.

13 Dicot Seedling Leaf The seed of a dicot has two halves. It has two cotyledons that are fleshy and has network of veins in leaves.

14 Dicot flower Dicots: have flowers in which the floral parts are in multiples of 4 or 5. The picture on the right shows a typical dicot floral structure with 5 petals and 4 anthers

15 Monocot flower If you count the number of petals, stamens or the other floral parts, you will find that monocot flowers have a number of parts that is divisible by three, usually three or six.

16 Monocot - root In the fibrous root system of monocots, the main root is almost non-existent. Many roots come out from the same point. These secondary roots are important in absorption but are not as deep as the primary root of most dicots.

17 Dicot - root The tap root system is deep with a long primary root. Less important secondary roots branch off.

18 Leaves of monocots This is a typical monocot leaf and it has parallel veins and the leaves are always straight, narrow and long. Examples of plants which are monocots include the Dwarf Fan Palm, Narcis, Daffodil and Ilsien in-nisa.

19 Leaves of dicots The leaves of dicots have network veins this means that they are spread out and the leaves are wide and broad. Examples of dicot plants are the Rose, Vine, Fig, Oak.

20 End

21 The Heart An important organ in your body

22 The Heart Your heart never rests. It started to beat before you were born and it will go on beating steadily throughout your life. Your heart is made of a special type of muscle called cardiac muscle and it gets bigger as you grow. It’s about the same size as your clenched fist, and weights about 250 grams. If you place your fist against the centre of your chest with your knuckles pointing to your left side, you will feel your heart beating about once every second. Surrounded by your lungs and protected by your rib cage, your heart works like a powerful pump, sending blood to every part of your body. Sometimes your heart changes its speed , by beating faster or slower depending on how much oxygen your body needs.

23 Inside your heart Your heart is divided into two halves which lie to the right and left of each other ,separated by a wall called the septum . Each half is made up of 2 parts: an upper chamber called the atrium and a lower chamber called the ventricle . The upper chambers fill with blood at the same time. Their thin muscular walls contract and squeeze blood into the lower chambers through valves which act like one-way doors, closing firmly once the blood has passed through them. When the ventricles are full of blood , they give a powerful squeeze and push blood into the arteries ,the strong tubes that carry blood away from the heart.

24 Have a look at your heart

Your heart is the centre of your body’s transport system , pumping blood to every part of your body , this is called circulation. There are 3 main parts to your circulation. 1) One circuit connects your heart to your lungs. 2) A second circuit collects blood from the abdomen area and carries it to the liver. 3) The third sends blood around the rest of your body again. The journey from the heart to the lungs and back again is called pulmonary circulation .

26 The Cardiac Cycle First of all , blood carrying carbon dioxide comes into the heart through the Vena Cava and collects in the right atrium. As the right atrium fills up with blood valves separating it from the right ventricle are closed. Then blood is squeezed into the right ventricle . The blood is then pumped to the lungs out of the Pulmonary Artery where through thousand of tiny air sacs, carbon dioxide is exchanged for a fresh supply of oxygen.

27 The oxygenated blood then flows back through the Pulmonary Vein to the left atrium of the heart. As the atrium fills up, valves are kept close. These then open when the blood is pushed into the left ventricle. Blood leaves the left side of the heart through the Aorta which pumps blood all over your body, delivering oxygen wherever it is needed . It picks up waste carbon dioxide and returns through veins to the right side of your heart to begin its journey all over again .

28 This is a photo showing the valves that stop blood from flowing backwards into the heart

29 This diagram shows how valves close when blood leaves the heart
This diagram shows how valves close when blood leaves the heart. These valves are called semi-lunar valves.

30 The right side of your heart sends deoxygenated blood (blood with carbon dioxide) back to your lungs, for a fresh supply of oxygen . This journey from the heart to the lungs is short so blood is pumped not under very high pressure. This gives time for gas exchange and also protects the delicate air sacs in the lungs. The left ventricle has to pump blood all round your body . To give it extra strength, its muscular walls are thicker than those of the right ventricle .

31 Heart disease Heart disease kills more people than any other type of illness. It’s worth looking for the reasons why because you can reduce the risk of heart disease . As you grow older, the elastic fibres in the arteries begin to lose their ability to expand and contract . Sometimes they become “clogged up” so that blood cannot flow as easily as it should. This blockages can lead to serious results . It’s certainly worth doing something positive to make sure that you avoid having problems with you heart . Life can be very hectic . People rush about getting tired and angry as they cope with over-crowded places or traffic jams . This leads to stress which, together with smoking and drinking , increase the risk of damage to your heart. Eating a lot of fatty food with cholesterol can also block your arteries and lead to heart disease. If you begin a healthy lifestyle when you’re young , you greatly improve your chances of having a fit and healthy heart .

32 THE END Leanne Mifsud

33 Vertebrates (animals with a backbone)
The Animal Kingdom Vertebrates (animals with a backbone) pppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppp

34 Vertebrates There are 5 classes of vertebrates: Mammals Reptiles
Amphibians Fish Birds

35 Fish Fish are cold blooded vertebrates, meaning they cannot control their body temperature internally but depend alot on the environment to get warmer or cooler. Their body is streamlined to swim faster. It is covered with scales. Their scales are continuously being replaced. Their fins help them move and they are made up of skin held by bony spines. They breathe through gills that are supplied with blood where oxygen comes in and carbon dioxide goes out. Nostrils are used for smelling.

36 Fish are divided into 2 groups Bony Fish
These fish have a skeleton made of bone and they breath through an operculum. They have a swimming bladder which helps them float even when they are not swimming. Their reproduction is external.

37 Cartillagenous Fish These fish have a skeleton made of cartilage. They breathe through 5 gills slits. These fish do not have a swimming bladder so they sink to the bottom if they stop swimming. Their reproduction is internal.

38 Mammals Mammals are warm blooded with four limbs and five digits.
The brain is better developed in mammals. They have sweat glands and a four chambered heart in between the lungs. They have lungs which are important for breathing. Mammals have a thick layer of fat to keep them warm and their bodies are covered with hair or fur. The tail is used for balance. Fertilization is internal and the young developed in the female’ s womb. The parents take great care of their young. They suckle their young on the milk from the mammary glands.

39 Reptiles These are cold blooded vertebrates but can control their temperature a bit by staying in the sun to get warm. They have tough skin and their body is covered in scales to resist water loss. They have well developed lungs and do not breathe through the skin. Fertilization occurs internal. Some reptiles keep the eggs inside them. Others lay legs and keep them well hidden. The eggs have a very tough shell that prevents water loss.

40 Amphibians These are cold blooded vertebrates and live in damp environments. Their skin is damp because gas exchange takes place through it. The adults also have lungs. They use their lungs for breathing. They have four limbs and their hind limbs are webbed and help in swimming. Their eyes bulge out to give them an all round vision. They lay soft eggs in water. Reproduction is external. They are carnivores.

41 Birds Birds are warm blooded vertebrates.
They have nostrils for breathing. They are covered with feathers which are used for flight and to keep warm. Birds have four limbs: the front limbs are the wings and the hind limbs are the legs and are covered in scales. The upper and lower jaw are developed into a beak. They have an ear drum but no external ear. Fertilization is internal and they lay eggs with hard shell.

42 Made by Audrienne Chetcuti

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