Digestion Slide Share Unit 1.1

DIGESTION

DIGESTION

• Your body is made up of trillions of tiny building blocks called cells. Cells need raw materials such as oxygen and food to work with. Your body is organised in a way that makes sure that the cells are supplied with the raw materials they need.
• In our body there are different levels of organisations.
• Cells of the same type that carry out the same job in the body are grouped together to form tissues such as muscles and nerves.
• At the next level of organisation, tissues are grouped to form organs, such as the stomach or brain.
• An organ is a structure that contains at least two different types of tissue that work together to complete a task.
• Organs are arranged into organ systems that have two or more different organs that work together.
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Systems of the body

• Respiratory system- takes in oxygen
• Digestive system- makes food available in a form the body can use
• Circulatory system- carries the food and oxygen to the cells where it is needed
• Excretory system- gets rid of wastes
• Skeletal system- supports the body and enables it to move
• Flash cards unit 1.1
• Flashcards 1.1 Part 2
• Flashcards 1.1 Digestion

Digestion

• Digestion is the process of breaking down food into a usable form and making the nutrients available.
• Digestion takes place in the digestive system which consists of:
• -a digestive tract, the pathway that the food takes through a series of organs. The first part of the digestive tract is the mouth.
• -organs off to the side of the digestive tract that produce chemicals that assist with digestion.
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Type of Digestion

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• Pie de imagen: Mechanical Digestion
• Pie de imagen: Chemical Digestion

Types of teeth in the mouth

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• Incisors- four pairs of teeth at the front and their job is to bite off pieces small enough to chew.
• Premolars and molars- when the food is pushed back, these teeth grind the food into smaller and smaller pieces as you chew.
• Canine teeth- helps animals hold onto the food as it is torn apart.
• -Biting and chewing is a form of mechanical digestion but chemical digestion also takes place in the mouth. As the food is being digested mechanically, it is mixed with saliva.

Swallowing

• Saliva is a watery liquid produced by your salivary glands.
• Saliva contains a chemical that starts to change any starch into glucose.
• Saliva also moistens the food, making it slippery, slimy and easy to swallow.
• -The tongue rolls the food into a ball called bolus, which is pushed down into the next part of the system, the oesophagus.
• -The oesophagus is a long muscular tube that has the mouth at one end and the stomach at the other end.
• -The muscles of the oesophagus push the ball of food down the tube by contracting behind the ball. The muscles then relax. This process is called peristalsis.
• A flap of skin called the piglottis closes the end of the windpipe as you swallow.
• This makes sure that the food goes into your stomach and not into the lungs via the windpipe.
• If food does get into the windpipe, you start to choke. You then cough to force the food back up into the mouth so that it could be swallowed correctly.

Stomach

• The stomach is shaped like a bag. Food is stored in the stomach for 1-6 hours.
• Once in the stomach, the food really begins to change.
• The muscular walls of the stomach contract and relax, churning up the food. This digests the food mechanically as well as mixing it with gastric juice.
• Gastric juices is produces by special cells in the stomach walls. Gastric juice contains:
• -hydrochloric acid- a strong acid that kills many of the bacteria that may have entered the body with the food.
• -mucus- creates a layer on the lining of the stomach and prevents the stomach from digesting itself.
• -digestive juices- contains chemicals that start the digestion of protein, the main nutrient found in meat.
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Digestive Disorders