Unit 2.4 The Digestive System Flashcards
What is the purpose of the digestive system?
The purpose of the digestive system is to move food and water into the body and mechanically and chemically break it down (digest it) so useful components can be absorbed into the body large insoluble molecules are broken down into smaller soluble molecules that can be absorbed and used by the body.
What happens to indigestible components?
They are removed from the body.
How much solid food and liquid does the average adult consume each day?
About 1 kilogram of solid food and 2 litres of fluid.
What does the food we eat provide us with?
The food we eat provides energy and the raw materials to maintain the structures we already have. It allows us to generate new tissues and repair damaged one - in children and adolescents food also provides the raw materials for growth.
What are other words for the digestive system?
The gastrointestinal tract or digestive tract.
How long is the average digestive system in an adult? Where does it start and end?
The digestive system opens at both ends of the body and runs form the mouth to the anus, the lumen of the canal is in effect outside the body, and is 8 -9 metres long.
The secretion of enzymes at strategic parts of the GI tract facilitates the digestive process, secretions from other organs also help process food, what do these include?
The salivary glands, liver, gall bladder and pancreas.
Where are the products of the digestive process first delivered to?
The products of the digestive process are delivered first to the liver for processing.
What happens to useful products and waste materials?
Useful products are dispatched as needed or stored for later use. Waste products are extracted and sent elsewhere for disposal.
Billions of bacteria live in the GI tract and are important in the digestion of food, when can these become a threat?
If the wall of the GI tract is broken for example if the appendix ruptures as a result of appendicitis - there is a danger of infection known as peritonitis.
What is the only part of the GI tract that has a bony skeleton?
The mouth - the first part of the GI tract.
What happens when food moves about the mouth?
As food moves about the mouth, taste buds are stimulated which in turn stimulate the salivary glands and other gastric secretions.
What crushing force do the teeth exert?
The teeth bite down on the food and exert a crushing force of 50-80kg during chewing or mastication.
What receptors on the tongue trigger swallowing?
Sensory receptors.
What muscle is the tongue made from?
The tongue consists of skeletal muscle under voluntary control.
What is the whole cavity of the mouth lined with ?
The whole cavity is lined with a mucous membrane kept moist by saliva.
What is the tongues top surface covered with?
The tongues top surface is covered with a roughened mucous membrane caused by numerous tiny elevations called papillae which increase the tongues surface area and contain the taste buds.
Taste is a chemical sense caused by what?
Specialised nerve endings known as taste buds that can distinguish sweet, sour, salt, bitter and umami (savoy or meaty) flavours.
How many taste buds do a young adult have?
10,000
There are three main pairs of salivary glands in the mouth which in an average adult produce how much saliva each day?
1500cm3 of saliva each day (99.5% water, 0.5% solutes)w
Saliva has several functions what are these?
It moistens and softens food helping to turn it into bolus during mastication.
It lubricates the tongue to assist speech.
It also contains the enzyme salivary amylase that begins the chemical breakdown of starch .
It also contains another enzyme called lysosomes which can kill some kinds of bacteria and helps keep the mouth healthy.
Where does the tongue pass the food to?
The tongue passes the food back into the pharynx for swallowing.
What is swallowing controlled by?
Swallowing in a complex reflex action controlled in the brain by the medulla oblongata and pons.
How is food and liquid prevented from entering the trachea and going down into the lungs?
This is achieved by the closing of a flap of tissue known as the epiglottis over the entrance to the trachea, stopping food from entering the respiratory system accidentally.