Nutrition In Humans Flashcards
What contributes to differentiating energy requirement
Activity levels Age Pregnancy Lifestyle Climate Metabolic rate Health/medical conditions
From the mouth the food passes through the pharynx (back of throat) and then where?
Dow on the oesophagus
What is peristalsis?
Waves of muscular contraction followed by relaxation that pushes food down the oesophagus and down into the stomach. It occurs along the entire length of the digestive system
How is the oesophagus adapted to suit its function as a passage way?
Muscular
Mucus is produced from goblet cells to reduce friction
Describe three main events that take place in the stomach
HCL is produced. This gives the correct ph for the enzyme pepsin to work. Acid also kills any ingested bacteria
Mechanical digestion by peristaltic movements
Chemical digestion. Pepsin realised from stomach lining and breaks large protein molecules down to amino acids
Where is bile produced and stored
Produced by liver, stored by gall bladder
Why do we need bile
Neutralises stomach acid and emulsifies lipids
From the stomach the food enters a region of the small intestine called the
Duodenum
What is the alimentary canal?
The whole digestive system.
What happens in the duodenum
Pancreatic juices from the pancreas neutralises stomach acid and more enzymes are added.
What is the other part of the small intestine called?
The ileum
What happens in the ileum
Small molecules (final products of digestion) e.g glucose, amino acids, fatty acids and glycerol, vitamins and minerals are absorbed.
How is the ileum adapted to its absorption role?
The whole surface is folded and covered with villi
What passes into the large intestine?
Digestion is finished by this point and the waste material consists of fibre and water and some dead or living bacteria
What is the first part of the large intestine called?
Colon
What does the colon do?
Reabsorbs most of the water from the contents leaving faeces
What happens if the water is not absorbed?
Too much water is lost (dehydration)
The faeces is too liquid (diarrhoea)
Why is there so much water to be absorbed?
Lots of water has been added from the bile, pancreatic juices, saliva, music, gastric juices.
How does the structure of the large intestine compare to the small intestine?
Large also has some internal folds but no villi
Also muscular to move material by peristalsis
Wider diameters that the ileum but much shorter in length
What is the final region of the large intestine called?
The rectum where the faeces is stored temporarily
How does villi help absorption in the small intestine?
Big surface area
Contain blood capillaries to carry away absorbed nutrients
The villi have a rich blood supply. The blood supply has a lower concentration of food molecules and so diffusion occurs quickly.
