Chapter 05 - Nutrition in Humans Flashcards
Define nutrition
A process by which organisms obtain food and energy for growth, repair and maintenance of the body
What are 5 processes in digestion?
1) Ingestion
2) Digestion
3) Absorption
4) Assimilation
5) Egestion
What is the main function of the digestive system?
Break down large and complex food substances into simpler and smaller food substances
What are the 2 types of digestion?
Physical and chemical
What is physical digestion?
A mechanical breakdown of large pieces of food into smaller pieces, and the identities of food substances remain unchanged, so no new products formed
Why is physical digestion important?
Physical digestion increases surface area to volume ratio
Where does physical digestion occur?
Mouth - chewing
Stomach - churning
Small intestine - emulsification
What is chemical digestion?
It is a process whereby large and complex food substances are broken down into smaller, soluble, simple substances and identities of food substances change, so new products are formed
Why is chemical digestion important?
To allow food substances to enter bloodstream through the intestinal wall
Where does chemical digestion occur?
Mouth - Starch
Stomach - Proteins
Small intestine - Carbohydrates, Proteins, Fats
What is the human digestive system made up of?
Alimentary canal and the associated organs (pancreas, liver, gall bladder)
What are the 3 main actions along the alimentary canal?
1) Peristalsis moves food along gut
2) Mucus along gut acts as a lubricant
3) Digestion takes place outside living cells within the gut
What is the function of associated organs?
Secrete substances involved in digestion
Where is food received into the human body?
The mouth
What is the intake of food known as?
Ingestion
What is ingestion?
The process of taking food and other substances into the body
What glands does the mouth contain?
Salivary glands which produce saliva which consists of salivary amylase which digests starch into maltose
What is a gland?
A gland is a structure that produces and secretes a chemical substance
What does the tongue do?
The tongue mixes food with salivary amylase in the mouth, rolls the food into a bolus and moves the food to the back of the mouth for swallowing
What pH does saliva provide?
Saliva in the mouth provides the optimum pH at 7 (neutral) for salivary amylase to function effectively
What does the teeth do?
Food is chewed by teeth to cut and grind them into smaller pieces to increase surface area to volume ratio allowing enzymes to digest them faster
What connects the buccal cavity to oesophagus and the larynx?
The pharynx. Food travels from the buccal cavity to the oesophagus via the pharynx
What is the structure of the oesophagus?
A narrow muscular tube leading to the stomach
What process occurs to move food from the oesophagus to the stomach?
Peristalsis