The human digestive system Flashcards
(30 cards)
What are the three main nutrients?
Carbohydrates, proteins and fats.
Why do humans require a digestive system?
Humans need aa digestive system to break down food into small soluble molecules to be absorbed into the blood. These digested food substances are then used by body cells to release energy through cellular respiration, for growth and tissue repair.
Describe ingestion.
Ingestion is the taking in of food through the mouth.
Describe digestion.
Digestion is the breaking down of large complex food into small soluble molecules which can be easily absorbed into the bloodstream. Physical-Large pieces of food are separated into smaller pieces. It increases surface area to volume ratio for faster rate of chemical digestion by enzymes.
Chemical- Complex nutrient molecules are broken down into simpler, soluble molecules that can be easily absorbed. This requires the action of digestive enzymes.
Describe absorption.
nd products of digestion are absorbed into the bloodstream by diffusion and transported to body cells.
Describe assimilation.
absorbed food substances are used to make new cells, release energy, or stored.
Describe egestion.
undigested and unabsorbed food substances are passed out of the body as faeces.
Define enzymes.
Enzymes are biological molecules produced to speed up chemical reactions that occur within the body.
What is the enzyme that digests carbohydrates?
Carbohydrase or amylase
What is the enzyme that digests proteins?
Protease
What is the enzyme that digests fats?
Lipase
What are the end products of carbohydrates?
Glucose or simple sugars
What are the end products of proteins?
amino acids
What are the end products of fats?
glycerol and fatty acids
What is the function of stomach?
Churning of food into smaller pieces increases surface area to volume ratio and allows faster rate of chemical digestion by protease. Gastric juice secreted contains proteases to digest proteins into polypeptides. Gastric juice also contains hydrochloric acid which kills harmful microorganisms and provides optimum PH for protease to function
What is the function of liver?
Liver produces bile. Bile is temporarily stored into gall bladder and released into small intestine
What is the function of pancreas?
Secrete pancreatic juice which contains enzymes that aid in digestion.
What is the function of small intestine?
The emulsification of fats by bile occurs. The bile breaks up fats into smaller droplets, increasing surface area to volume ratio for faster rate of chemical digestion by lipase. Intestinal juice and pancreatic juice which carbohydrase, protease and lipase are secreted in the small intestine to digest all carbohydrates, proteins and fats. End products of digestion are absorbed into the bloodstream across intestinal walls.
What is the function of large intestine?
Remaining water and mineral salts are absorbed here.
Describe constipation.
Faeces moves through large intestine very slowly thus too much water is absorbed making it hard and dry.
Describe gastric pain.
commonly caused by gastritis, painful swelling of the stomach lining.
Describe food poisoning.
Stomach cramps, vomiting and diarrhea to get rid of harmful bacteria.
What are the causes of constipation?
The causes of constipation are stress, consumption of certain medicine and insufficient water and fibre in the diet.
What are the causes of gastric pain?
Bacterial or viral infection.
