Digestive System Flashcards
What is the oral/buccal cavity?
Mouth. This is where salivary glands secrete saliva with digestive enzymes like amylase in to digest starch to maltose. The teeth grind food into smaller pieces and the tongue mixes it with saliva to form a bolus - mechanical digestion.
What is the oesophagus?
Behind the trachea connecting mouth to stomach. When you swallow a piece of cartilage called the epiglottis covers the trachea so it doesn’t go down the windpipe. The bolus moves down it by gravity and peristalsis. A sphincter muscle at the bottom of the oesophagus opens up to let food into the stomach.
Define peristalsis.
Wave like contractions and relaxations of circular muscles to push food along.
What is the stomach?
Left side of the body under the diaphragm. A muscular, sac like organ that connects the oesophagus and small intestine. It chemically breaks down food. It has muscular walls that churn food and mix it with enzymes and mucus making chyme. The stomach wall has goblet cells secreting mucus, cells secreting HCL for acidic conditions for pepsin to work, and cells that secrete pepsin that breaks down proteins to amino acids. After 1-2 hours the sphincter opens and lets chyme into the duodenum.
What is the small intestine?
Has the duodenum, Jejunum and ileum. It digests proteins, lipids and carbohydrates with digestive enzymes - protease, lipase and amylase. It is pushed through by peristalsis and ingested food is absorbed across the villi. The small intestine receives bile from liver and enzymes in an alkaline juice from the pancreas. The alkaline neutralises HCL and bile breaks down large fat globules into smaller ones so lipase works.
What is the liver?
Stores glucose as glycogen and synthesis’s plasma proteins such as the blood clotting factor fibrinogen. Also produces bile which is stored in the gall bladder and flows into the duodenum along the bile duct. Bile doesn’t contain enzymes but breaks down large fat globules. This is emulsification and lets lipase works. It is to the right of the stomach.
What is the gall bladder?
Located under the liver and stores and releases bile via the bile duct into the duodenum.
What is the pancreas?
Feather shaped organ underneath the stomach. It produces pancreatic enzymes and digestive alkaline juices. It produces insulin, proteases like trypsinogen and lipase, amylase and Maltese. These go into the duodenum.
What is the large intestine?
Split into 3 parts; the caecum, colon and recriminations. Food is pushed through by peristalsis and remaining water is absorbed. It also absorbs vitamins from bacteria in the colon. It compacts farces and bacteria in large intestine and nutrients prevents pathogens from growing. It stores unusable food matter.
What is the rectum.
A chamber that ends in the Anus which temporarily stores undigested food.
Describe the process of digestion.
Buccal cavity and teeth mechanically digests food into a bolus and starch is slightly broken down from amylase in saliva. Bolus moves down oesophagus by gravity and peristalsis. It enters stomach through a sphincter where it is churned with hydrochloride acidic mucus and enzymes which breaks down proteins. It enters the small intestine (duodenum) through another sphincter and nutrients get absorbed by microvilli. Bile from the liver breaks down large fat globules and alkaline juices neutralises the HCL, and digestive enzymes break down proteins fats and sugars. It then goes through the jejunum and ileum into the large intestine. It moves through the caecum, then colon where water is reabsorbed and rectum which stores it.
Describe the absorption of food including the structure and function of gut villi.
Small intestine has villi. The villi has a lacteal or lymph vessel in the middle surrounded by a network of capillaries surrounded by epithelial cells. The villi increase the SA of the small intestine and microvilli from epithelial cells increase it further. Digestion in the SI breaks down food into fatty acids and glycerol, polypeptide and disaccharides. Then enzymes in the microvilli such as aminopeptidades, and disaccharidases like Maltase sucrose and lactase, break food down further. These components are absorbed in the capillary network and fatty acids and glycerol are absorbed into the lacteal.
What is a gastric ulcer?
Also known as a stomach ulcer, open sores that develop on the lining of the stomach. They can be gastric, duodenal or oesophageal.
What are the effects of gastric ulcers?
Weight loss bc pain from eating
Nutrients not absorbing properly so malabsorption and deficiency diseases
Pain in abdomen and back
Acid reflux where acidic contents of stomach come back through oesophagus
Vomiting
Vomiting blood from perforated ulcer.
How can diet cause a stomach ulcer?
Coffee as alcohol can cause an ulcer because they (especially mixed with nicotine) erode the mucous membrane of the stomach lining and increase the concentration of stomach Acid, so the acid damages the lining.
