Alimentary System Overview Flashcards
what does the mouth act as an opening to
the alimentary canal
what are the four individual components of teeth
enamel, dentin, cementum, and dental pulp
what is enamel
the hardest part of the tooth and the most mineralised
what is dentin
this is the component found between the enamel and the cementum
what is dental pulp
this is the central portion of the tooth which contains soft connective tissue
what is the main two function of the digestive system
digestion and absorption
what is digestion
the function to process food
what is cementum
the specialised bone covering the root of the tooth
what is absorption
the process to transfer nutrients to circulation
what organs aid in the processes of the gastrointestinal tract
accessory organs like salivary glands, gall bladder, liver and pancreas
how do salivary glands aid digestion
they secrete a watery secretion known as serous, a thicker secretion known as mucous and a mixed seromucinous. this saliva helps buffer the mouth pH and protect the surface of the mouth and gut. it also has antimicrobial action and maintains the tooth structure, aiding in taste and to a lesser extent aiding also with digestion.
how does the gall bladder aid with digestion
it helps to store and concentration bile which is producedby the liver, and helps with fat digestion.
what is the pharynx
muscular tube approximately 12-15cm in length. it is responsible for food to pass thorugh, as well as air. the oesophagus is also a muscular tuble and extends from this pharynx.
what is the oesophagus route
extends from the pharynx and reaches down to the stomach, passing behind the heart and the trachea. then leads onto the stomach where the first major portion of digestion will happen.
where does the first major portion of digetion happen
the stomach
what occurs in the stomach
the mixing and churning of what you have eaten and drunk. this is also a muscular organ and is located on the upper left of the abdomen. it secretes acid and enzymes that will start digestion, taking it on from the little amoutn of starch digestion that has happened with the amylase from the saliva in the oral cavity
what is food called after it has passed through the stomach
chyme
how does chyme move from the stomach to the small intestine
it will move through a sphincter (tight muscular structure) into the small intestine
what are the three parts of the small intestine called
duodenum, jejunum, ileum
what occurs in the duodenum section of the small intestine
progress from digestion to absorption. there are secretions from the pancreas, and bile will also enter at this point.
what is bile
a substance that helps with fat digestion. it enters the small intestine at the duodenum
what do the secretions of the pancreas aid with
digestion of fats, protein, starch and other carbohydrates
what does the pancreas also secrete
bicarbonate rich fluid which helps to maintain alkaline pH
what will move into the large intestine
the remaining material that was not digested or absorbed.
what staining is used when viewing the histology of the gastrointestinal system
H&E staining
what does mucosa line
the cavities of the body and the surface of internal organs
what is lamina propria
a thin layer of loose connective tissue which lies beneath the epithelium. contains inflammatory cells and provides support and nutrients to the overlyiung epithelium
what is muscularis mucosae
the next layer deep to the lamina propria. composed of smooth muscle and is continuous all the way through the entire length of the gastrointestinal tract
what is the submucosa composed of
dense irregular connective tissue - contains many blood vessels, nerves and lymphatic nerves.
what is the muscularis propria composed of
innter circular muscle and outer longitudinal muscle. this muscle is smooth muscle and is responsible for peristalsis
what is adventitia
the outer layer of fibrous connective tisue surrounding an organ. in the gut, this would be at the oral cavity, the upper end of the oesophagus, and ascending and descending colon and rectum.
what does the serous membrane allow for in the gastrointestinal tract
reduction of friction
what epithelium is found in the oral cavity
stratified squamous epithelium. ideal for their location to help with the repeated trauma from food and drink
is keratin found in the oesophagus
no, it is not found in any areas of the gastrointestinal tract that has stratified squamous epithelium due to the moisture to prevent it from drying out
what are some potential health issues associated with the gastrointestinal system
if there is contiaul reflux of acid from the stomach into the oesophagus, this can damage the lining of the epithelium of the oesophagus. this is called gastro-oestophageal reflux disease and is associated with heartburn, regurgitation or indigestion. can cause the cells of the lower oesophagus to change, which is called barrett’s oesophagus. change in epithelium refers to typically stratified squamous epithelium changing to simple columnar epithelium.
what is metaplasia
change of one differentiated cell type to another
what is dysplasia
an abnormal growth or development of cells - results in unequal cell size, abnormal shaped cells, and excess pigment. there are also more cells dividing.
how does epithelium change at the gastro-oesophageal junction
goes from stratified squamous epithlium of the oesophagus into the simple columnar epithelium
what are the different secretions in the stomach that aid with digestion
acid, mucous and enzymes
what are the different gastric glands found in the stomach
cardiac glands
fundic glands
pyloric glands
