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
where are fundic glands found
the fundus and body of the stomach
how is the secretory epithelium of glastric glands special
they secrete mucous, digestive enzymes and also bicarbonate which is ideal for digestion and maintenance of homeostasis
what is the epithelium like when moving from the stomach into the small intestine
it remains as simple columnar, but there is surface specialisation which shows prominently in the small intestine - this is the villi
what are villi
finger like projections that are designed to increase surface area and aid in the digestion and absorption which typically happens in the small intestine.
how many villi in the small intestine
10-40 per square millimetre. most prevalent at the beginning of the small intestine.
how many times does villi increase surface area
30
what is a disorder of the absorptive system of the gastrointestinal tract
coeliac disease
this is a condition where your immune system attacks your own tissues when you eat gluten. this damages the gut so you are unable to take in nutrients. histologically it results in villous atrophy, meaning there is a gradual decline and wasting away of villi, which leads to a flattened appearance of the surface of the mucosa, which reduces the wide surface area for absorption of essential nutrients
what are crypts
these are grooves between the villi
what are hyperlastic crypts
this is when the grooves become stretched or elongated
what is the purpose of the epithelium in the large intestine
to absorb water and secrete mucous
what is the mucous secreted by in the large intestine
paler cells in the epithelium which ensures indigestable material passes towawrd the rectum and anal canal for expulsion of faeces without damaging the epithelium
what is the large intestine mucosa responsible for
absorption of vitamins that are created by colonic bacteria like vitamin K - essential for blood clotting
what are colonic crypts
intestinal glands
what are the two main conditions of inflammatory bowel disease
crohns disease and ulcerative colitis
what is crohns disease
a life long condition that results in inflammation of the lining of the digestive or alimentary system. it can occur anywhere along the gastrointestinal tract and results in inflammation and collections of the granulomas or lymphoid infiltrates that are transmural or across the wall of the bowel and alimentary system
what can crohns disease affect
any part of the alimentary system from mouth to anal canal. this will affect someones ability to maintain oral hygiene and their deiet, and can result in a great deal of pain and weight loss
what occurs in ulcerative colitis
there is inflammation in the colon and rectum only. ulcers can develop or break down the epithelium. this can turn lead to receurrent bouts of diarrhoea and abdominal pain.
what are the different alimentary activities
secretion
digestion
motility
absorption
excretion
give a brief summary of the secretory activities of the alimentary system
we produce about 7500ml of fluid in the process of digestion in a 24 hour period, broken down as follows:
600ml saliva
1500ml liquids (consumed by us)
2000ml gastric juice
500ml bile
1500ml intestinal juice
1500ml pancreatic juice
100ml are excreted
what are the two mechanisms of digestion
mechanical and chemical digestion
give a summary of mechanical digestion
this is the use of muscle contraction to aid motility and the breakdown of particles. it is involved in ease of movement and mixing. think of “propulsive motility” where the contraction starts at one end and finishes at the other.
give a summary of chemical digestion
this is primarily enzymes, but also involves some of the hydrochloric acid from the stomach. it takes a complex and turns it to a simple molecule. there are specific enzymes that facilitate the processes like saliva and the pancreas. these enzymes are secreted at different points in the gastrointestinal tract
describe the process of motility at the different points of the mouth
chewing and swallowing in the mouth
churning in the stomach
peristalsis in the intestine
mass movements in defaecation
give a brief overview of the mouth and its involvement with digestion
this is the oral or buccal cavity with primary sensory and motor function. it also has other functions like salivation, lymphoid tissue and reflexes. in terms of the sensory functions of the mouth, there is general sensory that we experience elsewhere in the body as well such as pain, movement and temperature. but there is also taste, ie gustition, which is only experienced in the mouth. in terms of motor function, the mouth is involve in feeding, transport, breakdown and swallowing, which is an action that initiates digestion
what are the names of the different boundaries of the mouth
- anterior
- lateral
- inferior
- superior
- posterior
what surface of the mouth are the lips on
anterior
what surface of the mouth are the cheeks found
lateral
what boundaries of the mouth are the tongue and mylohyoid found
the inferior boundary
what boundaries of the mouth is the palate found on
superior boundary
what boundaries of the mouth is the fauces found on
the posterior boundary
what are the names of the facial muscles
temporalis muscle and the masseter muscle
what is the name of the facial muscle
orbicularis oris
what are the three salivary glands called
parotid gland which produces serous secretions
submandibular gland which produces a serous mucous mix
sublingual gland which produces mucous
what are some examples of exocrine secretions involved in digestion
salt and water, mucous, amylase
what are some disorders of the salivary gland
mumps, sialolithiasis, sialoadentitis
what is sialolithiasis
salivary gland stones, known as calculi, which are most common in the submandibular salivary gland
what is the sialoadenitis disorder
inflammation of the salivary gland
what is mumps
an enlarged parotid salivary gland
what body systems is the pharynx involved in
digestive and respiratory systems
what kind of acid is secreted by the stomach
hydrochloric acid
what are the different parts of the large intestine
caecum
ascending, transverse and descending colon
rectum
anus
what are the different layers to mucosa in the gastrointestinal tract
epithelium, lamina propria, submucosa and muscularis mucosae
where is the submucosa found
below the mucosa. it contains dense irregular tissue, blood vessels, nerves and lymphatics
what is the muscularis propria
has two layers; the inner circular layer of smooth muscle that goes all around the tube. the outer longitudinal layer comes out toward us
what does the type of epithelia in the gut depend on
its location
what kind of epithelium is found in the stomach
simple columnar
where are fundic glands found
the top of the stomach and in the body of the stomach, in the lamina propria
how is the digestive process initiated
swallowing
what is peristalsis
muscular contraction to aid motility
where does most of the absorption in the digestive process take place
in the small intestine
what is nociception
pain
what is mechanoreception
movement
what is thermoreception
temperature
what is deglutition
the term for swallowing
what are tonsils collections of
lymphoid tissue
what is the hard palate made up of
bone covered by a mucous membrane
what is the uvula part of
the lowest part of the soft palate
what are the fauces
the pillars of the mouth where the tonsils are found
what structures are found underneath the tongue
sublingual salivary gland, submandibular salivary galnd. the general folds under the tongue are the plica fimbriata. the lingual frenulum is also found there
what virus is mumps
paramyxovirus. it causes swelling of the parotid gland. this can cause infertility and is difficult to treat - no actual cure. treated by symptom release.
