Digestive system Flashcards
What are the 6 components of the digestive system?
Oral Cavity, Oesophagus, Stomach, Small Intestine, Large Intestine, Rectum
What is simple epithelium?
One layer
What is stratified epithelium?
More than one layer
What is pseudo stratified epithelium?
One layer that pretends to be two
What is squamous epithelium?
Flat
What is columnar epithelium?
Column like
What type of epithelium are the mouth and tongue covered with?
Stratified squamous
What is underlying the stratified squamous epithelium of the tongue and mouth?
A submucosa containing salivary glands
What muscle is the major effector in moving the lower jaw?
temporalis
What muscle elevates and protrudes the jaw?
Masseter
Which muscle creates the lateral movement of the jaw?
Pterygoids
Name the three types of salivary glands and what type of saliva they secrete
Parotid - serous saliva. Submandibular - both serous and mucous saliva. Sublingual - mucous
Where are the three types of salivary gland found?
Parotid - biggest, behind mouth. Submandibular - medium sized, in chin. Sublingual - small, below tongue
Define Mucus
Slimy, stringy, ropey and lubricous
Define serous
Thin or watery - like serum
Where is saliva produced?
Acini
How is saliva produced?
By active filtration
Where is saliva modified?
In the ducts of the gland
What does parasympathetic stimulation do?
Produce a large volume of watery saliva
What does sympathetic stimulation do?
Produce a small volume of mucous saliva
How is the saliva lubricating?
Due to mucin content
How is digestion aided by saliva?
Prescence of alpha amylase
How does the saliva protect the oral mucosa?
Through lubrication, rinsing action and alkaline ph
How is the saliva antibacterial?
Thiocynate content
What may the epithelium lining the gut tube contain?
Goblet cells and endocrine cells
What do goblet cells and endocrine cells secrete?
Mucous and digestive hormones
What is the lamina propria?
A layer of loose connective tissue.
What does the lamina propria act as?
The first immunological barrier
Why does the lamina propria act as an immunological barrier?
Because it contains lymphatics and numerous white blood cells
What is the muscularismucosa?
A thin layer of smooth muscle cells
What does the muscularismucosa cause?
localised contractions in the mucosa
What is the submucosa?
A layer of dense connective tissue
What does the submucosa contain?
The submucosal plexus
What does the submucosal plexus control?
secretion and blood flow
What does the submucosal plexus relay information from?
The gut epithelium and stretch receptors
What is the muscularis externa
Two layers of smooth muscle
What is the structure of the outer/inner layer of the muscularis externa?
Outer = longitudinal inner = circular
What does the action of the muscularis externa create?
Waves of contraction/relaxation - moves food down the digestive tract (peristalsis)
What is between the two layers?
The myetenic plexus
What does the myetenic plexus control?
GI motility
What is the serosa?
A layer of epithelium
What does the serosa form part of?
the peritoneum
What does the peritoneum line?
The abdominal cavity and covers abdominal organs
What is the enteric nervous system?
A branch of the autonomic nervous system
Why is the enteric nervous system different to other autonomic branches?
Because it can operate independently of the CNS
What does the enteric nervous system consist of?
myenteric and submucosal plexi
Which state of swallowing is voluntary?
The pharyngeal stage
What is the pharyngeal stage initiated by?
the muscles of the tongue pushing the bolus backwards - when it contacts the pharynx the swallow reflex is triggered
What do the palliative muscles do?
lift the soft palate to block off the nasopharynx
What is the larynx lifted by?
The infahyoid (muscles of the throat)
What does the action of the innfahyoid do?
Moves the epiglottis over the trachea, preventing food from passing down it
What do pharyngeal constrictors do?
Contract sequentially to move food down the pharynx
Which stage of swelling is involuntary?
Oesophageal
What is the oesophagus lined with?
Stratified squamous
What is the lower oesophageal sphincter formed by?
Bands of muscle from the diaphram
What does the muscular is externa of the upper third of the oesophagus consist of?
Skeletal muscle
What do the two lower thirds of the oesophagus consist of?
smooth muscle
What is the oesophagus innervated by?
Vagus Nerve
What vessels supply the GI tract?
Branches of the abdominal aorta
Which is the most superior branch?
Coeliac Trunk
What is the middle branch?
Superior mesenteric artery
What is the inferior branch?
Inferior mesenteric artery
What vertebral level to the coeliac trunk arise?
L1 (upper border)
What vertebral level does the superior mesenteric artery arise?
L1 (lower border)
What vertebral level does the inferior mesenteric artery arise?
L3
What does the coeliac trunk supply?
organs of the superior abdomen
What is the stomach supplied by?
The right and left gastric arteries, right and left gastroepiploic arteries
What is the superior duodenum supplied by?
superior pancreaticoduodenal artery
What is the liver supplied by?
The hepatic artery
What is the pancreas supplied by?
the superior pancreatic duodenal artery and splenic artery
What does the superior mesenteric artery supply?
Organs of the mid gut - the GI tract from the inferior duodenum to the left colic flexure
What does the inferior pancreaticodudenal artery supply?
inferior aspects of the duodenum and pancreas
What does the inferior pancreatic duodenal artery anatomise with?
the superior pancreaticoduodenal artery
What do numerous branches of the superior mesenteric artery form?
Large loops known as arcades
Where do the arcades run?
In the mesentery
What is supplied by the arcades?
The jejunum and ileum
What dies the ileocolic artery supply?
terminal illeum, veriform appendix and inferior ascending colon
What supplies to ascending colon?
right colic artery
What supplies the transverse colon?
middle colic artery
