L3 upper GI Flashcards
what are the tissue structures of the GI tract
mucosa
submucosa
muscular externa
serosa
mesentery
what are the layers of tissue in the mucosa
epithelium
lamina propria
muscularis mucosae
what are the layers of tissue in the muscular externa
longitudinal muscle
circular muscle
what are the layers of tissue in the serosa
epithelium
connective tissue
main parts of the lips and cheeks
- orbicularis oris (a complex circular muscle that surrounds the orifice of the mouth and forms the majority of the lips) and buccinator muscle
- vestibule: recess internal to lips and cheeks, external to teeth and gums
- oral cavity: lies between teeth and gums
- labial frenulum: median attachment of each lip to the gum
main parts of the palate
- hard palate: palatine bones and palatine processes of the maxillae. slightly corrugated to help create friction against the tongue
- soft palate: fold formed mostly of skeletal muscle. closes off the nasopharynx during swallowing. UVULA projects downwards from its free edge. anchored by palatoglossal and palatopharyngeal arches
main parts of the tongue
- lingual frenulum: attachment to the floor of the mouth
- intrinsic muscle: changes shape of the tongue
- extrinsic muscle: alter the tongue’s position
functions of the tongue
repositioning and mixing food during chewing
formation of a bolus
initiation of swallowing, speech, taste
what is the digestion process in the mouth
ingestion, mechanical digestion, chemical digestion, propulsion.
what is mastication
cheeks and closed lips hold food. teeth and tongue mixes the foos with saliva to soften it
teeth cut and grind solid food
pattern and rhythm of continued jaw movements are controlled mainly by stretch reflexes
saliva functions
cleanses the mouth, moistens and dissolves food chemicals, aids in bolus formation, contains enzymes that begin breakdown of starch.
what are the extrinsic salivary glands
- parotid, 2. submandibular, 3. sublingual
what is parotid gland and its function
largest salivary gland, produces 50% of stimulated saliva, secretes amylase. it opens up to the vestibule next to second upper molar
location of parotid gland
anterior to ear, external to the master muscle.
location of the submandibular gland
medial to the body of the mandible
function of submandibular gland
produces 70% of unstimulated saliva, and the ducts open at the base of the lingual frenulum
location of the sublingual gland
anterior to the submandibular gland, under the tongue
function of the sublingual gland
mainly secretes mucous and lingual lipase. only produces 5% of the saliva. the glands open via the 10-12 ducts into the floor of the mouth
what is mumps
inflammation of the parotid glands caused by myxovirus and is common in children.
risk of mumps
can cause sterility in males by infection of testes. there is a 24% chance of this occurring.
transmission of mumps
saliva
what is sjogrens syndrome
an autoimmune condition that commonly affects the salivary and lacrimal glands. is associated with rheumatoid arthritis
symptoms of sjogrens syndrome
xerostomia (dry mouth) and xerophthalmia (dry eyes)
diagnosis of sjogrens syndrome
biopsy
what is the composition of saliva
a slightly acidic solution that is made up of 97-99.5% water. the rest contains:
electrolytes (Na+, K+, Cl-, PO42-, HCO3-)
salivary amylase and lingual lipase
mucin
metabolic wastes (urea and uric acid)
lysozymes, IgA, defenses, cyanide compound that protects against microbes.
role of bacteria in saliva
friendly bacteria converts food derived nitrates into nitric acid
uses of saliva in clinic
detect and monitor some conditions
- HIV
- oral cancer
- diabetes
- hormones
control of salivation
intrinsic glands continuously keep the mouth moist, whereas extrinsic glands produce secretion when 1. ingested food stimulates mechano and chemoreceptors in mouth. salivary nuclei in the brain stem sends impulse along parasympathetic fibers in cranial nerves VII and IX.
what are chemoreceptors (in the mouth) activated by
acidic substances
what are mechanoreceptors (in the south) activated by
virtually any mechanical stimulus
what increases salivation
irritation of lower regions of GI tract (eg by bacteria, spicy food, hyperacidity), especially when accompanied by nausea.
what produced thick, mucin rich saliva
sympathetic stimulation
what does dehydration cause (in terms of salivation)
inhibition, due to reduced filtration at capillary beds
what is the oesophagus
a straight course through thorns from the pharynx to the stomach. it pierces the diaphragm
what are the layers of the oesophagus
- mucosa
- submucosa
- adventitia
- muscularis
what is the mucosa in the oesophagus
stratified squamous epithelium
what is the submucosa in the oesophagus
glands secrete mucus
what is the muscularis of the oesophagus (3)
proximal third is skeletal, middle is a mixture, inferior is smooth
adventitia of the oesophagus is instead of what
serosa
what is the adventitia of the oesophagus
a fibrous connective tissue
difference between adventitia and serosa
adventitia: dense connective tissue, retroperitoneal, mouth, pharynx, esophagus, pylorus of stomach, distal duodenum, saddening and descending colon, anal canal
serosa: connective tissue covered in mesothelium, intraperitoneal, most of stomach, duodenum, caecum, sigmoid and transverse colon, rectum
pharynx job and lining
allows passage of food, fluids, and air. histology similar to oral cavity, lining of epithelium is stratified squamous
what are the skeletal muscle layers of pharynx
inner longitudinal, outer pharyngeal constrictors
what is deglutition
swallowing
what is involved in deglutition
tongue, soft palate, pharynx, oesophagus, 22 muscle groups
two phases of deglutition
- buccal phase: voluntary contraction of tongue
- pharyngeal-esophageal phase: involuntary
what is hiatus hernia
part of the stomach squeezes up into the chest through an opening (“hiatus”) in the diaphragm.
causes of hiatus hernia
weak diaphragm, increased intrabdominal pressure, associated with obesity
what does hiatus hernia cause
acid reflux
anatomy of stomach
- cardiac region
- fundus (top arc)
- body (mid portion)
- pyloric region (lower arc)
- greater curvature (big, longer curve)
- lesser curvature (opposite to greater)
- omen (mesenteries from stomach curvatures)
- ANS nerve supply
- blood supply
what is the cardiac region of the stomach
surrounds cardiac orifice
what is the fundus of the stomach
- bulges higher than cardia
- dome shaped beneath the diaphragm
what is the pyloric region of the stomach
- pylorus, which is the gate keeper
- is funnel shaped, and has a pyloric sphincter
what is the omenta of the stomach
- mesenteries from the stomach curvature
- contains lesser and greater omentum.
- lesser: from liver to less curvature
- greater: drapes from greater curvature and contains fat deposits
what is the ANS nerve supply of the stomach
- sympathetic via splanchnic nerves and celiac plexus
- parasympathetic via vagus nerve (10)
what is the blood supply of the stomach
- celiac trunk
- veins of the hepatic portal system
what are the digestive processes
- physical digestion
- denaturation of proteins
- enzymatic digestion of proteins by pepsin
- secretes intrinsic factor required for absorption of vitamin B12
- delivers chyme to small intestine
functions of mucus in stomach
- mucus forms gel-like layer to protect mucosa from gastric juice.
- mucus traps layer of bicarbonate rich fluid beneath it.
gastric secretion
stomach lining is dotted with deep gastric pits that lead to tubular gastric glands that produce gastric juice. the stomach secretes 2.5L of juice, that contains pepsinogen (chief cells) and HCl (parietal cells)
what is the pH of the stomach
1-2 in lumen and 6-7 above the mucosa
what is the microscopic anatomy of the stomach
contains mucosa which are columns that contain mucous cells
what are produced by the mucous cells
alkaline layer of protective mucus, which traps bicarbonate-rich fluid beneath it.
what does chief cell produce?
pepsinogen (inactive enzyme) and lipase
what does parietal cell produce?
HCl and intrinsic factors
what is the pH level of the protective mucus layer in the stomach
~7
how often does the stomach lining get renewed?
3-6 days
what does the enteroendocrine cells release?
paracrine (serotonin and histamine) and hormones (somatostatin and gastrin)
what is gastritis
inflammation caused by anything that breaches mucosal barrier
what is a peptic/ gastric ulcer
erosion of the stomach wall
most gastritis are caused by
H. pylori bacteria
how do bacteria cause gastritis
burrows through mucus and destroys it
how much gastric juice is released per day?
3 litres
what are the phases of stimulatory and inhibitory secretion of gastrin
1) cephalic (reflex): few minutes prior to food entry
2) gastric: 3-4 hours after food enters stomach
3) intestinal: brief stimulatory as partially digested food enters duodenum and inhibitory effects after.
what are the neural (vagus) and hormonal (gastrin) mechanisms
1) vagus fires, all secretory and motility up.
2) gastrin increases motility, HCl and pepsinogen
3) Secretin from small intestine reduces HCl production
4) Gastric inhibitory polypeptide released from duodenum and jejunum.
5) enteroglucagon from colon decreases motility.
what is the gastric contractile activity
- peristalsis waves move towards pylorus at rate of 3 per min.
- the rhythm (basic electrical rhythm (BER)) is initiated by pacemaker cells
- most vigorous at the pylorus
how is chyme delivered
3ml spurts to duodenum or forced backwards to stomach, causing pyloric sphincter to contract. this helps to mix chyme more
what is emesis
vomiting
causes of emesis
spicy food, excess alcohol, bacterial toxins, drugs
