oesophagus and stomach Flashcards
oesophagus: list the main functions, anatomical levels, anatomical relations, organisation and function of muscle types, and epithelia of the oesophagus
what is the oral cavity bound by
teeth to front and sides, tongue to bottom, hard and soft plates to top, oropharynx to rear
how many teeth in an adult human
32
what types of teeth are present and how many
8 incisors, 4 canines, 8 premolars, 12 molars
function of incisors and canines
bite and rip food
function of premolars and molars
grind food down
what is the name for the jawbone
mandible
what is the largest jaw muscle
massater muscle
what is the massater muscle responsible for
biting action
what two major digestive enzymes do salivary glands secrete
lingual lipase, salivary amylase
what is lingual lipase involved with
fat digestion
what is salivary amylase involved with
carbohydrate digestion
what is the name given to the mixture of food and saliva
bollus
what two types of muscles form the tongue
intrinsic, extrinsic
what are intrinsic tongue muscles responsible for
fine motor control, including enunciating specific sounds or moving food around the mouth
what are extrinsic muscles responsible for
groos movements of the tongue (in, out, up, down), aiding mechanical digestion
key functions of the tongue
speech, eating, taste
what two structures ensure food reaches the stomach and air reaches the lungs
epiglottis, upper oesophageal sphincter
movements of epiglottis and upper oesophageal sphincter at rest and swallowing
at rest the oesophageal sphincter is tonically active (both sphincters shut) and the epiglottis is upright; during swallowing (centre in brain) the epiglottis comes down to cover the entrance to the trachea as the bolus of food moves through the pharynx, and the upper oesophageal sphincter relaxes to allow it to flow into the oesophagus (swallowing has a more powerful effect on upper oesophageal sphincter (skeletal) vs lower (smooth))
what is the oesophagus
conduit tube connecting oral cavity and stomach
what two muscles form the upper oesophagael sphincter
constrictor pharyngeal medius, constrictor pharyngeal inferior
what does the constrictor pharyngeal medius have commonality with
circular muscle layer of GI tract
what does the constrictor pharyngeal inferior have commonality with
longitudinal muscle layer
how long is the oesophagus in a typical adult male
25cm
what type of muscle makes up the upper oesophagus
skeletal
what type of muscle makes up the lower oesophagus
smooth
what type of muscle makes the middle third of the oesophagus
mixture of skeletal and smooth
what control is the oesophagus under
involuntary despite skeletal muscle
what pressure is the oesophagus under most of the time
negative
epithelial lining of oesophagus to jagged z-line and reason
non-keratinised stratified squamous cells, to allow abrasive damage (temperature and texture) of bolus without loss of function; after z-line becomes simple columnar
epithelial lining of lower oesophageal sphincter and reason
simple columnar epithelia to tolerate stomach conditions
swallowing: stage 0 - oral phase
chewing and saliva prepare bolus for swallowing; both oesophageal sphincters constricted
swallowing: stage 1 - pharyngeal phase
bolus moves to back of pharynx, pharyngeal musculature guides towards oesophagus; both oesophageal sphincters open
swallowing: stage 2 - upper oesophageal phase
upper sphincter closes; local effect as superior rings of circular muscle contract as inferior rings dilate (peristalsis); sequential contractions of longitudinal muscle guide food down; if bolus is stuck, signal up to brain so release of second peristalitc wave
swallowing: stage 3 - lower oesophageal phase
food passes through lower sphincter that then closes; peristaltic wave pushes food into stomach (able to work against gravity) - gastro-oesophageal junction; partly due to diaphagm (muscular contraction) and fold of stomach (empty so opening is narrow)
what is the major plexus which innovates the gastrointestinal tract
myenteric plexus
where does the myenteric plexus lie
immediately superficial to circular smooth muscle layer of gut wall and immediately deep to longitudinal smooth muscle
does absorption of nutrients occur in the oesophagus
no
structure of oesophagus when food is not pasing through
collapsed
what is secreted into oesophagus
mucous; saliva lubricates also (but from mouth)
colour of oesophageal epithelium
light pink
define digestion
process of breaking down macromolecules to allow absorption
define absorption
process of moving nutrients and water across a membrane
oesophagus wall: mucosa layers
epithelium, lamina propria (loose connective tissue), muscularis mucosae
oesophagus wall: submucosa layer
connective tissue containing nerve plexus, blood vessels and glands
oesophagus wall: muscularis layer
smooth muscle containing nerve plexus, blood vessels
oesophagus wall: serosa/adventitia layer
connective tissue +/- epithelium
examples of secretory tissues outside of GIT
liver, pancreas
what can oesophagus impact on
recurrent laryngeal nerves, pericardium
where does oesophagus originate and terminate
originates around C5, through thorax into stomach (in abdomen)
close structures to oesophagus
trachea, aorta, diaphragm, lungs, heart
