KuraCloud 2 - Oesphagus Flashcards
What anatomical features make the mouth well suited as the point of entry for ingested food?
- teeth
- tongue
- hard and soft palates
- oropharynx
How many teeth do we have?
Name the different types and how many there are of each in normal individual
32 altogether
- incisors = 8
- canine = 4
- premolars = 8
- molars = 12
What are the incisors and canines used for?
to bite and rip food into a manageable size for the mouth to handle
What are the premolars and molars sued for?
responsible for grinding food down into smaller pieces
What are the muscles of the oral cavity?
massater muscle
the largest jaw muscle, responsible for biting action
(if you clench your teeth you should feel it lateral to your clenched molars on both sides)
What is the function of the salivary glands?
What results from the mixing of food and saliva?
produces saliva
saliva - an aqueous secretion with digestive enzymes (lingual lipase and salivary amylase - used for the first stage of fat and carbohydrate digestion respectively)
The mixing of food and saliva creates a bolus that can be swallowed into the stomach once it is the right size and consistency.
What are the 2 types of muscle in the tongue?
INTRINSIC
responsible for fine motor control of the tongue, such as enunciating specific sounds, or for moving food from one part of the mouth to another
EXTRINSIC
responsible for gross movements of the tongue, such as in, out, up and down.
This is especially useful to assist mechanical digestion, by pounding the food bolus against the hard palate at the roof of the mouth.
What roles do the epiglottis and the upper oesophageal sphincter play?
What are there positions at rest?
How do these change during swallowing?
(get food and air to the correct destinations)
At rest, the oesophageal sphincter is tonically active and the epiglottis is in the upright position.
These structures move during swallowing, with the epiglottis coming down to cover the entrance to the trachea as the bolus of food moves through the pharynx, and the upper oesophageal sphincter relaxes allowing it to flow into the oesophagus.
What are the positions/appearances of the oesophagus and the trachea at rest?
oesophagus - mostly collapsed
trachea - held open by cartilagenous discs
Anatomically, what is the oesophagus?
It is a conduit tube connecting the oral cavity and the stomach
Its’ passage through the thorax places it in close proximity to key structures such as the heart, lungs and major blood vessels.
What are the 2 muscles of the upper oeaophageal sphincter?
CONTRICTOR PHARYNGEAL MEDIUS
which has commonality with the circular muscle layer of the GI tract
CONSTRICTOR PHARYGES INFERIOR
which has commonality with the longitudinal muscle layer
What type of muscle makes up the wall of the oesophagus?
skeletal and smooth
Specifically:
- the upper oesophagus is composed of skeletal muscle only
- the lower oesophagus is smooth muscle only
- the middle third is a mixture of the two as the proportion of skeletal muscle tapers along its length
NOTE: despite the involvement of skeletal muscle, it is not under voluntary control.
What are the 2 portions of the lower oesophageal sphincter?
INTERNAL COMPONENT - which is built into the circular smooth muscle of the oesophageal wall
EXTERNAL COMPONENT - which is formed by the right crus of the diaphragm (voluntary control)
What pressures are the oesophagus and stomach under?
oesophagus - negative pressure
stomach - positive pressure.
What is the structure of the epithelial lining of the oesophagus?
- non-keratinised stratified squamous cells
- —-> forms a robust wear-and-tear lining to protect the oesophagus (from a variety of ingested foods)
- at the lower oesophageal sphincter, simple columnar epithelia
because these epithelia need to tolerate different conditions (i.e. resistance against strong stomach acid) - this epithelial change occurs within the sphincter along a jagged line called the z-line
