Gastrointestinal Tract - Beginning of Tract Flashcards
Give two other names for the mouth.
Oral cavity
Buccal cavity
List the five functions of the oral/buccal cavity.
- Mechanical processing
- Mastication
- Analysis of bolus
- Lubrication (saliva)
- Limited digestion
What is mastication?
Chewing
What is used to lubricate food?
Saliva
List the seven structures present in the mouth.
- Stratified squamous epithelium
- Keratinised in places
- Buccinator muscles
- Hard & soft palate
- Palatoglossal arch
- Palatopharyngeal arch
- Uvula
What type of epithelia is found in the mouth?
Stratified squamous
Keratinised in places
Give an example of keratinised epithelia in the mouth?
Hard plate
Name the two plates of the mouth?
Soft plate
Hard plate
Name the two arches of the mouth.
Palatoglossal arch
Palatopharyngeal arch
What muscles are found in the mouth?
Buccinator muscles
What are buccinator muscles?
It holds the cheek to the teeth and assists with chewing
How many types of salivary glands are in the mouth?
Three
List the three salivary glands of the mouth.
Submandibular
Parotid
Sublingual
What percentage of your saliva is made by the submandibular gland?
70%
What percentage of your saliva is made by the parotid gland?
25%
What percentage of your saliva is made by the sublingual gland?
5%
What is present in the mucous from the submandibular gland?
3
HCO-3
Mucins
Amylase
What is HCO-3?
Hydrogencarbonate ion
What are mucins and amylase both called?
Glycoproteins
What is present in the mucous from the parotid gland?
Amylase
What is present in the mucous from the sublingual gland?
Its just mucous which acts as a lubricant
How many types of teeth are there?
Three
What are the three different types of teeth?
Incisors
Cuspids
Bicuspids
What are cuspids also called?
Canines
What are bicuspids also callled?
Premolars or molars
How are incisors shaped?
They are bladed teeth
Describe the positioning of incisors.
Central and lateral
How are cuspids shaped?
Conical shaped
How are bicuspids shaped?
Flattened crows and ridges
What do bicuspids do?
Crushing and mashing
What is the shape of the pharynx?
“Funnel-shaped”
Where is the pharynx?
It extends from the nostrils to the trachea
In relation to our voice what is the pharynx often called?
The resonating chamber
How many parts are there to the pharynx?
Three
What are the three parts of the pharynx?
Nasopharynx
Oropharynx
Larynx
What is the oesophagus?
A hollow muscular tube
What are the dimensions of the oesophagus?
25 x 2 cm
What is the oesophagus posterior to?
The trachea
Where does the oesophagus extend from and to?
Extends from the cricoid cartilage (C6) to the cardiac sphincter of the stomach
What is secreted in the oesophagus?
Abundant mucus
What causes Barrett’s Oesophagus?
GERD
What is GERD?
Gastroesophageal reflux disease
What happens in Barrett’s Oesophagus?
2
The epithelia adapt to chronic acid exposure from reflux esophagitis
The mucosa is replaced by metaplastic columnar epithelium
What replaces the mucosa in Barrett’s Oesophagus?
Metaplastic columnar epithelium
What is Barrett’s Oesophagus associated with?
Oesophageal cancer
What is oesophagitis?
Inflammation of oesophagus which causes a long term change in tissue - dysplasia
What is metaplasia?
Change in epithelia
What is deglutition?
Swallowing
How many times does one swallow a day?
2400 times a day -> every 40 seconds
What are the three phases of deglutition?
Buccal phase
Pharyngeal phase
Oesophageal phase
Is the buccal phase of deglutition voluntary or involuntary?
Voluntary
How does the buccal phase of deglutition happen?
4
The bolus is compressed by the hard palate
The tongue pushes the bolus posteriorly
The soft plate lifts
Bolus enters oropharynx
What part of the pharynx does the bolus enter first?
Oropharynx
Is the pharyngeal phase of deglutition voluntary or involuntary?
It is involuntary -> its a reflex
Describe the involuntary process of the pharyngeal phase of deglutition
It is a pre-programmed all or nothing sequence
How does the pharyngeal phase of deglutition occur?
4
The bolus contacts palatal arches and uvula
Receptors relay afferents via trigeminal and glossopharyngeal nerves to swallowing centre in medulla
Efferents to pharyngeal constrictor muscles move the bolus into the oesophagus by constricting the pharyngeal wall
Elevation of larynx, folding of epiglottis direct bolus past trachea
What is inhibited during the pharyngeal phase of deglutition?
Respiration
What nerves are involved in the pharyngeal phase of deglutition?
(2)
The trigeminal nerve
The glossopharyngeal nerves
Where is the swallowing centre?
The medulla
How is the bolus moved into the mouth?
By constricting the pharyngeal wall
What muscles are involved in the pharyngeal phase of deglutition?
The pharyngeal constrictor muscles
What happens to the epiglottis during the pharyngeal phase of deglutition?
The epiglottis is folded
What happens to the larynx during the pharyngeal phase of deglutition?
The larynx is elevated
Describe the oesophageal phase of deglutition.
4
Involuntary/reflex
Primary peristaltic waves drive bolus down oesophagus (10s)
Secondary stronger peristaltic waves may be required
Local stretch receptors detect distension and peristaltic contractions are modified (submucosal and myenteric plexus
Is the oesophageal phase of deglutition voluntary or involuntary?
It is involuntary
What drives the bolus down the oesophagus during the oesophageal phase of deglutition?
Primary peristaltic waves
How long do the primary peristaltic waves last?
10 seconds
What may be required after the primary peristaltic waves?
Secondary stronger peristaltic waves
What detects distension of the oesophagus?
Local stretch receptors
What is the function of the local stretch receptors in the oesophagus?
They detect distension and peristaltic contractions are modified accordingly
What tissues are responsible for the peristaltic contractions?
Submucosal and myenteric plexus
What is dysphagia?
Difficulty swallowing
What are the four main causes of dysphagia?
4
Stroke - neurological
Cleft palate - genetic
Tumour - obstructive
Scleroderma - muscular
What can be used to help dysphagia?
2
A nasogastric tube
A PEG tube
What is a PEG tube?
Percutaneous endoscopic gastronomy tube
