Physiology Of The Mouth And Oesophagus Flashcards
What happens to food in the mouth during chewing?
Food is mixed with saliva during chewing
Name the three pairs of salivary glands.
Parotid, submandibular, sublingual
How much saliva is secreted each day?
Around 1500ml of saliva is secreted each day
What are the components of saliva?
Mucous to help lubricate food
α-amylase to initiate the breakdown of carbohydrates
Lysozyme with antibacterial actions
Name the structures around the mouth and organs.
How is saliva formed?
Saliva is formed as an isotonic fluid produced by acinar cells that secrete electrolytes and water
What happens to the fluid as it flows along the salivary duct?
The fluid is modified as it flows along the salivary duct
What factors determine the final composition of saliva?
The final composition of saliva depends upon flow rate and neuronal input
How is saliva secretion regulated?
Saliva secretion is controlled by reflexes mediated via the Autonomic Nervous System (ANS)
What are the effects of the parasympathetic nervous system on saliva secretion?
Parasympathetic stimulation results in watery
saliva that is rich in amylase and mucous
It increases blood flow to the salivary glands
What are the effects of the sympathetic nervous system on saliva secretion?
Sympathetic stimulation promotes an increased output of thicker mucous
It reduces blood flow to the salivary glands, resulting in an overall reduction in the secretion of watery saliva
What happens during the voluntary stage of swallowing?
The tongue pushes the bolus backward to the oropharynx
Describe the pharyngeal stage of swallowing.
It is a reflex action controlled by the deglutition center in the medulla and pons of the brain
The soft palate and uvula move up to seal off the nasopharynx
The larynx is raised, glottis is sealed, and the epiglottis covers the glottis, suspending breathing for 1-2 seconds
What is the oesophagus?
The oesophagus is the tube connecting the laryngopharynx to the stomach.
Describe the muscularis layer of the oesophagus during swallowing.
The muscularis layer is striated for the first third to assist in swallowing.
What is the composition of the muscularis layer in the middle and lower thirds of the oesophagus?
The middle third is a mixture of striated and smooth muscle, while the lower third is composed entirely of smooth muscle.
How are drugs absorbed in the mouth?
Buccal or Sublingual delivery involves drugs crossing the epithelium (oral mucosa) and entering the bloodstream directly, typically resulting in greater bioavailability.
What are the advantages of Buccal or Sublingual delivery?
It avoids first-pass metabolism, which is the loss of drug during absorption via the gut wall.
This method is suitable if rapid action is required.
What factors need to be considered in the absorption of drugs in the mouth?
Solubility in saliva needs to be considered.
Only small lipophilic molecules are well absorbed through passive diffusion.
Barriers to absorption can be challenging.
What is the surface area of the oral mucosa?
The surface area of the oral mucosa is limited, approximately 200cm².
How does drug absorption occur in the oral mucosa?
Drug absorption in the oral mucosa primarily occurs through passive diffusion.
What is notable about the blood supply to the oral mucosa?
The oral mucosa has a rich blood supply, leading to a rapid onset of action with similar bioavailability to intravenous formulations.
What consideration is important for drug dissolution in buccal administration?
The drug must dissolve in saliva, making hydrophobicity an issue.
What is important to consider regarding the swallowing reflex in buccal drug delivery?
The swallowing reflex needs to be considered, and retention in the mouth is important for buccal delivery.
How does the surface area for absorption in buccal administration compare to other routes?
The surface area for absorption in buccal administration is limited, approximately 200cm², compared to 20,000cm² (skin) or 350,000cm² (GI tract)
What barriers must a drug overcome during oral delivery?
The drug must diffuse across the lipophilic cell membrane and the hydrophilic interior of the cell. These barriers must be taken into consideration.
What enzymatic barrier exists in buccal tissue, and what is its impact?
Aminopeptidase in buccal tissue is an enzymatic barrier causing rapid degradation of peptides and proteins, limiting their transport across the epithelium.
What is the challenge associated with oral drug delivery?
The challenge lies in developing suitable delivery systems to overcome these barriers.
What challenges are associated with buccal drug delivery in terms of keeping the drug in place?
The drug (dose) must be kept in place for absorption, and excess saliva could reduce this.
What limitation is associated with the surface area in buccal drug delivery?
The surface area for absorption is limited.
What considerations are important for the taste of a drug in buccal delivery?
The taste of the drug must be bland.
What are the requirements for a drug to be suitable for buccal delivery?
The drug must be a non-irritant to the mouth or teeth.
What is the term for dry mouth?
Xerostomia
What are common oral/dental problems?
Oral ulcers
Oral thrush
What complications can arise from dry mouth?
Dry mouth can lead to oral ulcers and dental caries and can affect both digestion and drug absorption.
How can dry mouth be treated?
Dry mouth can be treated with artificial saliva preparations, such as lozenges, sprays, or gels.
How are oral ulcers usually treated?
Oral ulcers usually clear up without treatment, but in some cases, anti-inflammatory (corticosteroid) and antimicrobial mouthwash may be required to prevent infection.
What is oral thrush?
Oral thrush is a yeast infection.
What are some causes of oral thrush?
Causes include overuse of antibiotics, poor immune system, underlying disease, smoking, and the use of dentures.
How is oral thrush typically treated?
Treatment is aimed at reducing fungal infection using oral antifungal gel, for example, miconazole or nystatin.
What is an example of a medication that may cause tooth decay due to sugar or artificial sweeteners?
Antacids
How can chewable antacids contribute to tooth decay?
Chewable antacids can get stuck between your teeth and over time, result in decay.
What is the impact of opioids, a type of pain medication, on tooth enamel?
Opioids can cause dry mouth and the consequent erosion of tooth enamel.
How can antihistamines contribute to tooth decay?
Antihistamines can block the release of saliva, resulting in dry mouth, which may lead to tooth decay.
What is a potential concern related to the use of inhalers for asthma?
Inhalers for asthma may contain a slightly acidic ingredient (beta-adrenergic agonist), which can be harmful to tooth enamel, causing susceptibility to tooth decay.
What is a key recommendation for dental hygiene regarding water intake?
Drink plenty of water
What are the recommendations for brushing teeth?
Brush your teeth twice a day and get regular dental check-ups
How can smoking be addressed for better dental hygiene?
Reduce or give up smoking
What drinks should be reduced for improved dental hygiene?
Reduce intake of caffeinated and dehydrating drinks like coffee, tea, and alcohol
What additional products can be used for oral hydration?
Use a moisturizing mouth spray and a hydrating mouth rinse.
