Mouth - Saliva Production and Swallowing

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Questions and Answers

What is the main purpose of segmentation in the digestive tract?

Propel food along the tract

Absorb nutrients

Metabolize drugs

Facilitate mixing of food (correct)

Which factor affects drug absorption through buccal delivery?

Temperature of the mouth

Drug's hydrophobicity (correct)

pH level of saliva

Drug's molecular weight

What is a major barrier to absorption in buccal delivery?

Low blood supply in oral mucosa

Enzymatic degradation in buccal tissue (correct)

Rapid absorption into the bloodstream

High surface area of the oral cavity

What oral/dental problem can dry mouth lead to?

Dental caries Signup and view all the answers

Which challenge must be considered for buccal drug delivery?

Retention in the mouth is important Signup and view all the answers

What is a key requirement for drugs to achieve greater bioavailability through buccal administration?

Avoid first-pass metabolism Signup and view all the answers

What factors could limit drug efficacy in buccal delivery?

Excess saliva production Signup and view all the answers

What is a common treatment for oral thrush?

Antifungal gel Signup and view all the answers

What role do tight junctions between mucosal epithelial cells serve in gastric protection?

They prevent leakage of gastric juice onto underlying tissue. Signup and view all the answers

During which phase of gastric secretion is there an increase due to the sight, smell, taste, thought of food, or a decrease in blood glucose?

Cephalic phase Signup and view all the answers

What effect do prostaglandins have on the gastric mucosa?

They increase mucosal thickness and stimulate bicarbonate. Signup and view all the answers

What triggers the intestinal phase of gastric secretion?

Presence of digested proteins and fats in the duodenum Signup and view all the answers

Which local hormones are involved in inhibiting gastric secretion during the intestinal phase?

Secretin, gastric inhibitory peptide, and cholecystokinin Signup and view all the answers

What role does saliva play in the digestive process?

It helps lubricate food for easier swallowing. Signup and view all the answers

Which pair of salivary glands produces watery saliva rich in alpha-amylase?

Parotid and submandibular glands Signup and view all the answers

What type of fluid do acinar cells produce in the salivary glands?

Isotonic fluid Signup and view all the answers

Which factor does NOT influence the final composition of saliva?

Type of food consumed Signup and view all the answers

What type of saliva does the sympathetic nervous system stimulate?

Thick mucous saliva Signup and view all the answers

During the pharyngeal stage of swallowing, what action is performed by the soft palate?

It moves upwards to seal off the nasopharynx. Signup and view all the answers

What characterizes the muscularis layer of the esophagus?

It includes a mix of striated and smooth muscle. Signup and view all the answers

Salivation can be stimulated by which of the following factors?

Fear or anxiety Signup and view all the answers

What is the primary function of alpha-amylase in saliva?

It initiates the breakdown of carbohydrates. Signup and view all the answers

What is the average daily secretion of saliva in milliliters?

1500 ml Signup and view all the answers

What role do zymogenic (chief) cells play in gastric juice production?

They secrete pepsinogen. Signup and view all the answers

Which of the following substances can contribute to tooth decay when misused?

Chewable antacids. Signup and view all the answers

What is the primary function of the parietal cells in the gastric glands?

Secretion of intrinsic factor and HCl. Signup and view all the answers

What is the role of gastrin in the stomach?

It stimulates gastric acid secretion. Signup and view all the answers

What is the main reason the stomach does not digest itself?

It has a mucosal barrier. Signup and view all the answers

Which type of cell is responsible for secreting mucous in the gastric glands?

Goblet (neck) cells. Signup and view all the answers

Which medication type potentially leads to oral health issues like dry mouth?

Antihistamines. Signup and view all the answers

What is the primary function of gastric lipase?

To initiate fat digestion. Signup and view all the answers

Which of the following is a recommended practice for dental hygiene?

Reduce intake of dehydrating drinks. Signup and view all the answers

In which part of the stomach are parietal cells most concentrated?

The body of the stomach. Signup and view all the answers

Study Notes

### Mouth - Saliva Production and Function

Saliva is produced by three pairs of salivary glands: parotid, submandibular, and sublingual.
Approximately 1500ml of saliva is secreted each day.
Saliva contains mucus for lubrication, alpha amylase for carbohydrate breakdown, and other enzymes.
Saliva formation begins as an isotonic fluid produced by acinar cells that secrete electrolytes and water.
The final composition of saliva depends on flow rate and neuronal input.
Saliva secretion is regulated by the autonomic nervous system (ANS).
Parasympathetic stimulation produces watery saliva, rich in amylase and mucous.
Sympathetic stimulation produces thicker mucous and reduces blood flow to the glands.

### Swallowing

Swallowing is a coordinated reflex controlled by the deglutition center in the medulla and pons of the brain.
The voluntary stage involves pushing the bolus of food backwards to the oropharynx.
During the pharyngeal stage, the soft palate and uvula move up to seal off the nasopharynx, the larynx raises and the glottis is sealed, and the epiglottis covers the glottis.

Oral Absorption of Drugs

Drugs delivered buccally or sublingually need to cross the oral mucosa to enter the bloodstream directly.
This bypasses the digestive system and avoids first-pass metabolism, leading to greater bioavailability and faster action.
Limited surface area of the oral mucosa (~200cm²) is a barrier to absorption.
Drug solubility in saliva and its passage through the lipophilic cell membrane and hydrophilic interior of cells are other barriers.
Enzymatic barrier in buccal tissue can rapidly degrade peptides and proteins, limiting their transport across the epithelium.

Dental Problems

Dry mouth (xerostomia) can lead to oral ulcers, dental caries, and complications with digestion and drug absorption.
Oral ulcers often resolve without treatment but may require intervention in some cases.
Oral thrush, a yeast infection, can be caused by antibiotic overuse, a weakened immune system, underlying illness, smoking, or dentures.
Tooth decay can be caused by some medications including antacids, pain medications like opioids, antihistamines, and asthma inhalers.

### Dental Hygiene Advice

Drink plenty of water.
Brush your teeth twice a day and get regular dental check-ups.
Use a moisturizing mouth spray.
Reduce or give up smoking.
Reduce intake of caffeinated and dehydrating drinks like coffee, tea, and alcohol.
Use a hydrating mouth rinse.

### Stomach - Physiology and Function

The stomach temporarily stores food, performs mechnical digestion, chemically digests proteins, regulates the passage of chyme into the small intestine, and secretes intrinsic factor necessary for vitamin B12 absorption.
Muscularis layer enables churning of food, particularly in the antrum where the muscle wall is thicker.
Food is mixed with gastric juice to produce chyme, which passes through the pyloric sphincter into the duodenum.

Gastric Glands

The stomach mucosa is composed of epithelium containing pits/glands.
Gastric glands contain three key cell types: zymogenic (chief/peptic) cells, parietal (oxyntic) cells, and goblet (neck) cells.
Zymogenic cells secrete pepsinogen.
Parietal cells secrete HCl and intrinsic factor.
Goblet cells secrete mucous.

Additional Gastric Gland Cells

G cells secrete gastrin.
Enterochromaffin-like cells secrete histamine.
D cells secrete somatostatin.

Gastric Acid Production

HCl secretion is facilitated by a proton pump in parietal cells.
HCl converts pepsinogen to pepsin, which actively breaks down proteins in the acidic environment of the stomach.

Stomach Protection

A mucosal barrier prevents leakage of gastric juice onto underlying tissue.
Mucus secreted by epithelial/goblet cells provides a localized neutralisation and physical barrier to acid.
Prostaglandins increase mucosal thickness and stimulate bicarbonate secretion.

Gastric Secretion Phases

Cephalic Phase: Stimulated by sight, smell, taste, thought of food, or decreased blood glucose. This leads to increased parasympathetic stimulation of HCl and pepsin secretion.
Gastric Phase: Stimulated by stomach distension and presence of food. This triggers further HCl, pepsin, and gastrin secretion.
Intestinal Phase: This phase inhibits gastric secretion and begins when chyme containing fat or enough HCl to lower the pH below 2 enters the duodenum.
- Neuronal impulses from the gut wall decrease parasympathetic stimulation.
- Local reflexes in the gut wall lead to decreased secretion.
- Hormones like secretin, gastric inhibitory peptide, and cholecystokinin inhibit gastric gland secretion.

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Description

This quiz explores the anatomy and physiology of saliva production and the swallowing process. It covers salivary glands, components of saliva, and the stages involved in swallowing. Test your understanding of how these bodily functions are regulated and coordinated.