Pharmacy Year 1 Digestion Lectures

Flashcards for Pharmacy Year 1 Digestion Lectures delivered by Dr Kalia

Which muscles are involved in jaw closing during mastication?

Temporalis, masseters, and medial pterygoid muscles.

Which muscle is involved in jaw opening during mastication?

Lateral pterygoid muscle.

Which cranial nerve innervates the muscles of mastication?

The trigeminal nerve (5th cranial nerve).

How is mastication controlled?

Chewing is a repetitive and rhythmical motor activity controlled by the masticatory central pattern generator (CPG) in the brainstem.

What modifies the 'type of chewing'?

The cortex (voluntary control) and sensory feedback from dental/periodontal receptors.

What is the function of the Rhythm Generator in the masticatory CPG?

Generates basic rhythm; does not need sensory feedback; opens and closes the jaws.

What is the function of the Burst Generator in the masticatory CPG?

Adapts rhythm; controls 'bite'; refines motor output for food viscosity, size, temperature, etc.

How is deglutition (swallowing) coordinated?

Swallowing is coordinated by the swallowing center in the medulla and requires 25 different muscles.

What are the three phases of deglutition?

Oral (voluntary), pharyngeal (involuntary), and oesophageal (involuntary). It is an all-or-none reflex.

What happens during the pharyngeal phase of swallowing?

Food activates pressure receptors in palate/pharynx, sending impulses to the swallowing centre, which lifts the soft palate, raises the larynx, closes the glottis, and inhibits respiration.

What happens during the oesophageal phase of swallowing?

Peristaltic action pushes food down the oesophagus, controlled by the swallowing centre. The lower oesophageal sphincter (LOS) opens to allow food into the stomach.

What are the learning outcomes for Lecture 1 Part 2 on Functions and Secretion of Saliva?

Functions of Saliva, Salivary glands, Composition of saliva, Mechanisms of saliva secretion and Control of saliva secretion.

What are the functions of saliva?

Moistens and cleanses oral mucosa, cools food, aids chewing, lubricates food, solubilises food, aids taste, digests food (alpha-amylase, lingual lipase), and acts as an anti-bacterial agent.

What are the main causes of salivary hypofunction?

Head and neck cancer radiotherapy, autoimmune diseases (Sjogren’s, Lupus, RA), and drug therapy.

What are the symptoms of salivary hypofunction?

Dry mouth (xerostomia), difficulty swallowing dry foods, loss of taste, and constant thirst.

What are the three major pairs of salivary glands?

Parotids (serous), submandibular (mixed), and sublingual (mixed).

What is the composition of saliva?

800-1500ml/day; >99% water; ions (Na+, K+, HCO3-, Cl-, Ca2+, Mg2+, PO43-, I-); proteins (alpha-amylase, lipase, mucins, immunoglobulins); pH range 6.1 – 8.0.

What is the primary saliva secretion like, in terms of tonicity?

The primary saliva secretion is very much like plasma – isotonic saliva.

How is saliva modified as the primary secretion moves down the duct?

Na+, Cl- are removed, and K+, HCO3- are added.

What type of saliva is formed in the duct?

A hypotonic saliva is formed with a lower salt concentration than plasma.

What controls saliva secretion?

Pressure and chemoreceptors, input from the cerebral cortex, and exclusively under ANS control (predominantly parasympathetic).

Which celebirty suffers from Sjogren's syndrome?

Venus Williams diagnosed with Sjogren’s syndrome.

List medications that cause xerostomia.

Anti-Cholinergics, Anti-Parkinson’s, Bronchodilators, Anti-Histamines, Anti-Depressants, Anti-Psychotics, Analgesics/Sedatives, Decongestants, Anti-Hypertensives, Diuretics

What are some treatments for Xerostomia?

Chewing gum, sucking ice chips, water/glycerine spray, artificial saliva substitutes, Sialogogues

What are the learning outcomes for Lecture 2 Part 1 on Secretions in the Stomach?

Functions of the stomach, composition of gastric juice, secretion of acid and other components, and control of secretion.

What are the functions of the stomach?

Stores food, kills bacteria, liquefies food, mixes chyme with gastric secretions, regulates chyme release, produces intrinsic factor, and has very little digestion and absorption.

List the secretions of the stomach and the cells that secrete them.

Mucus/HCO3- (Goblet cells), HCl Acid (Parietal cells), Pepsinogen (Chief cells), Histamine (ECL cells), Gastrin (G-cells), Somatostatin (D-cells), Intrinsic Factor (Parietal cells).

What stimulates HCl production?

Gastrin, ACh, and Histamine.

How stimulatory signals are delivered to the parietal cell to induce HCl Secretion.?

Histamine released from ECL cells, ACh released from vagus nerve neurons, and Gastrin released from stomach G-cells.

How does the alkaline tide occur?

The alkaline tide happens because Efflux of lots of HCO3- from the parietal cells into the blood after eating a meal disturbs the plasma buffer system which increases plasma pH.

Acid secretion occurs in response to which stimuli?

Neural (ACh), Hormonal (gastrin) and Paracrine (histamine).

What are the 3 phases of acid secretion?

Cephalic, gastric and intestinal.

What happens during the cephalic phase?

Sight, smell, thought of food chewing and swallowing. This leads to the release of ACh from the vagus nerve which causes acid secretion directly through its actions on the parietal cells, or indirectly by releasing histamine and gastrin.

What happens during the gastric phase?

Food entering the stomach causes stretch/distension of the stomach, detected by mechanoreceptors, which leads to vagal ACh release. Also, as proteins in the diet begin to get broken down, the peptides and amino acids generated act as a strong stimulus for gastrin release.

What happens during the intestinal phase?

The entry of food laden with acid (i.e. a low pH chyme) leads to the release of secretin from duodenal cells. Fatty chyme leads to the release of cholecystokinin (CCK) from duodenal cells. Both these hormones enter the bloodstream and inhibit acid secretion from the stomach.

What is the treatment for peptic ulcers?

H2-receptor antagonists (cimetidine, ranitidine) and proton pump inhibitors (omeprazole, lansoprazole).

What are the learning outcomes for Lecture 2 Part 2 on Secretions in the Pancreas?

Functions of the Pancreas, Secretions of the Pancreas, Mechanism of Pancreatic Secretion and Control of Pancreatic Secretion.

Exocrine Gland vs Endocrine Gland?

Juices released into duodenum Hormones released into bloodstream

99% of cell mass vs 1% of cell mass

Acinar cells and duct cells vs Islets of Langerhans.

Juices released into duodenum vs Hormones released into bloodstream

Breaks down all categories of foodstuff. vs Insulin, glucagon, somatostatin.

What digestive enzymes does the Pancreas secrete?

Proteases, Lipases, Carbohydrases and Nucleases.

Control of Pancreatic Secretion what happens in the intestinal phase?

Located in the INTESTINAL PHASE: Presence of HCl in duodenum leads to somatostatin, secretin and CCK release.

What cells are stimulated in Pancreatic Secretion?

ACINAR CELLS stimulated primarily by CHOLECYSTOKININ (CCK) to release enzymes. DUCT CELLS are stimulated by SECRETIN to release a HCO3- rich juice.

What are the learning outcomes for Lecture 3 parts 1-3 on Absorption of CHO, Proteins, Lipids and H2O?

Digestion of Carbohydrates, Absorption of Monosaccharides, Digestion of Protein, Absorption of Amino acids, Digestion of Lipids, Problems associated with absorption of Lipids, Absorption of water and Diarrhoea.

Into what smallest possible unit you have to break them down or digest them into?

Monosaccharides, amino acids, di-peptides, tri-peptides, monoglyceride and fatty acids.

Progressive increase in absorptive surface area from least to greatest.

Simple cylinder, Folds of Kerckring, Individual villi and Microvilli.

Following digestion, food is absorbed either into the?

The central villous capillary (proteins and carbohydrates) vs the central lymphatic lacteal (lipids).

Dietary Carbohydrate / Saccharides are?

Starch, Glycogen and Fibres / Cellulose.

Enzymes involved in Carbohydrate Digestion?

Salivary amylase, Pancreatic amylase and Intestinal (brush border) enzymes.

Eaten a meal and the glucose is high in the intestinal lumen than the blood.

Concentration gradient Glucose Glucose Glucose Glucose

To valuable too leave behind in Intestinal lumen, what reaction has to happen.

Na+ K+ ATPase requires ATP

Active Transport requires ATP to create.

2 Na+ Glucose Galactose. or Facilitated Diffusion GLUT-5

Protein enters the gut daily in various forms, what are these?

Plasma proteins (1-2g), Diet, Digestive Enzymes Desquamated epithelial cells , Mucus, and Microorganisms.

Endopeptidases that attack bonds in centre of peptide chains?

Gatric pepsin and Pancreatic trypsin.

Exopeptidases that split AA one at a time

Pancreatic enzymes and Intestinal (brush border) enzymes

Whole Protein Absorption?

Few days after birth with whole milk protein and maternal antibodies by pinocytosis – invagination of cell membrane to form vesicles.

Dietary Lipids are made up of?

95% : Triglycerides – source of energy and 5% : Cholesterol and Phospholipids.

Essential Lipids are what vitamins and how do they effect lipid absorption?

Vitamin A – visual system, Vitamin D – Ca2+ metabolism, Vitamin E – nervous system and Vitamin K – blood clotting

What is the Key for Lipid Absorption?

Bile salts are essential for lipid absorption.

Steps in Lipid Absorption?

4. Absorption and Re-esterification : Diffusion of hydrophobic FA and MG into enterocyte and Lipids incorporated into biliary micelles for transport. 5. Lymphatic Uptake : Mucosal cell chylomicrons → intestinal lymphatic system.

Solubilising lipids is essential how are lipids moved from the gut lumen and eventually into the bloodstream

INSOLUBLE lipids were moved from the gut lumen and eventually into the bloodstream by SOLUBILISING them in the gut chyme within BILE SALT MICELLES and in lymph vessels using CHYLOMICRONS.

Fat Malabsorption can occur with?

liver and/or gallbladder disease, pancreatic disease and intestinal disease.

Absorption of water and ions compartment are?

Intracellular fluid compartment vs Extracellular fluid compartment.

Osmosis – the process of water from SI absorbtion is where

Paracellular moves between cells and Transcellular moves / through cells Aquaporins.

Importance of Na+ in H2O, ion and nutrient absorption?

Establishing a Na+ electrochemical gradient across the enterocyte is the single most important process for the subsequent absorption of H2O, ions and nutrients such as glucose and amino acids.

Sodium Absorption in Jejunum is performed by?

Travelling on a Na+ co-transporter is faster. Most Na+ co-transporters are located in the jejunum.

ORT how doe help?

Death from infection related diarrhoea and subsequent dehydration can be prevented.