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Physiology II- Week 4.2 Notes, Study Guides, Projects, Research of Physiology

Virginia State University (VSU)Physiology

Physiology II- Week 4.2 NotesPhysiology II- Week 4.2 Notes

Typology: Study Guides, Projects, Research

2024/2025

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Physiology II- Week 4.2 Notes
1. What stimulates the medulla oblongata during the cephalic phase?:
The taste, smell, or thought of food or tactile sensations of food in the
mouth.
2. What do vagus nerves carry to the stomach during the cephalic phase?: -
Parasympathetic action potentials.
3. What is activated in the stomach by the vagus nerves during the
cephalic phase?: Enteric plexus neurons.
4. What do postganglionic neurons stimulate in the stomach during the
cephalic phase?: Secretion by parietal and chief cells, and gastrin and
histamine secretion by endocrine glands.
5. How is gastrin carried back to the stomach during the cephalic phase?: -
Through the circulation.
6. What do gastrin and histamine stimulate in the stomach during the
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Physiology II- Week 4.2 Notes

  1. What stimulates the medulla oblongata during the cephalic phase?: The taste, smell, or thought of food or tactile sensations of food in the mouth.
  2. What do vagus nerves carry to the stomach during the cephalic phase?: - Parasympathetic action potentials.
  3. What is activated in the stomach by the vagus nerves during the cephalic phase?: Enteric plexus neurons.
  4. What do postganglionic neurons stimulate in the stomach during the cephalic phase?: Secretion by parietal and chief cells, and gastrin and histamine secretion by endocrine glands.
  5. How is gastrin carried back to the stomach during the cephalic phase?: - Through the circulation.
  6. What do gastrin and histamine stimulate in the stomach during the

cephalic phase?: Secretion.

  1. What stimulates mechanoreceptors in the stomach?: Distention of the stom- ach
  2. What type of reflex is activated by mechanoreceptors in the stomach?: - Parasympathetic reflex
  3. Which nerves carry action potentials from mechanoreceptors to the medulla oblongata?: Vagus nerves
  4. What does the medulla oblongata increase in the vagus nerves?: Action potentials
  5. What do increased action potentials in the vagus nerves stimulate?: Secre- tions by parietal and chief cells
  6. What hormones are stimulated by the medulla oblongata?: Gastrin and histamine
  7. What type of reflexes are activated locally in the stomach?: Local reflexes that increase stomach secretions
  8. How is gastrin transported back to the stomach?: Through the circulation
  1. What type of epithelium lines the oral cavity?: Stratified squamous epitheli- um
  2. What is keratinization in the oral cavity?: Keratinization occurs in areas exposed to severe abrasion.
  3. What are examples of areas in the oral cavity that are keratinized?: Roof of mouth and superior tongue surface
  4. What is prehension?: Prehension is the process of seizing or grasping or otherwise getting food into the mouth.
  5. What is mastication?: Mastication, or chewing, is the first step in the break- down of complex foodstuffs.
  6. Is chewing a reflex or a voluntary action?: Chewing is, to a large extent, a reflex, although you can voluntarily masticate as well.
  7. What is swallowing also known as?: Swallowing is also known as deglutition.
  8. How can swallowing be described?: Swallowing is a complex process that can be thought of as occurring in three steps.
  1. What is the process of mixing food with saliva called?: Mastication (chew- ing)
  2. What is the purpose of mixing food with saliva?: Lubricating it to facilitate swallowing
  3. What does mastication do to the size of food particles?: Reduces the size of food particles to facilitate swallowing
  4. What enzyme begins carbohydrate digestion in the mouth?: Salivary amy- lase
  5. What type of component is the involuntary aspect of mastication?: It in- volves reflexes where mechanoreceptors in the mouth relay sensory signals to the brain stem.
  6. What is the role of the voluntary component in mastication?: It involves conscious control of the muscles involved in chewing.
  7. Can voluntary chewing override involuntary chewing?: Yes, voluntary chew- ing can override involuntary or reflex chewing at any time.
  8. What happens to the bolus of food during the voluntary step of

arch

  1. Salivary glands secrete a large amount of saliva at the rate of:: 1-1. L/day (70% by submandibular glands)
  2. What digests starch/polysaccharides?: Salivary amylase
  3. What in the saliva neutralizes the acids produced by oral bacteria?: Bicar- bonate ions
  4. of ingested food with mucous aids its movement through the esophagus.: Lubrication
  5. Parasympathetic stimulation:: Increase salivary secretion
  6. Salivary reflex triggered by stimulation to:: Receptors monitored by trigemi- nal nerve (V) Taste buds innervated by cranial nerves VII and IX Higher centers of the brain also affect salivary gland activity -Odors that trigger thoughts of food or the sensation of hunger can increase saliva secretion
  7. What decreases the amount of saliva made in the mouth?: Atropine
  1. Atropine belongs to a class of medicines called:: Anticholinergics
  2. Net absorption of Na+ and Cl causes the Na+ and Cl concentrations of saliva to become:: Lower than their concentrations in plasma
  3. Net secretion of K+ and HCO3 causes the K+ and HCO3 concentrations of saliva to become:: Higher than those in plasma
  4. Because more NaCl is absorbed into the blood than KHCO3 is secreted:: - There is net absorption of solute
  5. The osmolarity of saliva to becomes:: Lower than in plasma
  6. What is the function of Alpha-Amylase?: Initiates starch digestion
  7. What pH is required for optimal activity of Amylase?: pH of 8
  8. What effect does low pH in the stomach have on - ±amylase?: Stops the activity of ±a-mylase after ~1-2 hours
  9. What is the function of Lingual Lipase?: Begins a minor amount of lipid digestion, primarily of milk fat
  10. How does Lingual Lipase function at low pH?: Continues to work at a low pH
  1. What is Secretory IgA?: A type of antibody produced by many tissues that protects the entrances and exits of the body.
  2. What is the function of Lysozyme?: It breaks down the polysaccharides in the cell walls of many bacteria.
  3. What is the role of Salivary Kallikrein?: It is a protease that cleaves high- mol- ecular-weight kininogen to produce bradykinin, which is a vasodilator.
  4. What does Lactotransferrin do?: It binds iron and has bacteriostatic proper- ties.
  5. What is Muramidase?: An enzyme that hydrolyzes cell wall polysaccharides of certain bacteria.
  6. What is the function of Proline-rich proteins in saliva?: They bind toxic tannins and protect tooth enamel.
  7. What are the three phases of swallowing: oral, pharyngeal, esophageal
  8. What is the process of food passing from the oral cavity to the esopha- gus?: Deglutination
  9. What two functions does the pharynx serve?: Respiration and digestion
  1. What is required for the mechanism of swallowing?: Precise coordination between breathing and swallowing
  2. What is the protective value of the swallow reflex?: It prevents aspiration of foreign materials into the airways
  3. What is the first phase of deglutination?: Oral Phase
  4. What happens during the oral phase of swallowing?: Food is chewed and mixed with saliva to form a bolus, which the tongue moves to the back of the mouth.
  5. Which cranial nerves control the oral phase of swallowing?: Cranial nerves V, VII, and XII
  6. What is the second phase of deglutination?: Pharyngeal Phase
  7. What initiates the pharyngeal phase of swallowing?: The medulla oblongata
  8. What is the purpose of elevating the soft palate during the pharyngeal phase?: To seal off the nasopharynx and prevent aspiration
  9. Which cranial nerves control the pharyngeal phase of swallowing?:
  1. What is secreted by the stomach for digestion?: Gastric juice
  2. What acid is produced in the stomach?: Hydrochloric acid
  3. What enzyme is secreted by the stomach to digest proteins?: Pepsin
  4. What is formed in the stomach during digestion?: Chyme
  5. What does the stomach do to food before it enters the small intestine?: - Empty food at a rate suitable for proper digestion and absorption
  6. What does the Orad Region of the stomach contain?: The fundus and the proximal portion of the body.
  7. What is the wall thickness of the Orad Region?: Thin walled.
  8. What does the Caudad Region of the stomach contain?: The distal portion of the body and the antrum.
  9. What is the wall thickness of the Caudad Region?: Thick walled.
  10. What is the function of the contractions in the Caudad Region?: To mix the food and propel it into the small intestine.
  11. What is the upper part of the esophagus made of?: Entirely of skeletal muscle (2-4 cm)
  1. What is the middle part of the esophagus made of?: Mixture of skeletal and smooth muscle
  2. What is the lower part of the esophagus made of?: Entirely smooth muscle (~11 cm)
  3. Bolus moves from the to the esophagus.: Pharynx
  4. The upper esophageal sphincter (UES) opens and is mediated by the:: - Swallowing reflex
  5. Once the bolus enters the esophagus, the UES closes and prevents:: Re- flux into the pharynx
  6. Food bolus is propelled by down the esophagus.: Peristalsis
  7. The primary peristaltic wave is coordinated by:: Swallowing reflex
  8. What is the secondary peristaltic wave mediated by?: Enteric nervous system
  9. What produces relaxation in the smooth muscle of the lower esophageal sphincter?: VIP
  10. Vagovagal reflex: When food enters the stomach, a "vagovagal reflex"
  1. What are the three layers of the muscularis of the stomach?: An outer longitudinal layer, a middle circular layer, and an inner oblique layer.
  2. What is the function of the inner oblique layer of the stomach?: Retropul- sion
  3. What is the topic of the histology discussed?: Stomach histology
  4. What is retropulsion in the context of the stomach?: An important mixing mechanism that involves the propulsion of chyme back into the stomach for further mixing.
  5. What is the purpose of retropulsion in the stomach?: To further mix chyme and reduce particle size.
  6. What triggers forceful retropulsion in the stomach?: Noxious stimuli or excessive distension.
  7. What is a protective mechanism associated with forceful retropulsion?: - Vomiting.
  8. What is the semifluid material formed in the stomach called?: Chyme
  1. What is the primary function of the stomach?: To store and mix chyme
  2. What substances can be digested and absorbed in the stomach?: Ethanol (ETOH) and Aspirin (ASA)
  3. What is the function of the pyloric sphincter?: Controls stomach emptying
  4. What is the state of the pyloric sphincter most of the time?: Remains slightly contracted
  5. What does the constriction of the pyloric sphincter prevent?: Passage of food particles
  6. What must food particles be mixed with to pass through the pyloric sphincter?: Chyme to an almost fluid consistency
  7. What is accommodation in gastric motility?: Relaxation of the upper region of the stomach to receive the food bolus from the esophagus.
  8. What is trituration in gastric motility?: Contractions that reduce the size of the bolus and mix it with gastric secretions to initiate digestion.
  9. What is gastric emptying?: Controlled emptying that propels chyme into the small intestine.
  1. What happens if the stomach empties too fast?: If the stomach empties too fast, the efficiency of digestion and absorption is reduced, and acidic gastric contents dumped into the duodenum may damage its lining.
  2. How long do liquids take to exit the stomach?: Liquids exit the stomach within 1-2 hours after ingestion.
  3. How long does it typically take for the stomach to empty after a meal?: - After a typical meal, the stomach is usually empty within 3-4 hours.
  4. What is the clearance time for a meal of carbohydrates from the stom- ach?: A meal of carbohydrates (starch and glycogen) has the fastest clearance time from the stomach, typically 1 hour.
  5. How long does it take for a meal heavy with dietary fats and proteins to clear from the stomach?: A meal heavy with dietary fats and proteins takes up to 6 hours to clear from the stomach.
  6. What factors influence the rate of gastric emptying?: The rate of gastric emptying is influenced by the presence of protein/amino acids, degree of distention of the duodenum, degree of acidity of the duodenal chyme,

degree of osmolality of the chyme, sympathetic stimulation, irritation of the duodenal mucosa, and elevated concentration of lipids.

  1. What pH level in the duodenum inhibits stomach emptying?: 3- 4
  2. What condition in the duodenum can inhibit stomach emptying?: Duode- nal distension
  3. What effect does duodenal hypertonicity have on stomach emptying?: It inhibits stomach emptying
  4. What increases the osmolarity of gastric chyme and inhibits stomach emptying?: Increased osmolarity of gastric chyme
  5. What concentration of lipids in the duodenum inhibits stomach empty- ing?: Elevated concentration of lipids
  6. What type of stimulation inhibits stomach emptying?: Sympathetic stimu- lation
  7. What type of stimulation promotes stomach emptying?: Parasympathetic stimulation
  8. What effect does decreased volume of gastric contents have on