GI Exam Lecture 2 Flashcards
Cephalic Phase:
- Activation of the GI tract in readiness for the meal
- The stimuli are cognitive and include:
- All of these can trigger responses in the GI system in the absence of food ingestion
Cephalic Phase:
- Activation of the GI tract in readiness for the meal
- The stimuli are cognitive and include:
- Idea of food
- Olfaction
- Visual stimuli
- Auditory stimuli
- All of these can trigger responses in the GI system in the absence of food ingestion
Oral Phase:
- Many of the responses are ______, only difference is _________
- Additional activation of the GI from sensory inputs from ______ and ________ in the mouth and upper pharynx
Oral Phase:
Many of the responses are the same as in the Cephalic phase, only difference is food is present in the mouth (activation of mechanoreceptor, chemical receptors)
- Additional activation of the GI from sensory inputs from taste buds (tongue) and mechanical receptors in the mouth and upper pharynx
Chewing:
- Breaking of food into small pieces - mechanical digestion
- Mixing of food with enzymes- salivary ______ and lingual _____
- Mixing of food with salivary _____ (lubrication - helps in chewing and swallowing)
- No absorption in mouth except for ___ and ____
Chewing:
- Breaking of food into small pieces - mechanical disruption
- Mixing of food with enzymes - salivary amylases and lingual lipase (modest digestion in healthy)
- Mixing of food with salivary Mucin (lubrication)
- No absorption in mouth except for alcohol and some drugs (clinically relevant)
Chewing:
- Enhancement of the GI system, tonsils sense ______ to start training the ________
In the Clinic: Explain “xerostomia or dry mouth”
Chewing:
Enhancement of the GI system, tonsils sense foreign particles to start training the immune system
In the Clinic: Xerostomia or dry mouth - impaired salivary secretion - congenital or autoimmune. The decrease in secretion reduces pH in the oral cavity- causing tooth decay, esophogeal erosions, difficulty swallowing
Salivary Secretion:
- Considerable stimulation of salivary secretion occurs during _____ and ____ phases of a meal
- There are three pairs of major salivary glands:
- Extrinsic (90%):
- Intrinsic (in the mouth) (10%)
*
Salivary Secretion:
- Considerable stimulation of salivary secretion occurs during Cephalic and Oral phases of a meal
- There are three pairs of major salivary glands:
- Extrinsic (90%)
- Parotid (serous)
- Submandibular (mixed)
- Sublingual (mucous)
- Intrinsic (in the mouth) (10%)
- Additional smaller glands are found in the oral and buccal mucosa (constant rate)
Salivary Secretion:
- There are two types of secretions:
- Mixed - _______ glands
Salivary Secretion:
- There are two types of secretions:
- Serous (water, electrolytes, enzymes): parotid glands
- Mucous (mucin glycoprotein) - sublingual glands
- Mixed - Submandibular glands
- Papillae secrete saliva _____
- Salivary glands secrete ________
- Saliva is filtered _____
- Saliva contains _______ (pain killer)
- More nerve endings than anywhere else
- Papillae secrete saliva continuously
- Salivary glands secrete when needed (neuroregulation)
- Saliva is filtered blood
- Contains opiorphin (pain killer)
- More nerve endings than everywhere else
Salivary glands are formed by two main anatomical structures:
- __________ (secretory unit)
- and a network of _______ that
Salivary glands are formed by two main anatomical structures:
- acinus (secretory unit)
- and a network of collecting ducts that empty the secretory juice into the gut
Glandular Architecture:
- The _____ is the blind end of the branching duct system, lined with ____
- The acinar cells produce _____ composed of water, ions, enzymes, mucus
- The initial saliva passes through the _____ then the ______ lined with ductal cells
- The ductal cells modify initial saliva and produce ____ by altering electrolyte concentrations
- The acinus is the blind end of the branching duct system, lined with acinar cells
- The acinar cells produce initial saliva, composed of water, ions, enzymes, mucus
- The initial saliva passes through the intercalcalated duct then the striated duct - lined with ductal cells
- The ductal cells modify initial saliva and produce final saliva by altering electrolyte concentrations
Myoepithelial cells:
- Are present in the ___ and _____
- These cells contain ____ and ____ fibers which allows them to contract
- When stimulated by neural input, the ____ to ___
Myoepithelial cells:
- Are present in the acini and intercalcalated discs
- These cells contain actin and myosin fibers, which allows them to contract
- When stimulated by neural input, they contract to expel saliva in the forward direction
Salivary Secretion:
Saliva is produced by the salivary glands at a rate of ____ per day
Functions of Saliva are:
1.
2.
3.
Salivary Secretion:
Saliva is produced by the salivary glands at the rate of 1L per day
Functions of Saliva are:
- Lubrication of ingested food with mucus to aid its movement through esophagus (also required for speech)
- Protection: diluting and buffering of ingested foods, cleans mouth
- Initial digestion of starches and lipids by salivary enzymes - not a major contribution
Minor one: painkiller
Composition of Saliva:
- Inorganic Composition is entirely dependent on the _____ and ____ of salivary flow
- -The major inorganic components are:
The major organic constituents include:
Composition of Saliva:
- Inorganic Composition is entirely dependent on the stimulus and rate of salivary flow
- major inorganic components are Na, K, Mg, Cl
- fluoride can be secreted
Major Organic Constituents Include:
- salivary a-amylase (starch digestion)
- Lingual Lipase (lipid digestion)
- Glycoprotein (mucin forms mucous when hydrated)
- Lysozyme (attacks bacterial wall)
- Opiates
Formation of Saliva:
- In humans, salivary secretion is hypertonic/hypotonic
- _____ K and HCO3- concentrations
- ______ Na and Cl concentrations
Saliva is formed in a ______ process:
- The first step is the formation of an _____ like plasma solution by acinar cells : known as _______
- The second step is a modification of this plasma-like solution by the ductal cells to produce _____
Formation of Saliva:
In humans, salivary secretion is hypotonic
- Higher K+ and HCO3- concentrations
- Lower Na and Cl concentrations
Saliva is formed in a two step process
- The first step is the formation of an isotonic plasma like solution by the acinar cells - known as primary secretion or initial saliva
- The second step is the modification of this plasma like solution by the ductal cells to produce hypotonic final saliva
Formation of Saliva:
Step 1: Initial Saliva:
- The _______ secrete initial saliva, which is ____
- Thus, in initial saliva, osmolarity, Na, K, Cl, HCO3 concentrations are _____
Formation of Saliva:
Step 1: Initial Saliva:
- The acinar cells secrete initial saliva, which is isotonic
- Thus, in initial saliva: osmolarity, Na+, K+, Cl-, HCO3- concentrations are similar to plasma
Formation of Saliva:
Step 2: Final Saliva
- The ductal cells modify initial saliva via ______
The luminal membrane contains three transporters:
1.
2.
3.
The basolateral membrane contains the ____ and ____
The combined action of all of these results in absorption of ______ and secretion of ______
More ____ is absorbed than _____ is secreted, so there is net absorption of solute
Step 2: Final Saliva:
The ductal cells modify initial saliva via complex transport mechanisms
The luminal membrane contains three transporters
- Na-H exchange
- Cl-HCO3 exchange
- H-K exchange
The basolateral membrane contains the Na-K ATPase and Cl- ion channels
The combined action of all of these results in absorption of Na and Cl- and secretion of K+ and HCo3-
More NaCl is absorbed than KHCO3 is secreted, so there is a net absorption of solute
Step 2: Final Saliva:
The ductal cells modify initial saliva via complex transport mechanisms
The combined action of all of the transporters results in absorption of ____ and secretion of _______
More ___ is absorbed than _______ is excreted, so there is a _____ of solute
Step 2: Final Saliva:
The ductal cells modify the initial saliva via complex transport mechanisms
The combined action of all of the transporters results in the absorption of Na and Cl and the secretion of K+ and HCO3-
More NaCL is reabsorpted than KHCO3 is secreted, so there is a net absorption of solute
Step 2: Final Saliva
The ductal cells are water-_______, thus
The combination of these two makes saliva ___-
Step 2: Final Saliva:
The ductal cells are water impermeable, thus water is not absorbed with the solute
The combination of these two makes final saliva hypotonic
Regulation of Salivary Stimulation:
- Control of salivary secretion is _______ (exception in the GI system- other GI secretions are both neural and hormonal)
- Salivary secretion is stimulated by __________ subdivisions of the ANS, although _____ is dominant
- There is both ____ and _____ activation of acinar and ductal cells
- Stimulation of salivary cells results in increased ____, increased ______, and contraction of _____
Regulation of Salivary Stimulation:
- Control of salivary secretion is exclusively neural
- Salivary secretion is stimulated by both parasympathetic and sympathetic subdivisions of the ANS, although parasympathetic stimulation is dominant
- There is both PSNS and SNS innervation of acinar and ductal cells
- Stimulation of salivary cells results in increased saliva production, increased HCO3- and enzyme secretions, and contraction of myoepithelial cells
Regulation of Salivary Secretion:
- Parasympathetic Innervation:
branches of _____ and _______
post ganglipnic neurons release _____ which then interacts with _____ receptors: production of ____ and increased intracellular ____ increases saliva secretion
Parasympathetic Regulation of Saliva Secretion:
Parasympathetic Innervation:
Branches of Facial (CN7) and Glossopharyngeal (CN9)
post ganglionic neurons release ACh which interacts with muscarinic receptors — production of IP3 and increased intracellular Ca++ increases saliva production
Regulation of Salivary Secretion:
Sympathetic Innervation:
originates in thoracic segments T1-T3
preganglionic nerve synpase in superior cervical ganglion
post ganglionic neurons release _____ which interacts with _____ receptors
produces ______ which increases saliva secretion
Regulation of Salivary Secretion:
Sympathetic Innervation:
originates in T1-T3, preganglionic nerves synapse in superior cervical ganglion
post-ganglionic neurons release NE which interacts with beta-adrenergic receptors
produces cAMP which increases saliva secretion
Swallowing:
- Swallowing can be initiated voluntarily, and after that it is almost entirely under ______ control
- The swallowing reflex: propels food from ___ to ____ and then to ____. It inhibits ____
- ______ of the reflex- begins when touch receptors near the opening of the pharynx are stimulated-sensory impulses transmitted to the ______ (in the medulla and lower pons)
- _______ from swallowing center travel to pharnyx and upper esophagus (via ___ nerves) and to the remaining esophagus (via _____ neurons)
Swallowing:
- Swallowing can be initiated voluntarily, and after that it is almost entirely under reflex control
- The swallowing reflex: propels food from mouth to pharnyx and then to stomach. It inhibits respiration-inhibits food entrance into trachae while swallowing
- Afferent limb of the reflex: begings when touch receptors near the opening of the pharynx are stimulated- sensory impulses transmitted to the swallowing center (in the medulla and lower pons)
- Motor impulses from swallowing center travel to the pharnyx and upper esophagus (via cranial nerves) and to the remaining esophagus (via vagal motor neurons)
Draw the flowchart describing Long Reflex Control (explaining the swallowing reflex)
Words from class:
“when the stretch receptor in the pharynx is activated, sensory signals are sent to the swallowing center (in the medulla and pons)
the swallowing center then does various things:
sends signals to cortex to stop breathing
vagal input to start nonvoluntary swallowing
Different Phases of Swallowing:
There are 3 phases in swallowing: ____, ____, _____
Explain the first two in detail
Different Phases in Swallowing:
There are three phases in swallowing: oral, pharyngeal, esophageal
Oral phase (voluntary): this is initiated with the tongue forces a bolus of food back towards the pharynx - activates stretch receptors- initiates involuntary swallowing reflex
Pharnygeal phase (involuntary < 1 sec): the soft palate is pulled upwards and the palatopharnygeal fold moves inward, creates narrow passage- prevents reflux into nose, food moves into pharnyx
- Epiglottis moves to cover larynx, larynx moves upwards against epiglottis - preventing food entry into trachae. Respiration is inhibited.
Different Phases in Swallowing:
- The ________ relaxes to receive the food bolus
- A ________ wave of contraction is initiated, which forces the bolus through the relaxes UES
- After the bolus crosses the UES (pharyngeal phase) the swallowing reflex closes the sphincter, prevents reflex into pharynx
- The upper esophageal sphincter (UES) relaxes to receive food bolus
- Pharnyx contracts, further enhancing propulsion of food into the esophagus. A peristaltic wave of contraction is initiated, which forces the bolus through the relaxed UES.
- After the bolus crosses the UES (pharnygeal phase) the swallowing reflex closes the sphincter - prevents reflux into the pharynx
