Physiology of Swallowing

Question 1

α-Amylase (Ptyalin) –

Answer 1

Hydrolyses starch
Inactivated at pH <4

Question 2

Mucin

Answer 2

Lubricates food
Assists mastication
Facilitates deglutition
Aids speech (By facilitating movements of lip &tongue)
Protects oral mucosa by neutralising acid

Question 3

Lactoferrin

Answer 3

binds iron & arrests bact. multiplication & dental caries (bacteriostatic) Keeps mouth moist Solvent for molecules that stimulate taste buds. Vehicle for excretion of heavy metals(lead),viruses (polio,rabies ) & drugs.

Question 4

IgA

Answer 4

confers local immunity

Question 5

Lingual lipase

Answer 5

digestion of fat (active in stomach)

Question 6

Proline rich protein

Answer 6

binds toxic tannin & maintains oral pH

Question 7

Nerve growth factor

Answer 7

growth of sympathetic ganglia
Regulation of water balance
Middle ear pressure adjustment
Regulation of temperature (mainly in animals)

Question 8

Kallikrein

Answer 8

requires acidic pH activates bradykinin, potent vasodilator, Kallikrein is released when the metabolism of the salivary glands increases; it is responsible in part for increased blood flow to the secreting glands. Saliva also contains the blood group substances A, B, AB, and O.

Question 9

Anions

Answer 9

Chloride, Bicarbonate, Phosphate,
Halides (Iodine& Fluorine)

Question 10

Cations

Answer 10

Sodium, Potassium, Calcium, Magnesium

Question 11

Unique properties of Salivary secretion

Answer 11

Large volume relative to mass
Low osmolality
High potassium concentration
Specific organic material

Question 12

Primary secretion

Answer 12

Acinar cells
Isotonic to plasma
Secrete Ptyalin, mucus and ions

Question 13

Secondary Secretion-Modification by duct cells

Answer 13

Duct system
Rate of flow
Hypotonic to plasma

Question 14

Acinar-Primary secretion

Answer 14

Basolateral membrane
Na-K pump
Na-K-2Cl symporter
Apical membrane
Cl and HCO3- anion channel
Sodium and water paracellularly

Question 15

Modification by duct cells- Secondary secretion

Answer 15

Na-K pump
Apical membrane
Na-H Na and Cl reabsorption
Cl- HCO3- K and HCO3- secretion
H-K
Aldosterone

Question 16

rough objects cause

Answer 16

less salivation and occasionally even inhibit salivation

Question 17

The salivatory nuclei are located approximately at the juncture of the medulla and pons and are

Answer 17

excited by both taste and tactile stimuli from the tongue and other areas of the mouth and pharynx.

Question 18

sour taste (caused by acids), elicit

Answer 18

copious secretion of saliva—often 8 to 20 times the basal rate of secretion

Question 19

Theappetite areaof the brain

Answer 19

is located in proximity to the parasympathetic centers of the anterior hypothalamus, and it functions to a great extent in response to signals from the taste and smell areas of the cerebral cortex or amygdala.

Question 20

The parasympathetic preganglionic fibers are delivered by

Answer 20

the facial and glossopharyngeal nerves to autonomic ganglia

Question 21

The sympathetic preganglionic nerves originate

Answer 21

at the cervical ganglion

Question 22

Sympathetic saliva activity

Answer 22

is thicker compared to saliva produced during increased parasympathetic activity. The sympathetic nerves originate from the superior cervical ganglia and travel along the surfaces of the blood vessel walls to the salivary glands.

Question 23

Reflex secretion

Answer 23

Condition reflex
Cephalic phase
No gastric and intestinal phase

Question 24

Sympathetic

Answer 24

Norepinephrine
β-adrenergic
cAMP
Protein ≫ fluid secretion

Question 25

Deglutition reflex

Answer 25

Stimulus : food in mouth Receptor : touch receptors Afferents : V, IX and X cranial nerve Centre : deglutition center, medulla & lower pons Efferents : V, IX, X and XII Effector organ : pharyngeal muscles Response : involuntary stage of swallowing

Question 26

Swallowing center is located in the

Answer 26

Medulla

Question 27

Stage II- pharyngeal

Answer 27

Involuntary Soft palate elevated – nasal cavity Larynx rises Vocal cords approximated Breathing inhibited Deglutition apnea Epiglottis closes the laryngeal opening

Question 28

Stage III- Esophageal stage

Answer 28

Pressure is lower than in the pharynx and stomach Esophagus withstand the entry of air and gastric contents The barrier functions by the presence of sphincters Muscle an inner layer circular and outer longitudinal UES thickened circular muscle (cricopharyngeal) is striated The distal third is smooth muscle lower esophageal sphincter (LES) The middle third is composed of a mixture of muscle types Transport by peristalisis- primary and secondary

Question 29

The function of the UES

Answer 29

Separates the pharynx and the upper part of the esophagus is the UES Striated muscle and high resting tone Constricts and prevents entry of air into the stomach During swallowing- UES relaxes and glottis is closed Reflexly relaxes- neutrally mediated

Question 30

The function of the LES

Answer 30

To prevent reflux of gastric contents into the esophagus. Remains tonically contracted. The LES maintains a resting tone that is the result of both intrinsic myogenic properties of the sphincteric muscle and cholinergic regulation. Basal tone- vagal Ach fibers Gastrin increases tone Secretin decreases- relaxation To permit coordinated movement of ingested food into the stomach from the esophagus after swallowing Deglutition or distention of esophagus- causes relaxation

Question 31

Relaxation of the LES is mediated by

Answer 31

he vagus nerve mediated by VIP and by NO.

Question 32

Propulsive segment mechanism

Answer 32

Part behind the bolus (stimulus) Circular contract Longitudinal muscle relax

Question 33

Receiving segment mechanism

Answer 33

In front of bolus Receives bolus Circular muscles relax Longitudinal muscles contract

Question 34

Retrograde direction of neurotransmitters deynin

Answer 34

Release substance P and Ach Contraction of circular smooth muscle Propulsion of food

Question 35

Sympathetic stimulation

Answer 35

Inhibits peristalsis

Question 36

Anterograde direction of neurotransmitters kinesin

Answer 36

VIP and NO Relaxation of circular smooth muscle

Question 37

Parasympathetic stimulation

Answer 37

Stimulates peristalsis

Question 38

PRIMARY Esophageal peristalsis

Answer 38

Initiated by deglutition reflex When bolus enters esophagus, contraction is initiated Acts of swallowing initiates Vagal fibers

Question 39

SECONDARY Esophageal peristalsis

Answer 39

When food remains after primary peristalisis Mechanoreceptors activated by food Intrinsic nerves

Question 40

Hormones that increase LES Pressure

Answer 40

Gastrin, Motilin, Substance P, Histamine and Antacids protein meals α-adrenergic agonists β-adrenergic antagonists Cholinergic agonists

Question 41

What modulators decrease LES pressure

Answer 41

Secretin Cholecystokinin Somatostatin Vasoactive intestinal peptide (VIP) Progesterone β-adrenergic agonists α-adrenergic antagonists Anticholinergic agents Fat Chocolate Peppermint Theophylline Prostaglandins E2, I2

Question 42

Esophageal achalasia

Answer 42

achalasia-Disordered peristalsis and increased lower esophageal sphincter tone. Result of defective innervation of smooth muscle in the esophageal body and LES esophageal sphincter. LES is tightly contracted and does not relax in response to swallowing due to partial loss of neurons in the wall of the esophagus. Disorder caused by defective inhibitory pathways of the esophageal enteric nervous system. Injecting botulinum toxin into the LES diminishes the activity of the excitatory pathways Loss of normal peristalsis in the esophageal body is often seen in achalasia,

Question 43

Reflux esophagitis

Answer 43

Inappropriate lower esophageal sphincter relaxation results (decreased/loss of tone) .

Question 44

Gastroesophageal reflux disorder (GERD)

Answer 44

Normally LES is tonically contracted. Occurs when the LES allows the acidic contents of the stomach to reflux back into the distal part of the esophagus. Reflux of acid content Loss of LES tone (ie, the opposite of achalasia) Increased frequency of transient relaxations Loss of secondary peristalsis after a transient relaxation Increased stomach volume or pressure, or increased acid production. Recurrent reflux can damage the mucosa, resulting in inflammation. Commonly referred to as heartburn or indigestion