Topic 51 - Food intake, salivary secretion, process of swallowing

Question 1

Words to include in food intake

Answer 1

• Chewing
• Brain stem
• Reflex inhibition
• Stretch receptors
• Stretch reflex
• Bolus

Question 2

Words to include in process of swallowing

Answer 2

• Mouth
• Pharynx
• Espohagus
• Stomach
• Larynx
• Glottis
• Epiglottis
• Pharyngoesophagial sphinter
• Bolus
• Contraction
• Relaxation
• Voluntarly
• Reflex mechanism (involutarly)
• Saliva
• Peristaltic wave
• Pillars of fauces
• Tonsils
• Soft palate
• Tongue

Question 3

Words to include in saliva

Answer 3

• Serous secretion
  
  • Parotid gland
  • Mandibular gland
• Mucous secretion
  
  • Buccal gland
  • Labial gland
• Seromucous secretion
  
  • Sublingual gland
• Enzymes
• Ptyalin (α-amylase) (pig, rabbit, rat)
• Lipase (young ru)
• Iodine
• Heavy metals
• IgA
• Lysozyme
• Urea (ru)
• 1-4 glycosidic bonds
• Mucin
• Mucinous salivary glands
• Acinous glands

Question 4

Words to include in salivary secretion

Answer 4

• Bi-phasic process
• Acini
• Tubules
• Filtration
• Secretion
• Diffusion
• Reabsorption
• Double capillarization
• Primary secretion
• Secondary secretion
• pH
• Taste buds
• Olfactory epithelium
• Hearing/vision
• Hypothalamus
• Salivary reflex
• Na⁺
• Cl^-
• Phosphate (Ru)
• HCO₃^. (bicarobonate) (Ru)
• Ptyalin
• Mucin
• Parasympathetic saliva
  
  • Atropinge
  • Muscarine receptors
  • Acetylcholine
  • IP3 activating system
• Sympathetic saliva
  
  • Noradrenaline
  • cAMP system
• Aldosterone

Question 5

Topics to include in the essay

Answer 5

1. Food intake
2. Process of chewing
   
   • Figure
3. Process of swallowing
4. Saliva
   
   • Role of saliva
   • Composition of saliva
   • Salivary secretion
     
     • Glands secreting saliva
     • Primary and secondary saliva
     • pH of saliva
     • Regulation of salivary secretion
       
       • Parasymp. and symp. saliva
     • Aldosterone

Question 6

Food intake in different species

Answer 6

• Cats
  
  • Eat regularly in smaller amounts
  • They may use their front-paws to grab the food
• Dogs
  
  • Eat quickly, and great amounts on one occasion
  • They may use paws
• Pigs
  
  • Use nose ring to nuzzle and grab the food with the help of their extended lower lip
• Horses
  
  • Encircle food with their lips, and bite it of with their corner teeth
• Ruminants
  
  • Pull food with the tongue, and press it against their lower incisors and the dental plate to tear it off

Question 7

Process of chewing, figure

Answer 7

Question 8

Process of swallowing

Answer 8

• Arrange sequence of motions in the mouth, pharynx and the esophagus
  
  • Passes the bolus from the mouth to the stomach
• Controlled contractions and relaxations of the muscles
• Receptors are found in:
  
  • Pillars of fauces
  • Tonsils
  • Soft palate and tongue

Phase 1:

1. Bolus from oral cavity → pharynx
   
   • Swallowing begins voluntarily
   • Fragments of feed are mixed with saliva and forms bolus
   • Soft palate rises and closes the nasopharyngeal opening
   • Breathing is inhibited
   • Larynx rises and the glottis closes
   • Involuntarly
2. Bolus from pharynx → esophagus
   
   • Soft palate rises and closes the dorsal opening of the nasal-pharyngeal cavity
   • Breathing is inhibited
   • Larynx rises and the glottis closes
3. Passing bolus in esophagus

Question 9

Role of saliva

Answer 9

1. Digestion:
   
   • Chewing
   • Swallowing
   • Bolus formation
2. Taste sensation
3. Mouth hygiene
4. Ru: Buffer capacity of the forestomach
5. Ru: antifoaming
   
   • Inhibits formation of small gas bubbles (foam)
6. Car: thermoregulation (panting)
7. In the mouth:
   
   • Moisten
   • Washing off bacteria
   • Antibodies (IgA, IgG)
   • Bacteriolytic enzymes
     
     • E.g. Lysozyme

Question 10

Glands and secretion

Answer 10

• Serous
  
  • Parotid gland
  • Mandibular gland
  • Contains ptyalin
  • Cleaves the 1-4 glycosidic bonds of carbohydrates
• Mucous
  
  • Buccal gland
  • Labial gland
  • Contains mucin
• Seromucous
  
  • Sublingual gland

Question 11

Primary saliva secretion

Answer 11

• Produced by:
  
  • Diffusion
  • Secretion

Question 12

Secondary saliva secretion

Answer 12

Electrolytes composing the primary saliva is changed in the tubules

Question 13

Saliva secretion activation

Answer 13

• Activated by a unconditional reflex mechanism
• Generated by receptors:
  
  • Taste buds of the tongue
  • Olfactory epithelium
  • Hearing/vision
• Sense stimulus → higher centers → hypothalamus → salivary reflex

Question 14

pH of saliva

Answer 14

• Monogastric animals: 7.2
  
  • pH is equal with the blood pH
• Ruminants: 8.2
  
  • High buffer capacity of the saliva

Question 15

Interspecies saliva secretion

1. Highest amount
2. Lowest amount

Answer 15

1. Highest: cattle (60-180 l/day)
2. Lowest:
   
   1. Chicken
   2. Sheep
   3. Pig

Question 16

Regulation of salivary secretion

Answer 16

• Parasympathetic saliva
  
  • Produce high amount of saliva, poor in mucin, slightly viscous
    
    • Can be blocked by atropine
  • ​Acetylcholine binds to muscarine receptors, via the IP3 activating system
  • Increases IC Ca²⁺ → Increases Cl^- and Na⁺ secretion to lumen
• Sympathetic saliva
  
  • Small amount of saliva, rich in mucin, viscosity is high
  • By noradrenaline
  • Stimulated by cAMP system
• ​Aldosterone
  
  • ​Aldosteroneconcentration of blood modifies theNa⁺ absorptionin thetubules