Mouth Saliva And Oesophagus Flashcards
What is the function of a mouth
• ingestion of food
• digestion - mechanical + chemical
• formation of a bonus of food and the initiation of swallowing
NB-saliva, tongue
Explain function of tongue
- facilitates ingestion
- Gripping and repositioning good during chewing
- Mixing food with saliva and forming the bolus (mechanical digestion)
- Lingual lipase(chemical digestion)
- Sensation (taste, temperature, texture)
- Initiation of swallowing and speech
Explain the taste buds
- filiform- give the tongue roughness and provide friction
- Fungiform- scattered widely over the tongue and give it a reddish hue
- Circumvallate- v-shaped row in back of tongue
- Follate- only last 3 haver taste buds
Explain the process of taste transduction
- Ligand activates the taste cell
- Various intracellular pathways are activated
- Ca2+ signal in the gtoplasm triggers exocytosis or ATP formation
- Neurotransmitter or ATP is released
- Primary sensory neuron fires and a cheep potentials are sent to the brain
What do salivary glands do
- cleanses the mouth
- moistens and dissolves food chemicals
- aids in bonus formation
- contains enzymes that break down starch
Name the pairs of extrinsic and intrinsic salivary glands
- Submandibular,parotid, sublingual= extrinsic pairs
* buccal glands = intrinsic (scattered throughout the oral mucosa)
What is the location and function of salivary glands
Parotid= lies anterior to the ear between the masseter muscle and skin= function opens into vestibule next to the second upper molar Submandibular= lies along the medial aspects of the mandibular body= opens ather baser of the lingual frenulum Sublingual= lies anterior to the submandibular gland under the tongue= opens via 10-12 ducts into the floor of the mouth
Composition of saliva
- Mucus: lubricant, bolus formations, facilitates swallowing
- Salivary amylase: initiates digestion of complex carbohydrates
- Water and electrolytes: moistening of food solvent (taste)
- Lysozyme: kills bacteria
- Other functions: cleansing of mouth and teeth, assisting in speech
How do the intringio glands help in the control of secretion
They keep the mouth moist
How do the extrinsic glands control secretion
They secrete serous, enzyme rich saliva in response to:
- Ingested food which stimulates chemoreceptors and pressoreceptors
- The thought of food
What other factors assist in control of saliva secretion
Strong Sympathetic stimulation inhibits salivation and results in dry mouth
Reflex control of salivation → cephallo phase, oral phase, gastric phase.
Explain esophagus
• Muscular tuber (25cm) going from the largngophargnx to the stomach
• travels through the mediastinum and pierces the diaphragm
• Jains the stomach at the cardiac orifice
• contains stratified epithelium with mucus glands
Striated muscle in upper 1/3; smooth muscle in lower 2/3
Lower oesophagus sphincter
What are the phases of swallowing
Pharyngeal-oesophageal phase Oesophageal phase (peristalsis)
Explain the pharyngeal-esophageal phase
- All routes except into the digestive tracts are sealed off
- soft palate contracts
- Elevation of laying and closures of vocal chords
- sealing off of oral cavity from pharynx
- contraction of longitudinal muscles pulling pharynx upwards toward bolus
- relaxation of interior sphincter to open oesophagus
- contraction of superior constrictors to initiates peristaltic wave (primary peristalsis)
What happens during peristalsis
1.The reflex response initiated when gut wall is stretched
2.Initiates circular contraction behind stimulus and an area of relaxation in front
3.wave of contraction then moves in oral to caudal direction
4. Local stretch releases serotonin- activates sensory neuron→activator the myenteric plexus
5.this activates neurong that release substance P and acetylcholine→smooth
Muscle contraction
6.and activates neutrons that secrete NO vasoactive intestinal polypepticle
(VIP) and adenosine triphophater (ATP)→ relaxation ahead of the stimulus
