BIO210Y5 Lecture Notes - Lecture 18: Wisdom Tooth, Oral Mucosa, Dentin

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18 Feb 2016
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Lecture 18B Notes – Digestive System Organization
Physiological Importance
How do we obtain and absorb nutrients and transfer them throughout the body with the cardiovascular system
and integration of other systems
The Pathway of Food
The bulk of the mechanical processing (movement of the food with the action of the toungue and breakdown of
food with accessory structures like teeth) happens in the oral cavity
The pharynx is a pathway from the mouth to the esophagus to the stomach where chemical breakdown occurs
Secretions make digestion faster or easier in the stomach and intestines
Absorption is take up of the elements that your body needs to maintain life and grow
In the large intestine is where you produce feces by packing together the things that you don’t need
Saliva is very important for chemical digestion in the mouth
The helper organs are the liver, gall bladder, and pancreas
When you’re moving the food through the tube you’re actually outside your body
oThe membrane of your tube is actually the space from the outside world inside your body
Oral Cavity
On both the tongue and the palate you have oral mucosa more keratin in this layer so it is harder
oUnderneath the tongue it is a thinner membrane
Uvual blocks the food from going into the nasopharynx
Tonsils provide T cells that fight pathogens and viruses right when they enter the body
Accessory Mechanical Structures: Teeth
The tongue mechanically moves the food and makes the bolus
You have different occlusal surfaces the surface that are facing the food
Premolars grind the food
Later in age, you get the tricuspids (the wisdom teeth) mature tooth form has erupted
The neck area is very important because it is the boundary between the enamel and the gingival cells where
bacteria can collect
The dentin is where you may have inflammation if you’re having a tooth ache
Differentiation in the teeth increases the efficiency of digestion
Smooth Muscle
The bolus is compressed against the hard palate with forces the tongue to move up towards the hard palate for
the bolus to move more posterior
In the pharyngeal phase, the uvual moves up to close the nasopharynx and the esophagus to open the
epiglottis is moved down to protect the trachea
Esophageal phase is the combination of muscle actions to move the bolus down to the stomach
Gravity helps a little bit with moving the food down the esophagus
The bolus gets much smaller and they are also moving in your small and large intestine peristaltic motion is
important for the whole tube movement
Circular muscle layer contracts behind the bolus while the longitutidal is also contracting so making the space
smaller you’re effectively moving the bolus through this wavey motion
The circular muscle area folds and works kinda like a spring, so when you contract both groups of muscles you
move the bolus downwards
Layers of Smooth Muscle
Where the esophagus meets the stomach you have the greater curvature
The smaller curvature is between the two sphincters
There are different layers of the muscular externa striation are not in a specific form, they are generally
oriented in different directions
These muscles when they contract move the stomach in different directions
The rugae really help with muscle expansion
The visceral muscles they are non-striated so they can twist and turn the stomach muscle not just contract in
one direction
oYou want to move the bolus all around any surface in the stomach
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