How do we process food prior to delivering it to the stomach 411

1
How do we process food prior to delivering it to
the stomach? 4/11

• Move on to Chapter 25 Digestion
• What organs make up the digestive system?
• How does the tongue help with digestion?
• What is mastication and how does dentition
  process food in the oral cavity?
• How does saliva help process food in the oral
  cavity?
• What is deglutination and why is GERD such a
  problem today?
• What are the anatomical features of the stomach?
• How is information delivered to the stomach and
  leave the stomach?

2
The digestive system consists of several organs
that break up food, swallow, enzymatically digest
nutrients in chyme, propel these materials from
the mouth to the anus, and absorb nutrients into
the blood. Overview
3
Digestion starts with food ingestion, gustation,
and mastication in the oral (buccal) cavity.

• It all starts with taste!
• 4 types of tongue taste bud front-back/Left-right
  
• Sweet-energy
• Salt-sodium
• Sour-acidic
• Bitter-alkaline/poison
• Palatability and ingestion
• Flavor-Aroma-Texture
• As we age we become less able to taste and smell!
• Importance for hypertension and anorexia in
  elderly?

4
Matication We use teeth, tongue, lips and cheeks
to begin the mechanical aspects of the digestive
process.

• Mechanical function of tongue lingual muscles,
• lips and cheeks
• The Parts of a Tooth
• Enamel
• Dentin
• Pulp Cavity
• Root Canal
• Alveolar Bone
• Occlusion
• Occlusal Surface
• Cusps

5
We will normally have 20 deciduous milk teeth.
After the age of 6, these are replaced by 32
(4X8)permanent teeth that provide for us in
adulthood.

• Adults 32 Permanent Teeth
• Each Quadrant has 8 teeth
• 2 incisors-cut
• 1 canine-hold
• 2 premolars-sheer
• 2 molars-grind
• 1 Wisdom tooth The last to erupt!
• Bones Maxilla or Mandible
• 4X Quadrants 32 teeth
• Infants 20 Deciduous Teeth
• As the permanent teeth erupt, they push the
  deciduous teeth out of their sockets! Teething

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How does a lack of oral health hamper good
nutrition and digestion? Dentition determines if
you eat, grind, digest, talk, and even sleep
efficiently! Who is susceptible to problems? Why?

• Plaque
• Calculus or Tartar
• Flossing and brushing
• Caries
• Digestive enzymes and acids
• Grinding Out and Fillings as a solution
• Root Canal Therapy
• Pulp replacement
• Infection removed
• Gingivitis can lead to Peridontal Disease?
• How is tooth loss related to our diet in the USA,
  Third World, and in Prehistoric Peoples?

7
We produce saliva (1.5 L/day) for 3 reasons 1)
Lubrication/moisture of food during mastication
2) Mix enzymes for digesting bacteria, starch
and lipids 3) Addition of NaCO3- for control of
acidity/tooth decay

• Parotid (20) Serous
• Sublingual (5) Mucous
• Submandibular(70) Mixed
• Minor glands (5)
• Saliva Contents
• Water Main Content!
• ElectrolytesK, Cl-, NaCO3- Proteins Mucin and
  IgA
• Enzymes active only at pH 7 Lingual
  amylase Lysozyme
• Lingual Lipase?active in stomach
• Bites often bring infection! WHY?

8
Deglutination the tongue presses a food bolus
against the palate, through the fauces, into the
pharynx, past the epiglottis and into the
esophagus. Then peristaltic waves of smooth
muscle squeeze it into the stomach as the cardiac
sphincter relaxes.

• Activity coordinated by swallowing center of
  medulla22 muscles
• Three Stages to Swallowing
• 1) Buccal 2) Pharyngeal 3) Esophageal
• Entry into esophagus (skeletal then smooth
  muscle) creates a peristaltic wave in the
  muscularis externa that generates propulsion by
  shortening and narrowing the tube right-behind
  the bolus!
• Enteric Nervous System allows for conduction of
  depolarization along smooth muscle cells
  resulting in a wave of contraction!
• Finally Lower esophageal sphincter must relax
  (dilate) before bolus can pass through the
  cardiac orifice into the stomach!

9
Gastro Esophogeal Reflux Disease (GERD)is a huge
problem for many people! Have you seen adds for
the Purple Pill called Prilosec?
10
Stomach Provides for Mixing, Acidification and
Sterilization
11
There are several important anatomical structures
on the stomach that you should be aware of.

• Why are these clinically significant?
• Location inferior to the diaphragm and left lung
• Esophageal sphincter and diaphragm
• Pyloric sphincter
• Pyloric Canal
• Fundic, Cardiac and Pyloric Regions and the
  Body
• Greater and Lesser Curvatures
• Converting ingested material into Chyme
• Gas and the cause of indigestion

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The layers of the stomach are all responsible for
specific functions,,,what are these layers?

• Serosa (formerly called adventitial layer on
  esophagus)
• Muscularis Externa three smooth muscle layers
• Longitudinal
• Circular
• Oblique
• Provide mixing across three different
  orientations
• Submucosa Contains blood vessels and nerves
• Mucularis mucosa tiny muscle layer under mucosa
• Mucosa Contains arterioles, venules,
  capillaries, lymphatics, gastric pits/ducts,
  stomach does huge amount of work here! (ATP
  production required!)
• Epithelial layer?protection!

13
It is also important to remember that a layer of
protective glycocalyx coats and protects all
underlying simple columnar epithelial cells from
acids!
14
How do we bring information, oxygen, nutrients,
and blood into or out of the stomach?

• Blood Enters via gastric branch of celiac trunk
  artery
• Exits via hepatic portal vein for cleaning of
  blood toxins in liver
• Information
• Enters via two nerves
• Vagus Nerve parasympathtic info to stomach
• Vagus Nerve also carries sensory info from
  stomach to brain
• Sympathetic fibers of celiac ganglion
• Hormones
• Gastrin output hormone to blood
• CCK, GIP and Secretin Input hormones from blood
• Lymphatics are also very important for fluid
  drainage/inflammation!

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What digestive materials are secreted by the
stomach and how do we protect ourselves against
them?

• Stomach makes acids, pepsin and huge amounts of
  mucus
• Importance of mucus PROTECTION OF EPITHELIUM!
• Importance of stomach acid Antibacterial
  Digestion Nutrient availability
• Problem with stomach acids Potential self
  digestion stomach, esophagus, duodemum Potential
  enzyme de-activation due to pH
• Importance of Pepsin Break up proteins and
  Deactivate potential hazards Potential to
  autodigest your own body Solution activation
  only in acidic pH What happens to pepsin
  activity if Tums are taken?