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Digestive System
= Gastrointestinal (GI) tract or
_____________ plus Accessory organs
SEM$of$blood$supply$of$S.I.$
MODULE$22.1:$OVERVIEW$OF$THE$
DIGESTIVE$SYSTEM$$
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Digestive System. = Gastrointestinal (GI) tract or. ______ plus Accessory organs. SEM of blood supply of S.I.. MODULE 22.1: OVERVIEW OF THE.
Typology: Lecture notes
2021/2022
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- PPT file prepared by Suzanne Pundt, UT Tyler Digestive System = Gastrointestinal (GI) tract or _____________ plus Accessory organs SEM of blood supply of S.I.
MODULE 22.1: OVERVIEW OF THE
DIGESTIVE SYSTEM
Introduc9on
- DigesBve system
- breaks down food into nutrients that can be absorbed by bloodstream and delivered to body cells in useable form = GI tract or alimentary canal and ____________
Introduc9on
- Alimentary canal
- con9nuous tube consis9ng of _______ (mouth), pharynx , esophagus , stomach , small intesBne , and ____________
- Accessory organs
- located around alimentary canal and assist in diges9on in some way
- include teeth , tongue , salivary glands , liver , _____________________
Basic Diges9ve Func9ons and Processes
- Main processes include: 1. IngesBon – bring food and water into month 2. SecreBon –mucus, enzymes, acid, and hormones 3. ____________ – via peristalsis 4. DigesBon – mechanical and chemical 5. ____________ – through wall of alimentary canal into blood or lymph 6. DefecaBon – eliminate waste products Regula9on of Mo9lity by Nervous and Endocrine Systems MoBlity - key process in every region of alimentary canal
- Oral cavity, pharynx, superior esophagus, and last por9on of L.I. - _______________
- Remainder of alimentary canal - ____________ **Types: mixing & churning, propulsion RegulaBon:
- Nervous ANS:** SNS inhibits PSN s9mulates
- Endocrine hormones – s9mulate or inhibit
Histology of Alimentary Canal
- _______ = concentric layers of 9ssue surround a space
- 4 main layers:
- __________ - epithelium
- Submucosa – CT
- Muscularis externa - smooth muscle
- Serosa (or ___________) - CT
Histology of the Alimentary Canal
- Mucosa : a. epithelium – __________ or stratified squamous goblet cells à ________ b. lamina propria - CT c. muscularis mucosae – SMC
Histology of Alimentary Canal
- Serosa = _____________ - within peritoneal cavity
- simple squam. epithelium & loose CT or
- AdvenBBa
- outside peritoneal cavity
- dense irregular CT
Histology of Alimentary Canal
Figure 22.2 The basic 9ssue organiza9on of most of the alimentary canal.
Organiza9on of Abdominopelvic Organs
- Peritoneal membranes ( Figure 22.3 ):
- Outer parietal peritoneum < peritoneal cavity- serous fluid>
- Inner visceral peritoneum ( serosa)
- Mesenteries
- Folds of visceral peritoneum between loops of intes9nes
- ______________ “faey apron” : hangs from base of stomach
- Lesser Omentum : lesser curvature of stomach to liver
Organiza9on of Abdominopelvic Organs
Figure 22.3a The peritoneum, the largest serous membrane in the body.
Organiza9on of Abdominopelvic Organs
Figure 22.3c The peritoneum, the largest serous membrane in the body.
MODULE 22.2 THE ORAL CAVITY,
PHARYNX, AND ESOPHAGUS
Introduc9on
Oral cavity ( mouth)
-
- posterior to teeth and bounded by cheeks
- lined with stra;fied squamous nonkera;nized epith.
- beginning of alimentary canal
- accessory organs: ____________________
- forms ________ = saliva and chewed food
Structure of Oral Cavity
- Cheeks : _____________
- Lips :
- orbicularis oris muscle and covered with
- labial frenulum
- orbicularis oris muscle and covered with
- Ves%bule – space between lips, cheeks and gums
- _Gums – __________
- Palate: _hard palate (ant. 2/3) = __________________ soL palate (post. 1/3) = skeletal muscle uvula – prevents food from entering nasal cavity
The Teeth and Mas9ca9on
Figure 22.5a Types of teeth and the primary and secondary den99on. 4 1 2 3
Teeth and Mas9ca9on
- Secondary denBBon (_____ permanent teeth)
- Tooth structure
- ________ – above gum line
- Enamel – hard mineralized substances
- Den9n
- ________ – below gum line
- Pulp – blood vessels, nerves
Tongue
Tongue
- skeletal muscle covered w/ stra9fied squamous epith.
- lingual frenulum ______________________
- Papillae :
- ___________
- fungiform
- circumvallate
- foliate papillae
- All papillae except filiform contain sensory receptors called taste buds
Salivary Glands
Salivary glands à saliva contains water, enz., mucus, and other solutes (Fig. 22.7) 1. __________ (25-30% of saliva) à paroBd duct
- located over masseter muscle 2. ____________ glands (65-70%) à submandibular ducts
- located along mandible 3. ______________ (5%) à sublingual ducts
- situated inferior to tongue
Salivary Glands
- FuncBons of Saliva : Moistening , lubrica;ng , and cleansing oral mucosa - Lysozyme and IgA deter growth of bacteria - ____________ diges9on by moistening and mixing ingested food into a bolus so it can be swallowed - ___________ diges9on by salivary amylase - ______________ in water of saliva to s9mulate taste receptors on tongue
Pharynx
Common passageway for 2 systems:
- extends from internal nares à _______________
- Pharynx (throat)
– nasopharynx
– oropharynx
– laryngopharynx
Pharynx
Func9on of pharynx
• _________ - bolus passes into esophagus
- Pharynx is surrounded by three pairs of skeletal muscles: upper, middle, and lower pharyngeal constrictor muscles
Tonsils
Tonsils – defend body from pathogens that have
entered nasal or oral cavi9es
- ________ tonsils_
- posterior oral cavity on either side of tongue
- ________ tonsils_
- located under base of tongue 3. ________ tonsils
- located on posterior wall of nasopharynx
Esophagus
Figure 22.8 Histology of the esophagus.
Esophagus
- Primary func9ons of esophagus
- During swallowing, skeletal muscle and smooth muscle of muscularis undergo peristalsis
- Thick esophageal epithelium protects esophagus from abrasion by food, also prevents absorp;on
Swallowing or Deglu99on
Swallowing or __________
- specialized type of propulsion that pushes bolus of food from oral cavity through pharynx and esophagus to stomach (Figure 22.9):
Swallowing or Deglu99on
1. Voluntary phase – tongue pushes bolus posteriorly toward oropharynx 2. _______________ – bolus enters oropharynx - soj palate and epiglons seal off nasopharynx and larynx - swallowing reflex ini9ated by medulla
- all structures (uvula, larynx) move up and epiglons depresses 3. ___________ – peristal9c waves move bolus down esophagus to stomach