chapter 17: the digestive system
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VERY Basic. Chapter 17: The Digestive System. But first… A video. http:// www.youtube.com/watch?v=bfOyLuknD_4. Alimentary Canal. Extends from the mouth to the anus Mouth Pharynx Esophagus Stomach Small and large intestine Rectum Anus Accessory organs Salivary glands Liver - PowerPoint PPT PresentationTRANSCRIPT
CHAPTER 17: THE DIGESTIVE SYSTEM
VERY Basic
But first… A video http://
www.youtube.com/watch?v=bfOyLuknD_4
Alimentary Canal Extends from the mouth to the anus
MouthPharynxEsophagusStomachSmall and large intestineRectumAnus
Accessory organs Salivary glandsLiverGall bladderPancreas
Layers of the Wall Mucosa (mucous membrane)
Epithelium, connective tissue and smooth muscle Secretion and absorption
Submucosa Loose connective tissue, blood vessels, lymphatic vessels,
nerves Nourishment, transport absorbed materials
Muscular layer Smooth muscle in circular and longitudinal groups Movement of the tube and its contents
Serosa Epithelium, connective tissue Protection
Movements of the Alimentary Canal Mixing Segmentation Peristalsis
Mouth Site of both mechanical
and chemical digestionTeeth and chewing
(mastication)
Mouth Tongue: root, body
Lingual frenulum Uvula – extension of
soft palateDivision between the
pharynx and the nasal cavity
Tonsils (lymphatic tissue)PalatineLingual Pharyngeal
Teeth Incisor Canine Premolar Molar
Adult has 32 teeth (permanent) Children have 20 teeth (deciduous)
Pharynx and Esophagus Neither are involved in digestion Epiglottis
Pharynx Connects the nasal and oral cavities
with the larynx and esophagus
Skeletal muscles control swallowingUnder voluntary control
Swallowing 3 stages:
1. Food is chewed and mixed with saliva○ Formation of a bolus
2. Food is pushed to the pharynx to enter the esophagus
○ Triggers a swallowing reflex3. Peristalsis transports food from
esophagus to stomach
Esophagus Connects mouth to stomach
Lined with mucous glands
Cardiac sphincter (Lower esophageal sphincter)
Recap Food enters the mouth…then what?
What types of digestion takes place?
What organs/structures are involved?
Is it voluntary or involuntary?
Stomach Receives food from the esophagus Digestion
Muscle fibers run in all directionsCircularLongitudinalOblique
Very minimal absorption
Stomach Inner lining: rugae – thick folds Greater curvature Lesser curvature Regions of the stomach:
Cardia FundusBodyPylorus
Pyloric sphincter
Stomach As the food is
digested, it changes from a bolus (from the mouth and esophagus) to chymeChyme
○ Semifluid paste ○ Food mixed with
digestive enzymes
Accessory Organs Pancreas Liver Gall Bladder
Pancreas Secretion of pancreas juice Aids in digestion of
CarbohydratesFatsProteinNucleic acid
Liver Multi lobed
Makes bileDigestion of fats
Liver
Gall Bladder
Connected to the liver Storage and release of bile into small
intestine
Small Intestine Fills most of the abdominal cavity 5.5 – 6 meters long Receives secretions from pancreas, liver Absorption
Small Intestine Duodenum Jejunum
VascularThicker wall
Ileum High number of
lymph nodes (Peyer’s patches)
Small Intestine Mesentary
Connective tissue around the small intestine Greater omentum
Membrane drapes over lower digestive tractIf infection occurs, omentum will seal off
portion of digestive systemPrevents spread of infection to abdominal
cavity
Greater Omentum
Small Intestine Villi
Projections to increase surface area
Large Intestine Joins small intestine at the ileum
Water and electrolyte absorption Formation of feces
Large Intestine Cecum
Appendix – projection from cecum Colon:
AscendingTransverseDescendingSigmoid
Rectum Anus
Digestive Enzyme Table
Digestive System Dissection