Digestive System- Part I Flashcards
Digestive System Organs (6)
1) Oral Cavity
2) Pharynx
3) Esophagus
4) Stomach
5) Small Intestine
6) Large Intestine
Digestive System Accessory Organs (7)
1) Tongue
2) Teeth
3) Salivary Glands
4) Tonsils
5) Liver
6) Gallbladder
7) Pancreas
Digestive System Functions (6)
1) Ingestion
2) Propulsion & Mixing (Mechanical Breakdown)
3) Secretion
4) Digestion
5) Absorption
6) Storage & Elimination (Defecation)
What are the 4 Tunics of the Digestive Tract?
1) Mucosa (inner most)
2) Submucosa
3) Muscularis
4) Serosa or Adventitia (outer most)
Bolus vs. Chyme
Bolus- soft mass of food and liquid that moves from the oral cavity into the esophagus
Chyme- mass of undigested food that moves down the digestive tract from the esophagus
2 Types of Mixing Contractions
1) Mixing Waves- gentle contractions in the stomach that churn food with gastric secretions
2) Segmental contractions- mixing of food with secretions in the small intestine
SEE PG 916 FOR EACH PARTS ROLE IN BREAKDOWN OF FOOD & ABSORPTION OF NUTRIENTS
FIGURE 24.2
3 Major Types of Glands associate w/Digestive Tract
1) Unicellular mucous glands in mucosa
2) Multicellular glands in mucosa & submucosa
3) Multicellular glads outside digestive tract (such as Pancreas)
Mucosa of Digestive Tract (3)
1) Innermost tunic of digestive tract
2) Has 3 layers
3) Contains 2 Types of specialized cells –> Mechanoreceptors involved in peristaltic reflexes & chemoreceptors that detect chemical composition of food
3 Layers of the Mucosa
1) Mucous Epithelium- inner most layer composited of strat squam epithelium
2) Lamina Propria -middle layer of connective tissue
3) Muscularis Mucosae- thin outer layer of smooth muscle
Submucosa of Digestive Tract (4)
1) On top of Mucosa
2) Thick connective tissue
3) Contains nerves, blood vessels, lymphatic vessels & small glands
4) Contains portion of Submucosal Plexus which stimulates secretions throughout digestive tract (except esophagus & stomach)
Muscularis of Digestive Tract (3)
1) 3rd most outer layer
2) Muscular layer containing smooth muscle
3) Contains Myenteric Plexus- controls motility of the intestinal tract using a network if interstitial cells that operate as pacemakers to promote rhythmic contractions
Submucosal Plexus vs. Myesteric Plexus
- Submucosal Plexus- controls secretions from submucosa layer
- Myesteric Plexus- pacemaker found in muscularis layer
Enteric Nervous System (3)
1) Network of neuron cell bodies and axons within the wall of the digestive tract
2) Capable of controlling digestive tract independent of CNS through LOCAL REFLEXES (short, specific regional reflexes)
3) Division of the ANS through the Vagus nerve
Serosa or Adventitia of Digestive Tract
1) Outermost layer
2) Serosa- peritoneal cavity, aka Visceral peritoneum, composed of CT & simp squamous epithelium
3) Aventitia- esophagus & retroperitoneal organs, composed of CT
3 Types of Enteric Neurons (Nervous Regulations of Digestive System)
1) Enteric Sensory Neurons- detect changes in chemical compostition of contents and mechanical changes (such as stretch)
2) Enteric Motor Neurons- stimulate or inhibit smooth muscle contraction
3) Enteric Interneurons- connect enteric sensory & motor neurons
Hirschprung Disease
1) Painful developmental disorder caused by absence of enteric neurons in distal large intestine.
2) Results in poor intestinal morality and severe constipation
3 Major Neurotransmitters that chemically regulated Digestive system
1) Acetylcholine- STIMULATES motility & secretions
2) Norepinephrine- INHIBITS motility & secretions
3) Serotonin- STIMULATES motility –> over 95% of Serotonin in the body is in digestive tract which is why drugs that increase serotonin levels also cause nausea & vomiting
Peritoneum (definition) & it’s 2 layers
- the continuous serous membrane that lines the walls and organs of the abdominal cavity
1) Visceral Peritoneum- portion that covers the organs
2) Parietal Peritoneum- portion that covers the interior surface of the wall abdominal cavity
Peritonitis (2)
1) Life threatening inflammation of the peritonium
2) Caused by chemical irritation (bile from digestive tract) or infection from digestive tract (EX: appendix rupture)
Ascites (2)
1) An accumulation of excess serous fluid in the peritoneal cavity that occurs in peritonities
2) Also occurs during starvation, alcoholism, & liver cancer.
Mesentery (4)
1) Structure within the abdominal cavity that holds all digestive organs in place.
2) Continuous, double layer of epithelial tissue attached along it s full length to the posterior wall
3) Extends from junction between esophagus & stomach to the rectum
4) Has 6 continuous regions
2 Regions of the Mouth
What type of epithelium lines oral cavity?
1) Vestibule- space between lips or cheeks & teeth
2) Oral Cavity Proper- everything medial to teeth
- Nonkeratinized Stratified Squamous (protects against abrasion)
TEETH NUMBERS?
PG.921
Labial Frenulum
Buccinator Muscle
Buccal Fat Pad
1) central mucosal fold that attaches each lip to the gingiva (gums)
2) muscle inside cheek that flattens it against the teeth
3) inside each cheek that acts as a gliding pad for muscles of mastication
Terminal Sulcus
Lingual Frenulum
Where is the root vs. body of tongue?
1) groove of the tongue that divides it into 2 sections- the body & root
2) tissue fold that attaches tongue to floor of mouth
3) body in oral cavity & root is in the Oropharynx & Contains taste buds and the lingual tonsil
Intrinsic vs. Extrinsic Muscles of the Tongue
1) Intrinsic- inside tongue & responsible for changing shape of tongue such as flattening & elevating during drinking & swallowing
2) Extrinsic- outside the tongue but attached to it. Protrude & retract tongue, move it from side to side, & change it’s shape
Detention
Apical Foramen
1) teeth collectively known as
2) hole at point of each tooth root that nerves and blood vessels enter & exit the pulp
Pulp
Pulp Cavity vs. Root Canal
1) collection of blood vessels, nerves, & connection tissue inside each tooth
2) Pulp cavity- center of the tooth in the neck & root that’s filled with pulp.
3) Root Canal- portion of pulp cavity within the root of a tooth
Dentin
Enamel
Cementum
1) living, cellular, calcified tissue that surrounds the pulp cavity
2) nonliving, a-cellular, extremely hard substance that covers the dentin of the tooth CROWN –> protects tooth against abrasion & acids produced by bacteria in the mouth
3) bone-like substance that covers dentin surface in the ROOT which helps anchor to the periodontal ligament in the jaw
How are teeth anchored into the jaw?
Anchored in alveoli along processes of the jaw by periodontal ligaments which secure each tooth to alveoli. Then gingiva (gums) cover alveolar processes (made of dense fibrous connective tissue).
Gingivitis
Periodontal Disease
Halitosis
1) inflammation of gums caused by food deposited in crevices and not promptly removed by brushing or flossing.
2) Inflammation and degradation of the periodontal ligaments, gingiva, & alveolar bone that can stem from Gingivitis
3) “bad breath” that occurs with periodontal disease
What are the roles of anterior teeth vs. premolars & molars during mastication?
- Incisors & canines- cut & tear food
- Premolars & molars- crush & grind food
What are the muscles involved in mastication? Which one opens the jaw?
4 Pairs of Muscles
1) Temporalis
2) Massester
3) Medial Pterygoid
4) Lateral Pterygold- opens jaw
What parts of the brain function during the mastication reflex?
1) Reflex is integrated in the Medulla Oblongata
2) Descending pathways from the Cerebrum influence the start & stop of reflex & rate & intensity of chewing movements
3 Pairs of Salivary Glands
1) Parotid Glands
2) Submandibular Glands
3) Sublingual Glands
Acinar Gland (3)
1) Compounded to make up the larger Salivary glands
2) Contain clusters of acini (resembling grapes)
3) Produce Saliva
Parotid Gland (5)
1) Largest Salivary gland
2) Produces mostly watery saliva
3) Located anterior to the ear on each side of the head
4) Enters oral cavity adjacent to the 2nd upper molars
5) Mumps used to cause inflammation/swelling of Parotid Gland
Submandibular Gland (3)
1) Mixed glands with more serous than Mucous acini
2) Can be felt a long Inferior border of mandible (close to ear)
3) Enters oral cavity beside lingual frenulum
Sublingual Gland (3)
1) Smallest of paired glands
2) Mixed glands with more Mucous acini than serous.
3) Not one well defined draining duct, instead have 10-12 small ducts that open into oral cavity floor
3 Main Roles of Saliva
1) keeps oral cavity moist which is needed for normal speech & tasting food
2) protective functions
3) begins process of digestion
How much saliva is secreted each day?
1- 1.5 L/day
Serous vs. Mucous portion of Saliva (location & function)
1) Serous- secreted primary by the Parotid & Submandibular glands & provides MOISTENING function of saliva
2) Mucous- secreted by Submandibular & Sublingual glands & contain MUCIN which gives LUBRICATING quality to saliva
4 Protective Functions of Saliva
1) large volume helps prevent bacterial infections in the mouth by washing oral surface
2) Biocarbinate ions (HCO3-) act as butter to neutralize acids produced by oral bacteria (protects tooth enamel)
3) Contains Lysozyme & Immunoglobulin A proteins which help prevent bacterial infection
4) Mucosa in saliva protect digestive tract from physical irritation
Salivary Amylase (def, function, & limitation (3))
1) Digestive enzyme found in serous part of saliva
2) Breaks the covalent bonds between glucose molecules in start to produce disaccharides maltose & isomaltose (sugars) which gives starches sweet taste
3) Cannot break down food covered by cellulose (found in plants but destroyed by cooking & thoroughly chewing food)
What stimuli stimulate release of Saliva? (3)
1) Tactile stimulation in oral cavity
2) Certain tastes, especially sour
3) Odors
What nerves involved in Salivary secretion stimulation? (3)
1) Both PNS & SNS but mostly PNS
2) Facial Nerve (VII)
3) Glossopharyngeal Nerve (IX)
What parts of the Pharynx are involved in digestion?
Oropharynx & Laryngopharynx
Pharyngeal Constrictors (3)
1) 3 muscles- Superior, Middle, & Inferior
2) found in posterior walls of the Oropharynx & Laryngopharynx
3) arranged one inside the other (like stacked flowerpots)
What regulates the movement of materials into & out of the Esophagus?
Upper & Lower Esophageal Sphincters
Swallowing (aka, # of phases, & number of muscles involved)
1) aka Deglutition
2) 3 Phases –> Voluntary, Pharyngeal, & Esophageal
3) Over 20 separate muscles involved in swallowing
Describe the processes involved in each phase of swallowing (short)
1) Voluntary- bolus formed & pushed to back of mouth
2) Pharyngeal- soft palate elevates (closes passage between Nasopharynx & Oropharynx) Pharynx elevates to receive bolus, successive constriction of Pharyngeal Constrictors & simultaneous relaxation of Upper Esophageal Sphincter then pushes bolus down Pharynx to Esophagus
3) Esophageal- moves food from the Pharynx to the Stomach via Peristalsis of Esophagus
What nerves are stimulated during Pharyngeal Phase of swallowing? (3)
1) Reflex initiated by stimulation of tactile receptors in the Oropharynx
2) Sensory action potentials –> Trigeminal (V) & Glossopharyngeal (IX) nerves –> swallowing center in Medulla Oblongota
3) Motor neuron action potentials –> Trigeminal (V), Glossopharyngeal (IX), Vagus (X), & Accessory XI) nerves –> Soft Palate & Pharynx
How do the Pharyngeal Constrictors & Esophageal Sphincters operate during swallowing?
1) Once bolus enters Pharynx the superior, middle, & Inferior pharyngeal constrictor muscles contract in succession forcing food through the Pharynx
2) Simultaneously, the Upper Esophageal sphincter relaxes and the elevated Pharynx pushes food into Esophagus
What happens during swallowing that prevents food from entering Larynx? What phase is this?
1) Vestibular folds & vocal chords close & Epiglottis tipped so Epiglottic cartilage covers opening to Larynx
2) Pharyngeal Phase
What nerves regulate the peristaltic waves during the Esophageal phase & how?
1) Food presence in Esophagus stimulates Myenteric Plexus (controls peristaltic waves)
2) Also stimulate tactile receptors –> sensory impulses via Vagus (X) Nerve –> Medulla Oblongota –> motor impulses via Vagal efferent fibers of Esophagus stimulates contractions
During which phase of the swallowing reflex is it not possible to talk or even breathe? Why? (3)
1) Pharyngeal Phase
2) Can’t breathe due to closure of Nasopharynx by soft palate which blocks connection to nasal passages
3) Can’t speak due to closure of vestibular & vocal folds and Epiglottis
