Chapter 24 Digestive System Flashcards
Organs used in mechanical processing, moistening, mixing with salivary secretions.
Oral cavity, teeth, tongue
Secretes fluid which contains enzymes which help to break down foods; located at back of throat and in mouth.
Salivary glands
Muscles propel materials down esophagus
Pharynx
Tube that leads from throat to stomach; this transports nutrients/food to stomach
Esophagus
Chemical breakdown of food by acids and enzymes; mechanical processing occursthrough muscle contractions.
Stomach
Secretes bile which is used to break down lipids; stores nutrients
Liver
Storage and concentration of bile
Gall bladder
Exocrine cells secrete buffers and digestive enzymes; endocrine cells secrete hormones
Pancreas
Enzymatic digestion and absorption of water, organic substrates, vitamin and ions
Small intestine
Dehydration and compaction of indigestible materials in preparation for elimination
Large intestine
Occurs when materials enter the digestive tract by the mouth
Ingestion
Crushing and shearing of materials to make it easier to move through tract.
Mechanical processing
Breakdown of food by chemicals into small fragments suitable for absorption.
Digestion
What can be absorbed intact?
Glucose
What most be broken down prior to absorption?
- Proteins
- Polysaccharides
- Triglycerides
Release of water, acids, enzymes, buffers and salts by digestive tract and by glandular organs
Secretion
Movement of substrates, electrolytes, vitamins and water across digestive epithelium wall and into digestive tract.
Absorption
Removal of waste products from body
Excretion
The ejection of materials from digestive tract
Defecation
The lining of digestive system protects body from corrosive acids, abrasion and bacteria
Protection
The muscular wall of the digestive system contains 4 layers. What are they?
- Mucosa- Internal section of the wall which comes into contact with food.
- Submucosa
- Muscularis externa
- Serosa
Which layer of the muscular wall is not found in the pharynx, esophagus, or rectum?
Serosa
Contraction of the muscles of digestive tract behind material to be digested; pushing material downward through the digestive system.
Peristalsis
What two muscles work in conjunction to move bolus of food?
- Circular muscle
- Longitudinal muscle
Allows food to move in one direction (acts like a valve)
Circular muscle
Contraction causes food to move through digestive tract.
Longitudinal muscle
Small mass of digestive contents
Bolus
Contracts which occur in stomach, SI and some in LI which cause churning and mixing of bolus with intestinal secretions. This does not move bolus through GI.
Segmentation
Also called the Buccal cavity.
Oral cavity
The mouth opens to lead into this cavity; ingestion/food entry occurs at this location.
Oral cavity or Buccal cavity
What type of tissue primarily makes up the oral cavity?
Stratified squamous epithelial tissue
What is the pH in the mouth?
6.35-6.85
The Oral cavity is formed by? (4)
- Lips
- Cheeks
- Palate
- Tongue
What are the functions of the oral cavity? (3)
- Ingestion: Intake of food
- Mechanical digestion:Chewing of food
- Chemical digestion: Enzymatic breakdown of food
Used to manipulate food inside the oral cavity.
Tongue
Functions of the tongue? (4)
- Mechanical processing by compression, abrasion and distortion.
- Manipulate food to assist in chewing and prepare material for swallowing.
- Sensory analysis by touch, temperature, and taste receptors.
- Secretes mucins and “lingual lipase”.
The tongue can be divided into 2 sections. What are they?
- Anterior body
- Posterior root
Membrane of inferior side of tongue which connects tongue to floor of oral cavity
Lingual frenulum
Protein secreted by glands which can break down lipids which acidic pH activates the enzyme.
Lingual lipase
The tongue has two groups of skeletal muscles both controlled by hypoglossal nerve XII. What are they?
- Intrinsic tongue muscles
- Extrinsic tongue muscles
Tongue muscles used in speech
Intrinsic tongue muscles
Tongue muscles used in gross movements of tongue.
Extrinsic tongue muscles
Three pairs of glands secrete into oral cavity; these glands will either have serous cells and/or mucous cells.
Salivary glands
Produce salivary amylase.
Serous cells
Produce mucins which produce mucus for lubrication.
Mucous cells
Glands located in the back of throat inferior to zygomatic arch.
Parotid salivary glands
Gland covered by mucous membrane of floor or mouth
Sublingual salivary gland
Gland found in floor of mouth
Submandibular salivary gland
Produces about 25% of total saliva with salivary amylase which is drained into the oral cavity by parotid duct into oral cavity.
Parotid salivary glands
Also called Stenson’s duct
Parotid duct
Produces saliva that acts as buffer and lubricant which is drained into the oral cavity by the sublingual duct.
Sublingual salivary gland
Also called Rivinus duct
Sublingual duct
Produces and secretes 70% of total saliva with both serous and mucous cells; missed gland sends both and salivary amylase into the oral cavity by the submandibular duct.
Submandibular salivary gland
Also called Whartons duct
Submandibular duct
How much saliva does the body produce each day?
1 liter
What is saliva made up of? (7)
- water (99%)
- electrolytes
- buffers
- glycoproteins
- antibodies
- enzymes
- waste
Helps to control bacterial in mouth?
IgA (antibody)
What does the mumps virus target?
Salivary glands especially parotid salivary gland
Any object in mouth can trigger salivary reflex by stimulating which nerve(s)?
-Trigeminal nerve (V) or VII, IX, or X
Opposing surfaces of teeth match to perform mastication.
Occlusal
Blade shaped teeth in front of oral cavity used for cutting or clipping, has a single root
Incisors
Have pointed tip; used for tearing or slashing; have single root.
Cuspids (canines)
Have flat crowns; they mash, crush, and grind; have one or two roots.
Bicuspids (Premolars)
Large flattened crowns; good at crushing and grinding; have 2 or 3 roots.
Molars
First set of teeth
Deciduous
How many teeth to children typically have?
20
`Second set of teeth
Secondary dentition or permanent dentition.
How many Permanent teeth?
32
Permanent teeth push out primary teeth which is called what?
Eruption or emergence
Visible top portion of teeth?
Crown
area between crown and root?
Neck
Inferior invisible portion of tooth?
Root
Outer protective covering of teeth?
Enamel
Protective covering along side of tooth.
Cementum
Mineral component; soft section of tooth.
Dentin
Chamber with blood vessels and nerves in tooth.
Pulp cavity
Skin/gum between teeth.
Gingiva
Where nerves and blood vessels pass through to dentin of tooth
Root Canal
Hole where vessels and nerves first enter tooth.
Apical foramen
Attaches root to bone of tooth.
Peridontal ligament
Serves as common passageway for solid, liquids, and air (breathing).
Pharynx
Pushes bolus towards esophagus.
Pharyngeal constrictor muscle
Muscles that elevates the larynx
- Palatopharyngeus
- Stylopharyngeus
Elevates the soft palate.
Palatal muscle
The superior portion posterior to nasal cavity; is air passageway only; epithelium produces mucus; houses the pharyngeal tonsils; superior portion which extends from internal nares to soft palate.
Nasopharnynx
Continuous with the oral cavity; posterior to and continuous with oral cavity; is both air and food passageway; epithelium changes to deal with abrasive food; houses palatine and lingual tonsils; middle portion which extends from soft palate to base of tongue.
Oropharynx
Area between the hyoid bone and the esophagus; posterior to epiglottis and extends from base of tongue/ hyoid bone to larynx/esophagus; increases mucosal surface area exposed to air and enhance air turbulence in nasal cavity.
Laryngopharynx
Primary function is to carry food to stomach
Esophagus
Parameters of esophagus?
About 1 foot in length with .75in in diameter
Muscular wall of esophagus contains 3 layers and 1 layer of connective tissue.
- Mucosa
- Submucosa
- Muscularis externa
- Adventitia
Outermost connective tissue layer; replaces the serosa.
Adventitia
3 phases of swallowing
- Buccal phase
- Pharyngeal phase
- Esophageal phase
Begins with compression of bolus against hard palate, then tongue forces bolus towards pharynx; this phase is voluntary.
Buccal phase
Starts when bolus contacts palatoglossal and palatopharyngeal arches which have tactile receptors that are activated by bolus; brain sends a command to swallow; peristalsis begins in this phase.
Pharyngeal phase
Begins as bolus enters esophagus; peristalsis also continues during this phase; as bolus gets close to stomach it triggers the opening of esophageal/cardiac sphincter to allow entrance into stomach.
Esophageal phase
Functions of the stomach (5)
- Bulk storage of ingested food
- Mechanical breakdown of ingested food
- Disruption of chemical bonds in food by acid and enzymes
- Produces intrinsic factor (required for absorption of B12)
- Absorption of alcohol and some drugs
The ingested substance, enzymes and acid (soupy mixture of digested food).
Chyme
Folds in the stomach which allow it to expand as food enters stomach.
Rugae
What drug can be absorbed across stomach but also tends to erode stomach lining with extensive use.
Aspirin
4 regions of the stomach
- Cardia
- Fundus
- Body
- Pylorus
Smallest part of stomach, most superior; contains many mucous glands that coat and protect esophagus from acid and enzymes in stomach; only as mucus cells.
Cardia
Portion of stomach that is superior to the stomach/esophagus connection. Also has some gastric glands.
Fundus
Area between fundus and curve of the J (pylorus); largest part of stomach; mixes food and secretions produced in stomach; gastric glands in body secrete most of the acids in stomach.
Body
The curve of the J; has 2 sections; has both gastrin and mucus cells.
Pylorus
Connects to the body of stomach
Pyloric antrum
Empties into duodenum; a sphincter (pyloric sphincter) regulates the release of chyme into duodenum; gastrin, a hormone which stimulates gastric glands is produced here.
Pylorus
2 types of cells that dominate the gastric glands.
- Parietal cells
- Cheif cells
Produces gastrin which stimulates parietal and cheif cells
G cells
Produces somatostatin; which inhibitis G cells
D cells
Inflamation of gastric mucosa due to excessive alcohol, drugs, or aspirin use.
Gastritis
Occurs when acids erodes stomach lining in stomach (gastric ulcer) or intestine (duodenal ulcer).
Peptic ulcer
The production of acid and enzymes can be controlled by (3)
- CNS
- Enteric Nervous system (ENS) in stomach
- Hormones in digestive tract
What are the 3 phases of Digestion?
- Cephalic Phase
- Gastric phase
- Intestinal phase
3 subdivisions of the small intestine
- Duodenum
- Jejunum
- Ileum
Found on folds caled plicae
Villi
