Exam 4 - Digestive System 1 Flashcards
Ingestion
intake of food
Digestion
mechanical and chemical breakdown of food
Absorption
uptake of nutrients (into blood/lymph)
Defecation
elimination of undigested residue
Mechanical digestion
- PHYSICAL BREAKDOWN of food into smaller particles
- responsibility of TEETH and CHURNING ACTION OF STOMACH and intestines
Chemical digestion
- series of HYDROLYSIS reactions that break macromolecules into their MONOMERS
- involves enzymes from SALIVA, STOMACH, PANCREAS, and INTESTINES
Digestive tract (GI tract)
- 30 foot long TUBE extending from mouth to anus
- LUMINAL CONTENTS are considered EXTERNAL TO BODY
Accessory organs
- teeth
- tongue
- salivary glands
- liver
- gallbladder
- pancreas
How are the functions of the digestive tract controlled?
- Nervous system
- Hormones
- Paracrine secretions
Nervous system: short myenteric reflexes (swallowing)
Stretching or chemical stimulation acts through MYENTERIC PLEXUS to produce contractions in muscularis externa (muscularis layer)
Where is the myenteric plexus?
between the MUSCULARIS MUCOSAE and MUSCULARIS LAYER
Nervous system: long vagovagal reflexes
(parasympathetic stimulation of digestive motility and secretion)
- act through autonomic fibers and carry sensory signals from digestive tract to CNS, and motor signals back to digestive tract
Hormones that control digestive tract
messengers diffuse into bloodstream to reach distant targets
EX) gastrin, secretin
Paracrine secretions that control digestive tract
messengers diffuse to nearby target cells
EX) histamine, prostaglandins
intrinsic muscles of the tongue
change the shape of the tongue (making a taco)
extrinsic muscles of the tongue
protrude or retract tongue and move it from side to side
Styloglossus m.
pulls your tongue back
Hyoglossus m.
pulls your tongue down
Genioglossus m.
sticks out the tongue
Primary, deciduous, milk, baby teeth
- 20 teeth that start erupting at 6 MONTHS
- 1 PAIR OF TEETH PER MONTH (until you get 20)
Permanent or secondary teeth (adult teeth)
- 32 teeth total
- erupt between age 6 and 12
Incisors
used for biting (flat, narrow surface that slice food)
Canines/cuspids
tearing (vampire teeth)
Premolars and molars
crushing and grinding (2 humps - bicuspids, multiple humps - molars)
Anatomic crown
enamel-covered part of tooth
Clinical crown
section of tooth above the gum line
Neck
enameled part of tooth below gum line
Dentin
living, cellular, calcified tissue
Pulp cavity
filled w/ blood vessels, nerves and connective tissue
Periodontal ligaments
hold tooth in socket
Gingiva
dense, fibrous connective tissue covered by stratified squamous epithelium
Cementum
bone-like substance which is penetrated by periodontal ligament
Where does a cavity have to penetrate when you experience at tooth ache?
pulp cavity
