Digestive System

mouth, pharynx, exophagus, stomach, small intestine, large intestine

teeth, tongue, gallbladder, salivary glands, liver, pancreas

• Ingestion
• Propulsion
• Mechanical Digestion
• Chemical Digestion
• Absorption
• Defecation

taking food into digestive tract

• -swallowing: tongue pushes bolus of food back and downward into the esophagus
• -Peristalsis: waves of contraction and relaxation of muscles in the organ walls, moves food

• 3 Processes
• -Chewing-teeth
• -Mixing-mouth, stomach, small intestines
• -Churning food(Segmentation)-stomach and small intestines

catabolic breakdown of food by enzymes and acid

movement of nutrients from the GI tract to the blood or lymph (fats through lacteals)

elimination of indigestible solid wastes

• 1. Mechanical and Chemical Receptor Stimuli
• 2. Extrinsic control by CNS centers
• 3. Intrinsic control by local centers

• a. Stretch of alimentary canal
• b. osmolarity (solute concentration)
• c. pH increases as the canal is stretched
• d. Presence of substrate increases digestion, and end products of digestion decreases digestion

• -Initiate Relflexes:
• Activate/Inhibit Digestive glands, and mixes lumne contents and move along

• Intrinsic: (short reflexes)
• -gut brain, automatic reflexes like peristalsis and segmentation

• Extrinsic: (long reflexes)
• -arising within/outside GI tract
• -sends signals to small and large intestines

serous membrane of the abdominal cavity

covers external surface of most digestive organs

lines body wall

• Lubricates organs
• allows them to slide across from one another

• double layer of peritoneum that provides:
• -vascular and nerve supplies to visceral organs
• -hold digestive organs in place and store fat

• organs outside peritoneum
• ex) kidneys

• organs surrounded by peritoneum
• ex) liver

arteries that branch off the abdominal aorta to serve digestive organs and the hepatic portal circulation

Celiac Trunk: hepatic, splenic, left gastric, spleen, liver, stomach

Superior and Inferior Mesenteric: small/large intestines

1. collects nutrient rich venous blood from digestive viscera

2. delivers blood to liver for metabolic processing and storage

• 1. Mucosa-Epithelium
• 2. Sub Mucosa-Connective Tissue
• 3. Muscularis Externa-Muscle
• 4. Serosa-Outer Wall

• 1st Tunic:
• -lines lumen of canal
• -secretes mucus
• -absorbs end products of digestion
• -protects against infectious diseases

Contains 3 layers: epithelium, lamina propia, muscularis mucosae

• -simple columnar epithelium, mucus secreting goblet cells
• -mucus protects digestive organs from digesting themselves
• -ease food along tract
• -stomach and small intestine
• -enzyme and hormone secreting cells

• -loose areolar and reticular connective tissue
• -nourishes epithelium and absorbs nutrients
• -contains lymph nodes, defense against bacteria

smooth muscle cells that produce local movements of mucosa

• 2nd Tunic:
• -dense connective tissue containing:
• -elastic fibers
• -blood
• -lymphatic vessels
• -lymph nodes
• -nerves

responsible for segmentation and peristalsis

protective visceral periotneum

-replacd by fibrous adventitia in esophagus

• occupies submucosa
• -sensory and motor neurons
• -regulates activity of glands and smooth muscle in mucosa

• between muscle layers of muscularis externa
• -provide major nerve supply to GI tract wall and mobility
• -lined to long autonomic reflex arc

• -mouth lined with stratified squamous epithelium
• -gums, hard palate, dorsum of tongue are slightly keratinized

Orbicularis Oris

Buccinators

bounded by lips and cheeks externally, teeth and gum internally (tobacco place)

area that lies within teeth and gums

median fold that joins internal aspect of each lip to gum

• underlain by palatine bones and palatine processes of the maxillae
• -assists tongue in chewing by being platform for food
• -slightly corrugated on either side of raphe (midline ridge)

• mobile fold formed mostly of skeletal muscle
• -closes nasopharynx during swallowing
• -uvula projects downward from edge, assists food with downward projection, directs food

• occupies floor of mouth
• -gripping/repositioning food during chewing
• -mixing food w/saliva =bolus
• -initiation of swallowing and speech

change shape of tongue

alter tongue position (left, right, up, down)

secures tongue to floor of mouth and presents tongue from sliding posterior

tongue tied, lingual frenulum too tight

• 1. Filliform: roughness/friction
• 2. Fungiform: taste, give reddish hue
• 3. Circumvallate: V shaped row

• groove that seperates tongue into 2 areas:
• Oral Cavity=anterior 2/3
• Oropharynx=posterior third

• -cleanse mouth
• -moistens/dissolves food
• -aid in bolus formation
• -contains enzymes that break down starch

• Parotid
• Submandibular
• Sublingual

• aka. Buccal Glands
• scattered throughout oral mucosa

opens into vestibule next to second upper molar

ducts open at base of lingual frenulum

opens with 10-12 ducts into floor of mouth

dry mouth

• Epidemic Parotitis
• -viral disease of human species, caused by mumps virus
• -painful swelling of salivary glands (mostly parotid)
• -testicular swelling, rash, infertility, subfertility

serous and mucous cells of salivary glands

• 1. 97-99.5
• 2. hypo-osmotic
• 3. acidic

• Electrolytes: NA+, K+, CL-, PO2-4, HCO-3
• Digestive Enzyme: salivary amylase
• Proteins: mucin, lysozyme, defensins, IgA
• Metabolic wastes: urea and uric acid

keep mouth moist

• secrete serous, enzyme-rich saliva in response to:
• -ingested food stimulating chemoreceptors and pressoreceptors
• -thought of food

inhibits salivation and results in dry mouth

21

20 deciduous teeth that erupt at intervals between 6 and 24 months.

englarge and develop causing root of deciduous teeth to be resorbed and fall out between ages 6 and 12.

32

• Incisors
• Canines
• Premolars
• Molars

exposed part of tooth above the gingiva

acellular, brittle material composed of calcium salts and hydroxyapatite crystals is the hardest substance in the body

portion of tooth embedded in jawbone

constriciton where crown and root come together

• calcified connective tissue
• -covers root
• -attaches to periodontal ligament

• anchors tooth in the alveolus of jaw
• forms fibrous joint called gomphosis

depression where the gingiva borders the tooth

bonelike material deep to enamel cap that forms bulk of tooth

cavity surrounded by dentin that contains pulp

connective tissue, blood vessels, and nerves

portion of pulp cavity that extends into root

proximal opening to the root canal

secrete and maintain dentin throughout life

• gradual demineralization of enael and dentin by bacterial action
• -acid produced by bacteria in plaque dissolves calcium salts
• -without salts, organic matter is digested by proteolytic enzymes
• -daily flossing and brushing help prevent cavities by removing forming plaque

as plaque accumulated, it calcifies and forms calculus, or tartar

• disrupts seal between gingivae and the teeth
• puts gum at risk for infection

• serious gum disease resulting from an immune response
• immune system attacks intruders as well as body tissues, carving pockets around teeth and dissolving bone

• odors produced mainly due to anaerobic breakdown of proteins.
• Bad Breath:
• 1. Anerobic bacteria of tongue
• 2. Nasal sinus infection and gum infections
• 3. Stomach reflux

• Smell caused by:
• 1. Food
• 2. Obesity
• 3. Smoking