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builds amino acids-> muscle, used raw materials to synthesize essential compounds


breaks down amino acids, decomposes substances to provide energy cells needed to function

digestive tract

aka gastrointestinal tract or alimentary canal


occurs when materials enter digestive tract via the mouth

mechanical processing

crushing & shearing; makes materials easier to propel along digestive tract


the chemical breakdown of food into small organic fragments for absorption by digestive epithelium


the release of H2O, acids, enzymes, buffers, and salts; by epithelium of digestive tract; by glandular organs


movedment of organic substances, electrolytes, vitamins, and H2O; across digestive epithelium; into interstitial fluid of digestive tract


removal of waste products from body fluids


double sheets of peritoneal membrane; suspended portions of digestive tract w/in the peritoneal cavity by sheets of serous membrane; that connectparietal peritoneum with visceral peritoneum; areolar tissue between mesothelial surfaces; provides an access route to & from the digestive tract; for passage of blood vessels, nerves, & lympatic vessels; stabilize portions of attached organs; prevent intestines from becoming entangled

lesser omentum

belly fat; stabilized position of stomach; provides access route for blood vessels and other structures entering or leaving liver

falciform ligament

helps stabilize position of liver; relative to diaphragm & abdominal wall

major layers of digestive tract

mucosa, submucosa, muscularis externa, serosa

mucosa layer

inner lining of digestive tract; is a mucous membrane consisting of - epithelium, moistened by glandular secretions; lamina propria of areolar tissue

digestive epithelum

mucosal epithelium is simple or statified; depending on loaction, function, and stresses: oral cavity, pharynx, & esophagus > mechanical stresses, lined by statified squamous epithelium; stomach, small intestine, and most of large intestine > absorption, simple columnar epithelium with mucous (goblet) cells

enteroendocrine cells

are scattered among coulumnar cells of digestive epithelium; screte hormones that: coordinate activities of the digestive tract and accessory glands

lamina propria

anchors mucosa to submucosa; consists of a layer of areolar tissue that contains: blood vessels, sensory nerve endings, lymphatic vessels, smooth muscle cells, scattered areas of lymphoid tissue

submucosa layer

layer of dense, irrergular connective tissue; surrounds muscularis mucosae; has large blood vessels and lymphatic vessels; may contain exocrine glands; secrete buffers & enzymes into digestive tract

submucosal plexus

also called plexus of Meissner; innervates the mucosa and submucosa; contains- sensory neurons, parasympathetic ganglionic neruons, sympathetic postganglionic fibers

muscularis externa

dominated by smooth muscle cells; arranged in- inner circular layer; outer longitudinal layer; involved in mechanical processing; movement of material along digestive tract


serous membrane covering muscularis externa; execept in oral cavity, pharynx, esophagus, & rectum; where adventia, a dense sheath of collagen fibers firmly attaches the digestive tract to adjacent structures

movement of digestive materials

by muscular layers of digestive tract; consist of viceral smooth muscle tissue; along digestive tract: has rhythmic cycles of activity, controlled by pacestetter cells; cells undergo spontaneous depolarization: triggering wave of contraction through entire muscular sheet


movement of food; consists of waves of muscular contractions; moves a bolus along the length of the digestive tract

control of digestive function

neural mechanisms; control: movement of material along digestive tract; secretroy functions; motor neurons: control smooth muscle contraction and glandular secretion; loacted in myenteric plexus

hormonal mechanisms

at least 18 peptide hormones that affect: most aspects of digestive function; activities of other systems: are produced by enteroendocrine cells in digestive tract; reach target organs after distribution in bloodstream

oral mucosa

lining of oral cavity; has stratified squamous epithelium; of cheeks, lips, & inferior surface of tongue - is relatively thin, nonkeratinized, & delicate; inferior to tongue is thin & vascular enough to rapidly absorb lipid-soluble drugs; cheeks are supported by pads of fat and the buccinator muscles


also called lips; anteriorly, the mucosa of each cheek is continuous with that of the lips


space between the cheeks (or lips) and the teeth


(gums) ridges of oral mucosa; surround base of each tooth on alveolar processes of maxillary bones and mandible


manipulated materials inside mouth; functions of tongue: mechanical processing by compression, abrasion, & distortion: manipulation to assist in chewing and to prepare material for swallowing: sensory analysis by touch, temp, & taste receptors: secretion of mucins and the enzyme lingual lipase

parotid salivary glands

inferior to zygomatic arch; produce serous secretion- enzyme salivary amylase (breaks down starches); drained by parotid duct (Stensen Duct)- which empties into vestibule at second molar

sublingual salivary glands

covered by mucous membrane of floor of mouth; produce mucous secretion- act as a buffer & lubricant; sublingual ducts (Rivinus ducts)- either side of lingual frenulum; in floor of mouth

submandibular salivary glands

within mandibular groove; secrete buffers, glycoproteins (mucins), & salivary amylase; submandibular ducts (Wharton Ducts)- open immediately posterior to teeth- either side of lingual frenulum

purpose of digestive system

to breakdown food, absorb nutrients, & eliminate waste

2 categories of digestive system organs

1) alimentary canal (tube) 2) accessory organs

digestive processes

1. ingestion 2. propulsion 3. mechanical digestion 4. chemical digestion 5. absorption 6. defecation


-serous membrane of the abdominal cavity - consists of: visceral & parietal layers; peritoneal cavity with serous fluid; messentery; two serous membranes fused together; provide routes for blood vessels, lymphatics & nerves; holds organs in places, stores fat; peritonitis- caused by ruptured appendix, wound, ulcer, ect

mucosa (his notes)

lines lumen from mouth to anus; moist epithelial membrane; major functions- secretion: mucus, digestive enzyme, & hormones; absorption; protection; simple columnar epithelium; Goblet cells- mucus secreting; lamina propria- underlies eithelium, connective tissue, capillaries nourish the epithelium and absorb nutrients, contain lymph nodes (conpose MALT)- important against defense against bacterial

submucosa (his notes)

contains C.T., blood & lymph vessels, lymph nodes and nerve fibers- elastic fibers- stretch

muscularis externa (his notes)

or just muscularis, responsible for peristalsis, contains circular (inner) and longitudinal (outer), muscles for sphincters along GI tract

serosa (his notes)

protective outer layer, visceral peritoneum, replaced by adventitia around esophagus

enteric nervous system (ENS) [his notes]

own in-house nervous system, regulates digestive system activities, linked to CNS by afferent fibers, also linked to sympathetic and parasympathetic NS

mouth (his notes)

oral or buccal cavity, opening- oral orifice, lined with stratified squamous epithelium<many layers of fat cells>, gums, hard palate, dorsum of tongue are keratinized for extra protection, produces defensins (antimicrobial)

lips & cheeks (his notes)

lips (labia), skeletal muscles cover by skin, obicularis oris forms bulk of lips, cheeks- buccinators,vestibule (pouch), red margin (lipstick); transitional zone, keratinized skin meets oral mucosa; poorly keratinized, translucent; no sweat glands or sebaceous glands; labial frenulum, median fold that joins lip to gum

palate (his notes)

roof of mouth; hard palate (palatine process), rigid surface, tongue forces food against during chewing; corrugated to increase friction; soft palate- mostly skeletal muscles, uvula, covers nasopharymx during swallowing

tongue (his notes)

occupies the floor of the mouth; composed mostly of skeletal muscle; helps form food into a bolus - ball of food that we swallow; speech; intrinsic muscles- confined to tongue, not attached to bone; extrinsic muscles- protrude and retract tongue, move side to side; lingual frenulum- fold of mucosa, secures tongue to the floor of the mouth, limits posterior movements; papillae: 3 types- filiform- white, stiff, gives tongue roughness, fungiform- reddish, contains taste buds, circumvallate- "v" at back of tongue; sulcus terminalis- posterior groove, lacks papillae, bumpy due to nodular lingual tonsils

salivary glands (his notes)

produce and secrete saliva; saliva: cleanses the mouth, dissolves food chemically to aid in taste, moistens food and help for bolus, contains amylase to start digestion of starch

3 saliva glands (his notes)

parotid, submandibular, sublingual

composition of saliva (his notes)

97-99.5% water; slightly acidic (6.75-7), can vary; contains amylase, lysozyme, IgA, electrolytes, and even some nitrogenous waste, and growth factors (dogs); also have beneficial bacteria and defensins; production of saliva increases when we eat or even when we think about food, average output ~ 1 to 1.5 L/day

halitosis (his notes)

bad breath; caused by bacteria

teeth (his notes)

set in sockets (alveoli) fo mandible and maxilla; mastication (chewing); tear and grind food; break into smaller pieces to increase surface area; dentition and dental formula- by age 21, 2 sets of teether; 20 primary deciduous (baby teeth) or milk teeth & 32 permantent teeth (adult teeth); permanent teeth- 8 incisors, 4 canines, 8 premolors, 12 molars

crown of tooth (his notes)

above the gum (gingiva); covered with enamel (hardest substance in the body)

root of tooth (his notes)

embedded in jawbone; neck- connect crown and root; cementum- gomphosis joint, anchors in socket by periodontal ligament; ginival sulcus- recedes as we age; "long in the tooth"

dentin (his notes)

bond-like material; underlies cap; forms bulk of tooth

pulp cavity (his notes)

contains vessels, nerves, collectively called pulp; supplies nutrients to the tooth, provides sensation; becomes root canal; apical foramen at the tip

root canal therapy (his notes)

inflammation caused blood supply to tooth to be cut off, nerve dies, pulp becomes infected by bacteria

tooth and gum disease (his notes)

cavities, calculus, gingivitis, periodontal disease

cavities (his notes)

results from demineralization of enamel and dentin; caused by dental plaque; plaque => sugar, bacteria, and debris

calculus (his notes)

tarter; calcified plaque

gingivitis (his notes)

swelling and separation at sulcus caused by tarter

periodontal disease (his notes)

progression of ginigvitis; causes loss of tooth

pharynx (his notes)

oropharynx -> laryngopharynx; lined with friction resistant stratified squamous epithelium; 2 layers of skeletal muscles; circular and longitudinal; propel food to esophaugs

esophagus or gullet (his notes)

~ 10" long; collapsed unless food passes through; lined with squamous epithelial mucosae; esophageal hiatus- pass through diaphragm; gastroesophageal spincter- between stomach and esophagus- GERD- heartburn- can lead to esophagitis and esophageal ulcers

stomach (his notes)

temporary storage chamber; food is broken down mechanically and chemically to form Acid Chyme- liquified food

gross anatomy of stomach (his notes)

10" long; depending on amoung of food; can hold about 4L of food (usually 2L); rugae, longitudinal folds; greater curvature, convex lateral surface; lesser curvature, concave medial surface; cardiac orifice, food enters, cardiac sphincer or LES; fundus, superior protion, dome-shaped; body, mid portion; pyloris, inferior portion, connected to SI, pyloric, pyloric sphincter

microscopic anatomy of stomach (his notes)

wall has 4 tunics; muscularis is modified for mixing and churning of food; linning- simple columnar epithelium composed of goblet cells; produce alkaline mucus; dotted with millions of gastric pits, lead to gstric gladns that produce gastric juice: 4 types: cheif cells- secretes pepsinogen (inactive form); pepsinogen is activated by HCl to form pepsin; also produces lipase; parietal cells- secrete HCl and intrinisc factor (B12), HCl- ph 1.5-3.5, activates pepsinogen and dismantles food; mucus neck cells- produce acidic mucus, functions neot yet known; enteroendocrine cells- releases a variety of hormones, gastrin, histamine, endorphins, serotonin, CCK, and somatostatin; protection of stomach- very acidic environment (100,000x's more than blood)- mucosal barrier, thick coat of bircarb-rich mucus, tight junctions of epithelial cells prevent "leaking", epithelial cells are shed and replaced completely every 3-6 days; gastric ulcers- stress, once thought to be the major cause, now H. pylori

small intestine & gross anatomy (his notes)

90% of digestion and absorption; gross anatomy- ~ 20' long[in cadaver] (8-13' due to muscle tone[in living person]) and 1" in diamerter; 3 divisions: duodenum, jejunum, and ileum

duodenum (his notes)

1st 10" from pyloric sphincter (shortest segment); bile and pancreatic ducts deliver juices here- hepatopancreatic sphincter- valve that contols entry of bile and pancreatic juices; aka Sphincer of Oddi

jejunum (his notes)

middle 8'

ileum (his notes)

12' terminal portion; joins LI at the ileocecal valve; messentery suspend jejunum and ileum in lower abdominal cavity; framed by LI

microscopic anatomy of small intestine (his notes)

surface area and structural modifications make the SI well adapted for absorbing nutrients; 3 modifications- a. plicae cirulares: circular folds similar to rugae in stomach, deep folds of mucosa and submucosa, cause chime to spiral thru lumen: mix with intestinal juices: slow and allow time for full nutrient absorption; b. villi: finger-like projections, 1mm high, increase surface area, core has a dense capillary bed and lacteals; c. microvilli: form brush border, projections of plasma membrane, increase surface area and contain digestive enzymes that complete the digestion of carbs and proteins

histology of the intestinal wall (his notes)

intestinal crypts or crypts of Leiberkuhn; secrete intestinal juices, serves as a carrier for absorption of nutrient from chime, contain Paneth cells- release lysozome; epithelium is replaced every 3-6 days; Peyer's patches- trap bacteria that cross the epithelium and prevent from entering the blood stream; duodenal glands: submocosa, produces an alkaline mucus to neutralize the acid chime

large intestine (his notes)

larger in diameter but only 1.5m long; absorbs water and eliminates undigested food (feces)

gross anatomy of large intestine (his notes)

tenae coli: "ribbon of the colon", longitudenal muscle layer; reduced to 3 bands, tone cause LI wall to pucker into pocket-like sacs called Haustra; epiploic appendages: small fat-filled pouches of visceral peritoneum, unknow significance; subdivision of LI: cecum- blind pouch, below ileocecal valve, beginning of LI, vermiform appendix: part of MALT: Vestigal (no longer needed as adult): appendicitis; colon- ascending, transverse, descending, sigmoid, hepatic & sphlenic flexures; rectum- rectal valves, 3 transvers folds, stops feces from passing along with gas; anal canal- 2 sphincters, internal AS (invol), external AS (vol); anus- opening to the exterior of the body

microscopic anatomy of large intestine (his notes)

no vili or plicae circulares, anal canal: mucosa merger with true skin; lined with squamous epithelium for high abrasion; anal sinus- b/w columns, exude mucus when compressed by feces, aid in emptying the anal canal; hemorrhoidal vein: superficial vein associated with anus and anal column

bacterial flora of large intestine (his notes)

ferment carbs, produce acids, gas, vitamine B & K, & keep harmful bacteria in check

digestive functions of larger intestine (his notes)

few nutrients reach LI, hold undigested food for 12-24 hrs, main function is to absorb water and vitamins; remove undigested food or eliminate waste

imbalance of large intestine (his notes)

diverticulosis- leads to diverticulitis; caused by lack of fiber in the diet; small herniations of the mucosa colon wall; coloscopy & colon cancer; inflammatory bowel disease; diarrhea or constipation

defecation reflex of large intestine (his notes)

pressure on the wall of sigmoid colon and rectum cause contraction and anal sphincter to relax

liver (his notes)

largest gland, wt ~ 3lbs, most on rt side below diaphragm, functions of the liver: detoxify poisons, synthesize nutrients, cholesterol, ect., store glycogen, vitamins, ect., produce bile; 4 lobes

liver lobules (his notes)

hexagonal; size of a sesame seed; hepatocytes- liver cells, arranged around a central vein

diseases of the liver (his notes)

hepatitis: bacterial or viral: Hep A.- 32% cases- fecal -> from others feces; Hep. C- kills 10,000 americans annually -> silent killer; Cirrhosis: alcoholism & chronic hepatitis, liver becomes fatty and fibrous due to the regeneration of connective tissue that replaces hepatocytes, scars eventually shrink but obstruct blood flow through portal system- blood finds alternate routes that can not accommodate the voulum of blood- leads to caput medusase

bile of liver (his notes)

yellow-green, alkaline solutin, contains lots of substances, bile salts, phospholipids, aid in digestions, functions: emulsifies fat (breaks down fat into smaller fat pieces), produce more bile when fatty foods enter the digestive system, bile salts are recycled; pigments are eliminated, bilirubin: gives feces its brown color; recycles Hb

gall bladder (his notes)

stores bile, bile leaves via the cystic duct then flows into the bile duct, gall stones; crystallization of cholesterol; imbalance of bile salts and cholesterol

pancreas (his notes)

1. structure- gland located near stomach - head, body, tail - empties its contents into duodenum- Sphincter of Oddi 2. function- it is both endocrine and exocrine; exocrine: produces digestive juices, contain bicaronates (neutralized acid), digestive enzymes- lipase, amylase, proteases (trypsin); exocrine: Isltes of Langerhans produce insulin (lowers blood sugar) & glucagon (raises blood sugar)

purpose of nutrition (his notes)

build cell structures; replace worn out cell parts; synthesis of functional molecules; most are used to produce chemical energy- ATP; energy is measured in calories - amount of heat energy needed to increase the temp of 1g of water 1°C, very small unit of meaurement, nutritionist uses kilocalorie or 1,000 calories

nutrition (his notes)

6 categories: major nutrients: carbs, lipids, proteins; vitamins & minerals; water *essential nutrients- can not be made by teh body: must be consumed

nutrient (his notes)

substance in fod that is used by the body for growth, maintenance & repair

carbohydrates (his notes)

most are derived from plants: plant -> sunlight -> photosynthesis -> glucose; simple sugars- monosaccharides; polysaccharides- starch, glycogen (animal starch), and cellulose (fiber)

uses in the body: glucose (his notes)

major fuel source to make ATP; excess glucose is converted to glycogen or fat

dietary requirements for carbs (his notes)

125-175g of carbs/day; <50/day is consumed, use fat and protein for energy; Americans typically consume 200-300g /day; empty calories: candy & sodas; lack vitamins & minerals; sugar & glycemic index make sugar spike& then store as fats

lipids (his notes)

saturated fats- animals & H+ ions; unsaturated fats- 1 or more double bonds

uses of fat (his notes)

help absorb fat soluble vitamins; energy; myelin sheaths and cell membranes

good fats (his notes)

omega 3 & 3 fatty acids, cold water fish (salmon), olive & vegistable oils

fat deposition (his notes)

cushion body organs (holds kindey's in place); insulation; energy reserves; prostaglandins & steroid based hormones

dietary requirments for lipids (his notes)

<30% of total caloric intake; unsaturated- good; daily cholesterol ~ 200mg (1 egg)

protein (his notes)

complete protein: meet all body's amino acid requirments; legumes (beans), meats, milk

uses in the body: protein (his notes)

structural materials- keratin, collagen, ect.; muscle; hormones; enzymes; proteins require all necessary A.A; if one is lacking, the protein can not be made- cant store AA; requires daily intake

adequate caloric intake (his notes)

protein will be used as fuel if carbs and fat is not vailable

nitrogen balance (his notes)

protein synthesis = protein breakdown; negative nitrogen balance when protein is used to produce energy; positive nitrogen balance in growing children and pregnant women

hormonal controls (his notes)

anabolic hormones accelerate protein sysnthesis- growth hormone, sex hormone; glucocorticoids are catabolic

dietary requirments for proteins (his notes)

depends on age, sex, size, metabolic rate, and current nitrogen balance; generally .8g/kg of body wt.; ~30g in 1 glass of milk; most Americans eat more protein than needed

vitamins (his notes)

most are coenzymes; 2 classes of vitamins; fat soluble and water soluble; fat soluble = A, E, D, K (too much can be toxic to liver); water soluble = B & C (too much and you will pee out or get diarreaha)

minerals (his notes)

7 minerals needed in moderate amounts: calcium, phosphorus,potassium, sodium, chloride, sulfur, & magnesium; make up 4% of body wt: calcium and phosphorus in bone- 75% of that; most minerals are ions in body fluids = electrolytes; dozens other minerals are needed in very small amounts- called trace minerals: toxic in high amounts

metabolism (his notes)

anabolic & catabolic

anabolic (his notes)

builds; takes small molecules & build & use energy

catabolic (his notes)

breakdown; takes large molecules & breaksdown to produce energy

cell respiration (his notes)

how our bodies produce energy; cell organell that carry on cell respiration = mitocondira; glucose most readily produces energy;

anareorbic respiration steps (his notes)

1) glycolysis (split glucose) 2) acetol CO.A 3) Kreb's Cycle 4) electorn transport chain <need all 3 of the last steps for oxygen present>: produces 36 ATP's: produces about 100lbs of ATP/day (ADP + P = ATP)

anareobic (his notes)

no oxygen (2 ATP's; not efficent) & produce lactic acid as waste products

Vit A (his notes)

vision/ deficency causes night blindness (found in orange type fruits, carrots)

Vit D (his notes)

deposit calicum & phosphorus to bones/ deficency causes Rickets (found in sunlight & added to milk)

Vit E (his notes)

oxidation (found in oils to cut down on scars & stretch marks)

Vit K (his notes)

helps the blood clott

Vit C (his notes)

antioxident & collagen production/ deficency causes Skruvie (found in cirtius fruits & kiwi)

B Vitamins (his notes)

B1- thymine, B2- ribofain, B3- nadcin, B5- pantothenic, folic acid- help get PG, B12- increases energy levels, for red blood cells, & intrinsic factors


sodium- salt/ needed for fluid balance, potassium- meats, milk, fruits & veggies/ needed for fluid balance, chloride- needed for fluid balance, calcuim- dairy products & leafy green veggies/ needed for bones, phosphorus- meat, fish, poultry/ needed for bones, magnesium- cardiovascular & immune system health, sulfur- meats, poulty, fish, eggs/ for hair strength/ found in protein molecules

trace minerals

iron- for RBC/ organ meats, red meats, fish, poultry, zinc- needed for making protein, sexual health, immune system/ meats, fish, wole grains, iodine- helps regulate growth/ seafood, bread, selenium- antioxident, copper, maganese, flouride- formation of bones & teeth, chromium- works with insulin to regulate blood sugar, molybclenum- part of enzymes

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