Date post: | 31-Mar-2015 |
Category: |
Documents |
Upload: | jaren-garl |
View: | 216 times |
Download: | 3 times |
Digestive System
HS I
What are the structures and functions of the Digestive System?
• Objective 2.07 & 2.08• Essential questions:
• What are the structures of the digestive system?
• What are the fxs & disorders of the digestive system?
Structures of the digestive system
Digestive system
• Also known as:• Alimentary Canal• Digestive Tract• Gastrointestinal
Tract• Upper GI• Lower GI
• Approximately 30’ in length from mouth to anus
3
1. Physical breakdown of food
2. Chemical digestion of food into the end products of fat, carbohydrates and protein.
3. Absorb nutrients into blood capillaries of the small intestines
4. Eliminate waste products of digestion
Functions of the Digestive System
• DIGESTION – the process of changing complex solid foods into simpler soluble forms which can be absorbed by body cells.
• ENZYMES – chemical substances that promote chemical reactions in living things.
• ALIMENTARY CANAL – digestive tract or gastrointestinal tract (GI Tract). A 30 ft. tube from mouth to anus.
• PERITONEUM – double-layered serous membrane that lines the abdominal cavity (Lining of the Digestive System)
Primary Organs of Digestion
• Mouth• Esophogus• Stomach• Small Intestines• Large Intestines
(a.k.a Colon
Accessory Organs of Digestion
• Mouth• Tongue• Teeth• Salivary Glands
• Pancreas• Liver• Gall Bladder
Structure of Organs of Digestion - Mouth
• A.K.A. Buccal Cavity• Food enters digestive system through
mouth • Inside of mouth covered with mucous
membrane• Roof of mouth is HARD PALATE (bone)
and SOFT PALATE• UVULA – flap that hangs off soft palate –
prevents food from going up the nose when you swallow
Structure of Organs of Digestion - Tongue• Attached to floor of mouth• Helps in chewing and swallowing• Made of skeletal muscle attached to four
bones• Taste buds on the surface – sweet, sour,
bitter, salty
Structure of Organs of Digestion – Teeth
• GINGIVA – gums, support and protect teeth
• MASTICATION – chewing, teeth help in mechanical digestion
• DECIDUOUS (primary) teeth – 20 baby teeth
• Permanent (secondary) teeth – 32 adult teeth
Did you know???
Canine teeth are also
known as cuspids and
eye teeth
Structure of Organs of Digestion – Teeth• Incisors – cutting and chopping food
• Cuspids – ripping food
• Bicuspids – ripping food
• Molars – crushing and grinding food
Structure of Organs of Digestion – Salivary Glands
• Three pairs of glands – parotid, sublingual, submandibular
• PAROTID – largest salivary glands, they become inflamed during mumps
• Secrete saliva
Structures of the digestive system• Pharynx (throat) – permits
swallowing food and liquids• Nasopharynx• Oropharynx• Hypopharynx
• - 13
Structure of Organs of Digestion – Esophagus
• Muscular tube, 10” long• Connects pharynx and
stomach• Esophageal wall layers
– Mucosa– Submucosa– Muscular– External serous
Structure of Organs of Digestion – Stomach
• Upper part of abdominal cavity - LUQ
• CARDIAC SPHINCTER – circular layer of muscle, controls passage of food into stomach from esophagus
• PYLORIC SPHINCTER – valve, regulates the entrance of food into duodenum
• RUGAE – mucous coat lining of stomach in folds when the stomach is empty
• Stomach has muscular coat that allows it to contract (peristalsis) and push food into the small intestine
Structure of Organs of Digestion – Small Intestines• DUODENUM – first segment, curves
around pancreas, 12” long• JEJUNUM – next section, 8 ft. long• ILEUM – final portion, 10-12 feet long• ABSORPTION – in small intestine,
digested food passes into bloodstream and on to body cells, undigestible passes on to large intestine
Accessory Organs of Digestion - Pancreas
• Located behind stomach• Exocrine function – secretes digestive
enzymes• Also has endocrine function
Accessory Organs of Digestion - Liver
• Largest organ in the body• Located below the diaphragm,
upper right quadrant• Connected to gallbladder and
small intestine by ducts• Functions:
• Produce and store glucose in the form of GLYCOGEN
• Detoxify alcohol, drugs and other harmful substances
• Manufacture blood proteins• Manufactures bile• Store Vitamins A, D and B
complex
Accessory Organs of Digestion – Gall Bladder
• Small green organ, inferior surface of the liver
• Stores and concentrates BILE from the liver until needed by the body
• When fatty foods digested, bile released by gallbladder for digestion
• CHYME – semi-liquid food
• Approx 2” in diameter• Also called the colon• CECUM – lower right
portion of large intestine• APPENDIX is finger-like
projection off cecum• RECTUM – last portion
of large intestine• ANUS – external
opening
Accessory Organs of Digestion – Large Intestines
Understand the functions of the digestive system
22
Digestion• BOLUS – soft, pliable ball – creating from
chewing and addition of saliva – it slides down esophagus
• PERISTALSIS – wavelike motions, moves food along esophagus, stomach and intestines
In the mouth…• saliva softens food to make it easier to
swallow• PTYALIN in saliva converts starches into
simple sugar (maltose)• under nervous control – just thinking of
food can cause your mouth to water
DigestionIn the stomach…• gastric (digestive) juices are released
• Acid and enzymes• Pepsin – enzyme that breakdowns
proteins• stomach walls churn and mix (This
mixture is chyme) • small amount of chyme enters duodenum
at a time - controlled by pyloric sphincter• takes 2-4 hours for stomach to empty
DigestionMore about gastric juices…
• Enteroendocrine glands– Gastrin – stimulates secretion of
gastric acid by • Parietal cells of the stomach
– HCL (gastric acid) and intrinsic factor (glycoprotein-absorption of B12 in small intestines)
• Chief type cells– Pepsinogen – converted into
pepsin by gastric acid• Mucus cells
– alkaline mucus• Rennin – digestion of milk proteins
DigestionIn the small intestine… • where digestion is completed and
absorption occurs• addition of enzymes from pancreas and
bile from liver/gallbladder• Villi – small finger-like projections that
protrude from the epithelial lining of intestinal wall – increase surface area of the intestinal wall for increased absorption area
DigestionIn the small intestine-pancreas… • enzymes release into the small intestines• amylase – breaks down starch• steapsin – breaks down fat• pancreatic proteases – breaks down
proteins
DigestionIn the large intestine…• regulation of H2O balance by absorbing large quantities
back into bloodstream• bacterial action on undigested food – decomposed
products excreted through colon – bacteria form moderate amounts of B complex and Vitamin K
• gas formation – 1-3 pints/day, pass it through rectum (FLATULENCE) 14 times a day, bacteria produce the gas
• FECES – undigested semi-solid consisting of bacteria, waste products, mucous and cellulose
• DEFECATION – when large intestine fills, defecation reflex triggered – colon and rectal muscles contract while internal sphincter relaxes – external anal sphincter under conscious control
Functions of the digestive system
• Fecal transplant• Allows the
bacteria from the healthy stool to repopulate the gut of the patient who has lost healthy bacteria in their gut
Used to treat Clostridium difficile that grows in human intestines Symptoms range from
persistent diarrhea to life-threatening inflammation of the colon to death
What are the characteristics and treatment of common digestive disorders?
Disorders of the digestive system
• Anorexia• Decreased or poor
appetite
• Symptom
• Anorexia nervosa • Eating disorder
characterized by refusal to eat
• Psychiatric disorder
31
VS
Disorders of the digestive system
Caries • Tooth decay
32
Disorders of the digestive systemCleft palate
• Fissure or opening – non fusion of the palate
• Abnormal facial development during gestation – congenital deformity
• Speech, hearing, and psychosocial problems
• Babies have breathing problems while nursing/suckling
33
Heartburn (indigestion)Gastroesophageal Reflux Disease (GERD)• Acid reflux• Symptoms – burning sensation• Rx – avoid chocolate and peppermint,
coffee, citrus, fried or fatty foods, tomato products – stop smoking – take antacids – don’t lay down 2-3 hours after eating
GASTROENTERITIS• Inflammation of mucous membrane
lining of stomach and intestine• Common cause = virus• Symptoms – diarrhea and vomiting
for 24-36 hours• Complication = dehydration• See a Gastroenterologist
Peptic Ulcer• Sore or lesion that forms in the mucosal lining of
the stomach• Gastric ulcers in the stomach and duodenal
ulcers in the duodenum• Cause – H. pylori (bacteria) is primary cause• Lifestyle factors that contribute: cigarette
smoking, alcohol, stress, certain drugs• Symptoms – burning pain in abdomen, between
meals and early morning, may be relieved by eating or taking antacid
• DX – x-ray, presence of bacteria• Rx – H2 blockers (drugs) that block release of
histamine, avoid spicy food
APPENDICITIS• When appendix becomes inflamed• If it ruptures, bacteria from appendix can
spread to peritoneal cavity • Symptoms – RLQ pain (rebound pain)• Rx – Antibiotics and appendectomy
HepatitisHEPATITIS A • Infectious hepatitis• Cause – virus• Spread through contaminated food or H2O – fecal-
oral• Treat symptoms, rest, no ETOH or fatty foods,
stay hydrated
HEPATITIS B• Caused by virus found in blood• Transmitted by blood transfusion or being stuck
with contaminated needles (drug addicts)• Health care workers at risk and should be
vaccinated• Use standard precautions for prevention
HepatitisHEPATITIS C• Chronic infectious hepatitis• Cause – virus (HCV)• Spread through blood to blood contact• Transmitted by blood transfusion or being stuck
with contaminated needles (drug addicts)
HEPATITIS D• Caused by virus found in blood• Only occur in people who have Hepatitis B –
transmitted at same time• Super Hepatitis – Delta Hepatitis
HepatitisHEPATITIS E• Acute viral infectious hepatitis• Cause – virus (HEV)• Spread through fecal-oral transmission• Lethal – no cure• Mostly in under developed countries due to poor
sanitation
CIRRHOSIS• Chronic, progressive disease of liver• Normal tissue replaced by fibrous
connective tissue• 75% caused by excessive alcohol
consumption• S&S – edema, ascites, jaundice, fatigue,
itching, bruise easily, weight loss, red palms, confusion
• Rx – no cure, avoid Tylenol and ibuprofen, low Na diet, stop ETOH consumption,
CHOLECYSTITIS
• Inflammation of gallbladder• Symptoms– RUQ pain, fever, nausea,
vomiting, pale stool, jaundice• Causes – Gallstones (cholelithiasis), bile
duct blockage• Rx – bed rest, antibiotics, pain
medications, hospitalization, Cholecystectomy (surgical removal of gallbladder)
CHOLELITHIASIS• Gallstones• Can block the bile duct causing pain
and digestive disorders• Small ones may pass on their own,
large ones surgically removed • CHOLECYSTECTOMY
IRRATABLE BOWEL SYDROME - IBS
• Spastic colon – chronic abdominal pain, discomfort, bloating
• Diarrhea or constipation• Urgency for bm• Etiology - Unknown • No cure• Rx – diet, stress relief, exercise,
medication
Other DisordersDIARRHEA• Loose, watery, frequent bowel movements when
feces pass along colon too rapidly• Caused by infection, poor diet, nervousness, toxic
substances or irritants in food
CONSTIPATION• When defecation delayed, feces become dry and
hard • Rx – diet with cereals, fruits, vegetables, (roughage),
drinking plenty of fluids, exercise, and avoiding tension
OBSTIPATION• Blockage of intestines – severe constipation
JAUNDICE• Yellow color of the skin
Relevance of nutrition to the digestive system
• Healthy dietary habits help maintain homeostasis of body systems
46
Relevance of nutrition to the digestive system
• Vitamins• Fat soluble
• Vitamins A, D, E, K
• Water soluble• Vitamins C, B
• Electrolytes• Calcium• Chloride• Magnesium• Phosphorus• Potassium• Sodium
47
QUESTIONS