Transcript Digestive System

Digestive System
Unit 11
Role of Digestive System
A. Prepare food for ______________ and utilization by all the body
cells
B. Excess food material (not absorbed) becomes _______to be
eliminated
C. Ingestion vs. Digestion
1. Ingestion – process of taking food ______ the GI tract
2. Digestion - food undergoes a chemical process called
__________________________
a. food and fluid is broken down into their
smallest parts so the body can use them to
build and nourish cells, along with providing energy
b. absorption – movement of nutrients into internal
environment
A. Gastrointestinal (GI) Tract [aka alimentary canal] (listed in order of food pathway)
1.
2.
3.
4.
5.
6.
mouth
oropharynx
pharynx
esophagus
stomach
small intestine
a. duodenum
b. jejunum
c. ileum
7. large intestine
a. cecum
b. colon
1.
2.
3.
4.
8. rectum
9. anus
B. Accessory Organs
1.
2.
3.
4.
5.
6.
7.
salivary glands
tongue
teeth
liver
gallbladder
pancreas
vermiform appendix
ascending colon
transverse colon
descending colon
sigmoid colon
Layers of the walls of the gastrointestinal (GI) tract
1. (deepest) mucosasubmucosamuscularisserosa (most superficial)
2. Tissue layers have variation in different organs
Mouth and Pharynx
• __________________ Cavity
– Lips – external is skin; internal is mucous membranes
– Cheeks – lined by mucous membranes; contain
mucous secreting glands
– Hard and Soft Palates
• Hard palate – _______ bones
• Soft palate – _______________; forms partition
between mouth and nasopharynx; uvula extend
from soft palate
– Tongue – muscle covered by mucous membrane
• mastication (_____________) and deglutition
(____________________)
• papillae – surface of tongue; some contain taste
buds
• lingual frenulum – mucous membrane fold that
anchors tong to bottom of mouth
Mouth and Pharynx
• Salivary Glands
– Secrete about __L of saliva/day
• Salivary amylase – ________ in saliva that converts starch to sugar
– ___ pairs of glands (parotid, submandibular, sublingual)
Mouth and Pharynx
•
Teeth
– Anatomy
• crown - covered in enamel
• neck – connects crown to root
• root – fits into socket in the gum
– Types
• ________________ teeth (20 baby
teeth)
–
–
–
–
Incisors
Canines
first molars
second molars
• Permanent Teeth (32 adult teeth)
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incisors
canine
premolars
1st & 2nd Molars
third molars – wisdom teeth
Pharynx – tube through which bolus
(chewed ball of food) passes when moved
from mouth to esophagus (deglutition)
Esophagus and Stomach
• Esophagus
– Extends from ________ to stomach
– Resides in both abdominal and
thoracic cavities
– Peristalsis __________
Esophagus and Stomach
• Stomach
– Functions
• reservoir for food until it is partially digested and
moved along GI tract
• secretes ________ juice
• breaks food into small particles and mixes them with
gastric juice
• limited absorption
• helps protect body from bacteria swallowed with food
• produces ____________ – hormone that causes the
stomach to produce acid
Esophagus and Stomach
•
Stomach
– Sphincter Muscles
• lower esophageal sphinter (LES)/cardiac sphincter controls opening of esophagus into ____________
• pyloric sphincter - controls opening of stomach into
___________ intestine (duodenum)
– gastric reflux – sphincter working improperly causing
heartburn
– Stomach wall
• Gastric mucosa
– ____________ – folds in lining of the stomach
• gastric glands – below rugae; secrete most of gastric
juice
– chief cells – secrete the enzymes of gastric juice
– parietal cells – secrete___________l
» Zantac – reduces HCl formation in stomach
– endocrine cells – secrete ____________
• Gastric muscularis – thick layer of muscle that allows
stomach to contract
Gastroesophageal
Reflux
Gastric Ulcer
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Helicobacter pylori – bacteria that causes ____________ ulcers
Stomach lining replaces itself every _____ days
_____________ – liquefied food; form that food leaves the stomach
Gastroenteritis – stomach inflammation
____________ – vomiting
_____ million digestive glands in the stomach
Small Intestine
• Proximal to stomach
duodenumjejunumileum
• Microvilli (villus) allow for
_________________
(increase surface area by
hundreds)
• Where majority of substances
are absorbed
• ______ feet long
• Food can stay here for up to
____ hours
Large Intestine
Large Intestine
• Proximal to small intestine
cecum ascending colontraverse colondescending colonsigmoid colon rectum
• _____________ – pouchlike structures
• Constipation – movement of lower colon and rectum
contents at a rate slower than normal
• __________________ – outpouchings of intestinal wall
• Colitis – inflammation of large intestine
• ____ feet long
• Waste stays _____ hours
• Main function is ________ absorption in order to
eliminate feces
Appendix and Peritoneum
• Vermiform Appendix
– function not fully known; but thought to provide safe
place for good ___________
– appendicitis
• inflammation of appendix
• not common in elderly
• appendectomy – surgical removal of appendix
• Peritoneum
– large, continuous sheet of serous membrane
– parietal and visceral portions
– ______________ : extension of parietal peritoneum
that anchors GI tract to abdominal wall.
Liver
•
Anatomical units – lobes and lobules
–
–
left lobe
right lobe – biggest section of liver
–
hepatic lobules – branch of hepatic vein extends through each _______ (main
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Blood flows to hepatic lobules via branches of the hepatic artery and hepatic portal vein
____________ _______ ________ – merger of the hepatic duct and cystic duct
_________________ bile
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–
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Bile salts – aid in the absorption of ___________; most essential part of bile
No enzymes
Functions of liver
–
–
_________________
Bile ____________________
•
secrete 1 pint/day
– Metabolizes proteins, fats,
and carbohydrates
•
anat unit)
Misc. Info
– Hepatic refers to liver
– Largest _______ in the body
– Hepatitis – inflammation of the liver
– ___________ – degenerative liver
condition
– Removes harmful substances from
the blood
– Stores vitamins and sugars until your
body needs them
•
Gallbladder
– ____________ bile (holds 30-50 ml bile)
– Cholecystokinin (CCK) – hormone that stimulates gallbladder to release
________ into duodenum (small intestine)
– Secretin – stimulates release of bile
– Cholelithiasis - gallstones
– Cholecystectomy – surgical removal of gallbladder
– Below liver
– Pear shaped
Cholelithiasis - Gallbladder with
yellow cholesterol gallstones
Cholecystectomy
Gallbladder before removal
•
Pancreas
– Both endocrine and exocrine gland
– Pancreatic juice secreted by exocrine acinar cells
– Pancreatic cancer – form of adenocarcinoma
– Breaks down sugar
– Beta cells secrete _____________
Types of Digestion
• Mechanical
• Chemical
Digestive Physiology
Mechanical Digestion
--Mastication
--Deglutition
--Peristalsis
Oral stage – mouth to oropharynx
- ___________________ control
- bolus formed
- soft palate acts as valve to prevent
food from enetering
nasopharynx
Pharyngeal stage – oropharynx to
esophagus
- _______________________ control
- epiglottis prevents bolus from
entering larynx to trachea
Esophageal stage – esophagus to
stomach
- ______________________ control
Peristalsis
•_____________ ripple of smooth muscle
•ring of contraction occurs where GI wall is
stretched, pushing bolus forward
•stimulated by ______ – secreted by endocrine
cells in presence of chyme
Segmentation
•_______________ movement
•forward and backward movement that
mechanically breaks down food and mixes it with
digestive juices
Organ
Mouth (teeth and tongue)
Pharynx
Esophagus
Stomach
Small Intestine
Ascending and
Transverse Colon
Descending Colon
Rectum
Mechanical
Process
Mastication
Deglutition
Deglutition
Deglutition
Peristalsis
Churning
Peristalsis
Segmentation
Peristalsis
Segmentation
Peristalsis
Mass peristalsis
Defecation
Chemical Digestion
Digestive ________________
a. extracellular, organic (protein) catalysts
b. enzyme action
1. specificity
2. optimal pH
Stomach
pH
3.0
Jejunum
Ileum
Colon
6.0-7.0
7.5
6.8-7.3
3. catalyst
4. continually destroyed or eliminated,
so constantly being made
Digestive Enzyme Action
•proenzyme altered by kinase to form active enzyme
1. kinase removes prosthetic group to expose active
site
2. substrate (food) binds to active site of active
enzyme
3. enzyme splits substrate into components and
releases them
4. enzyme can now digest new substance
Carbohydrate digestion
(bread, potato, rice, pasta, fruit, vegetables)
•Starch and sugar are broken down by saliva,
pancreatic and small intestinal juices
salivary amylase,
pancreatic juices
* starch
small intestine
enzymes
maltose
absorbed into blood
glucose (monosac)
liver (stored or used)
small intestine enzymes
* sugar (sucrose)
glucose + fructose
absorbed into blood
* fiber – undigestible
•_________________ cannot be broken down;
eliminated in feces
Lipid Digestion
•_______________________ – bile
breaks down fat into small droplets
within the small intestine
•Steatorrhea - impaired fat absorption
producing large, greasy, foul-smelling
stool
micelle
•Fat-soluble vitamins – ___________
(stored in liver and fatty tissue)
•Pancreatic ____________ – main
fat-digesting enzyme
Disorders
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Mumps
Tooth Decay
Malocclusion
GERD (gastroesophageal reflux disease)
Ulcers
Pyloric stenosis
Appendicitis
Hemorrhoids
Proctitis
Diabetes
Gastroenteritis
Anorexia
Nausea
Emesis
Diarrhea
Constipation
Malabsorption
Diverticulitis
Colitis
Irritable Bowl Syndrome
Colorectal Cancer
Hepatitis
Cirrohsis
Pancreatitis
Pancreatic cancer