Download Outline

Digestion Overview
I.
II.
Picture
Organ grouping
A. Alimentary canal or gastrointestinal tract (
)
1. continuous tube mouth to anus (
)
2. breaks down food, nutrients__________ and wastes _________
3. organs – mouth, pharynx, esophagus, stomach, small intestine,
large intestine and anus.
B. Accessory organs
1. some are part of GI tract and some are connected to GI tract
2. aid in digestion by chemical and mechanical breakdown of
food
3. organs – teeth, tongue, salivary glands, liver, gall bladder and
pancreas
III. Digestive Processes (or the 6 essential activities involved processing food)
A. _____________– food entering the mouth
B. _____________ – moves food through the GI tract
1. swallowing – initiated voluntarily
2. peristalsis
a. alternate waves muscular contraction and relaxation of
organ walls
b. squeezes food to next organ and mixes food
C. ___________________
1. physically prepares food for chemical digestion
2. includes chewing, mixing food with saliva, churning of stomach
and segmentation
3. ________________ is rhythmic contractions that mixes food
with digestive enzymes and increases efficiency of absorption.
D. ___________________
1. series of chemical reactions to break down food into their
building blocks
2. accomplished by ______________
3. begins in mouth and completed in small intestines
E. __________________
1. passage of digested food and water form GI tract to blood
2. most of absorption occurs in small intestine
F. __________________
1. elimination of undigested substances form body
2. exits anus in form of feces
IV. Nutrients
A. Carbohydrates
1. ____________ source of energy
2.
digestion breaks carbohydrates down into ______________
3. saccharide, disaccharide, polysaccharide
B. Lipids
1. ____________ source of energy
2. digestion breaks lipids down into ___________and _________
3. fats, hormones, phospholipids
C. Proteinsphotographic pictures
1. ____________ source of energy
2. primary function is to build, repair in body
3. digestion breaks proteins down into their ______________
4. enzymes, hormones, connective tissues, blood proteins
D. Nucleic acids
1. get DNA and RNA from cells you eat
2. digestion breaks down nucleic acids into______________
3. DNA is the instructions for life (instructions to make ________)
E. Vitamins and minerals
1. support specific body functions
2. vitamins A, B, C, D, etc…
3. sodium, calcium, potassium, etc…
F. Water-solvent in which chemical reactions occur
V.
Functional Concepts of Digestion
A. Digestion is controlled by intrinsic and extrinsic means
1. intrinsic – nerves in _________________ monitor activity and
digestion
2. extrinsic – nerves from ____________________ effect digestion
B.
Digestion provoked by range of stimuli
1. sensors monitor stretchosmolaritypHpresence of substrates and products2.
digestive system reacts to these by activating or inhibiting
glands (enzymes) and by speeding or slowing down contents
lumen through GI tract
VI. Generalized structure of the GI tract
A. Layers of the GI tract wall
1. mucosa
a. _______________-layer
b. typically contains simple columnar epithelium
(
)
along with a thin connective tissue layer (
)
and a thin smooth muscle layer (
)
c.
functions to __________ (mucus, enzymes, and hormones)
and __________ (nutrients into the blood)
and __________ (against disease)
2.
submucosa
a. second layer in from lumen
b. connective tissue rich in _________ and _______________
3.
muscularis externa
a. third layer in from lumen
b. functions in propelling food (
), mixing food
in stomach and intestines (
)
c.
contains an inner _______________ layer of muscles and
an outer layer of ______________________- muscles
d. parts of the inner circular layer thickens to form
____________________ that act like valves to prevent
backflow and control the passage of food to the next
organ in the GI tract
4.
serosa
a. the outermost protective layer of the organs wall
b. also called the _________________________
VII. Serous membrane
A.
Peritoneum
1.
2.
3.
4.
5.
6.
– attached to the organs
– attached to the cavity wall
– space between visceral and parietal
- visceral and parietal layers connected
– behind peritoneum
– within peritoneum
B. adaptations of the peritoneum
1. _____________________ = fatty apron
a. mesentery that covers abdominal organs
b. function - to protect and hold organs in place
c. hangs from stomach and transverse colon
2. _____________________
a. mesentery that suspends the liver from the diaphragm and
the ventral wall
b. also separates liver into lobes
3. ________________ – mesentery that suspends stomach from liver
4. ________________ – mesentery that anchors small intestine to
dorsal cavity wall
5. ________________ – mesentery that anchors large intestine to
dorsal cavity wall
Organs of the Digestive System
I.
Mouth or oral cavity
A. lined with __________________ epithelium
B. epithelium slightly keratinized on gums, hard palate and tongue
C. review hard palate, soft palate, uvula, fauces
D. tongue
1. mixes food with saliva to make a ______
2. composed of skeletal muscles
3. repositions food during chewing
E. salivary glands
1. functions
a. ___________mouth
b. ___________ food to be tasted
c. ___________ food to become bolus
d. contains enzymes which begin to chemically break down
of _____________ foods
2. names
a. ______________ gland – next to ear
b. ______________ gland – deep in floor of mouth
c. ______________ gland – under tongue
F. teeth
1. function - _____________ or chew
2. teeth shapes
a. incisors – chisel-shaped for__________ of pieces
b. canines – fang-like/ __________
c. premolars and molars – rounded for ____________
3. deciduous teeth = milk = baby teeth
a. _____total
b. lose them - 6 years Æ 12 years
c. 4I, 2C, 4M in upper and lower jaw
4. permanent teeth
a. _____ total
b. added premolars (bicuspids) and
third molar (wisdom teeth)
c. 4I, 2C, 4PM, 6M in upper and lower jaw
II.
Pharynx
A. oropharynx to laryngopharynx for food
B. passageway for ________ and ______
C. lined with __________________________ epithelium
D. when swallowing, ________ goes up to cover nasal opening and
____________ goes down to cover glottis
III. Esophagus
A. hollow tube about 25 cm (10 inches) long
B. located ______________ to trachea and serviced by __________ nerve
(parasympathetic)
C. 3 layers in wall (
)
D. lined with ________________which secretes mucus for lubrication
E. sphincters located at each end
1. upper esophageal sphincter
2. lower esophageal sphincter (
)
F. pH optimal for amylase activity (
)
G. esophageal _________ is the opening through the diaphragm
H. moves food voluntarily (swallowing = deglutition) and then
involuntarily (
)
IV. Stomach
A. J-shaped organ which contains all 4 layers of GI tract
B. contains _________ = bolus + stomach secretions
C. regions
1. __________ – entrance of esophagus
2. __________– upper domed portion above cardiac region
3. __________ – largest main part
4. __________ – narrow distal end of stomach
D. sphincters located at each end
1. ___________________sphincter – esophagus/stomach
2. ___________ sphincter – stomach/small intestine
E. curvatures
1. greater curvature
a. lateral side
b. longer
c. connected to greater _______________
2. lesser curvature
a. medial side
b. shorter
c. connected to lesser ________________
F. rugae
1. internal _______ in stomach
2. _______ go away when stomach full
G. stomach lining or mucosa
1. _________________ epithelium
2. almost entirely lined with goblet cells
3. alkaline (
) mucus lines stomach to protect it
4. “You are what you eat”/ you don’t want to digest yourself
H. gastric pits
1. valleys (
) of mucosa
2. lined with goblet cells
I. gastric glands (produce acidic secretions, pH = ____________)
1. produce gastric juice which is first step in protein digestion
2. 3 regions of gastric gland
a. mucus neck cells – top of gland
- produce ____________ mucus
b. parietal cells – middle of gland, cells produce hydrochloric
acid (
)
c. chief cells – deepest cells in gland produce _______________
3. function of HCl
a. turns inactive pepsinogen into pepsin
(HCl)
pepsin breaks down proteins into smaller peptides
(pepsin)
b. provides optimal pH for pepsin to work (pH = 1.5 – 3.5)
c. denatures ___________
d. destroys ____________
V.
Small Intestine
A. General
1. Digestion and absorption will be completed here but _______ all
enzymes found here.
2. Called small, not because of its length, (20 – 23 feet), but because
of its _________________.
3. ___________________ epithelium lining
B. Regions
1. Duodenum
a. first section, about 1 foot long
b. retroperitoneal
c. wall is only 3 layers thick because no ______________
d. hepatopancreatic ampulla – opening for secretions from
__________ and ______________
2. jejunum
a. middle 8 feet
3. Ileum
a. distal 12 feet
b. joins to large intestine
C. Modifications of mucosa
1. plicae circulares (or circular folds)
a. folds or plates spiral down small intestine (
)
b. function to increase ______________________for absorption
2. Villi
a. fingerlike projections of mucosa
b. function to increase _____________________ for absorption
3. Microvilli
a. on villi, they are projections into lumen
b. function is to increase ____________________ for absorption
c. also called “brush border”
4. Peyers patches
a. lymphatic nodes in ileum
b. help prevent ____________ from entering bloodstream
D. Secretions of small intestine
1. goblet cells – produce mucus for __________ from stomach acidic
chyme
2. duodenal glands - produce basic or alkaline mucus to __________
chyme
3. intestinal glands or crypts – secrete intestinal juice to water down
chyme and help carry nutrients to be ____________
4. mucosal enzymes (or brush border enzymes)
a. produced on ____________ of mucosa
b. found on ________on intestine, not in chyme
c. optimum pH, _______, for intestinal and pancreatic enzymes
d. peptidases – reduce peptides to ______________
pepsin
peptidases
e. disaccharidases – reduce diasaccharides to monosaccharides
amylase
disaccharidases
f. nucleases – reduces nucleic acids to nucleotides
nuclease
g. enterokinase – used to _____________ pancreatic enzymes
E. Functions of small intestine
1. receive chyme
a. when enters small intestine – ___________
b. when exits small intestine – ___________
2. propulsion of chyme – _____________
3. churning of chyme – ______________
4. completes _____________ digestion
5. absorption of nutrients
6. secrete ____________ which regulate digestion
7. accessory organ attach here: liver gall bladder, pancreas
VI. Large Intestine
A. regions (most have simple columnar epithelium lining )
1. cecum – first part of large intestine
a. ileoceceal sphincter – connect small to large intestine
b. connects to _____________
2. colon (4 parts) – water ________________ to concentrate feces
a. ascending colon
b. transverse colon
c. descending colon
d. sigmoid colon
3. rectum (
) – storage of feces
4. anal canal – tapered end of rectum
a. numerous veins – weakened, dilated veins =_____________
b. muscular sphincters: circular muscles
i. internal sphincter – (
) smooth muscle
- urgency
ii. external sphincter – (
) skeletal muscle
- hold in feces or gas
c. epithelium
i. upper anal canal – same as intestines, simple columnar
ii. lower anal canal – stratified squamous
5. anal orifice - ___________
B. characteristics
1. teniae coli – longitudinal muscle that pulls and puckers large
intestine
2. haustia – puckers that form are called teniae coli
3. epiploic appendages – fat filled sacks on visceral peritoneum
4. diarrhea – chyme rushed through large intestine
- less reabsorption of water
5. constipation – chyme slowed in large intestine
- too much reabsorption of water
VI. Pancreas
A. anatomy
1. location – __________to stomach next to curve of duodenum
2. structure
a. ________ – largest, most medially located
b. ________ – middle, elongated
c. ________ – thinning, lateral end
d. hepatopancreatic ampulla – junction to duodenum
e. pancreatic duct+common bile duct = hematopancreatic duct
B. secretions of pancreas
1. all enzymes secreted are in an ___________ form until they reach
duodenum (pro- or –ogen)
2. pancreas is only organ that makes enzymes for _____categories of
organic molecules
3. pancreatic enzymes are ________ in small intestine (as opposed to
small intestine enzymes which are stuck to the walls)
4. secretions are both exocrine and endocrine
a. endocrine – contains cells that produce ______________
i. insulin – causes reduction of blood sugar levels
ii. glucagon – causes elevation of blood sugar levels
b. exocrine – secretes digestive ______________
i. protein digesting enzymes
trypsinogen to trypsin
chymotrypsinogen to chymotrypsin
procarboxypeptidase to carboxypeptidase
*Enterokinase activates trypsinogen to trypsin in small
intestine. Trypsin activates others.
ii. nucleic acid digesting enzymes
nucleases – reduces nucleic acids to _____________
iii. carbohydrate digesting enzymes
- pancreatic amylase converts polysaccharides to
disaccharides, (amylase works only 10 seconds)
iv. lipid digesting enzymes (
)
lipase
monoglycerides and fatty acids
lipids
v. bicarbonate ion– helps neutralize chyme to
optimum pH (
)
VI. LIVER (Hepar)
A. location and description
1. upper right quadrant of abdominopelvic cavity
2. partially fused to diaphragm (
)
3. surfaces
a. diaphragmatic surface – _____________
b. visceral surface – _______________
4. 4 lobes
5. porta hepatis = hilus of liver
a. portal vein
i. blood going _______ liver from intestines,
stomach, pancreas, and spleen
ii. 80% of blood going into liver is venous
b. hepatic artery
i. blood going ______ liver branching from aorta
ii. 20% of blood entering liver is good clean blood
c. common hepatic duct
i. bile __________ liver
ii. eventually joins cystic duct (gall bladder) to form
common bile duct. Common bile duct connects to
pancreatic duct to form hepatopancreatic duct
B. functions
1. maintain _____________ levels
a. too much sugar
glycogenesis = convert glucose to glycogen
b. not enough sugar
glycogenolysis = reduce glycogen to glucose
2. store minerals and _______________
3. protect body
a. detoxify drugs (legal or illegal)
b. “take 3 times daily”
c. phagocytosis by Kupffer cells
4. makes _________ - blood proteins and clotting factors
5. makes ______________
6. excretion
a. _____________ (heme without Fe+)
b. _____________ (byproduct from protein catabolism)
C. hepatic partal system
1. portal = generally means veins to capillaries to veins
2. primary capillaries (intestines, stomach, pancreas, and spleen)
portal veins
secondary capillaries (in liver called sinusoids)
hepatic vein
inferior vena cava
D. microscopic structure of liver
1. lobule
a. shape of __________
b. central vein in middle – ___________c. triad at corners
i. _______________ – bile in from lobule
ii. _______________ – blood to lobule
iii. ______________ – blood to lobule
d. blood flows from perimeter of lobule to center vein (
e. blood is filtered as it goes through lobule (
)
)
VII. Gall Bladder
A. hollow sac found on _____________ surface of liver to store bile
B. smooth muscle in wall – vigorous contractions
C. serviced by cystic duct
1. dilute bile in
2. concentrated bile out
VIII. Bile
A. contents
- water, electrolytes, bilirubin, bile salts (no enzymes)
B. bile salts
1. _____________– to break up fat globule
2. _____________ – orient toward water
- face out from fat
3. _____________ – orient toward fat
- causing emulsification
4. _____________– large fat globule broken down into small fat
droplets
5. _____________ – to assist lipase by increasing surface area
6. if too concentrated, bile forms gallstones