Download A & P of the Gastrointestinal Tract

A & P of the Gastrointestinal
Tract
By: Sara Anderson
Food!!!!!
• It is necessary for existence
– Pssstt…and it’s darn good too!!!!!
– What happens once we chew & swallow it?????
• The rest of the world may never know..but YOU
will!!!!!
Digestive Tract
•AKA: Alimentary
Canal
–Musculoskeletal
membranous tube
extending from the
mouth to the anus
•Approximately 30 FEET
long!!!
What is peristalsis?
•Coordinated, rhythmic,
serial contraction of
smooth muscle that
forces food through the
digestive tract, bile
through the bile duct,
and urine through the
ureter.
•**Interesting note**
–During peristalsis, the
tract shortens from
approximately 30 feet to
15 feet!
Accessory Organs
• These aid in the digestive tract but
AREN’T considered part of the digestive
tract:
–
–
–
–
–
–
Teeth
Tongue
Salivary Glands
Liver
Gall Bladder
Pancreas
I’m hungry..let’s eat!!!
•We should all know it all
begins at our MOUTHS!
–TONGUE:
•Muscular appendage
•Aids in chewing,
swallowing and
formation of speech
•Papillae contain
taste buds
– BITTER,
SWEET, SOUR
AND SALTY
TEETH
•The teeth shred, grind and
breakdown
–Each tooth has a special
function
•Incisors (center) for
biting and cutting
•Canines (posterior
incisors) are pointed
for tearing and
shredding
•Molars (rear) with 4
cusps are for
mastication;
crushing and
grinding
SALIVARY GLANDS
•3 Pairs:
–Parotid
–Submandibular
–Sublingual
–Secrete saliva – 99%
water with enzymes
& mucus
–1,000 – 1,500 mL of
saliva every day
–After food is
ingested, continue to
secrete saliva to
cleanse the mouth
•Salivary amylase
(ptyalin) - major
enzyme – initiates
carbohydrate
metabolism
•Lysozyme – destroys
bacteria
ESOPHAGUS
•Muscular, collapsible
tube approximately 10”
long
–Mouth to thoracic
cavity
–Esophageal hiatus to
stomach
–No digestion takes
place here
–Bolus: broken down
food with saliva that
moves to the stomach in
5-6 seconds
Bolus Transport
STOMACH
•Located in the LUQ
•When full it’s the size
of a football
•Holds approximately 1
Liter
•Entrance- Cardiac
sphincter
–Churns, contracts &
compresses contents with
gastric juices & water
–Protein digestion
begins
Hydrochloric acid
•softens connective
tissue of meat
•kills bacteria
•activates pepsin,
which converts
proteins into
proteoses & peptones
•Mucin- protects stomach
lining
•Intrinsic factor- absorption
of B12
•Broken down into viscous
semiliquid called CHYME
•Exit- Pyloric sphincter
STOMACH
SMALL INTESTINE
•90% of digestion
•20 feet long
•1” diameter
•Starts at the pyloric
sphincter and ends at
the ileocecal valve
•3 major sections
–Duodenum
–Jejunum
–Ileum
Lacteals absorb
metabolized fats
•Intestinal juices finish
carb & protein
metabolism
•Bile breaks molecules
into smaller droplets
•Pancreatic juices
– break down
proteins to amino
acids
–Dietary fats to
glycerol & fatty
acids
–Starch to simple
sugars
SMALL INTESTINE
LARGE INTESTINE
•Cecum
•Appendix
•Ascending colon
•Transverse colon
•Descending colon
•Sigmoid colon
•Rectum
•anus
LARGE INTESTINE
•2” diameter, 5’ long
•4 Major functions
–Completion of
absorption
–Manufacture
certain vitamins
–Formation of feces
–Expulsion of feces
**NOTE**
No function for
appendix is known
as of today
•Bacteria
–Changes chyme into
fecal material by
releasing remaining
nutrients
–Synthesizes Vitamin
K
–Produces some Bcomplex vitamins
•Remaining water &
vitamins are absorbed
into bloodstream
through OSMOSIS
RECTUM
• Last 8” of Large intestine
• Fecal material is expelled
• This is the desired outcome….
ACCESSORY ORGANS: THE LIVER
•Largest glandular organ &
one of the most complex
•3 lbs
•Divided into 2 lobes
•15oo mL of blood are
delivered to the liver every
minute via the portal vein &
hepatic artery
•Bile
–Yellow-brown or greenbrown color
–Necessary for
metabolism of fats
•500-1,000 mL/daily
•Many functions:
–Manages blood coagulation
–Manufactures cholesterol
–Manufactures albumin
(maintains normal blood
volume)
–Filters old RBC’s & bacteria
–Detoxifying poisons (alcohol,
nicotine, drugs)
–Turns ammonia into urea
–Main source of body heat
–Stores back up glycogen
–Activates Vitamin D
–Breaks down nitrogenous
waste
–And that’s it!!!!!!!!!!
THE LIVER
ACCESSORY ORGANS: THE PANCREAS
• Endocrine & EXOCRINE
• 1,000 – 1,500 mL juice to aid in digestion
• Protease (trypsin), lipase (steapsin), &
amylase (amylopsin) digest proteins, fats
and carbohydrates
• Empties through the duodenum in the
papilla of Vater
• Contains sodium bicarbonate to neutralize
hydrochloric acid
THE PANCREAS
Regulation of food intake!!
•Hypothalamus
–2 centers to
stimulate to eat
and to STOP
eating!!!!
•And THIS..is
your stomach on
too much good
food!!!!!!!!!!!!!