1. What do animals need to live?
Animals make __________ using:
__________________
Animals _______________ using:
amino acids, sugars, fats, nucleotides
food
ATP O2
__________________

2. Getting & Using Food ________________ taking in food
__________________________
breaking up food into smaller pieces
breaking down food into molecules small enough to be absorbed into cells
enzymes
absorb across cell membrane
___________________
undigested material passes out of body
intracellular digestion
extracellular digestion

3. Mouth Functions _______________________ _______________
break up food
__________________________
____________________________
mucus
protects soft lining of digestive system
lubricates food for easier swallowing
buffers
neutralizes acid to prevent tooth decay
anti-bacterial chemicals
kill bacteria that enter mouth with food
All that in spit!

4. Swallowing (& not choking)
________________________
flap of cartilage
closes __________ (windpipe) when swallowing
food travels down _______________
involuntary muscle contractions to move food along

5. Stomach Functions ______________________ hydrochloric acid = pH 2
kills bacteria
can stretch to fit ~2L food
_____________________
Still, the epithelium is continually eroded, and the epithelium is completely replaced by mitosis every three days.
Gastric ulcers, lesions in the stomach lining, are caused by the acid-tolerant bacterium Heliobacter pylori.
Ulcers are often treated with antibiotics.
Pepsin is secreted in an inactive form, called pepsinogen by specialized chief cells in gastric pits.
Parietal cells, also in the pits, secrete hydrochloric acid which converts pepsinogen to the active pepsin only when both reach the lumen of the stomach, minimizing self-digestion.
Also, in a positive-feedback system, activated pepsin can activate more pepsinogen molecules.
What stops the stomach from digesting itself?
mucus secreted by stomach cells protects stomach lining

6.   Ulcers Used to think ulcers were caused by stress
Free of H. pylori
Colonized by H. pylori
Used to think ulcers were caused by stress
tried to control with antacids
Now know ulcers caused by bacterial infection of stomach
H. pylori bacteria
now cure with antibiotics
inflammation of stomach
inflammation of esophagus
H. pylori
cell damaging proteins
(VacA)
inflammatory proteins
(CagA)  
cytokines
helper T cells
neutrophil cells
white blood cells

7. Small intestine Functions ______________________
_______________________
amylase from pancreas
trypsin & chymotrypsin from pancreas
bile from liver & lipase from pancreas
nutrients move into body cells by:
diffusion
active transport
This is where all the work is done!
About every 20 seconds, the stomach contents are mixed by the churning action of smooth muscles.
As a result of mixing and enzyme action, what begins in the stomach as a recently swallowed meal becomes a nutrient-rich broth known as acid chyme.
At the opening from the stomach to the small intestine is the pyloric sphincter, which helps regulate the passage of chyme into the intestine.
A squirt at a time, it takes about 2 to 6 hours after a meal for the stomach to empty.

8. Absorption by Small Intestines
________________________________
finger-like projections
_________________________________
SMALL INTESTINES 6 meters long, but can stretch to cover a tennis court

9. Pancreas _______________________________ Buffers
trypsin, chymotrypsin
amylase
lipase
Buffers
neutralizes acid from stomach
small intestine
pancreas

10. Liver & Gall Bladder ________________________
_________________________________
that’s why you can have your gall bladder removed
bile contains colors from old red blood cells collected in liver =
iron in RBC rusts & makes feces brown

11. Large intestines (colon)
Function
___________________________________
use ~9 liters of water every day in digestive juices
if don’t reabsorb water, would die of dehydration
> 90% of water re-absorbed
not enough water re-absorbed
____________________
can be fatal!
too much water re-absorbed
reabsorb by diffusion

12. You’ve got company!
Living in the large intestine is a community of helpful bacteria
Escherichia coli: ___________
____________________________
digests fruits & vegetables
vitamin K & B vitamins
by-product of bacterial metabolism
methane, hydrogen sulfide
STINKY!
PEE-YOO!

13. Rectum Last section of large intestines eliminate feces
what’s left over?
___________________________
mainly cellulose from plants
called ___________________________
keeps everything moving & cleans out intestines
masses of bacteria
So don’t forget to wash your hands!