Digestion

Digestive System PPT

1. Animal Digestion
Gazelle and Python

2. How do animals get their food?
filter (suspension) feeding substrate feeding
fluid feeding bulk feeding

3. Eating a balanced diet
What happens if an animal’s diet is
missing an essential nutrient?
deficiency diseases
scurvy — vitamin C (collagen production)
rickets — vitamin D (calcium absorption)
blindness — vitamin A (retinol production)
anemia — vitamin B
12
(energy production)

4. Digestion System Diversity
Intracellular Digestion
•food particles engulfed
by phagocytosis
•food vacuoles fuse
with lysosomes
containing hydrolytic
enzymes
•Example: sponges
Extracellular Digestion
•the breakdown of food
particles outside of
cells
•occurs in
compartments that
are continuous with
the outside of the
animal’s body
•Examples: hydra,
worms, insects,
humans
intracellular
digestion

5. Digestive System Diversity
Animals, such as hydra,
with simple body plans
have a single opening
pouch called the
gastrovascular
cavity that functions
in both digestion and
distribution of
nutrients.
extracellular
digestion

6. Digestive System Diversity
Everybody’s got one!
More complex animals, such as
humans, have a digestive
tube, the alimentary canal,
with two openings, a mouth
and an anus.

7. stomach
kills germs
break up food
digest proteins
store food
small intestines
breakdown food
- proteins
- starch
- fats
absorb nutrients
pancreas
produces enzymes to
digest proteins & carbs
liver
produces bile
- stored in gall bladder
break up fats
large intestines
absorb water
mouth
break up food
moisten food
digest starch
kill germs
Digestive
Organ Review

8. Maintaining Homeostasis
•Interactions between certain organs
help to regulate homeostasis.
•Example:
•After stomach mechanically breaks
down food, enzymes are produced by
the stomach and small intestine to
chemically digest them into nutrients.
•These nutrients are absorbed by the
small intestine and eventually delivered
to cells.

9. Maintaining Homeostasis:
Stomach
•Functions
disinfect food
HCl = pH 2
kills bacteria
breaks apart cells
Components of HCl are
produced by parietal cells
chemical digestion
Example: pepsin
enzyme breaks down proteins
chief cells secrete pepsinogen
activated by HCl
But the stomach is made out of protein!
What stops the stomach from digesting itself?
mucus secreted by stomach cells protects
stomach lining
Ooooooh!
Zymogen!

10. Maintaining Homeostasis:
Small intestine
Function
chemical digestion
digestive enzymes
absorption through villi & microvilli:
finger-like projections
increase surface area for absorption
over 6 meters!
small intestine has huge surface area = 300m
2
(~size of tennis court)
most nutrients are absorbed across the
epithelium of the small intestine
Structure
3 sections
duodenum = most digestion
jejunum = absorption of nutrients & water
ileum = absorption of nutrients & water

11. Duodenum
1st section of small intestines
acid food from stomach mixes with
digestive juices from accessory glands:
pancreas
liver
gall bladder

12. Accessory Organ:
Pancreas
Digestive enzymes
peptidases
trypsin
trypsinogen
chymotrypsin
chimotrypsinogen
carboxypeptidase
procarboxypeptidase
•pancreatic amylase
Buffers
reduces acidity
alkaline solution rich in
bicarbonate (HCO
3
-)
buffers acidity of material from
stomachnygm!aoh !iag !g !y!
eonunyt!uyenu!oc!
ititu cmigom!iaueu(
Explain how this is a
molecular example of
structure-function theme.
small intestines

13. Accessory Organ: Liver
Digestive System Functions
produces bile
bile contains bile salts
ostored in gallbladder until needed
obreak up and absorb fats in the duodenum
act like detergents to breakup fats)gtnyiot!% iue!
)ommuigom
Circulatory System
Connectiongnu!omiygm !
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tuZ!nooZ!unn !
onnuiuZ!gm!ngut!*
gtom!gm!+&)!t i !"!
eyu !cuu !toh m
bile contains
colors from old
red blood cells
collected in liver =
iron in RBC rusts &
makes feces brown

14. Evolutionary Adaptations of
Vertebrate Digestive Systems
specialization in teeth
length of digestive system
number & size of stomachs

15. Digesting cellulose
How well you digest cellulose
governs life strategy of herbivores
bond between the sugars governs digestibility
starch
cellulose

16. Cow
can digest cellulose well;
no need to eat
supplemental sugars
Gorilla
can NOT digest cellulose
well; must supplement with
sugar source, like fruit
Cow
can digest cellulose well;
no need to eat
supplemental sugars
Gorilla
can NOT digest cellulose
well; must supplement with
sugar source, like fruit

17. Mutualistic Adaptations
Ruminants
additional
mechanical
digestion by
chewing food
multiple times
after mixing it
with enzymes
How can cows digest cellulose efficiently?
symbiotic bacteria in stomachs help digest cellulose-
rich meals
rabbit vs. cow adaptation: eat feces vs. chew cud
ruminantcaprohagy

18. liver
pancreas
liver
Example: Regulation of Blood Sugar
blood glucose level
(90 mg/100 mL blood)
insulin
body
cells take
up glucose
from blood
liver stores
glucose as
glycogen
reduces
appetite
glucagon
pancreas
liver
releases
glucose
triggers
hunger
high
low
Maintaining Homeostasis through Feedback1 !iag !y!muryigu!ot!
o gigu!cuuZy!
iuep
Is this a negative or
positive feedback
system?

19. Homeostatic Imbalance
Diabetes mellitus
•caused by a deficiency of insulin or a
decreased response to insulin
•marked by elevated blood glucose
levels