Transcript Document

Animal Nutrition
Human Digestion
Regents Biology
2006-2007
What do animals need to live?
 Animals make energy
using:
food
 oxygen

food
 Animals build bodies
using:

food for raw materials
 amino acids, sugars,
fats, nucleotides

ATP
O2
ATP energy for synthesis
Regents Biology
How do animals get their food?
suspension feeding
Regents Biology
fluid feeding
substrate feeding
bulk feeding
Regents Biology
Different diets; different lives
 All animals eat other organisms

Herbivores
 eat mainly plants
 gorillas, cows,
rabbits, snails

Carnivores
 eat other animals
 sharks, hawks, spiders, snakes

Omnivores
 eat animals & plants
 cockroaches, bears, raccoons, humans
 humans evolved as hunters, scavengers & gatherers
Regents Biology
Getting & Using Food
 Ingest

taking in food
 Digest

mechanical digestion
 breaking up food into smaller pieces

chemical digestion
 breaking down food into molecules
small enough to be absorbed into cells
 enzymes
intracellular
digestion
 Absorb

absorb across cell membrane
 diffusion
 active transport
 Eliminate
undigested material passes out of
digestive system
Regents Biology

extracellular
digestion
Digestive systems
Everybody’s got one!
Regents Biology
Human digestive system
Regents Biology
Swallowing (& not choking)
 Epiglottis



flap of cartilage
closes trachea (windpipe) when swallowing
food travels down esophagus
 Peristalsis
 involuntary
Regents
Biology
muscle contractions to move food along
Ingestion
 Mouth

mechanical digestion
 teeth
 breaking up food

chemical digestion
 saliva
 amylase
enzyme digests starch
 mucin
 slippery protein (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

Regents Biology
mouth
break up food
digest starch
kill germs
moisten food
Regents Biology
Stomach
 Functions

food storage
 can stretch to fit ~2L food

disinfect food
 HCl = pH 2
 kills bacteria

chemical digestion
 pepsin
 enzyme breaks down proteins
But the stomach is made out of protein!
What stops the stomach from digesting itself?
mucus secreted by stomach cells protects
Regents Biology
stomach
lining
mouth
break up food
digest starch
kill germs
moisten food
stomach
kills germs
break up food
digest proteins
store food
sphincter
sphincter
Regents Biology
Coevolution of parasite & host
Ulcers
Colonized by
H. pylori
 Used to think
ulcers were
caused by stress

tried to control
with antacids
inflammation of
stomach
H. pylori
 now cure with
antibiotics

Regents Biology
inflammation of
esophagus
H. pylori
 Now know
ulcers caused by
bacterial
infection of
stomach
Free of
H. pylori
inflammatory
proteins
(CagA)
cytokines
cell damaging
proteins
(VacA)
helper T cells
neutrophil cells
white blood cells
Revolutionizing healthcare
2005 Nobel prize in medicine
J. Robin Warren
Barry Marshall
Regents Biology
Small intestine
 Function

chemical digestion
 major organ of digestion & absorption

absorption through lining
 over 6 meters!
 small intestine has huge surface area =
300m2 (~size of tennis court)
 Structure

3 sections
 duodenum = most digestion
 jejunum = absorption of nutrients & water
 ileum = absorption of nutrients & water
Regents Biology
Duodenum
 1st section of small intestines
acid food from stomach
 mixes with digestive juices from:

 pancreas
 liver
 gall bladder
Regents Biology
Pancreas
 Digestive enzymes

digest proteins
 trypsin, chymotrypsin

digest starch
 amylase
 Buffers

neutralizes
acid from
stomach
Regents Biology
mouth
break up food
digest starch
kill germs
moisten food
pancreas
produces enzymes to
digest proteins & starch
Regents Biology
stomach
kills germs
break up food
digest proteins
store food
Liver
 Function

produces bile
 bile stored in gallbladder until needed
 breaks up fats
 act like detergents to breakup fats
bile contains
colors from old
red blood cells
collected in liver =
iron in RBC rusts &
Regentsfeces
Biology
makes
brown
mouth
break up food
digest starch
kill germs
moisten food
liver
produces bile
- stored in gall bladder
break up fats
pancreas
produces enzymes to
digest proteins & starch
Regents Biology
stomach
kills germs
break up food
digest proteins
store food
Absorption by Small Intestines
 Absorption through villi & microvilli
finger-like projections
 increase surface area for absorption

Regents Biology
mouth
break up food
digest starch
kill germs
moisten food
liver
produces bile
- stored in gall bladder
break up fats
pancreas
produces enzymes to
digest proteins & starch
Regents Biology
stomach
kills germs
break up food
digest proteins
store food
small intestines
breakdown food
- proteins
- starch
- fats
absorb nutrients
Large intestines (colon)
 Function

re-absorb water
 use ~9 liters of water every
day in digestive juices
 > 90% of water reabsorbed
 not enough water absorbed
diarrhea
 too much water absorbed
 constipation

Regents Biology
You’ve got company!
 Living in the large intestine is a
community of helpful bacteria

Escherichia coli (E. coli)
 produce vitamins
 vitamin K; B vitamins
 generate gases
 by-product of bacterial metabolism
 methane, hydrogen sulfide
Regents Biology
mouth
break up food
digest starch
kill germs
moisten food
liver
produces bile
- stored in gall bladder
break up fats
pancreas
produces enzymes to
digest proteins & carbs
Regents Biology
stomach
kills germs
break up food
digest proteins
store food
small intestines
breakdown food
- proteins
- starch
- fats
absorb nutrients
large intestines
absorb water
Appendix
Vestigial organ
Regents Biology
Rectum
 Last section of colon (large intestines)

eliminate feces
 undigested materials
 extracellular waste
 mainly cellulose from plants
 roughage or fiber
 masses of bacteria
Regents Biology
Different diets; different bodies
 Adaptations of herbivore vs. carnivore
teeth
 length of digestive system
 number & size of stomachs

Regents Biology
Teeth
 Carnivore
sharp ripping
teeth
 “canines”

 Herbivore
wide grinding
teeth
 molars

 Omnivore

both kinds of
teeth
Regents Biology
Length of digestive system
 Herbivores & omnivores


long digestive
systems
harder to digest
cellulose (cell walls)
 bacteria in intestines
help
 Carnivores


short digestive
systems
protein easier to
digest than cellulose
Regents Biology
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 B12 (energy production)
 kwashiorkor — protein
Regents Biology
Vegetarian diets
 Need to make sure you get enough protein

20 amino acids to make protein
 12 amino acids humans can produce
 8 we have to eat = “essential amino acids”


Grains (like corn) have 6 (missing 2)
Beans (like soybean & red beans) have 6 (missing different 2)
 mix beans & grains
for complete group of
amino acids
 rice & beans
 taco/tortilla & beans
 tofu & rice
 peanut butter & bread
Regents Biology
Feedback: Maintaining Homeostasis
 Balancing glucose levels in blood
depress
appetite
pancreas
insulin
cells
take up
glucose
from blood
liver
takes up
glucose
for storage
liver releases
glucose
to blood
Regents Biology
glucagon
pancreas
stimulate
hunger
Any Questions??
Regents Biology
2006-2007