UNIT 14
NUTRITION &
DIGESTION
CH. 20
•Which
characteristic of life
relates to this unit?
•How
do they get that energy?
How do they get food?
•
What do they do to it so that the
nutrients can get into their cell(s)?
•
•What
about multicellular organisms???
How do nutrients get to all of their cells?
300
NUTRIENTS
 What

are nutrients?
complex & simple substances required for life processes
 What
must be done to large molecules
(carbohydrates, fats, & proteins) that doesn’t need
to be done small molecules (water, vitamins, &
minerals)? Why?

large molecules need to be digested (broken down) so
they are small enough to diffuse through cell membranes
•Are indigestible materials
considered nutrients?
•No, b/c not usable by body.
•Why is water important?
•for chemical
reactions to take
place, part of blood,
cooling body
AUTOTROPHS VS. HETEROTROPHS
What
is another name for autotrophs?
 producers
How
do they get their nutrients?
 make

their own food
most by photosynthesis
nutrient made = glucose
AUTOTROPHS VS. HETEROTROPHS
 Another name for heterotrophs?
 consumers

How do they get nutrients?


absorption
ingestion (eating)
AUTOTROPHS VS. HETEROTROPHS
•
Types of heterotrophs?
herbivores (eat producers/plants)
 carnivores (eat consumers/meat)


scavengers (feed on already dead animals)

ex. vultures, buzzards, crabs
omnivores (eat both plants & animals)
 decomposers (break down dead material &
recycle nutrients)


Must be part of EVERY ecosystem!
FOOD INTAKE PATTERNS
 Chunk


Take in food in large pieces
Require structures for physical/mechanical digestion


ex. teeth, gizzard
Require enzymes for chemical digestion


feeders
Ex. amylase, pepsin, lactase
Examples?

Humans, hydra, birds, earthworm
FOOD INTAKE PATTERNS
 Filter
feeders
Generally sessile or slow-moving
 Take in water; filter out food
(microorganisms and/or nutrients
floating in water); expel water
 Examples


bivalves (clams, oysters, mussels),
whale shark, baleen whales
Cells with flagella draw
water through pores
 food particles are
filtered out
WHAT IS DIGESTION?

What is
digestion?

breakdown of
complex organic
molecules into
simple
molecules


polymers 
monomers/
building blocks
Organic Biological
Macromolecule
Polymer
Monomer
(building blocks)
Function
Carbohydrates
(sugars, starches,
cellulose)
polysaccharide
(such as starch &
cellulose)
monosaccharide
(simple sugars such
as glucose)
Energy source,
energy reserve,
plant cell walls
Lipids
(fats, oils, & waxes)
Not applicable
Fatty acids &
Glycerol
(Built from 2 types of
simple “building
block” molecules…
NOT monomers.)
Energy reserves,
cell membrane,
hormones,
insulation, nerve
transmission
Protein
Polypeptides
Amino acids
(20 different A.A.)
Structure,
enzymes,
transport
materials in & out
of cells hormones,
muscle
Nucleic Acids
(DNA & RNA)
Polynucleotide
(Nucleic Acids)
Nucleotides
(sugar-phosphate
backbone &
nitrogenous bases)
Carries genetic
code (“blueprint
for organism) &
directs protein
synthesis
Why is this
necessary?

so molecules can
diffuse through
cell membranes
WHAT ARE THE 2 TYPES OF DIGESTION?

mechanical/physical (ex. chewing)

chewing (mouth), churning (stomach), grinding (gizzard)


to increase surface area & make chemical digestion faster
chemical

enzymes break large molecules (polymers) into smaller
molecules (monomers)

so can diffuse through cell membrane
DIGESTION IN HETEROTROPHS
Intracellular

vs. extracellular
Where does digestion take place in:

Intracellular?


inside cell
Extracellular?

outside of cell


in digestive cavity surrounded by body (stomach)
outside of organism (in environment)
INTRACELLULAR DIGESTION
Paramecium
Amoeba
EXTRACELLULAR DIGESTION
Many have circulatory system
to transport digested nutrients
throughout body
HYDRA
Intracellular
or
extracellular digestion?
 BOTH!

extracellular


gastrovascular cavity
intracellular

small pieces taken into cells
that line cavity by phagocytosis
How
do nutrients get to
all of the Hydra’s cells?
 only
2 layers of cells, so
digested food can diffuse
readily to all cells…
DIGESTION IN HETEROTROPHS
Two-way traffic
 One

opening to body
food enters & waste
exits same way (mouth)

“dead-end” digestive system
 Examples

Hydra


Food = Daphnia
Planaria
basal disc
DIGESTION IN HETEROTROPHS
One-way traffic
 Two
openings to
body/digestive tract

food enters & waste
leaves through different
openings (“tunnel”)


mouth & anus
thorough & efficient

eat more while digesting
 complex
animals

multicellular
ex. earthworm, bird,
human, grasshopper
EARTHWORM DIGESTION
What would happen
if the earthworm
had no gizzard?
Mouth – ingests & moistens food
 Pharynx – muscular contractions pull food from mouth
 Esophagus – muscular contractions push food to crop
 Crop – storage organ
 Gizzard – gravel & muscular contractions grind food to
small particles
 Intestine – enzymes digest food into small molecules which
are absorbed through intestinal walls.
 Anus – expels undigested material or “castings"

EARTHWORM DIGESTION
How
is the increased surface area of
the intestine an adaptation?
 helps
increase absorption of nutrients
HUMAN NUTRITION & DIGESTION
 Examples
of
complex nutrients?



proteins
fats (lipids)
carbohydrates
 Do
complex
nutrients require
digestion? Why/why
not?

Yes, b/c too big to
diffuse through cell
membrane.
 Examples
nutrients?



of simple
vitamins
minerals
water
 Do
simple nutrients
require digestion?
Why/why not?

No, b/c small enough to
diffuse through cell
membrane
HUMAN NUTRITION & DIGESTION
 Why
is it important to eat a balanced diet?
HUMAN DIGESTIVE
SYSTEM
•See table 20.3 (summary
of digestion in humans)
•On pg 565 in textbook
Human Digestion
 What
type of digestion
takes place in the mouth?

mechanical/physical

chewing
increases surface area & speeds
up chemical digestion


chemical

enzymes (starches  sugars)
 What
does saliva do?
moistens food
 contains enzymes

 Starch
digestion
in mouth.
enzyme (salivary amylase)
begins
starch
(polysaccharide )
maltose sugar
(disaccharide)
Human Digestion
 What

connect mouth to stomach
 How

do the pharynx & esophagus do?
is food moved down esophagus?
peristalsis

alternating contraction & relaxation of smooth
muscle move food to stomach
Human Digestion
 What
•
is the epiglottis?
flap of tissue that protects trachea (windpipe)
while swallowing
peristalsis
Human Digestion
 What happens in the
stomach?

mechanical/physical digestion


chemical digestion

of protein (into smaller
polypeptides begins)


churning (muscle contractions)
by gastric juices (enzyme = pepsin &
hydrochloric acid)
storage

rugae
stomach slowly releases chyme
(partially digested food) into
small intestine (pH = 2)
•What is the function of rugae?
•Help w/ mechanical
digestion
•Why doesn’t your stomach
digest itself???`
•Does food go through these
organs (accessory glands?
•no
Human Digestion
Accessory Glands
Pancreas
 secretes
pancreatic
fluid containing
enzymes into small
intestine:

trypsin


amylase


proteins  peptides
starch  maltose
lipase

lipids (fats) 
fatty acids + glycerol
Liver & gallbladder
 liver

produces bile
bile stored in gall bladder

emulsifies fats
 breaks fats into tiny drops
Human Digestion
 Small
intestine
What is the purpose of villi?
What do they “add” to the
small intestine?
pancreatic enzymes & bile are added to chyme
 digestion COMPLETED


starch digestion completed

pancreatic amylase (enzyme)

polysaccharides & disaccharides 
monosaccharides

protein digestion completed

trypsin (enzyme)


fats emulsified by bile

digested by lipase (enzyme)


polypeptides  amino acids
How is structure related to
function in the digestive system?
Lipids  fatty acids & glycerol
nutrients absorbed thru villi into bloodstream
Human Digestion
What
does the
large intestine
(colon) do?
 reabsorbs
water
& salts
 forms solid feces
stored in rectum
eliminated
through anus

anus
Human digestion
•How long is the
small intestine?
•6.0 meters
•How long is the
large intestine?
•1.5 meters
QUESTIONS TO PONDER
Unity within diversity in relation to nutrition & digestion?
 How does form follow function?
 Think about surface area and the digestive system…
 Why the saying “you are what you eat?”
 What should you eat before a game or a run?
 What should you eat after weight-lifting?
 What foods should you avoid?
 What is the best way to maintain a healthy body
composition (lean/fat balance, weight)?

THE EARTHWORM
 Label
each part.
 What is the function of each part?
3.
4.
2.
1.
5.
2.
1.
4.
3.
5.
8.
9.
6.
10.
7.
12.
11.
13.