NUTRITION
How Organisms Obtain
Nutrition
AUTOTROPHS
Examples are green plants, algae, some microorganisms
•
Most are photosynthetic
 Using sunlight, CO2, water food
 Are called phototrophs
•
Some bacteria are chemosynthetic
 Using energy from chemical reactions
to produce food
 Are called chemotrophs
How Organisms Obtain
Nutrition
HETEROTROPHS
•
•
All animals
Some microorganisms
Energy content of food
• Energy is provided to the organisms by the chemical
breakdown of carbo’s, fats, and proteins
• Energy is released and stored as ATP in certain
molecules during the process of cellular respiration
• The measure of this energy released by cellular
respiration is in calories
• Energy released by 1 gram of a carbohydrate = 4
kilocalories
• Energy released by 1 gram of a protein = 4
kilocalories
• Energy released by 1 gram of a fat = 9 kilocalories
Humans need 6 nutrients
1.
2.
3.
4.
5.
6.
Proteins
Carbohydrates
Fats
Vitamins
Minerals
Water
See page 5 and 6 in your packet
Four (five) basic food groups
1.
2.
3.
4.
5.
Milk and cheese
Meat, poultry, fish, beans
Legumes – plants that have seeds w/ pods
Beans, peas, peanuts are high in proteins
Fruit, vegetables
Bread and cereals
Sweets
Fiber
•bulky indigestible materials including cellulose from
the cells walls of fruits, vegetables, and grains
fiber stimulates the digestive muscles
decreases the risk of colon cancer
Mechanical breakdown vs.
chemical breakdown of food
• Mechanical breakdown = foods are
broken, crushed into smaller pieces with
out being changed chemically. This gives
the materials a greater surface area so
that the digestive enzymes can work more
efficiently on them.
Mechanical breakdown vs
chemical breakdown of food
• Chemical breakdown (digestion) =
carried out by digestive enzymes breaking
down large molecules into smaller and
smaller ones by chemical reactions.
• Example: hydrolysis
Nutrition in an Ameba
• Has pseudopods “false feet”
• Surrounds food when it contact
with it
• The cell membrane forms a food
vacuole
• Food vacuole joins with a
lysosome and digestive juices
break down the food particle
• Small particles diffuse out of the
vacuole into the cytoplasm
• Indigestible materials remain in
the vacuole until the contents are
expelled from the cell
Nutrition in an Ameba
Ameba ingestion
http://www.youtube.com/watch?v=W6rnhiMxtKU
Nutrition in a paramecium
• Cilia sweep food particles down
the oral groove
• Into the gullet which pinches off
to form a form a food vacuole
• Food vacuole joins with a
lysosome and digestive juices
break down the food particle
• Usable materials diffuse into the
cytoplasm
• Indigestible materials are
discharged from the cell
through the anal pore
Nutrition in a paramecium
http://www.youtube.com/watch
?v=saLYHUs6cWk
Nutrition in a hydra
•
•
•
•
Performs intra- and extracellular digestion
Threads in the tentacles wrap and poison prey
Captured food is pushed into the oral groove
Endoderm cells secrete digestive enzymes into the
gastrovascular cavity (extracellular digestion)
• Nutrients are absorbed into the cells forming food vacuoles
(intracellular digestion)
• Wastes can diffuse two ways:
– Out the ectoderm into the
outside environment
– Out the endoderm into the
gastrovascular cavity and
out the mouth
Nutrition in a hydra
http://www.youtube.com/watch?v=zkF
_1r6ll54&feature=related
Nutrition in an earthworm
• Digestive tube called an
alimentary canal
• Food is sucked into the
mouth by a muscular
pharynx to
→Esophagus to
→Crop for storage to
→Gizzard for grinding
(mechanical digestion)
→To the intestine for
chemical digestion and
absorption
→Indigestible material pass
out through the anus
Nutrition in an earthworm
• A typhlosole is a fold in the digestive wall
• It increases surface area
• Therefore increases absorption
Nutrition in a grasshopper
→ Mechanical digestion by mouth parts
→ Salivary glands (saliva) secrete digestive enzymes
→ To the esophagus to the crop (storage)
→ To the gizzard (mechanical digestion)
→ To the stomach (chemical digestion and absorption)
→ Indigestible (dry) materials go through the intestine out
the anus
→ Water is absorbed in the rectum
Grasshopper eating a leaf
http://www.youtube.com/watch?v=F3JJFSsVUBg
Organism
Adaptations
Or
Specialized
structures
Protists
(ameba)
Pseudopod
(false feet)
Protests
(paramecium
Cilia
Function
Or
Special structures
•Contact and surround food
•Membranes join
•Food vacuole forms
•Vacuole fuses with lysosome
•Cilia sweep food into oral groove
•Gullet pinches off into vacuole
•Vacuole fuses with lysosome
Hydra
Special stinging cells
Wrapping Treads out of
tentacles
•Poisons prey
•Tentacles capture food and push it into the
mouth
•Exrtacellular digestion in gut
•Absorption into the endoderm
Earthworm
Alimentary canal
Typhlosole
(↑ surface area)
Mouth – pharynx-esophagus-crop (storage)–
gizzard (mech dig) – intestine (chem dig and
absorption)
Grasshopper
Tube in a tube
digestive system
Mouth parts (mech dig) –salivary glands (chem
dig) – esophagus – crop (storage) – gizzard
(mech dig) – stomach (chem dig and absorption)
– intestine – rectum (water absorption) – anus
(dry waste)
The Human Digestive System
• Complete the diagram on page 14 in your
note packet
The Human Digestive System
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Mouth
Tongue
Salivary glands
Epiglottis
Esophagus
Liver
Stomach
Pancreas
Large intestine
Small intestine
Appendix
Rectum
Anus
Accessory organs
14. Stomach (not
seen here)
15. Pancreas
16. Gallbladder
17. Liver
18. (Common) Bile
duct
19. Duodenum
20. Pancreatic duct
The Human Digestive System
(in more detail)
The mouth and pharynx
1. teeth - mechanical digestion
2. tongue - moves and shapes the
food mass
3. 3 pair of salivary glands secrete
saliva
– thin saliva wets food
– thick saliva sticks food together into
a bolus
•
•
contains digestive enzymes for
chemical digestion
salivary amylase breaks down starch
to maltose (a polysaccharide to a
disaccharide)
4. tongue pushes food into the
pharynx - starts swallowing reflex
Action of the epiglottis
The esophagus
• flap of tissue called epiglottis
prevents food from going
down the trachea instead of
the esophagus
• peristalsis - alternating
relaxation and contraction of
the muscular walls
• sphincter (ring of muscle)
where the esophagus opens
to the stomach called the
cardiac sphincter
The stomach
• mechanical digestion by
contractions of stomach
walls
• chemical digestion by
glands in stomach lining
– pyloric glands - mucus to
protect the stomach lining
– gastric glands - acidic gastric
juices
• kills bacteria
• contains pepsin to break down
large proteins into polypeptides
• solids form soupy liquid called
chyme
• pyloric sphincter opens to
the small intestine
The small intestine
• chemical digestion
– pancreatic juice from the
pancreas
– bile from the liver
– intestinal juice from glands in the
walls
• absorption
– simple sugars, amino acids,
vitamins, minerals absorbed
through villi into the blood stream
– increased surface area
• very long
• many folds
• villi and microvilli
– fatty acids and glycerol absorbed
into lymphatic system
Intestinal villi
• Intestinal villi (singular: villus) are tiny, finger-like
projections that come out from the wall of the small
intestine and have additional extensions called
microvilli (singular: microvillus) which protrude from
epithelial cells lining villi. They increase the absorptive
area and the surface area of the intestinal wall. It is
important that the food is absorbed at a considerably
fast rate so as to allow more food to be absorbed. (If
the process is too slow, the concentration of the blood
in the blood vessels and the food will be equal, thus,
diffusion will not occur.) Digested nutrients (including
sugars and amino acids) pass into the villi through
diffusion. Circulating blood then carries these nutrients
away.
Intestinal villi
Blood capillaries absorb
amino acids, glucose,
vitamins and minerals
into the blood
The lacteals absorb fatty
acids and glycerol into
the lymphatic system
peristalic movement
•
•
•
•
squeeze chyme through
intestine
mix chyme with digestive
juices
breaks down mechanically
speed absorption by
pushing chyme against
walls
pancreas
•
hormones from the stomach stimulate pancreas to
secrete pancreatic juices and enzymes into the small
intestine (duodenum)
– pancreatic juice neutralizes stomach acid
– pancreatic enzymes
1. amylase breaks down starch to maltose
2. proteases break down proteins
3. lipase breaks down fats
Gall bladder
• stores bile made in
the liver
• bile travels from liver
to gallbladder
(storage) into bile
duct to duodenum
(small intestine)
• bile emulsifies fat bile has no enzymes
Large intestine
• small pouch where large and
small intestine join is the
appendix
• undigested and unabsorbed
materials pass through large
intestine
• reabsorption of water from the
food mass
• absorbs vitamins produced by
bacteria here
• elimination - removal of
undigested material (feces)
• feces stored in the rectum and
then defecated out the anus
Digestive glands
• glands that secrete substances that aid in
digestion
• the food mass never passes through these
glands
Digestive glands:
the liver
1. produces bile
2. bile emulsifies fat
3. stores excess carbohydrates in the form of
glycogen
4. bile is slightly basic and assists in neutralizing
acid chyme from the stomach
5. bile stored in the GALLBLADDER
6. bile travels:
GALLBLADDER
BILE DUCT
DUODENUM
(small intestine)
Digestive glands:
the pancreas
1. produces pancreatic juices
2. aids in digestion of
– proteins
– starch
– fats
3. pancreatic juices are basic
and neutralize the acid
chyme from the stomach
The small intestine is slightly basic (pH ~ 8)
Human nutrition
page 20 in your packet
Organ
1.
2.
3.
4.
5.
6.
7.
8.
9.
Chief function
1.
2.
3.
Salivary glands
esophagus
stomach
Begins chemical digestion of starch
Wets food
Sticks food together
Transports food to the stomach
1.
2.
Begins chemical digestion of protein
Mechanical digestion
1.
2.
liver
Produces bile
Stores extra starch as glycogen
pancreas
Produces pancreatic juice that aids in
chemical digestion of all food groups
Gall bladder
Stores bile
1.
2.
Small intestine
Large intestine
rectum
1.
2.
Completes chemical digestion
Absorption of nutrients
reAbsorption of water
Production and absorption of vitamins
Storage of feces
Which organs have a “S” on them?
1.
2.
3.
4.
5.
Salivary glands
Stomach
Liver
Pancreas
Small intestine
Which organs have a “ D” on them?
1. Mouth (not shown)
2. Stomach
3. Small intestine
Digestive juice
Secreted by
Which acT upon
(substrate)
Saliva
Salivary
glands
starch
Gastric juice
(contains HCl)
glands in
stomach walls
proteins
bile
liver
emulsification of
fats
Pancreatic
juice
pancreas
fats, starch,
proteins
Intestinal juice
glands in the
intestinal wall
fats, starches
proteins
1. The end products of the digestion of
carbohydrates are simple sugars or
monosaccharides
2. The end products of the digestion of
proteins are amino acids
3. The end products of the digestion of
lipids are 3 fatty acids and
1 glycerol
Turn to page 21 in your packet
Digestive
juice
Secreted
by
Contains
enzymes
saliva
salivary
glands
salivary
amylase
Gastric
acid
(hcl)
Bile
stomach
pepsin
Acts upon
End
products
starch or
maltose
polysaccharides disaccharide
proteins
small amino
acid chains
activates
pepsin
liver
none
fats
Pancreatic
juice
pancreas
trypsin →
amylase →
lipase →
proteins →
starch →
fats →
Intestinal
juice
glands in
the
intestinal
wall
peptidase →
lactase →
maltase →
sucrase →
peptides →
lactose →
maltose →
sucrose →
Emulsifies
fats in to
droplets
peptides
maltose
f. a. + glycerol
amino acids
glucose
glucose
glucose