One ATP Sandwich
With extra phosphate
Comin’ up
Chapter
Processing
Food and
Nutrition
Chapter 21
Processing Food and Nutrition
Objectives:
1. Understand the concepts of digestion
2. Identify the anatomical parts
3. Describe the function of the noted parts
4. Describe the changes in processing food
through the animal kingdom with a focus on
vertebrates
Jargon
Elimination: Getting rid of digestive waste
(called egestion in lower critters)
Excretion: Getting rid of metabolic waste
(function of kidneys and lungs)
What Is The Diversity Of Digestive Systems In NonHuman Animals
• Intracellular digestion in a sponge
Digestion:
1. Break apart food into component
molecules
“Degrade macromolecules into simpler
compounds”
2. Rearrange these molecules
3. Use now or later
Wa te r, une a te n food,
a nd wa s te s a re e x pe lle d
through the la rge ope ning
a t one e nd of the s ponge
Wa s te produc ts a re
e x pe lle d by e x oc y tos is
H2O
H2O
(a) Tube s ponge s
The food
v a c uole m e rge s
with a ly s os om e
c olla r c e ll
H2O c a rry ing
food pa rtic le s
e nte rs the pore s
H2O
H2O
Food pa rtic le s
a re filte re d from the
wa te r by the c olla r
(b) A s im ple s ponge
Food e nters the
c olla r c e ll by pha goc y tosis ,
form ing a food v a c uole
food v a c uole
(c) Colla r c e ll
ly s os om e
with
dige s tiv e
e nz y m e s
Fig. 21-6
Animals?
•
•
• Annelids, mollusks, arthropods, and vertebrates are examples of
animals with tube shaped gut.
Extrace l l u l ar d i ge sti o n
Di ge sti o n i n a sac
• Lots of functions
Soil with
food par ticles
is ingested
pre y
Indigestible r em nants
ar e expelled
intestine
(a) Hy dra with pre y
Te nta cle s with
s tinging c ells c apture
the pre y a nd ca rry
it into the m outh
anus
m outh
Gla nd c ells s ec rete
dige s tiv e enzy me s into
the dige s tive s ac and
be gin e x tra ce l ular
dige s tion
m outh
phar ynx
pre y
Nutritiv e ce l s e ngulf
food pa rtic les and
c om ple te diges tion
within food v ac uoles
esophagus
cr op
gizzar d
dige s tiv e
sac
(b) Food proc e ss ing in Hydra
Food is gr ound
up in the gizzar d
Fig. 21-7
Evolution of Digestion
• Complete digestion
• Gut runs from mouth to anus - food moves in
one direction
• Digestion occurs outside the cells:
Extracellular digestion
- Food absorbed by epithelial cells in gut
Generic Digestive Parts
Structures that take in food
Holding tank (some have crop)
Pulverizer (gizzards in birds and reptiles)
Place to expose food to enzymes
Place to absorb nutrients
Refuse area (where elimination stuff is
stored)
Fig. 21-8
Complete Gut Digestion
Functions:
1. Movement
2. Secretion
3. Digestion
4. Absorption
Salivary glands: Secr ete
lubr icating fluid and
star ch-digesting enzym es
Pharynx: Shar ed digestive
and r espir ator y passage
1.
2.
3.
4.
5.
6.
Food is digested
and absor bed in the
intestine
Oral cavity. tongue,
teeth: Gr ind food,
m ix with saliva
Epiglottis: Dir ects food
down the esophagus
Esophagus: Tr anspor ts
food to the stom ach
Stomach: Br eaks
down food and
begins pr otein
digestion
Liver: Secr etes bile (also
has m any non-digestive
functions)
Gallbladder: Stor es bile
fr om the liver
Pancreas: Secr etes buffer s
and sever al digestive
enzym es
Large intestine: Absor bs
vitam ins, m iner als, and
water ; houses bacter ia;
pr oduces feces
Small intestine:
Food is digested
and absor bed
Rectum: Stor es feces
Fig. 21-9
Vertebrate Digestive Tract
The Swallowing Thing
Mouth - Mastication
1. Capture and crush food
Teeth! Why chew?
2. Lubrication and Enzyme (Amylase)
Saliva
• Bolus is formed in mouth
1. With tongue, move food to back of
mouth
Pressure against pharynx closes epiglottis
against larynx (lungs), sealing airway
2. Pharynx to esophagus (connects to
stomach)
3. Peristaltic movement down esophagus
Digestion in the Stomach
Salivary glands: Secr ete
lubr icating fluid and
star ch-digesting enzym es
Pharynx: Shar ed digestive
and r espir ator y passage
Oral cavity. tongue,
teeth: Gr ind food,
m ix with saliva
• Enters through Sphincter muscle
• Bolus enters stomach and mixes with
digestive juices = chyme
• 3 layers of muscle – mechanical digestion
• Stomach used for:
Storage and digestion
Very little absorption occurs in
stomach
Epiglottis: Dir ects food
down the esophagus
Esophagus: Tr anspor ts
food to the stom ach
Stomach: Br eaks
down food and
begins pr otein
digestion
Liver: Secr etes bile (also
has m any non-digestive
functions)
Gallbladder: Stor es bile
fr om the liver
Pancreas: Secr etes buffer s
and sever al digestive
enzym es
Large intestine: Absor bs
vitam ins, m iner als, and
water ; houses bacter ia;
pr oduces feces
Small intestine :
Food is digested
and absor bed
Rectum: Stor es feces
Fig. 21-9
Digestion in the Stomach
Digestion in the Stomach
• Parietal cells secrete Hydrochloric acid
• Chief cells secrete Pepsinogen
LET’S DIGRESS FOR A MOMENT!!
Hydrochloric Acid:
- kills bacteria
- converts Pepsinogen to enzyme Pepsin (breaks
apart proteins)
Puking and throat burn!!!!!!!!!!!!
Protection from Acid?
• Tightly packed epithelial cells
• Mucus for lubricates and protects
• Chyme remains in stomach ~ 2 hours
- leaves stomach through pyloric sphincter
Peptic Ulcer: Too much HCl, or too little mucus
– or – Bacterium Helicobacter pylori
Pancreatic Juice
• Contains water, bicarbonate, and digestive enzymes
Salivary glands: Secr ete
lubr icating fluid and
star ch-digesting enzym es
Accessory digestive
organs
Oral cavity. tongue,
teeth: Gr ind food,
m ix with saliva
Pharynx: Shar ed digestive
and r espir ator y passage
• Digestive enzymes include amylase for starch, trypsin for
proteins, and lipase for fats, deoxyribonuclease ???
Epiglottis: Dir ects food
down the esophagus
Liver
weighs 3 lbs.
below diaphragm
- Makes bile
Stomach: Br eaks
down food and
begins pr otein
digestion
Esophagus: Tr anspor ts
food to the stom ach
Liver: Secr etes bile (also
has m any non-digestive
functions)
Gallbladder: Stor es bile
fr om the liver
Gallbladder
Pancreas: Secr etes buffer s
and sever al digestive
enzym es
Small intestine:
Food is digested
and absor bed
Large intestine : Absor bs
vitam ins, m iner als, and
water ; houses bacter ia;
pr oduces feces
Rectum: Stor es feces
Fig. 21-9
On to the Small Intestine
Salivary glands: Secr ete
lubr icating fluid and
star ch-digesting enzym es
(5-6 meters long – 18 Ft!)
Oral cavity. tongue,
teeth: Gr ind food,
m ix with saliva
Pharynx: Shar ed digestive
and r espir ator y passage
3 regions:
1) Duodenum – 10 inches
2) Jejunum - 8 feet
3) Illium – 12 feet
Epiglottis: Dir ects food
down the esophagus
Stomach: Br eaks
down food and
begins pr otein
digestion
Esophagus: Tr anspor ts
food to the stom ach
Liver: Secr etes bile (also
has m any non-digestive
functions)
Most Digestion and absorption occurs here
Bile from liver added (fats)
Enzymes from pancreas added (fats,
peptides, carbs)
Small intestine has characteristics that enhance surface
area!
- Folding of lining, Villi and Microvilli
Gallbladder: Stor es bile
fr om the liver
Pancreas: Secr etes buffer s
and sever al digestive
enzym es
Small intestine :
Food is digested
and absor bed
Large intestine: Absor bs
vitam ins, m iner als, and
water ; houses bacter ia;
pr oduces feces
Rectum: Stor es feces
Fig. 21-9
• The small intestine
lacteal
fold of
intestinal
lining
microvilli
villi
capillaries
intestinal
gland
(a) Small intestine
18-73
(b) A fold of the
intestinal lining
(c) A villus
arteriole
lymph
vessel
venule
(d) Cells of a villus
• Chyme remains in small intestine from 3 to 10 hours
• Nutrients move to liver (Fat to cardiovascular system!)
Fig. 21-12
Summary of digestion
Carbohydrates:
Mouth, Stomach, Small Intestine
Proteins:
Stomach, Small Intestine
Lipids (fats):
Small Intestine
Nucleic Acids: Small intestine
Last, but not Least,,,
The Large Intestine
•Little nutritional absorption
occurs here!
Parts: Cecum, ascending
colon, transverse colon,
descending colon, sigmoid
colon, rectum, anus
• Elimination of w aste
•Absorption of w ater and
sodium
5 -6 feet long
Salivary glands: Secr ete
lubr icating fluid and
star ch-digesting enzym es
Pharynx: Shar ed digestive
and r espir ator y passage
Oral cavity. tongue,
teeth: Gr ind food,
m ix with saliva
Epiglottis: Dir ects food
down the esophagus
Esophagus: Tr anspor ts
food to the stom ach
Stomach: Br eaks
down food and
begins pr otein
digestion
Liver: Secr etes bile (also
has m any non-digestive
functions)
Gallbladder: Stor es bile
fr om the liver
•Production of vitamin K and
some B vitamins (bacteria)
Pancreas: Secr etes buffer s
and sever al digestive
enzym es
•Chyme can stay in Large Int
for a few hours up to days.
Large intestine : Absor bs
vitam ins, m iner als, and
water ; houses bacter ia;
pr oduces feces
Small intestine :
Food is digested
and absor bed
Rectum: Stor es feces
Fig. 21-9
Herbivores have special adaptations?
Why?
Cellulose!!
• Teeth adaptations:
Premolars and molars
- High crowned
- Broad flat occlusal surfaces
•
Coprophagy
• Reingesting feces Why?
- Cecum (houses bacterial microorgs.)
Stomach adaptations:
- bacteria micro-organisms
- dry and gelatenous pellets
- increased vitamins B and K