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Happy Wednesday!
Bellwork: March 5
• Write one similarity and one difference
between the nervous and endocrine systems.
GO BUFFS!
CO: I will describe how the
digestive system interacts with
other systems.
LO: I will fill in a graphic organizer. I
will listen to descriptions. I will
create a brochure.
Think-Pair-Share
• What do animals (includes humans) need to
survive?
• How/where do they get what they need?
What do animals need to live?
• Animals make energy using:
– Food (glucose)
– Oxygen
• This process is known as
cellular respiration
• Animals build bodies
using:
food
ATP
– food for raw materials
• amino acids, sugars,
fats, nucleotides
– ATP energy for synthesis
– Water for hydrolysis and
dehydration synthesis
O2
mitochondria
Take Off, Touch Down!
Stand up for true, sit down for false.
• Food spends 2-6 hours partially digested in
the stomach
• In 12 to 24 hours, any undigested material
passes through the large intestine, and feces
are expelled through the anus
• Your stomach can stretch to fit ~1/2 gallon of
food in it.
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 nutrients across cell membranes
• diffusion
• active transport
• Eliminate
– undigested material passes out of body
extracellular
digestion
Digestive systems
Everybody’s got one!
Human digestive system
Mouth
• Functions
– mechanical digestion
• teeth
– break up food
– chemical digestion (saliva)
• amylase enzyme
– digests starch
• 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
All that
in spit!
Swallowing (& not choking)
• Epiglottis (flap of cartilage)
– closes trachea (windpipe) when swallowing
– food travels down esophagus
• Peristalsis
– involuntary muscle contractions to move food
along
• (NERVOUS SYSTEM)
mouth
break up food
digest starch
kill germs
moisten food
Stomach
• Functions
–disinfect food
• hydrochloric acid = pH 2
– kills bacteria
–food storage
• can stretch to fit ~2L food
–digests protein
• pepsin enzyme
But the stomach is made out of protein!
What stops the stomach from digesting itself?
mucus secreted by stomach cells protects stomach
lining
mouth
break up food
digest starch
kill germs
moisten food
stomach
kills germs
break up food
digest proteins
store food
sphincter
sphincter
Pancreas
• Produces digestive enzymes
– digest proteins
• trypsin, chymotrypsin
– digest starch
• amylase
– digest lipids
• lipase
• Buffers
– neutralizes
acid from
stomach
small
intestine
pancreas
mouth
break up food
digest starch
kill germs
moisten food
pancreas
produces enzymes to
digest all foods
stomach
kills germs
break up food
digest proteins
store food
Liver & Gall Bladder
• Produces bile
– breaks up fats
– gallbladder only stores bile
• that’s why you can have your gall bladder removed
bile contains colors from old
red blood cells collected in
liver =
iron in RBC rusts & makes
feces 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
stomach
kills germs
break up food
digest proteins
store food
Small intestine
• Functions
– digestion
• digest carbohydrates
– amylase from pancreas
• digest proteins
– trypsin & chymotrypsin from pancreas
• digest lipids (fats)
– bile from liver & lipase from pancreas
– absorption
• nutrients move into body cells by:
– diffusion
– active transport
This is
where all the
work is done!
Absorption in Small Intestines
• Absorption through villi & microvilli
– finger-like projections
– increases surface area for absorption
SMALL INTESTINES
6 meters long,
but can stretch
to cover a
tennis court
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
stomach
kills germs
break up food
digest proteins
store food
small intestines
breakdown food
- proteins
- starch
- fats
absorb nutrients
Large intestines (colon)
• Function
– re-absorbs water
• use ~9 liters of water every day in
digestive juices
– if don’t reabsorb water
would die of dehydration
• > 90% of water re-absorbed
– not enough water re-absorbed
» diarrhea
» can be fatal
– too much water re-absorbed
» constipation
• reabsorb by diffusion
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
stomach
kills germs
break up food
digest proteins
store food
small intestines
breakdown food
- proteins
- starch
- fats
absorb nutrients
large intestines
absorb water
You’ve got company!
• Living in the large intestine is a community
of helpful bacteria
– Escherichia coli: E. coli
• digest cellulose
– digests fruits & vegetables
• produce vitamins
PEE-YOO!
– vitamin K & B vitamins
• BUT generate gases
– by-product of bacterial metabolism
– methane, hydrogen sulfide
– STINKY!
Appendix
Vestigial organ
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
appendix
stomach
kills germs
break up food
digest proteins
store food
small intestines
breakdown food
- proteins
- starch
- fats
absorb nutrients
large intestines
absorb water
Rectum
• Last section of large intestines
– eliminate feces
– what’s left over?
• undigested materials
– mainly cellulose from plants
– called roughage or fiber
– keeps everything moving & cleans out intestines
• masses of bacteria
So don’t forget
to wash
your hands!
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 amino acids
• missing 2
– Beans (like soybean & red beans)
have 6 amino acids
• missing different 2
• mix beans & grains
for complete group of
amino acids
–
–
–
–
rice & beans
taco/tortilla & beans
tofu & rice
peanut butter & bread
Homeostasis
Balancing Blood Sugar levels
insulin
liver stores
sugar
body
cells take
up sugar
from blood
pancreas
high
reduces
appetite
liver
blood sugar level
low
triggers
hunger
liver
releases
sugar
liver
pancreas
glucagon
Feedback
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
glucagon
pancreas
stimulate
hunger
Ulcers
Colonized by
H. pylori
• Used to think ulcers
were caused by
stress
inflammation of
stomach
– tried to control with
antacids
• Now know ulcers
caused by bacterial
infection of
stomach
– H. pylori bacteria
– now cure with
antibiotics
Free of
H. pylori
inflammation of
esophagus
H. pylori
inflammatory
proteins
(CagA)
cell damaging
proteins
(VacA)
 
cytokines
helper T cells
neutrophil cells
white blood cells
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
Digestion Brochure
• Choose and research one of
the following
diseases/disorders:
–
–
–
–
–
–
–
Ulcers
Scurvy
Rickets
Diarrhea
Constipation
Anemia
Acid Indigestion (heartburn)
Given the information
about the disorder, YOU
have to determine how it
could it fixed or treated!
• Create a brochure (like you
might see at a doctor’s
office) that explains:
–
–
–
–
what the disease is
how it’s caused
how to treat it
illustrate the part of the
digestive system it affects
• The front cover needs to
have a question as a title.
For example, if you were
researching lactose
intolerance, “Why can’t I
drink milk?”
Ulcers
Peptic ulcers are holes or breaks in the protective lining of the upper part
of the small intestine or the stomach -- areas that come into contact with
stomach acids and enzymes
Scurvy
Rickets
A disease resulting from a deficiency (lack) of vitamin C (“pirate disease)
Diarrhea
Constipation
A softening of bones in immature mammals due to deficiency or impaired
metabolism of vitamin D, phosphorus, or calcium, potentially leading to
fractures and deformity. It can also be caused by severe diarrhea and
vomiting
The condition of having three or more loose or liquid bowel movements
per day. The loss of fluids through diarrhea can cause dehydration and
electrolyte disturbances such as potassium deficiencies or other salt
imbalances
Refers to bowel movements that are infrequent or hard to pass.
Constipation is a common cause of painful defecation. Severe constipation
includes obstipation (failure to pass stools or gas) and fecal impaction,
which can progress to bowel obstruction and become life-threatening.
Anemia
A decrease in number of red blood cells (RBCs) or less than the normal
quantity of hemoglobin in the blood. A deficiency in iron can result in
anemia.
Acid Indigestion
(“Heartburn”)
The pain often rises in the chest and may radiate to the neck, throat, or
angle of the jaw. Heartburn is usually associated with regurgitation
(bringing back up) of gastric acid.