UNIT 6: BODY SYSTEMS
Miss Sabia
Regents Living Environment
(adapted from Mrs. Folgia from Division Ave High School)
standards
• 1.2c-control mechanisms in body
• 1.2d-disruption in human
system=disruption in homeostasis
• 5.2a=homeostasis is constantly
threatened…failure to correct results in
death or diaseas
• 5.3-feedback mechanisms, respond to
stimuli
DIGESTIVE SYSTEM
Essential Question
• What are the main organs of the digestive
system and their functions?
Different Diets, Different Lives
• Herbivores: eat only plants
• Carnivores: eat only animals (meat)
• Omnivores: eat plants and animals
Functions of the Digestive System
• Ingest: taking IN food
• Digest: breaking up food into smaller pieces
– Mechanical digestion: breaking up food into smaller pieces
– Chemical digestion: breaking down foods into molecules
small enough to be absorbed into cells
– With the help of our friends, ENZYMES
• Absorb: absorb nutrients across cell membranes
– Diffusion
– Active transport
• Eliminate: undigested material passes out of body
Overview of the MVP’s
Introducing…
THE ORGANS!!!
The Mouth
• Mechanical digestion—chewing breaks food into
smaller pieces
• Chemical digestion—breaking down complex
molecules into simpler ones
– Salivary amylase (in saliva) starts the breakdown of
carbohydrates
– Mucus: protects soft lining of digestive system; lubricates
food for easier swallowing
– Anti-bacterial chemicals: kill bacteria that enter mouth with
food
Unsalted Cracker Challenge
Don’t Choke!
• Epiglottis: flap of tissue that seals off your
trachea (windpipe) and prevents food from
entering
• Bolus: mass of chewed food
The Esophagus
• Esophagus: muscular
tube that connects mouth
and stomach
• Peristalsis: involuntary
muscle contractions that
move food
Stomach
• Functions:
–disinfect food
• hydrochloric acid = pH 2
– kills bacteria
–food storage
• can stretch to fit ~2L food
–Chemical digestion:
digests protein
• pepsin enzyme
–Mechanical digestion:
muscles of stomach
contract to produce a
churning
But the stomach is made out of protein!
What stops the stomach from digesting itself?
mucus secreted by stomach cells protects
stomach lining
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)
cytokines
cell damaging
proteins
(VacA)
helper T cells
neutrophil cells
white blood cells
Small Intestine
• Almost all chemical
digestion and absorption of
nutrients occurs here
• 6 meters long, makes up
2/3 of the digestive system
– Called “small” because of its
diameter, only 2-3 cm wide
Small Intestine-Organs & Enzymes
• Enzymes in small intestines are produced by
other organs
– Liver  bile (emulsifies fats)
– Gallbladder  stores bile
– Pancreas:
• amylase (break down carbs)
• trypsin and chymotrypsin (break down proteins)
• Lipase (breaks down lipids)
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
Large Intestine (colon)
• 1.5 meters long
– Large diameter, about 4-6
cm wide
• The last section of the
digestive system
– As material moves through,
water is absorbed into the
bloodstream
– Everything else is readied
for elimination
Water Re-Absorption
• More than 90% of water is reabsorbed
– diffusion
• Not enough water re-absorbed…
– Diarrheah
– Can be fatal!
• Too much water re-absorbed…
– constipation
Helping Friends
• Living in the large intestine is a community
of helpful bacteria
– Escherichia coli: E. coli
• digest cellulose
– digests fruits & vegetables
• produce vitamins
– vitamin K & B vitamins
• BUT generate gases
– by-product of bacterial metabolism
– methane, hydrogen sulfide
– STINKY!
Do Now
• Label the
organs of the
digestive
system on the
worksheet
provided
Large Intestine (cont’d)
• Ends in the rectum, a
short tube that
compresses waste
into a solid form
• Waste is eliminated
through the anus, a
muscular opening at
the end of the rectum
Appendix
Vestigial organ
Another function of the Pancreas!
Wait for it…
• Buffer: neutralizes acid
from stomach
Different diets; different bodies
• Adaptations of herbivore vs. carnivore
– teeth
– length of digestive system
– number & size of stomachs
Teeth
• Carnivore
– sharp ripping
teeth
– “canines”
• Herbivore
– wide grinding
teeth
– molars
• Omnivore
– both kinds of
teeth
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
appendix
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
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
2013: “The International Year of the
Quinoa”
• (according to the Food and Agricultural
Organization of the United Nations)
• A complete protein source—contains all
the essential amino acids!
CIRCULATORY SYSTEM
RESPIRATORY SYSTEM
EXCRETION
NERVOUS/ENDOCRINE SYSTEM
standards
• 1.2j-receptor molecules for hormones, if
interrupted it can block cellular
communication
SKELETAL/MUSCULAR SYSTEM
IMMUNE SYSTEM
standards
• 5.2a=homeostasis is constantly
threatened…failure to correct results in
death or diaseas
• 5.2-all