Download Human Digestive System

Human Digestive System
Open notes quiz
1.
2.
3.
4.
5.
CO2+H2O+light  C6H12O6 + O2
Producers
Energy always lost
Decomposers recycle nutrients
Complex carbs  simple sugars
Proteins  amino acids
Fats  fatty acids and glycerol
6. Stages of digestion
•
•
•
•
Ingestion
Digestion
Absorption
Egestion
7. Organic = C and H
8. Carbohydrates, proteins, fats
9. Autotrophic nutrition = photosynthesis
10.Nutrients get recycled by decomposers
11.Omnivore
Step 1: Ingestion
• Mouth  esophagus
• Swallow = food moved down esophagus
– Muscles of esophagus force food down
(peristalsis)
Swallowing
• Epiglottis = cartiligonous flap  covers
trachea when swallowing  prevents food
from going down wrong tube
Note: uvula = flap
that hangs down
in back of throat helps
make guttural sounds
http://www.uic.edu/classes/bios/bios100/lectf03am/swallow_1.gif
epiglottis = behind
that attached near base
of the tongue
Step 2: Digestion
• Begins in Mouth
– Salivary glands  starch digesting enzymes
(ex: amylase)
• Then continues in stomach and intestines
Stomach digests proteins
• Stomach = produces acids and
enzymes  chemical digestion
– Acids = low pH
– Stomach enzymes have low optimum
pH
• Which enzyme in the graph above would
most likely be found in the stomach? Why?
• Stomach muscle  mechanical digestion
– Grinds, churns and mixes foods
– made of protein
– Mucus protects inner layer of stomach muscles
• Ulcer = hole in mucus lining and cells of
stomach or duodenum (upper part of small
intestine)
http://www.sciencedaily.com/articles/health_medicine/ulcers/
Stomach
Ulcer
http://www.helico.com/images/du_gu_1.jpg
Caused by stress, alcohol,
hi salt diet, smoking, too much aspirin, bacteria…
Practice question
• Which statement best describes enzymes?
a) Every enzyme controls many different
reactions
b) The rate of activity of an enzyme might
change as pH changes
c) Temperature changes do not affect enzymes
d) Enzymes are produced from the building
blocks of carbohydrates
Practice questions
• Before starch can enter a cell, it must be
a)
b)
c)
d)
Absorbed by simple sugars
Diffused into simple sugars
Digested to form simple sugars
Actively transported by simple sugars
Practice questions
• The diagram below represents a
sequence of events that occurs
in living things
• Letter X represents
a)
b)
c)
d)
Inorganic molecules
Biological catalysts
Organic molecules
Simple sugars
Practice questions
• Which substance can enter a cell by
diffusion without having to be digested?
a)
b)
c)
d)
Protein
Water
Starch
Fat
Digestion continues in Small
Intestines
• Chemical digestion of proteins, lipids, and
carbohydrates is completed
• Contains lots of enzymes
– Secreted from intestinal glands and pancreas
• Bile (from the liver and gall bladder) help
breakdown fats and neutralize stomach acid
– Bile = made in liver stored in gall bladder
Step 3: Absorption occurs in
small intestines
• End products of digestion
diffuse into blood
• Small intestines have hairlike villi  increased
surface area  increased
absorption
• Villi are surrounded by lots
of capillaries
• Nutrients diffuse into blood
http://www.jpp.krakow.pl/journal/archive/0605_s3/gfx/rys0502_5.jpg
Diffusion = passive transport
• Movement from Hi  lo
• Smaller particles diffuse in larger
(undigested) foods cannot
• Requires no energy
Step 4: Egestion
• Large intestines = Re-absorb water
• Undigested food  feces -removed from
body
• = EGESTION
Symbiotic relationships
• Mutualism = both benefit
• Parasitism = one harmed one helped (dog
and flea)
• Commensalism = one helped one unaffected
(moss on a tree)
Ex: Mutualistic bacteria live in
large intestines
• Lots of bacteria in feces
• Help digest food further (some animals (like
mice and rabbits) eat their feces  extra
nutrition)
• Produce vitamins (ex: e. coli  vit. K,
others  B12)
Scanning electron microscope images of B.
thetaiotaomicron, a prominent human gut bacterium,
and the intestine. Photo: Public Library of Science
Failure to maintain homeostasis
• Nausea = often caused by pathogens
– If severe can lead to dehydration treat with fluids
• Gas = caused by bacteria in intestines
– Treat by changing diet (ex: fewer sugars)
• Diarrhea = not enough water is reabsorbed by
Large intestines (foodborne pathogens and
______________
antibiotics)
dehydration
– Severe  ________________
treat with fluids
– Fiber slows food down  better absorption
More failure to maintain
homeostasis
• Constipation = too much water reabsorbed by
Large intestines
___________________
(caused by dehydration)
– Treat with laxatives, fluids, and fruits
• Heartburn = stomach acid moves into esophagus
(overeating, smoking, drinking)
– Treat with antacids
• GIR = extreme heartburn (weak sphincter valve)
– Treat with surgery
• Ulcers = hole in mucus lining (from bacteria, salt,
stress)
– Antibiotics sometimes work
More failure to maintain
homeostasis
lactase
• Lactose intolerance = missing enzyme _______
that breaks down lactose (sugar in milk)
– Give them enzymes
• Colon cancer = uncontrolled cell division
– Colonoscopy = technique to diagnose
• Pancreatitus = inflamation of pancreas (usually
caused by alcohol)
– Treat with anti-inflamatory drugs
• Gall Stones = cholesterol deposits in gall bladder
– Surgery
• Apendicitis = inflamation of appendix
– Must be removed
Appendix
• Thought to be vestigial
(no purpose)
• Possibly used as a place
for good bacteria to
grow.
– Could be important if
you survive a cholera
epidemic - that wipes out
all of your good bacteria.
https://www.youtube.com/watch?
v=p7D6Y9857uk
Review digestion Nova “Universe
Within”