Download Lecture I (PowerPoint) "Digestion, Absorption & Excretion"

Today’s Agenda:
(1) Journal Questions: What did you
have for breakfast today? Was it
healthy? Explain your response.
*(2) Lecture: Digestion, Absorption,
Excretion. (Ending on slide 56)
(3) Film: The Diet (Body Story)
(4) Homework: Read Chapter 49.
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By Dr. Rick Woodward
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Digestion & Nutrition:
1. What is a calorie?
A calorie is defined as a unit
of energy supplied by food.
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Digestion & Nutrition
2. What is normal daily caloric intake?
a. Teenage Girls, Active Women, Most Men: 2,000 Calories
per day
b. Teenage Boys, Active Men: 2,400 Calories per day
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Digestion & Nutrition
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Obesity Definition:
A. Obesity is defined by a Body Mass
Index (BMI) of greater than 30%
with a body fat percentage of:
(1) Greater than 28% for males.
(2) Greater than 36% for females.
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Who’s Big? (NIH Study 2010)
A. Prevalence of overweight and
obesity in the United States 2010
(1) Adults (20 years of age and up)
a. 32.9% of U.S Adults are
obese.
(2) Children (Ages 2 – 19)
a. 31.9% are overweight and
obese.
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The Children of 2010
A. From 2006 - 2010, millions of
teenagers and young adults joined
the ranks of clinically obese.
B. There is an increased incidence
in type II diabetes in teens.
C. Even our pets are overweight,
25% of dogs and cats are heavier
than they should be.
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Fat Animals in the Wild
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The Children of 2010
D. Twenty years ago, 5% of
American kids were overweight.
E. Today 20% are overweight and
another 15% are headed that
way.
F. In 1969, 80% of kids played
sports everyday; today only 20%
play sports everyday.
G. By age 17, a child has spent 38%
more time in front of the
television or computer than in
school.
H. 80% of a teenager’s calories
come from sodas.
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Fruit Juices vs. Soft Drinks
A. Look at sugar content:
(1) Which has the most grams
of total sugar?
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Who’s Big? (CDC 2010)
B. Obese children and
adolescents are more likely to
become obese as adults.
(1) One study found that
approximately 80% of the
children who were overweight at
ages 10 – 15 years of age were
obese adults at age 25.
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Who exercises?
A. The proportion of youth (18 years
of age) who report engaging in no
physical activity is high, and the
proportion increases with age.
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Why is this happening?
A. We eat too much highcalorie food and we do
not burn it off with enough
exercise.
B. 3,500 calories = 1 pound
of fat; It is very easy to
gain 1 pound of fat in a
week.
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Fat Cells
A. The amount of fat cells you are
born with will probably be the
same number when you die.
(Only the size of the cell increases or
decreases depending on weight gain
and weight loss)
B. There are 3 times in life when you
can increase the number of fat cells
your body has:
(1) The Toddler Years
(2) Puberty
(3) Third Trimester of Pregnancy
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First Law of Thermodynamics
A. Calories In = Calories Out
B. If the calories you take in are greater
than the calories you expend (exercise)
you will get fat.
C. Excess calories are stored as fat.
D. Average daily caloric intake varies:
2,000 – 2,500 calories per day.
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Role Models???
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What did Sushi A say to Sushi B?
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Was up B? (Wasabi)
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Digestion,
Absorption &
Excretion
By Rick Woodward
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Digestion Starts in
the Mouth
I. The Mouth
1. Secretion of saliva upon the
sight or smell of food.
A. Lubricates each morsel with
mucus to make passage
easier.
-Saliva contains amylase,
mucus, and lysozymes.
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The Mouth
B. Contains amylase, an
enzyme that breaks
down starch
(carbohydrate chains).
-Starch digestion begins in
the mouth.
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The Mouth
C. Lysozymes break into
the cell walls of
bacteria that are on or
in your food.
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The Mouth
D. The body
manufactures 1-2
quarts of saliva a day.
E. Saliva is mostly water
and it is weakly
alkaline (basic) with a
pH of 7.4
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The Mouth
2. Chewing creates
smaller particles whose
increased surface area
allows digestive
enzymes to access
more surface area of
swallowed food.
(Mastication)
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The Mouth
3. The tongue assesses
the amounts and types
of food found in saliva.
a. Tastes include:
(1) Sweet
(2) Salty
(3) Sour
(4) Bitter
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The Esophagus
II. The esophagus is
a tube through
which your food
travels to your
stomach.
A. Food is
transported with a
peristaltic
(pumping) motion.
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The Esophagus
B. An opening called the
glottis is covered by a
flap of tissue called the
epiglottis.
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The Esophagus
C. The epiglottis
prevents
choking by
covering the
trachea (wind
pipe/breathing
tube) when
swallowing.
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The Esophagus
D. The lower esophageal valve
prevents backflow of the
stomach’s contents from going
back into the esophagus.
(Heartburn/Acid Reflux)
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The Stomach
III. The stomach secretes mucus,
hydrochloric acid, pepsin, lipase,
and an intrinsic factor which is
necessary to activate and absorb
Vitamin B-12.
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The Stomach
A. Digesting protein using:
1. Stomach acid juices, like
hydrochloric acid (HCl) pH = 2.
a. Pepsin, an enzyme, works
directly on large proteins.
b. Protein digestion begins in the
stomach.
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The Stomach
B. The average capacity of
the stomach is one liter.
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The Stomach
C. Food stays in the stomach for
about 2-3 hours.
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The Stomach
D. Fatty meals or solid
foods take longer to
digest than liquids
and low-fat meals.
-Lipase, an enzyme,
starts the digestion
of certain fats.
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The Small Intestine
IV. The Small Intestine
(Duodenum): 95% of all
digestion and nutrient
absorption takes place
here.
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The Small Intestine
A. Food entering the small
intestine from the
stomach is strongly
acidic.
-Secretions from the
pancreas alkalize the
food coming in from the
stomach.
-Small Intestine has a
pH = 8.3
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The Small Intestine
B. Can be up to 10 feet long (referred
to as “small” because of its small
diameter.)
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The Small Intestine
C. Food may remain
in it from 4-10
hours.
D. Most nutrient
absorption
occurs within the
small intestine.
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The Pancreas
V. The Pancreas supplies the
following enzymes to the duodenal
are of the small intestine:
(1) Trypsin, an enzyme, for
protein digestion.
(2) Amylase, an enzyme, for
starch digestion.
(3) Lipase, an enzyme, for fat
digestion.
(4) Bicarbonate, for acid
neutralization.
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The Liver
VI. The Liver supplies the
duodenum with bile.
A. Bile envelopes fat droplets in
a fluid for intestinal absorption.
B. Bile emulsifies fats.
C. Up to one liter of bile is stored
in the gall bladder.
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The Large Intestine
VII. The large intestine
can be up to six feet
long.
A. Can hold food for
as long as three
days.
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The Large Intestine
B. Colonies of helpful bacteria are
permanent residents.
(1) They aid in the digestion of
plant matter.
(2) Bacteria produce vitamins:
B12, Riboflavin, Thiamine, and
Vitamin K.
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The Large Intestine
C. Water is removed from
food in the large intestine.
(water absorption)
(1) Some diseases that affect
the large intestine can cause
diarrhea.
(2) Waste matter is
packaged for removal.
a. About ½ of waste is dead
bacteria.
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Overview of Digestive System
A. Something happens to
your food through each
part of the digestive
tract.
B. Nutrients become
available and
transported
throughout your body
via the circulatory
system (blood).
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Excretory System
A. Your excretory system works in
a similar way to the
equipment that purifies
water.
B. Your excretory organs are:
(1) Kidneys
(2) Lungs
(3) Skin
C. The organs help your body
get rid of waste products.
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Excretory System
D. The amount of water in blood is
important to maintain:
(1) Normal Blood Pressure (120/80)
(2) Movement of Gases
(3) Excretion of Solid Waste.
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Excretory System
E. Filters out nitrogen wastes
and helps maintain osmotic
balance.
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Excretory System
F. The main excretory organs
are two kidneys; fist size,
bean-shaped structures that
lie near the dorsal
abdominal wall.
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Excretory System
G. Kidneys filter blood that has
collected waste products
from cells.
-If waste products build up,
they act as poisons to the
body cells.
(1) Each kidney is made up of
about 1 million nephrons, the
tiny filtering units of the
kidney.
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Excretory System
H. Each nephron is made up of a
cup-shaped Bowman’s capsule,
which narrows into a long, coiled
tubule.
(1) In the center of each
Bowman’s capsule is a mass of
capillaries called the
glomerulus.
(2) A glomerulus forms from a
small artery that branches from
one of the two renal arteries.
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Excretory System
I. The Filtering Process:
1. Blood entering the kidney
contains needed materials being
transported to body cells, plus urea
and excess salts.
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The Filtering Process
2. The blood acquires urea
when it passes through the
liver, which converts
ammonia to urea.
a. Urea is less toxic than
ammonia.
b. It conserves water because
it requires less water for
excretion.
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The Filtering Process
3. The continuous flow of blood into the
kidneys forces the liquid out of the
cup portion of Bowman’s capsule and
into the tubule.
a. In the tubule is where the actual
filtering process takes place.
b. 99% of the water passing
through the kidneys is reabsorbed.
c. What remains in the collecting duct
of the nephron is: urea, salts, and a
small amount of water.
-This is called urine.
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The Filtering Process
4. Urine passes from the
collecting duct to the ureter,
which conveys urine to a
muscular storage sac, called
the urinary bladder.
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The Filtering Process
5. When the bladder
becomes filled, a
muscular valve relaxes,
and urine is excreted
and discharged
through the urethra.
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With the remainder of class time:
1. Answer the vocabulary
activity in your packet.
2. Color in sections of the
digestive system in your
packet.
3. Label the organs of the
digestive system on page 1
of your packet
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