Download Chapter 39 - Industrial ISD

Chapter 39
Digestive and
Excretory Systems
FOOD PYRAMID
• Fats, oils, and sweets (top of the pyramid)
• Use sparingly
• Milk, Yogurt, Cheese
• 2-3 servings a day
• Meat, Beans, Eggs, Nuts
• 2-3 servings a day
• Vegetables
• 3-5 servings a day
• Fruits
• 2-4 servings a day
• Grains, bread, cereal
• 6-11 servings a day
• Regardless of the source,
the excess calories you eat
will be stored as either
glycogen or body fat and you
will gain weight
• Obesity is being more than
20% heavier than your ideal
body weight and significantly
increases the risk of
diabetes and heart disease.
• Vitamins are organic substances that occur in
many foods in small amounts that are
necessary for normal metabolic functioning and
dissolve in water or fat.
• Minerals are naturally occurring inorganic
substances that are used to make certain body
structures and substances, in normal nerve and
muscle function, and maintain osmotic
balances. Minerals are soluble in water.
Digestion
• The process of breaking down food into
molecules the body can use is called
digestion.
• The digestive system takes in food, breaks it
down into molecules that can be absorbed, and
gets rid of undigested molecules and wastes.
• Food travels more than 8 m (26 ft) through your
digestive tract.
• Digestion begins: as soon as food is ingested
• Saliva moistens and lubricates food and
contains amylases which are enzymes that
begin the breakdown of carbohydrates.
• Digestive tract
includes:
mouth,
pharynx,
esophagus,
stomach, small
intestine, large
intestine, and
rectum.
• Liver, pancreas, and
gallbladder deliver secretions
to digestive tract.
• Food moves past the
pharynx, triggers a
swallowing response
which moves the
epiglottis moving the
food into the
esophagus instead of
the trachea.
• Successive rhythmic
waves of smooth
muscle contractions in
the esophagus is called
peristalsis move the
food into the stomach.
• Esophagus is a long
tube that connects the
mouth and stomach and
is around 10 inches
long.
• The stomach is the
saclike organ just below
the diaphragm that
stores food and
chemically and
mechanically break
down food.
• Gastric juice is a
combinations of
hydrochloric acid and
pepsin.
• Swallowed food can
spend 2 to 6 hours in
the stomach.
• A coating of mucus
protects the lining of
the stomach from
gastric juices.
• Food passes from the
stomach to the small
intestine which is
about 6m long and
functions mainly in
digestion and
absorption of
nutrients.
• Food remains in the
small intestine for 3 to
6 hours.
• The first part of the
small intestine,
called the
duodenum,
receives secretions
from the pancreas,
liver, and
gallbladder.
• Lipases from the
pancreas digest
fat.
• Lining of small
intestine is covered
with fingerlike
projections called
villi which increase
the area available
for absorption.
• Wastes then
move into the
large intestine.
• Mostly mineral
ions and water
are absorbed in
the large
intestine.
• The final segment of
the large intestine is
the rectum; from
here solid feces are
eliminated through
the anus.
• Undigested material
pass through the
large intestine and
are expelled in 12 to
24 hours.
• Liver’s role in digestion and metabolism:
Secrets bile which aids in emulsification of fats
Breaks down glycogen when its needed for energy
Digestive System Disorders
• Jaundice is a condition in which the eyes,
skin and urine become abnormally yellow
as a result of increased bile pigments in
the blood.
• Anorexia nervosa is an eating disorder in
which people starve themselves.
• Bulimia is an eating disorder in which
people engage in frequent binging then
purging.
EXCRETION
• Excretion is the process that rids the
body of toxic chemicals, excess water,
salts, and CO2, while maintaining
osmotic and pH balances.
• Organs of excretion:
– Lungs
rid the body of CO2
– Kidneys
rid the body of nitrogen
wastes, salt, water, and urea.
– Skin
and salts
rids the body of water
Kidney
• Each kidney is composed of roughly 1
million microscopic blood filtering units
called nephrons.
• 3 phases occur as blood flows through
nephrons: filtration, reabsorption, and
secretion.
Urine that is excreted from the body is
formed from water, urea, and salts that
are left over after the reabsorption and
secretion processes.
• Ureters are tubes that carry the
urine from the kidneys to the
urinary bladder which stores the
urine and expands as it fills.
• The urinary bladder can hold
about 0.6L of urine.
• Urine leaves the bladder and exits
the body through a tube called the
urethra.
• Elimination of urine from the body
through the urethra is called
urination.
• Kidney dialysis or hemodialysis is
a procedure for filtering blood by
using a machine.
• Kidney Transplant is a more
permanent solution to kidney
failure. Major problem is rejection
of the organ.