Download Digestive and Excretory Systems

Digestive and Excretory Systems
What is “digestion”
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Process of breaking down food into simpler
molecules that can be absorbed by the body
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Break up food into smaller pieces (mechanical)
Chemically break down food (chemical)
Absorb nutrients
http://www.med.umich.edu/1libr/aha/digestiv.gif
I. Mouth
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Mechanical digestion
Chemical digestion
Amylase in saliva breaks down starch.
 II Pharynx
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Epiglottis covers trachea so you don’t choke
III. Esophagus
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~ 25 cm long
Connects pharynx to
stomach
Smooth muscles use
peristalsis to move the
food (wave
contractions)
IV. Stomach
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Chemical and
mechanical digestion
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Produces mucus
Hydrochloric acid
Pepsin to break down
protein
Food here 2-3
hours…called chyme
Ulcer (stomach): This
sharply punched out
gastric ulcer has been
present for some time
as judged by the
amount of puckering
of the surrounding
mucosa and by the
undermining and
depth of the ulcer.
Frequently, vessels in
the base of the ulcers
will ulcerate and the
patient will bleed
profusely, if not fatally.
http://www.pathology.vcu.edu/education/dental2/images/sc3-2.jpg
V. Small intestine
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~ 7 meters long
3 parts
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Duodenum
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Chyme flooded with enzymes and digestive fluids from
intestine, pancreas, liver
Pancreas digests carbs, fats, proteins, makes sodium
bicarbonate to neutralize the acid
Liver secretes bile to break up fat
The Liver and the Pancreas
Liver
Gallbladder
Duodenum
Bile duct
Pancreas
Pancreatic
duct
To small
intestine
Pancreas
V. Small intestine
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Jejunum
Ilium (Ileum)
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Both absorb nutrients

Villi in small intestine increase surface area
for better absorption
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Food is now nutrient free
The Small Intestine
Villus
Small Intestine
Circular folds
Epithelial cells
Villi
Capillaries
Lacteal
Vein
Artery
Villi
VI. Large intestine (colon)
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~1.5 meters long
Remove water from
material
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Too much…constipation
Not enough…diarrhea
Food here 18-24 hours
Feces stored in
rectum, out through
anus
Excretory system
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Maintaining Homeostasis by ridding the body
of waste products
Excretion:
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Process of getting rid of waste
Water, urea, salt, carbon dioxide
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Skin: water and salt
Lungs: water and carbon dioxide
Kidneys: water and urea
Kidneys (Renal)
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Kidneys: water and urea (salts)
Filtration, reabsorption, secretion
Acts as a filter system
Gets rid of waste products
Balances the body's fluid content
Produces hormones that control blood pressure
Produces the hormone Erythropoietin to help make
red blood cells
Activates vitamin D to maintain healthy bones
The Urinary System
Section 38-3
Vein
Kidney (Cross Section)
Kidney
Cortex
Medulla
Ureter
Urinary bladder
Urethra
Artery
Structure of the Kidneys
Section 38-3
Kidney
Nephron
Bowman’s
capsule
Cortex
Capillaries
Glomerulus
Medulla
Renal
artery
Renal vein
Ureter
Collecting
duct
Vein
To the bladder
Artery
Loop of Henle
To the ureter
Filtration
The Nephron
Most filtration occurs
in the glomerulus.
Blood pressure
forces water, salt,
glucose, amino
acids, and urea into
Bowman’s capsule.
Proteins and blood
cells are too large to
cross the membrane;
they remain in the
blood. The fluid that
enters the renal
tubules is called the
filtrate.
Reabsorption
As the filtrate flows
through the renal
tubule, most of the
water and nutrients
are reabsorbed into
the blood. The
concentrated fluid
that remains is
called urine.
Secretion
Substances such
as hydrogen ions
are transferred
from the blood to
the filtrate.
Human Kidney
Blood Vessels in the Kidney
Liver (Hepatic)
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Filters harmful chemicals out of blood
Breaks down amino acid into urea
Bile Production
Heaviest organ (iron)
Skin (Dermal)
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Largest surface area (Largest organ)
Perspiration gets rid of wastes (urea, water,
salt) and regulates body temp