The Excretory System
The Body’s Filter
Function of the Excretory System
• The human excretory system functions to
remove waste from the human body.
• During this process animals get rid of
nitrogenous waste products of metabolism,
including ammonia, urea, and uric acid.
• Although excretory systems are diverse, nearly
all produce urine in a process that involves
several steps.
Function of the Excretory System
• STEPS :
• 1. Filtration: the excretory tubule collects filtrate from the
blood. Water and solutes are forced by blood pressure across
the selectively permeable membranes of a cluster of
capillaries and into the excretory tubule.
• 2. Reabsorption: The transport epithelium reclaims valuable
substances from the filtrate and returns them
• 3. Secretion: Other substances are extracted from body fluids
and added to the contents of the excretory tube.
• 4. Excretion: The filtrate leaves the system and the body
Structure of the Excretory System
• This system consists of specialized structures
and capillary networks that assist in the
excretory process.
• The human excretory system includes the
kidney and its functional unit, the nephron.
• The excretory activity of the kidney is changed
by specialized hormones that regulate the
amount of absorption within the nephron.
Structure of the Excretory System
• Kidney:
• Blood enters the kidneys through renal arteries and leaves
through renal veins.
• Tubes called ureters carry waste products from the kidneys
to the urinary bladder for storage or for release.
• During urination, urine is expelled from the urinary
bladder through the urethra.
Structure of the Excretory System
Human excretory system and the details of the kidney and nephron.
Structure of the Excretory System
• The functional and
structural unit of the
kidney is the
nephron.
• The nephron
produces urine and is
the primary unit of
homeostasis in the
body.
• It is essentially a long
tubule with a series of
associated blood
vessels.
Structure of the Excretory System
• The upper end of the tubule is an
enlarged cuplike structure called the
Bowman's capsule.
• Below the Bowman's capsule, the
tubule coils to form the proximal
tubule, and then it follows a turn
called the loop of Henle. After the
loop of Henle, the tubule coils again
as the distal tubule. It then enters a
collecting duct, which also receives
urine from other distal tubules.
• Within the Bowman's capsule is a
coiled ball of capillaries known as a
glomerulus.
Diverse Excretory Systems
• In insects, Malphigan
tubules function in
osmoregulation and
removal of nitrogenous
wastes from hemolymph
• Insects produce a
relatively dry waste
matter, an important
adaptation to terrestrial
life.
Diverse Excretory Systems
• Extracellular fluid is filtered
into the flame bulb system
in flatworms.
• These tubules excrete a
dilute fluid and also
function in osmoregulation
• Each segment of an
earthworm has a pair of
open ended tubules that
collect coelemic fluid and
produce dilute urine.
The Excretory system word-search!
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-Urine
-eliminated
-urethra
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-Kidney
-urinary
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-excretion
-urea
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The Excretory System
Matching Column!
urea
excretion
ureters
urethra
nephron
One of a million tiny, filtering
structures found in the kidneys
that removes wastes from blood
and produces urine
A narrow tube that
carries urine from one of
the kidneys to the
urinary bladder
A chemical that comes from the
breakdown of proteins and is
removed from the body by the
kidneys
The process by which wastes are
removed from the body
A small tube through
which urine flows from
the body
The Digestive Tract
The Road to digestion
• Before our food is processed and released
from the anus it has to pass through the
various organs
• The Path of Food
– Mouth Stomach Small Intestine  Large
Intestine  Anus
The Oral Cavity, Pharynx, and Esophagus
•
•
•
We begin our journey with the
mouth
Physical digestion begins with our
teeth grinding and smashing our
food. This increases the surface area
of our food
Next our salivary glands deliver saliva
to our oral cavity
– Saliva makes our mouths slippery,
easier for the food to be swallowed,
and contains salivary amylase, an
enzyme that hydrolyzes starch and
glycogen
•
Out tongue makes the food into a
ball called a bolus. The tongue
pushes the bolus into the pharynx
• When the food travels down the pharynx, the
epiglottis is down, covering the windpipe.
• The esophagus conducts food from the
pharynx down to the stomach by peristalsis.
The Stomach
• The stomach stores food.
• The stomach releases gastric
juice. One function of the acid is
to disrupt the extracellular matrix
that binds cells together in meat
and plant material
• Also in gastric juice is the enzyme
pepsin that begins the hydrolysis
of proteins.
– Pepsin is secreted in the inactive
form called pepsinogen. This
allows for the lining of our
stomach not to be destroyed
from the acidity
• As a result of mixing and enzyme action, what
begins in the stomach as a recently swallowed
meal becomes a nutrient rich broth known as
acid chyme.
• At the opening from the stomach to the small
intestine is the plyoric sphincter, which helps
regulate the passage of chyme into the
intestine, one squirt at a time.
The Small Intestine
• The small intestine is the major
organ of digestion and
absorption.
• Acid chyme from the stomach
mixes in the duodenum with
intestinal juice, bile, and
pancreatic juice.
• Diverse enzymes complete
hydrolysis of food molecules to
monomers, which are absorbed
into the blood and lymph across
the lining of the small intestine.
• Hormones help regulate digestive
juice secretions
The Large Intestine
• A major function of the colon is to recover water that has
entered the alimentary canal as the solvent of the various
digestive juices.
• The colon reclaims much of the remaining water that was not
absorbed in the small intestine
• The wastes of the digestive tract, the feces, become more
solid as they move along the colon by peristalsis
• The terminal portion of the colon is called the rectum, where
feces are stored until they can be eliminated. Between the
rectum and the anus are two sphincters, one involuntary and
the other voluntary.
Key Words
•
anus - the opening at the end of the digestive system from which feces exit the body.
•
•
appendix - a small sac located near the start of the large intestine.
•
gall bladder - a small, sac-like organ located by the duodenum. It stores and releases bile (a digestive
chemical which is produced in the liver) into the small intestine.
•
large intestine - the long, wide tube that food goes through after it goes theough the small intestine.
•
liver - a large organ located above and in front of the stomach. It filters toxins from the blood, and makes
bile (which breaks down fats) and some blood proteins.
•
mouth - the first part of the digestive system, where food enters the body. Chewing and salivary enzymes
in the mouth are the beginning of the digestive process (breaking down the food).
•
pancreas - an enzyme-producing gland located below the stomach and above the intestines. Enzymes
from the pancreas help in the digestion of carbohydrates, fats and proteins in the small intestine.
•
rectum - the lower part of the large intestine, where feces are stored before they are excreted from the
body.
•
small intestine - the long, thin winding tube that food goes through after it leaves the stomach.
•
stomach - a sack-like, muscular organ that is attached to the esophagus. When food enters the stomach,
it is churned in an acid bath.
esophagus - the long tube between the mouth and the stomach. It uses rhythmic muscle movements
(called peristalsis) to force food from the throat into the stomach.
DIGESTIVE
SYSTEM
QUIZ
A.
B. C.
D.
WHICH
DIAGRAM
DISPLAYS THE
CORRECT
LABELING OF
THE DIGESTIVE
SYSTEM?
A.
B.
C.
D.
ORGANISMS
WHOSE DIET
COSNISTS
PRIMARILY OF
VEGETABLES
WOULD LIKELY
BECOME…
A.
Undernourished
C.
Malnourished
B.
D.
Obese
Overnourished
A.
An area in the vertebrate
throat where air and food
passages cross
B.
Rhythmic waves of
contraction of smooth
muscle that push food
along the digestive tract
D.
An integrated group of
cells with a common
function, structure, or
both.
PERISTALSIS
CAN BE
DEFINED AS…
C.
The portion of the
respiratory tube that has
cartilagenous rings and
passes from the larynx to
two bronchi
• Word Bank:
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rectum
Small intestine
Large intestine
Pancreas
Liver
Mouth
Esophagus
stomach
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CHECK OUT OUR SOURCES FOR MORE
INFORMATION!
• Campbell, N, & Reece, J (2005). Biology
Seventh edition.San Francisco, C
• http://www.enchantedlearning.com/subjects/
anatomy/digestive/labeleasy/
• http://www.studystack.com/matching-111474