Presentation for Day 2

1. Digestive System
Excretory System
Presented by : Franz Christian D. Irorita, 2012

2. Digestive System
 Single vs. Two Opening Digestive Systems
 Parts of the Digestive System
Excretory System
 Different Nitrogenous Wastes
 Osmoregulation
 Parts of the Excretory System

3. Digestive System

4. Single Opening Digestive Systems
Sponge
Hydra Planarian

5. Two Opening Digestive System
 More specialized in
digesting food
 Digestion is both
mechanical and
enzymatical.

6. Digestion starts in the mouth
Mechanical Digestion
through the teeth
Chemical Digestion through
the saliva, which contains
an enzyme called salivary
amylase that starts the
digestion of starch into
sugar.

7. Pharynx and Esophagus
 Bolus – used to refer to
the food that has already
been chewed and
swallowed.
 Epiglottis – a small flap
of tissue at the opening
to the airway that is
closed when swallowing.
 Peristalsis – muscular
contraction that pushes
the food down the
epiglottis.

8. Stomach
 Parietal cells produce
hydrochloric acid
 Chief cells produce
pepsinogen
 The hydrochloric acid
activates the pepsinogen
in the stomach
 Pepsinogen converts to
pepsin, the main
digestive enzyme of the
stomach

9. Small Intestine
-Responsible for most of the
chemical digestion
-Responsible for absorption of
nutrients
-Tiny finger-like projections
located at the lining of the
intestines called villi increases the
surface area for absorption.
Additionally, there are microvilli
protruding from the villi.

10. Parts of the small intestine
 Duodenum – first part of the small
intestine, responsible for absorbing iron and most of
the digestion
 Jejunum – middle part of the small
intestine, responsible for absorbing carbohydrates and
protein
 Ileum – final part of the small intestine, responsible
for absorbing vitamin B12 and Bile salts

11. Large Intestine
 Responsible for waste
removal
 Where water and sodium
are absorbed
 After the large
intestine, defecation takes
place.

12. Accessory Organs in Digestion
 Liver – secretes bile that is
released to the small intestine.
Bile digests fats. Liver is also
helping maintain homeostasis
by adding or removing
nutrients from the or to the
blood. It converts glucose into
glucogen, amino acids to fatty
acids and urea, stores iron, and
detoxifies alcohol, drugs and
poisons that enters the body.

13. Accessory Organs in Digestion
 Pancreas – secretes enzymes
and hormones that assist in
digestion. Its enzymes are
responsible for digesting
polypeptides into
dipeptides, carbohydrates
(except cellulose) into
disaccharides, degrading
neutral fats, and RNA and
DNA to free nucleotides.

14. Digestive System

15. Excretory System

16. Different Nitrogenous Wastes
 Ammonia
 Uric acid
 Urea

17. Ammonia
 Produced when the amino group of amino acids are
removed and then converted to ammonia.
 Highly toxic.
 Excreted by aquatic animals and some terrestrial
animals.
 Soluble in water

18. Uric acid
 Produced from ammonia and
by the breakdown of nucleotides
from nucleic acids.
 Conserves water.
 Water insoluble.
 Expelled usually with the feces.
 Non-toxic.

19. Urea
 Produced in the liver.
 Less toxic, meaning it can be stored in higher
concentrations without tissue damage.
 Dissolves in water.
 Requires more water to be excreted than uric acid.

20. Two Processes that maintain
homeostasis of fluids in animals:
 Osmoregulation
 The active regulation of osmotic pressure of body fluids
to keep them from becoming too dilute or too
concentrated.
 Excretion
 The ridding of metabolic wastes from the body.

21. Excretory System
 Its function is to maintain homeostasis by adjusting
the concentrations of salts and other substances in
blood.
1st step 2nd step 3rd step
• Excretory • Excretory • Excretory
system collects system adjusts system
fluids from the the eliminates
blood. composition of wastes and
the fluid. excretes
metabolic
wastes.

22. What is the difference between
excretion and elimination?
 Excretion = disposal of metabolic wastes as urine
 Metabolic wastes = substances from the excretory
process that can no longer be used by the body
 Elimination = ejection of undigested and unabsorbed
food as feces

23. Osmoconformers vs. Osmoregulators
 Osmoconformers
 Animals whose body fluids are in osmotic equilibrium
with the surrounding environment.
 Osmoregulators
 Animals who maintain an optimal salt concentration in
their tissues regardless of changes in the salt
concentration of their surroundings.

24. Human Excretory System
• Urine is produced flowing from collecting ducts
into the renal pelvis.
Kidneys • Urine flows to the urinary bladder via the ureter.
• Holds up to 800 mL of urine.
Urinary
Bladder
• During urination, the urine is released from the
bladder and flows through the urethra.
Urethra

25. The Kidney
 Contains at least a million nephrons.
 A nephron consists of a Bowman’s Capsule, which is
connected to a renal tubule.
 The Bowman’s Capsule has a
cluster of capillaries within called
a glomerulus.
 The renal tubule has three
regions :
 Proximal Convoluted tubule
 Conducts the filtrate from
the Bowman’s Capsule.
 Loop of Henle
 Distal Convulated tubule
 Conducts the filtrate to a
collecting duct.

26. Nephrons
 Two types:
 Cortical nephrons
 Have small glomeruli
 Juxtamedullary nephrons
 Have large glomeruli
 Have very long loops of Henle
 Contributes to the
concentration of urine.

27. Loop of Henle
 Descending – receives filtrate from the proximal
convoluted tubule
 Ascending – filters the filtrate to the distal convoluted
tubule
 Countercurrent Exchange

28. The Kidney : Overview
 Bowman’s Capsule  proximal convoluted tubule 
Descending Loop of Henle  Ascending Loop of
Henle  Distal Convoluted Tubule  Collecting Duct

29. Production of Urine
 Filtration
 Reabsorption
 Secretion

30. Filtration
 Non-selective to ions and small molecules
 Glomerular capillaries are permeable to most fluids
and small solutes found in the blood
 This allows the solutes to pass through the glomerular
capillaries to joined the filtrate, at the same time
holding back the blood from joining the filtrate.

31. Reabsorption
 Permits regulation of blood chemistry by the kidneys.
 Without Regulation, the body would excrete 180 Liters
of urine per 24 hours. With reabsorption, this is
lessened to 1.5 L.
 Happens in the renal tubule.
Tubular Transport Maximum (Tm) = maximum rate at
which a substance can be absorbed

32. Secretion
 Happens in the distal convoluted tubule.
 Important to regulate blood pH level as it secretes
Potassium, hydrogen and ammonium ions.
 Secreted substances go straight to thee filtrate.

33. Questions?
 Assignment for tomorrow : Learn the names of the
bones in your body. More bones named, higher grade.
Most bones named, +10 house points.