Transcript Notes

Evolution of Organ Systems
AS ORGANISMS
EVOLVED THEIR BODY
SYSTEMS BECAME MORE
COMPLEX
Body Symmetry
C omp l e x an i mal s t en d t o have
hi g h l e v e l s of c el l s p ec i al i zat i on
a n d i n t e r n a l bod y or g a n i zat i on ,
bi l a t e ra l body s ymmet ry, a f ron t
e n d o r he a d w i t h s e n s e org a n s ,
a n d a body c avi t y.
W i t h t he e xce p t ion of s p ong e s ,
e ve ry ki n d o f a n i ma l e x h i bi t s s ome
t yp e of body s ymme t ry in it s
a n a t omy, or body s t ru ct u re .
Body Symmetry
 Asymmetry
 no planes can be drawn through the body and create equal
halves
 radial symmetry
 similar to that of a bicycle wheel, in which any number of
imaginary planes can be drawn through the center, each
dividing the body into equal halves.
 bilateral symmetry
 a single imaginary plane can divide the body into two equal
halves.
Body Symmetry
Radial
Bilateral
Body Cavity
MOST COMPLEX ANIMAL
PHYLA HAVE A TRUE
COELOM THAT IS LINED
COMPLETELY WITH TISSUE
DERIVED FROM
MESODERM.
Body Cavity
 Acoelomates
 meaning that no coelom, or body cavity, forms between the
germ layers.
 Pseudocoelomates
 body cavity lined partially with mesoderm (roundworms)
 Coelomates
 completely with tissue derived from mesoderm.
Body Cavity Comparison
Skeletal System
USUALLY ONE OF THREE MAIN
KINDS OF SKELETAL SYSTEMS:
HYDROSTATIC SKELETONS,
EXOSKELETONS, OR
ENDOSKELETONS.
Skeletal System
 No skeleton
 instead spicules (sponge) or some other form of support
(muscles)
 Hydrostatic skeleton
 muscles surround a fluid-filled body cavity that supports the
muscles. When the muscles contract, they push against fluid in
the body cavity, causing the body to change shape.
 Exoskeleton
 external skeleton, is a hard body covering made of chitin.
 Endoskeleton
 structural support located inside the body.
Skeletal system
Hydrostatic skeleton
Endoskeleton
Respiratory System
RESPIRATORY ORGANS
HAVE LARGE SURFACE
AREAS THAT ARE IN
CONTACT WITH THE AIR OR
WATER. ALSO, FOR
DIFFUSION TO OCCUR, THE
RESPIRATORY SURFACES
MUST BE MOIST.
Respiratory System
 Diffusion
 respire through their skins
 Gills
 feathery structures that expose a large surface area to the water. Gills are rich in
blood vessels that bring blood close to the surface for gas exchange.
 Book lungs
 parallel, sheetlike layers of thin tissues that contain blood vessels.
 Spiracles
 in insects, air enters the body through openings called spiracles. It then enters a
network of tracheal tubes, where gases diffuse in and out of surrounding body
fluids.
 Lungs
 Inhaling brings oxygen-rich air from outside the body through the trachea
(TRAY-kee-uh) and into the lungs. The oxygen diffuses into the blood inside the
lung capillaries.
Respiratory System
Gills
Book Lungs
Respiratory System
Spiracles
Lungs
Excretory System
MOST ANIMALS HAVE AN
EXCRETORY SYSTEM THAT RIDS
THE BODY OF METABOLIC
WASTES WHILE CONTROLLING
THE AMOUNT OF WATER IN THE
TISSUES.
Excretory System
 Diffusion

ammonia diffuses from their body tissues into the surrounding
water.
 Nephridia

annelids and mollusks, urine forms in tubelike structures called
nephridia. Fluid enters the nephridia through openings called
nephrostomes. Urine leaves the body through excretory pores.
 Malpighian Tubes

saclike organs that convert ammonia into uric acid.
 Kidneys

urea is removed from the bloodstream along with other metabolic
wastes
Cloaca- frogs only one tube for solid and liquid waste
 Humans- two tubes one for solid waste the other for liquid waste

Excretatory System
Cloaca
Malpighian Tubes
Reproductive System
MOST INVERTEBRATES REPRODUCE
SEXUALLY DURING AT LEAST PART
OF THEIR LIFE CYCLE. DEPENDING
ON ENVIRONMENTAL CONDITIONS,
HOWEVER, MANY INVERTEBRATES
MAY ALSO REPRODUCE ASEXUALLY.
MOST VERTEBRATES REPRODUCE
SEXUALLY
Reproductive System
 Asexually
 only need one
 Sexually
 need two
Internal
 eggs are fertilized inside the female's body.
 External
 eggs are fertilized outside the female's body

Circulatory System
MOST COMPLEX ANIMALS
MOVE BLOOD THROUGH THEIR
BODIES USING ONE OR MORE
HEARTS AND EITHER AN OPEN
OR CLOSED CIRCULATORY
SYSTEM.
Circulatory System
 Diffusion
 Open system
 blood is only partially contained within a system of blood vessels.
Instead, one or more hearts or heartlike organs pump blood through
blood vessels into a system of sinuses, or spongy cavities. The blood
comes in direct contact with the tissues and eventually makes its way
back to the heart.
 Closed system
 a heart or heartlike organ forces blood through vessels that extend
throughout the body. The blood stays within these blood vessels.
Materials reach body tissues by diffusing across the walls of the blood
vessels.


Frog
 three chamber heart
Human
 four chamber heart
Circulatory System
Open System
Closed System
Circulatory System
Single and Double Loop
Human Circulatory System
How Does Blood flow?
Digestive System
THE SIMPLEST ANIMALS BREAK
DOWN FOOD PRIMARILY THROUGH
INTRACELLULAR DIGESTION, BUT
MORE COMPLEX ANIMALS USE
EXTRACELLULAR DIGESTION.
Digestive System
 Intracellular

food is digested inside cells
Simple animals such as cnidarians and most flatworms ingest food
and expel wastes through a single opening.
 filter feeders

 Extracellular

food is broken down outside the cells in a digestive cavity or tract and
then absorbed into the body.

More-complex animals digest food in a tube called the digestive tract.
Food enters the body through the mouth, and wastes leave through
the anus.
 One way track
• Mouth/anus
• characteristic of roundworms, mollusks, arthropods, and echinoderms

Two way track
• Mouth and anus
Digestive System
One way track
Two way track
Nervous System
INVERTEBRATES SHOW THREE TRENDS IN THE
EVOLUTION OF THE NERVOUS SYSTEM:
CENTRALIZATION, CEPHALIZATION, AND
SPECIALIZATION.
NONVERTEBRATE CHORDATES HAVE A
RELATIVELY SIMPLE NERVOUS SYSTEM WITH A
MASS OF NERVE CELLS THAT FORM A BRAIN.
VERTEBRATES HAVE A MORE COMPLEX BRAIN
WITH DISTINCT REGIONS, EACH WITH A
DIFFERENT FUNCTION.
Nervous System
 Centralization

Nerve Nets

consist of individual nerve cells that form a netlike arrangement
throughout the animal's body.
 Cephalization

concentration of nerve tissue and organs in one end of the body

Vertebrates display a high degree of cephalization, or concentration of
sense organs and nerve cells at the front of the body. The head
contains a well-developed brain
 The cerebrum is the “thinking” region of the brain.
 Specialization

specialized sense organs that detect light, sound, chemicals,
movement, and even electricity to help them discover what is
happening around them.
Comparison and Complexity of Nervous Systems
Human Body Exhibit
THE END