As organisms evolved their body systems became more complex

1
Evolution of Organ Systems

• As organisms evolved their body systems became
  more complex

2
Body Symmetry

• Complex animals tend to have high levels of cell
  specialization and internal body organization,
  bilateral body symmetry, a front end or head with
  sense organs, and a body cavity.
• With the exception of sponges, every kind of
  animal exhibits some type of body symmetry in its
  anatomy, or body structure.

3
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.

4
Body Symmetry

• Radial

• Bilateral

5
Body Cavity

• Most complex animal phyla have a true coelom that
  is lined completely with tissue derived from
  mesoderm.

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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.

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Body Cavity Comparison
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Skeletal System

• Usually one of three main kinds of skeletal
  systems hydrostatic skeletons, exoskeletons, or
  endoskeletons.

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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.

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Skeletal system

• Hydrostatic skeleton

• Endoskeleton

11
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.

12
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.

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Respiratory System

• Gills

• Book Lungs

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Respiratory System

• Spiracles

• Lungs

15
Excretory System

• Most animals have an excretory system that rids
  the body of metabolic wastes while controlling
  the amount of water in the tissues.

16
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

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Excretatory System

• Cloaca

• Malpighian Tubes

18
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

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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

20
Circulatory System

• Most complex animals move blood through their
  bodies using one or more hearts and either an
  open or closed circulatory system.

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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

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Circulatory System

• Open System

• Closed System

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Circulatory System
Single and Double Loop
24
Human Circulatory System

• How Does Blood flow?

25
Digestive System

• The simplest animals break down food primarily
  through intracellular digestion, but more complex
  animals use extracellular digestion.

26
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

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Digestive System

• One way track

• Two way track

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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.

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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.

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Comparison and Complexity of Nervous Systems
31
Human Body Exhibit
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THE END