This document summarizes the key body systems in animals and how they have evolved from simple unicellular organisms to complex multicellular organisms. It describes the 11 main body systems - circulatory, digestive, endocrine, excretory, immune, integumentary, muscular, nervous, reproductive, respiratory, and skeletal systems - and how their functions have become increasingly specialized through evolution from basic intracellular processes to differentiated organs and organ systems. It also discusses comparative anatomy and the concepts of adaptation, natural selection, homologous and analogous structures in evolution.

1. Animal Body Systems

2. 1. Range from Unicellular to Multicellular
2. Autotrophic and/or heterotrophic
3. Life-sustaining functions (energy production, waste
removal) range from intracellular means to
organelles to structured systems.
Living Organisms:

3. 1) Multicellular organisms
2) Cells form tissues, tissues form organs, organs form
organ systems
3) Heterotrophic – must ingest nutrients
4) Aerobic respiration is used
5) Tissue layers that include ectoderm, endoderm, and
sometimes mesoderm
What defines an animal?

4. Smallest living unit, has the ability to survive and
reproduce on its own
Cells

5. A group of cells that function together for one or more
specialized tasks
Tissues

6. A structure with a definite form and function made up
of one or more tissue
Organs

7. Two or more organs that work together for a common
task
Organ System

8. A means to study the evolution, history and lineages of
living organisms
What is Comparative Anatomy?

9. An adaptation is a change in the genotype (genes) and
potentially the phenotype (physical expression of the
genes) that enables an organism to survive better
Result of a DNA mutation
Adaptations

10. Similarities between structures or functions of
structures represent either a common ancestor
(common evolutionary path) or a similar adaptation to
an environment
Evolution

11. “The Survival of the Fittest”
Those that have adaptations that enable a higher rate
of survival will live to reproduce and thus pass on the
desirable trait. Over time these changes/adaptations
can lead to new species.
Natural Selection

12. Similar structures that suggest a similar evolutionary
path but could have different functions
Homologous Structures

13. Similar adaptations to a similar environment, do not
mean they are the same structure or suggest a similar
evolutionary path
Analogous Structures

14. Structures that no longer serve a purpose and our
remnants of an adaptation that is no longer needed
Vestigial Structures

15. Takes in and distributes oxygen and nutrients to
various parts of body through blood
Circulatory

16. Transportation of nutrients and wastes can occur by:
a. Osmosis and diffusion through cell membranes
(unicellular and simple organisms)
b. Closed (blood in vessels) and open (blood pumped
by heart but diffuses through cells)
c. Water Vascular system – a system of using water
and canals to move nutrients
Variations:

17. Absorbs nutrients through cell walls/membranes
Digestive

18. From simple to complex organisms: intracellular to a
simple digestive chamber to formal stomachs to
digestive organs (i.e. intestines)
Digestive Evolution

19. Uses chemicals/hormones to elicit a bodily response
Endocrine

20. Removes wastes from the body
Excretory

21. From simple to complex:
Diffusion and/or exocytosis through cell membrane to
single opening digestive chambers to development of
the anus to specialized structures and organs
Excretory Evolution:

22. Stops and destroys foreign bodies from entering the
body and causing damage or sickness
Immune System

23. Protects the body from the outside world
Integumentary

24. Provides support and movement for an organism
Muscular

25. Movement mechanisms:
a) Cell based – flagellum, cilia
b) Water Vascular System – water used to “pressurize”
canals and chambers
c) Muscles – from single celled muscles to muscle
groups
Muscular System Evolution:

26. Provides communication throughout the body
Nervous

27. From simple to complex:
Unknown pathways to nerve nets to centralized
systems including a brain and nerve cord
Nervous System Evolution

28. Allows for the replication of the species and thus allows the genes to
remain in the population
Asexual Reproduction:
- Simple organisms
- Results in genetically identical offspring via budding, binary
fission, and autonomy
Sexual Reproduction:
- More complex organisms
- Results in genetically diverse offspring
- Development of secondary sex characteristics
Reproductive

29. The exchange of gases with the atmosphere
Respiratory

30. Developed from exchange of gases across cell
membranes to gills to pseudo lungs to lungs
Respiratory Evolution:

31. Provides support and protection to the body
Skeletal

32. - Hardened structures found within (spicules in
sponges)
- Complete lack of (jellyfish)
- Secreted shells
- Endoskeleton vs. Exoskeleton
SkeletalVariation: