Animal Body Systems

Comparative Anatomy

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:

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?

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

Cells

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

Tissues

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

Organs

Two or more organs that work together for a common task

Organ System

A means to study the evolution, history and lineages of living organisms

What is Comparative Anatomy?

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

Similarities between structures or functions of structures represent either a common

ancestor (common evolutionary path) or a similar adaptation to an environment

Evolution

“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

Similar structures that suggest a similar evolutionary path but could have different

functions

Homologous Structures

Similar adaptations to a similar environment, do not mean they are the same structure or

suggest a similar evolutionary path

Analogous Structures

Structures that no longer serve a purpose and our remnants of an adaptation that is no

longer needed

Vestigial Structures

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

Circulatory

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:

Absorbs nutrients through cell walls/membranes

Digestive

From simple to complex organisms: intracellular to a simple digestive chamber to

formal stomachs to digestive organs (i.e. intestines)

Digestive Evolution

Uses chemicals/hormones to elicit a bodily response

Endocrine

Removes wastes from the body

Excretory

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:

Stops and destroys foreign bodies from entering the body and causing damage or

sickness

Immune System

Protects the body from the outside world

Integumentary

Provides support and movement for an organism

Muscular

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:

Provides communication throughout the body

Nervous

From simple to complex:

Unknown pathways to nerve nets to centralized systems including a brain and

nerve cord

Nervous System Evolution

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

The exchange of gases with the atmosphere

Respiratory

Developed from exchange of gases across cell membranes to gills to pseudo lungs to

lungs

Respiratory Evolution:

Provides support and protection to the body

Skeletal

- Hardened structures found within (spicules in sponges)

- Complete lack of (jellyfish)

- Secreted shells

- Endoskeleton vs. Exoskeleton

Skeletal Variation: