Chapter 41: Animal form and function
Anatomy is the study of an organism’s physical structure
Physiology is the study of how the physical structures in an organism function.
Biologists who study animal physiology and anatomy are studying adaptions- heritable traits that allow
individuals to survive and reproduce in a certain environment better than individuals that lack those traits.
41.1 Form, function and adaptation
Natural selection not only process that leads to changes in allele frequencies over time.
Evolutions occurs through random changes in allele frequencies called genetic drift, through gene flow – meaning
the movement of alleles in and out of population by migration- and through constant introduction of new alleles
Natural selection is the only mechanism that increases ability of organisms to survive and reproduce in particular
Role of fitness trade-offs
One of the most important constraints on adaptation is trade–offs, which may involve expenditures of time or
energy. A trade–off is an inescapable compromise between traits.
Researchers investigated the predicted trade–off between egg size and egg number (clutch size) by manipulating
these parameters in side–blotched lizards. Their results showed that there is indeed a trade–off (Figure 41.1).
Trade–offs such as the inescapable compromise between egg size and clutch size are pervasive in nature. Adaptation and acclimatization
Adaptation is a genetic change that occurs over generations in response to natural selection in
a population in response to short tern changes in environment.
Acclimatization is a phenotypic change that occurs in an individual in response to a short–term change
in environmental conditions.
Adaptation is often use incorrectly to describe acclimatization.
Moved to Tibet, body would acclimatize to high elevation by making more haemoglobin and more
haemoglobin carrying RC. To increase fitness at high elevation. Gentic changes have also occurred.
Ability to acclimatize is adaptation
41.2 Tissues, organs, and systems: How does structure correlate with function?
If a structure found in an animal is adaptive—if it helps the individual survive and produce offspring—
the structure’s size, shape, or composition often correlates closely with its function.
Mechanism responsible for these types of structure function coorelations is straight forward: if mutant
allele alters size or shape of structure in way that makes it fcn more efficiently, then individuals who
have that allele will produce more offspring than will other individuals. As, a result allele will increase
in frequency in population overtime.
Correlating structure with function is a pervasive theme in research on animal anatomy and physiology.
Structure function correlation not limited to molecular and cellular level but also at levels of tissues,
organs and systems.
Animals are multicellular—their bodies contain distinct types of cells that are specialized for different
Sponges simplest animals in morphology. Contain cells that are distinct structurally and perform
A tissue is a group of similar cells that function as a unit. Animal cells similar in structure and fcn are
physically attached to each other and form tissue.
Sponges have 1 type of tissue: epithelial tissue that forms exterior and interior surface of individual.
There are four basic adult tissue types: connective, nervous, muscle, and epithelial.
Connective tissue consists of cells that are loosely arranged in a liquid, jellylike, or solid extracellular
matrix (Figure 41.4) which is secreted by CT cells themselves
Each type of CT secretes a distinct type of extracellular matrix.
Loose connective tissue contains array of fibrous proteins in a soft matrix and serves as a packing
material between organs or padding under the skin.
Cartilage and bone provide structural support for the body or protective enclosures for the brain and
other components of the nervous system.
Blood is CT that has cells surrounded by a liquid extracellular matrix called plasma; transports material
throughout the body. Nervous tissue
Nervous tissue consists of nerve cells, or neurons, and
several types of supporting cells.
Although they vary widely in shape, all neurons have
connections to other cells and deliver electrochemical signals in the
form of electrical impulses.
Muscle tissue functions in movement.
There are three types of muscle tissue: skeletal muscle, cardiac muscle, and smooth muscle.
Most muscle tissue is skeletal muscle, which consists of the long cells called muscle fibers (Figure
41.6a). muscle fibres are packed with long protein filaments that move sliding past eachother.
Cardiac muscle makes up the walls of the heart. It is similar to skeletal muscle in structure, except that
each cardiac muscle cell branches and makes direct contact with other cardiac muscle cells. These
connections help transmit signals from one cardiac muscle cell to another during a heartbeat (Figure
Smooth muscle cells a