Human anatomy is the scientific study of the body’s structures. Some of these structures are very small and can only
be observed and analyzed with the assistance of a microscope. Other larger structures can readily be seen, manipulated,
measured, and weighed. The word “anatomy” comes from a Greek root that means “to cut apart.” Human anatomy was
first studied by observing the exterior of the body and observing the wounds of soldiers and other injuries. Later, physicians
were allowed to dissect bodies of the dead to augment their knowledge. When a body is dissected, its structures are cut apart
in order to observe their physical attributes and their relationships to one another. Dissection is still used in medical schools,
anatomy courses, and in pathology labs. In order to observe structures in living people, however, a number of imaging
techniques have been developed. These techniques allow clinicians to visualize structures inside the living body such as a
cancerous tumor or a fractured bone.
Like most scientific disciplines, anatomy has areas of specialization. Gross anatomy is the study of the larger structures of
the body, those visible without the aid of magnification (Figure 1.2a). Macro- means “large,” thus, gross anatomy is also
referred to as macroscopic anatomy. In contrast, micro- means “small,” and microscopic anatomy is the study of structures
that can be observed only with the use of a microscope or other magnification devices (Figure 1.2b). Microscopic anatomy
includes cytology, the study of cells and histology, the study of tissues. As the technology of microscopes has advanced,
anatomists have been able to observe smaller and smaller structures of the body, from slices of large structures like the heart,
to the three-dimensional structures of large molecules in the body.
Anatomists take two general approaches to the study of the body’s structures: regional and systemic. Regional anatomy is
the study of the interrelationships of all of the structures in a specific body region, such as the abdomen. Studying regional
anatomy helps us appreciate the interrelationships of body structures, such as how muscles, nerves, blood vessels, and other
structures work together to serve a particular body region. In contrast, systemic anatomy is the study of the structures that
make up a discrete body system—that is, a group of structures that work together to perform a unique body function. For
example, a systemic anatomical study of the muscular system would consider all of the skeletal muscles of the body.
Whereas anatomy is about structure, physiology is about function. Human physiology is the scientific study of the chemistry
and physics of the structures of the body and the ways in which they work together to support the functions of life. Much
of the study of physiology centers on the body’s tendency toward homeostasis. Homeostasis is the state of steady internal
conditions maintained by living things. The study of physiology certainly includes observation, both with the naked eye and
with microscopes, as well as manipulations and measurements. However, current advances in physiology usually depend
on carefully designed laboratory experiments that reveal the functions of the many structures and chemical compounds that
make up the human body.
Like anatomists, physiologists typically specialize in a particular branch of physiology. For example, neurophysiology is
the study of the brain, spinal cord, and nerves and how these work together to perform functions as complex and diverse as
vision, movement, and thinking. Physiologists may work from the organ level (exploring, for example, what different parts
of the brain do) to the molecular level (such as exploring how an electrochemical signal travels along nerves).
Form is closely related to function in all living things. For example, the thin flap of your eyelid can snap down to clear away
dust particles and almost instantaneously slide back up to allow you to see again. At the microscopic level, the arrangement
and function of the nerves and muscles that serve the eyelid allow for its quick action and retreat. At a smaller level of
analysis, the function of these nerves and muscles likewise relies on the interactions of specific molecules and ions. Even
the three-dimensional structure of certain molecules is essential to their function.
Your study of anatomy and physiology will make more sense if you continually relate the form of the structures you are
studying to their function. In fact, it can be somewhat frustrating to attempt to study anatomy without an understanding
of the physiology that a body structure supports. Imagine, for example, trying to appreciate the unique arrangement of the
bones of the human hand if you had no conception of the function of the hand. Fortunately, your understanding of how
the human hand manipulates tools—from pens to cell phones—helps you appreciate the unique alignment of the thumb
in opposition to the four fingers, making your hand a structure that allows you to pinch and grasp objects and type text
messages.
be observed and analyzed with the assistance of a microscope. Other larger structures can readily be seen, manipulated,
measured, and weighed. The word “anatomy” comes from a Greek root that means “to cut apart.” Human anatomy was
first studied by observing the exterior of the body and observing the wounds of soldiers and other injuries. Later, physicians
were allowed to dissect bodies of the dead to augment their knowledge. When a body is dissected, its structures are cut apart
in order to observe their physical attributes and their relationships to one another. Dissection is still used in medical schools,
anatomy courses, and in pathology labs. In order to observe structures in living people, however, a number of imaging
techniques have been developed. These techniques allow clinicians to visualize structures inside the living body such as a
cancerous tumor or a fractured bone.
Like most scientific disciplines, anatomy has areas of specialization. Gross anatomy is the study of the larger structures of
the body, those visible without the aid of magnification (Figure 1.2a). Macro- means “large,” thus, gross anatomy is also
referred to as macroscopic anatomy. In contrast, micro- means “small,” and microscopic anatomy is the study of structures
that can be observed only with the use of a microscope or other magnification devices (Figure 1.2b). Microscopic anatomy
includes cytology, the study of cells and histology, the study of tissues. As the technology of microscopes has advanced,
anatomists have been able to observe smaller and smaller structures of the body, from slices of large structures like the heart,
to the three-dimensional structures of large molecules in the body.
Anatomists take two general approaches to the study of the body’s structures: regional and systemic. Regional anatomy is
the study of the interrelationships of all of the structures in a specific body region, such as the abdomen. Studying regional
anatomy helps us appreciate the interrelationships of body structures, such as how muscles, nerves, blood vessels, and other
structures work together to serve a particular body region. In contrast, systemic anatomy is the study of the structures that
make up a discrete body system—that is, a group of structures that work together to perform a unique body function. For
example, a systemic anatomical study of the muscular system would consider all of the skeletal muscles of the body.
Whereas anatomy is about structure, physiology is about function. Human physiology is the scientific study of the chemistry
and physics of the structures of the body and the ways in which they work together to support the functions of life. Much
of the study of physiology centers on the body’s tendency toward homeostasis. Homeostasis is the state of steady internal
conditions maintained by living things. The study of physiology certainly includes observation, both with the naked eye and
with microscopes, as well as manipulations and measurements. However, current advances in physiology usually depend
on carefully designed laboratory experiments that reveal the functions of the many structures and chemical compounds that
make up the human body.
Like anatomists, physiologists typically specialize in a particular branch of physiology. For example, neurophysiology is
the study of the brain, spinal cord, and nerves and how these work together to perform functions as complex and diverse as
vision, movement, and thinking. Physiologists may work from the organ level (exploring, for example, what different parts
of the brain do) to the molecular level (such as exploring how an electrochemical signal travels along nerves).
Form is closely related to function in all living things. For example, the thin flap of your eyelid can snap down to clear away
dust particles and almost instantaneously slide back up to allow you to see again. At the microscopic level, the arrangement
and function of the nerves and muscles that serve the eyelid allow for its quick action and retreat. At a smaller level of
analysis, the function of these nerves and muscles likewise relies on the interactions of specific molecules and ions. Even
the three-dimensional structure of certain molecules is essential to their function.
Your study of anatomy and physiology will make more sense if you continually relate the form of the structures you are
studying to their function. In fact, it can be somewhat frustrating to attempt to study anatomy without an understanding
of the physiology that a body structure supports. Imagine, for example, trying to appreciate the unique arrangement of the
bones of the human hand if you had no conception of the function of the hand. Fortunately, your understanding of how
the human hand manipulates tools—from pens to cell phones—helps you appreciate the unique alignment of the thumb
in opposition to the four fingers, making your hand a structure that allows you to pinch and grasp objects and type text
messages.
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