Chapter One: The Human Body

M.C. Shamier, MDShenzhou University

Subjects Anatomy

Anatomy defined The language of anatomy

Physiology Physiology defined Levels of organization Homeostasis

Anatomy Greek: ἀνατέμνειν “to cut open”

tonsillec-tomy: cutting away the tonsils of the throat. The study of the structure of living things 

Michiel van Mierevelt, 1617

Subdivisions Gross or macroscopic anatomy Microscopic anatomy

Histology Cytology

Developmental anatomy and embryology Radiographic anatomy Pathological anatomy

Histology and cytology

Radiographic and pathological anatomy

The language of anatomy Anatomical position Directional terms Regional names Body planes Abdominopelvic

regions

Body cavities

Arbitrary

Physiologic

The language of anatomy

Anatomical position

Directional terms

Directional terms

Directional terms

Directional terms

Directional terms

Regional names

Body planes

Abdominopelvic regions

Body cavities

“Body cavities are spaces within the body that are closed to the outside and contain the

internal organs.”

Body cavities

Example: cranial and spinal cavity Together one continuous space, home to the

central nervous system (CNS) Confined by bone: skull and vertebral column Filled with cerebrospinal fluid

Are there any questions?

Next: Physiology

Physiology Greek:

Φύσις: “nature -λογία:  “the study of”

The science of the functioning of living things. Inseperately connected to anatomy:

function reflects shape

Levels of structural organization Question:

What is the smallest unit that the body is essentially composed of?

Levels of structural organization

Question Could you think of a seventh level?

The seventh level: environmental context

Hendrick Avercamp

New York City

And the environment also contains:

Yellow fever

Organism and environment The organism is subject to:

Climate Microbes Social interaction Air pressure

And dependent on the environment for: Oxygen Nutrients Water

Boundaries Question:

What seperates the organism from its environment?

‘Milieu intérieur’ and ‘milieu extérieur’ “The fixity of the milieu supposes a perfection

of the organism such that the external variations are at each instant compensated for and equilibrated. All of the vital mechanisms, however varied they may be, have always one goal, to maintain the uniformity of the conditions of life in the internal environment. The stability of the internal environment is the condition for the free and independent life.” Claude Bernard, French Physiologist, 1854:

Example: Temperature Question

What is the baseline temperature of the human body?

Question What happens when the environmental

temperature drops?

Example: Temperature

This is called: Homeostasis Homeostasis:

The ability of the body to maintain a relatively constant internal environment, regardless of environmental changes.

How does it work?

The mechanism of negative feedback: failure leads to imbalance which means disease.

Concluded There are several levels of structural

organization within an organism: from the atom to the organism (living in an environment).

All vital systems work together to maintain a stable internal environment, compensating for external variations. The mechanism is negative feedback.

This is called homeostasis.

End of Chapter One