Chapter 1

The Human Body: Anatomical Regions, Directions, and Body

Cavities

Overview of Anatomy and Physiology

• Anatomy – the study of the structure of body parts and their relationships to one another

1. Gross anatomy and 2. Microscopic anatomy)

• Physiology – the study of the function of the body’s structural machinery

1. Gross Anatomy• Regional – all structures in one part of the

body – Example: studying all structures in the

abdomen

• Systemic – gross anatomy of the body studied by system– Example: studying the digestive system

• Surface – study of external features as they relate to the underlying features– Example: The jugular notch/ sternal angle can

help locate the second rib.

2. Microscopic Anatomy

• CytologyCytology – study of the cell– “cyto” means cell

• HistologyHistology – study of tissues– “histo” means tissue

Physiology

• Considers the operation of specific organ systems– Renal – kidney function– Neurophysiology – workings of the nervous

system– Cardiovascular – operation of the heart and

blood vessels

• Focuses on the functions of the body, often at the cellular or molecular level

Physiology

• Understanding physiology also requires a knowledge of physics, which explains electrical currents, blood pressure, and the way muscle uses bone for movement

Chemical levelAtoms combine to form molecules

1

2

3

4

Cellular levelCells are made up of molecules

Tissue levelTissues consist of similar types of cells

5 Organ system levelOrgan systems consist of different organs that work together closely

Organ levelOrgans are made up of different types of tissues

6 Organismal levelThe human organism is made up of many organ systems

Atoms

Molecules

Smooth muscle cell

Smooth muscle tissue

Connective tissue

Smooth muscle tissue

Epithelial tissue

Blood vessel (organ)

Heart

Blood vessels

Cardiovascular system

Levels of Structural Organization

Figure 1.1

Levels of Structural Organization

• ChemicalChemical – atoms combined to form molecules

• CellularCellular – cells are made of molecules• TissueTissue – consists of similar types of cells• OrganOrgan – made up of different types of

tissues• Organ systemOrgan system – consists of different

organs that work closely together• OrganismOrganism – made up of the organ

systems

Homeostasis• Homeostasis is the ability to

maintain a relatively stable internal environment in an ever-changing outside world

• The internal environment of the body is in a dynamic state of equilibrium

• Chemical, thermal, and neural factors interact to maintain homeostasis

Negative Feedback

• When a deviation from homeostasis occurs, the system makes the deviation smaller.

• Think of negative as opposite.

Positive Feedback

• When a deviation from homeostasis occurs, the system responds by making the deviation EVEN greater.

• Rare in healthy individuals. • Not enough blood to the heart? Your

heart will contract and move blood – but if you’ve LOST blood, the heart rate increases and pumps more. And you lose MORE blood, so the heart pumps more…etc. etc.

Anatomical Position

• Body erect • Feet slightly apart• Palms facing

forward • Thumbs point away

from body

• Right and Left are absolute.

Figure 1.7a

LEFTLEG

RIGHTLEG

Anatomical Position

• Body erect • Feet slightly apart• Palms facing

forward • Thumbs point away

from body

• PRONE is face down.• SUPINE is face up.

Figure 1.7a

LEFTLEG

RIGHTLEG

Directional Terms

• Superior and inferior – toward and away from the head, respectively

• Anterior and posterior – toward the front and back of the body

• Medial, lateral, and intermediate – toward the midline, away from the midline, and between a more medial and lateral structure

Directional Terms

• Proximal and distal – closer to and farther from the origin of the body

• Superficial and deep – toward and away from the body surface

Directional Terms Table 1.1

Directional Terms Table 1.1

Regional Terms: Anterior ViewIn your book: Page 11 Figure 1.8

Regional Terms: Posterior View

• Axial – head, neck, and trunk• Appendicular – appendages or limbs

Body Planes• Sagittal – divides the body into right

and left parts• Midsagittal or medial – sagittal

plane that lies on the midline• Frontal or coronal – divides the

body into anterior and posterior parts• Transverse or horizontal (cross

section) – divides the body into superior and inferior parts

Body Planes

Body Planes Figure 1.8

Midsagittal section through

head