1. ORGANIZATION OF THE HUMAN BODY
Francis G. Moria, MD, DPSP

2. Contents Overview of Anatomy & Physiology
Levels of Structural Organization
Homeostasis
The Language of Anatomy

3. Overview of Anatomy & Physiology

4. Overview of Anatomy & Physiology
The study of the structure and shape of the body and body parts and their relationship to one another
Derived from the Greek words: to cut (tomy) apart (ana)

5. Overview of Anatomy & Physiology
Gross Anatomy
The study of large, easily observable structures (eg, heart, bones)
Microscopic Anatomy
A microscope or magnifying instrument is used to see very small structures in the body (eg, cells, tissues)

6. Overview of Anatomy & Physiology
The study of how the body and its parts work or function
Derived from the Latin words: nature (physio), the study of (ology)

7. Overview of Anatomy & Physiology
Subdivisions of Physiology (Examples)
Neurophysiology: explains the workings of the nervous system
Cardiac physiology: studies the function of the heart

8. Levels of Structural Organization

9. Levels of the Hierarchy
Atoms: building blocks of matter
Molecules: groups of atoms (eg, water, sugar, proteins)
Organelles: basic components of microscopic cells
Cells: smallest units of all living things

10. Levels of the Hierarchy
Tissues: groups of similar cells that have a common function
Organ: a structure composed of two or more tissue types that perform a specific function for the body
Organ System: a group of organs that cooperate and work closely together to accomplish a common purpose
Organism: the highest level of structural organization

14. Homeostasis

15. Homeostasis
The body’s ability to maintain relatively stable internal conditions even though the outside world is continuously changing
It indicates a dynamic state of equilibrium, or a balance, in which internal conditions change and vary, but always within relatively narrow limits

16. Homeostasis
The body is in homeostasis when its needs are being adequately met and it is functioning smoothly
Every organ system plays a role in maintaining the constancy of the internal environment

17. Homeostatic Control Mechanism
Three components
Receptor
Control center
Effector

18. Homeostatic Control Mechanism
RECEPTOR
It is some type of sensor that monitors and responds to changes in the environment
It responds to changes, called stimuli, by sending information (input) to the control center
Information flows from the receptor to the control center along the afferent pathway

19. Homeostatic Control Mechanism
CONTROL CENTER
Determines the level (set point) at which a variable is to be maintained
Analyzes the information it receives and then determines the appropriate response or course of action

20. Homeostatic Control Mechanism
EFFECTOR
Provides means for the control center’s response (output) to the stimulus
Information flows from the control center to the effector along the efferent pathway
The results of the response then feed back to influence the stimulus

21. Feedback Mechanisms NEGATIVE FEEDBACK
The net effect of the response to the stimulus is to shut off the original stimulus or reduce its intensity (eg, blood glucose regulation)
POSITIVE FEEDBACK
Tends to increase the original stimulus and to push the variable farther from its original value (eg, blood clotting)

23. The Language of Anatomy

24. Anatomical Position
The body is erect with the feet parallel and the arms hanging at the sides with the palms facing forward

26. Directional Terms Superior (cranial or cephalad)
Toward the head end or upper part of a structure of the body
Inferior (caudal)
Away from the head end or toward the lower part of a structure or the body
Anterior (ventral)
Toward or at the front of the body
Posterior (dorsal)
Toward or at the backside of the body

27. Directional Terms Medial Toward or at the midline of the body Lateral
Away from the midline of the body
Proximal
Close to the origin of the body part or the point of attachment of a limb to the body trunk
Distal
Farther away from the origin of a body part or the point of attachment of a limb to the body trunk
Superficial
Toward or at the body surface
Deep
Away from the body surface; more internal

29. Regional Terms Axial makes up the main axis of the body.
consists of the head, neck, and trunk
Appendicular
consists of the appendages or limbs

32. Body Planes & Sections Sagittal section
A cut made along the lengthwise or longitudinal plane of the body
Divides the body into right and left parts
Midsagittal/Median section
The cut is made down the median plane of the body and the right and left parts are equal in size

33. Body Planes & Sections Frontal section
A cut made along a lengthwise plane that divides the body (or an organ) into anterior and posterior parts
Also called a coronal section
Transverse section
A cut is made along a horizontal plane, dividing the body or organ into superior and inferior parts
Also called a cross-section

39. Body Cavities DORSAL BODY CAVITY
Has two subdivisions which are continuous with each other
Cranial cavity: the space inside the skull
Spinal cavity: extends from the cranial cavity nearly to the end of the vertebral column

40. Body Cavities VENTRAL BODY CAVITIES Much larger than the dorsal cavity
Contains all the structures in the chest and abdomen
Two major subdivisions:
Thoracic cavity: houses the lungs, heart and mediastinal structures
Abdominopelvic cavity: stomach, liver, intestines, spleen, reproductive organs, urinary bladder, etc

42. Abdominopelvic Quadrants and Regions

45. Thank you