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. ANATOMY 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 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. 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 1.Receptor 2.Control center 3.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 1.Cranial cavity: the space inside the skull 2.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: 1.Thoracic cavity: houses the lungs, heart and mediastinal structures 2.Abdominopelvic cavity: stomach, liver, intestines, spleen, reproductive organs, urinary bladder, etc

42. Abdominopelvic Quadrants and Regions

45. Thank you