ORGANIZATION OF THE HUMAN BODY

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 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. 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