Introduction to the Human Body A. Anatomy and physiology defined A. Anatomy and physiology definedA B. Levels of structural organization B. Levels of structural organizationB C. Life processes C. Life processesC D. Anatomical position D. Anatomical positionD E. Directional terms E. Directional termsE F. Planes and sections F. Planes and sectionsF G. Body cavities G. Body cavitiesG H. Homeostasis H. HomeostasisH 1. Body fluids and exchange 1. Body fluids and exchange1 2. Regulation by nervous and endocrine 2. Regulation by nervous and endocrine2 mechanisms mechanisms 3. Feedback systems 3. Feedback systems3

Anatomy (Greek “anatome” =to cut up or dissect Physiology (Greek “physis” =nature

Levels of Structural Organization

Life Processes Metabolism= catabolism + anabolism ResponsivenessMovementGrowthDifferentiationReproduction

Anatomical Position

Directional Terms Superior vs. Inferior Anterior vs. Posterior Medial vs. Lateral Proximal vs. Distal Superficial vs. Deep AnteriorPosterior superior inferior MedialLateral Proximal Distal

Planes and Sections 1.Sagittal a. midsagittal b. parasagittal 2. Frontal (coronal) 3.Transverse (cross) 4.Oblique Planes of the Body

Sections Through the Body

Body Cavities Body Cavities (also material In Atlas A (A. 12-A.22) and Handout 1-Body Regions 1.Dorsal a. cranial b. vertebral (spinal 2. Ventral a. thoracic (1) pleural-2 (2) mediastinum (a) anterior (b)middle(pericardial) (c) posterior b. abdominopelvic

Homeostasis (Greek “homoi” =same “stasis” =standing still)

Body Fluids and Exchange 1.Extracellular fluid (ECF) a. interstitial fluid b. plasma 2. Intracellular fluid

The homeostatic responses of the body are regulated by the combined effects of the nervous system and the endocrine system.

REGULATION OF HOMEOSTASIS Nervous system = electrical messages control events on a millisecond basis; short-term and very specific effects Endocrine system = chemical messages control events on a minute, hour, daily, monthly, etc. basis; longer-term and more widespread effects

Operation of a Feedback System ConditionReceptor Control Center Control CenterEffectorsResponse

Condition- A stimulus or stress disrupts homeostasis in a controlled condition which is monitored by a receptor. Receptor- responds to specific changes in the controlled condition and sends input to control center. Control Center- Receives input from receptors, integrates the information and provides output to specific effectors. Effectors-respond to output from the control center by bringing about some type of change in the body that counteracts the disruption in homeostasis. Response-the activity of the effectors brings the controlled condition back into normal homeostasis and the negative feedback system is shut down. Feedback System: Main Players

WHAT IS A FEEDBACK SYSTEM? CONTROLLED CONDITION RECEPTOR RETURN TO HOMEOSTASIS EFFECTORS CONTROL CENTER some physiologic state senses a change in the condition integrates incoming information structure that restores homeostasis

WHAT IS A NEGATIVE FEEDBACK SYSTEM? A feedback loop in which the body senses a change and activates mechanisms that reverse the change CONTROL CENTER medulla of brain nervous output RETURN TO HOMEOSTASIS blood pressure rises turns off CONTROLLED CONDITION blood pressure decreased RECEPTOR baroreceptors in blood vessels decreased activity EFFECTORS heart and arterial smooth muscle increased heart rate and vasoconstriction end

Positive Feedback

WHAT IS A POSITIVE FEEDBACK SYSTEM? A feedback loop in which the response reinforces the stimulus, triggering a cycle of ever-increasing response EFFECTORS uterine smooth muscle contraction CONTROL CENTER hypothalamic neurons of brain oxytocin secretion RETURN TO HOMEOSTASIS labor forces baby’s head further into cervix reinforcing effects CONTROLLED CONDITION level of uterine stretch increased RECEPTOR stretch receptors in cervix increased activity