Chapter 01 Organization of the body Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Introduction Anatomy – structure of a part and its relationship to other structures Physiology – function of a part, individually and as part of a system Example: a neuron is a brain cell that is structured to transmit both electrical and chemical signals to allow for communication. The structure of a part suits the function of a part (they complement each other).

Organization of Body Parts Levels of Organization Chemical – atoms, molecules, and macromolecules that compose the cellular organelles that perform the functions of the cell Cellular – basic unit of life Tissue – similar cells that perform a specific function Organs – several types of tissues that perform a specific function Organ Systems – several organs that work together to perform related functions Organism – all the systems that interact to make the whole organism

Anatomical Position Anatomical position Common reference point for all anatomical terms Standing erect, face, palms, and toes facing forward, arms at sides

Directional Terms

Regions of the Body Axial portion – head, neck, and trunk Appendicular portion – upper and lower limbs

Terms for body parts and areas

Planes and Sections of the Body Sagittal (median) plane – divides body into right and left portions Midsagittal – exactly through the midline Parasagittal – any cut not through the midline Frontal (coronal) plane – divides body into anterior and posterior portions Transverse (horizontal) plane – divides body into superior and inferior portions

Gummy bear activity Obtain 3 gummy bears, a scalpel, and a paper plate from the teacher Make one of each of the below cuts to create two different body sections on 3 different gummy bears Cuts: Gummy bear 1: transverse plane Gummy bear 2: midsagittal plane Gummy bear 3: frontal plane Use the correct terminology as you work!! Please place the scalpels in the provided container Return to your seats with your gummy bear body sections

Body planes and sections

Homeostasis Homeostasis is the relative constancy of the body’s internal environment External conditions may change dramatically Internal conditions stay within a narrow range Sensor – detects a change in the internal environment Control center – activates the effector Effector – produces a response to the change Example: eyes (sensors) detect a bright light and generates an impulse to the brain (control center) that causes and effector like a muscle around the eye to contract Illness results if internal conditions change to any great degree

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Primary homeostatic mechanism: negative feedback

Mechanical example of negative feedback

Mechanical example of negative feedback

Body temperature regulation

Positive feedback Effector continues to stimulate the sensor so that a greater change in the internal environment occurs Helps in completing a process that has a cutoff point Blood clotting Childbirth Can be harmful

Positive feedback