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Chapter 1An Introduction to the Human Body

• Anatomy

• Physiology

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Levels of Organization• Chemical• Cellular• Tissue• Organs• System Level• Organismic Level

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Levels of Structural Organization

• Chemical Level

• Cellular level

• Tissue level

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Levels of Structural Organization

• Organ level

• Organ system

• Organismic level

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Life Processes

• Metabolism = sum of all chemical processes

• Responsiveness

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Life Processes• Movement at any structural level

• Growth

• Differentiation

• Reproduction

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Homeostasis

• Maintaining the internal environment within physiological limits

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Homeostasis of Body Fluids

• Delineation of fluid compartments

– intracellular fluid (ICF) =

– extracellular fluid (ECF) =

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Control of Homeostasis

• Homeostasis is continually being disrupted by– external stimuli or

– internal stimuli

• Disruptions are usually mild & temporary

• If homeostasis is not maintained, death may result

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Neural and Endocrine Controls

• Process of maintaining a controlled condition

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Components of Feedback Loop

• Receptor

• Control center

• Effector

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Negative & Positive Feedback Loops

• Negative feedback loop

• Positive feedback loop

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Homeostasis of Blood Pressure• Pressure receptors in walls of

certain arteries detect an increase in BP

• Brain receives input and signals heart and blood vessels

• Heart rate slows and arterioles dilate

• BP returns to normal

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Positive Feedback during Childbirth• Stretch receptors in walls of

uterus send signals to the brain• Brain releases hormone into

bloodstream• Uterine smooth muscle

contracts more forcefully• More stretch, more hormone,

more contraction etc.• Cycle ends with birth of the

baby & decrease in stretch

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Basic Anatomical Terminology

• Anatomical position

• Regions of the body

• Anatomical planes, sections and directional

terms

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Anatomical Position• Standardized position from which to

describe directional terms– standing upright

– facing the observer, head level

– eyes facing forward

– feet flat on the floor

– arms at the sides

– palms turned forward

• Prone position = • Supine position =

anatomical position?

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Common Regional Names

• Clinical terminology based on a Greek or Latin root word.

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Sagittal Plane

• Sagittal plane

• Midsagittal plane

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Other Planes and Sections• Frontal or coronal plane

• Transverse(cross-sectional) or horizontal plane

• Oblique plane–

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Planes and Sections of the Brain(3-D anatomical relationships revealed)

• Horizontal Plane

• Frontal Plane

• Midsagittal Plane

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Major Directional Terms

• See Definitions page 14

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Superior or Inferior

• Superior

• Inferior

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• Dorsal or Posterior

• Ventral or Anterior

Dorsal or Ventral

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Medial or Lateral• Medial

• Lateral

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Proximal or Distal• Proximal

• Distal

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Dorsal Body Cavity• Near dorsal surface of

body

• 2 subdivisions– cranial cavity

– vertebral or spinal canal

• Meninges line dorsal body cavity

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Ventral Body Cavity

• Near ventral surface of body

• 2 subdivisions– thoracic cavity

– abdominopelvic cavity

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Abdominopelvic Cavity

• Inferior portion of ventral body cavity below diaphragm• Encircled by abdominal wall, bones & muscles of pelvis

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Thoracic Cavity

• Encircled by ribs, sternum, vertebral column and muscle• Divided into 2 pleural cavities by mediastinum • Mediastinum contains all thoracic organs except lungs

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Mediastinum

• Midline wall of tissue that contains heart and great vessels, esophagus, trachea and thymus.

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Serous Membranes

• Thin slippery membrane lines body cavities not open to the outside– parietal layer

– visceral layer

• Serous fluid reduces friction

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Pleural & Pericardial Cavities

• Visceral pleura Visceral pericardium

• Parietal pleura Parietal pericardium

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Peritoneum

• Visceral peritoneum

• Parietal peritoneum

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Abdominopelvic Regions & Quadrants

• Describe locations of organs or source of pain• Tic-tac-toe grid or intersecting lines through navel

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Medical Imaging

• Allows visualization of structures without surgery

• Useful for confirmation of diagnosis

• Examples of imaging techniques

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Conventional Radiography

• A single burst of xrays• Produces 2-D image on

film• Poor resolution of soft

tissues

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Computed Tomography (CT Scan)

• Moving x-ray beam• Computer generated

image reveals more soft tissue detail– kidney & gallstones

• Multiple scans used to build 3D views

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Ultrasound (US)

• High-frequency sound waves emitted by hand-held device

• Safe, noninvasive & painless• Used for fetal ultrasound and

examination of pelvic & abdominal organs, heart and blood flow through blood vessels

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Magnetic Resonance Imaging (MRI)• Body exposed to high-

energy magnetic field• Protons align themselves

relative to magnetic field• Reveals fine detail within

soft tissues

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Positron Emission Tomography(PET)• Substance that emits

positively charged particles is injected into body

• Collision with negatively charged electrons in tissues releases gamma rays

• Camera detects gamma rays & computer generates image displayed on monitor