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Chapter 1
An Introduction to the Human Body
• Anatomy
• Physiology
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Levels of Organization
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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
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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 Ventral
• Dorsal or Posterior
• Ventral or Anterior
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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 highenergy 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
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