Chapter 1
An Introduction to the Human Body
Anatomy
science of structure
relationships revealed by dissection (cutting apart)
imaging techniques
Physiology
science of body functions
normal adult physiology studied in this text
some genetic variations described
Subdivisions of A & P =
Table 1.1
Clinical Observational Techniques
Palpation
feel body surface with hands
pulses and breathing rates
Auscultation
listen to body sounds with stethoscope
abnormal fluid in lungs
Percussion
tap on body surface and listen to echo
air in intestines
Levels of Organization
Chemical
Cellular
Tissue
Organs
System Level
Organismic Level
Levels of Structural Organization
Chemical Level
atomic and molecular level
Cellular level
smallest living unit of the body
Tissue level
group of cells and the materials surrounding them that work
together on one task
4 basic tissue types
epithelium, muscle, connective tissue, and nerve
Levels of Structural Organization
Organ level
grouping of 2 or more tissue types into a recognizable
structure with a specific function.
Organ system
collection of related organs with a common function
sometimes an organ is part of more than one system
Organismic level
one living individual.
Interaction of Organ Systems
All major body systems will be examined
Interaction of different systems of the body
skin produces vitamin
D needed for calcium absorption and bone growth
bone marrow produces
cells which help the skin resist infection.
Life Processes
Metabolism = sum of all chemical processes
breakdown of large molecules into small
building new structural components (proteins)
providing chemical energy for cells
Responsiveness
detect & respond to changes in internal or external
environment
some typical responses
muscle contraction, electrical signals, hormone or glandular
secretion
Life Processes
Movement at any structural level
the body, an organ, a cell or cell component
Growth
increase in number or size of cells or the material found
between cells
Differentiation
specialization of cells for a specific function
stem cells give rise to cells that specialize
Reproduction
formation of new cells or new individuals
Autopsy
Postmortem examination of body by dissection
Purpose
confirm or determine cause of death
support findings of other tests
provide information on effects of drug usage
educate healthcare students
reveal congenital defects
Homeostatis
Maintaining the internal environment within physiological
limits
First described by French physiologist, 1813-1878
Process named by Walter Cannon, 1871-1945
Example
blood glucose level is kept within narrow range 70-110/100ml
Homeostasis of Body Fluids
Delineation of fluid compartments
intracellular fluid (ICF) = within cells
extracellular fluid (ECF) =
outside cells
intercellular fluid = tissue fluid = interstitial fluid
plasma = fluid portion of blood
Composition of fluids change as substances move between
compartments
nutrients, oxygen, ions and wastes move in both directions
across capillary walls
Control of Homeostasis
Homeostasis is continually being disrupted by
external stimuli or
intense heat, cold , and lack of oxygen
internal stimuli
psychological stresses
exercise
Disruptions are usually mild & temporary
If homeostasis is not maintained, death may result
Neural and Endocrine Controls
Process of maintaining a controlled condition
sensory receptors detect change in a monitored variable
nervous system and/or endocrine system responds
Example of control of blood gas level
exercise increases blood CO2 levels
sensory receptors detect change
nervous system increases heart and breathing rates to remove
excess CO2
adrenal gland releases epinephrine to increase heart and
breathing rates
Components of Feedback
Receptor
monitors a controlled condition
Control center
determines next action
Effector
receives directions from the control center
produces a response that changes the controlled condition
Negative & Positive Feedback Loops
Negative feedback loop
original stimulus reversed
most feedback systems in the body are negative
used for conditions that need frequent adjustment
body temperature, blood sugar levels, blood pressure
Positive feedback loop
original stimulus intensified
seen during normal childbirth
Homeostasis of Blood Pressure
Pressure receptors in walls of certain arteries detect an
increase in BP
blood Pressure = force of blood on walls of vessels
Brain receives input and signals heart and blood vessels
Heart rate slows and arterioles dilate (increase in
diameter)
BP returns to normal
Positive Feedback during Childbirth
Stretch receptors in walls of uterus send signals to the
brain
Brain releases hormone (oxytocin)
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
Homeostatic Imbalances
Disorder = abnormality of function
Disease = homeostatic imbalance with distinct
symptoms---changes in body function felt by the patient such
as nausea and
signs----changes in body function that can be observed by
the doctor such as rash or fever
Diagnosis---skill of distinguishing one disease from another
Epidemiology----how disease is transmitted
Pharmacology --- how drugs used to treat disease
Basic Anatomical Terminology
Anatomical position
Regions of the body
Anatomical planes, sections and directional terms
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 = lying face down
Supine position = lying face up
Common Regional Names
Clinical terminology based on a Greek or Latin root word.
Planes and Sections
A plane is an imaginary flat surface that passes through the
body.
A section is one of the 2 surfaces (pieces) that results
when the body is cut by a plane passing through it.
Sagittal Plane
Sagittal plane
divides the body or an organ into left and right sides
Midsagittal plane
produces equal halves
Parasagittal plane
produces unequal halves
Other Planes and Sections
Frontal or coronal plane
divides the body or an organ into front (anterior) and
back (posterior) portions
Transverse(cross-sectional) or horizontal plane
divides the body or an organ into upper (superior) or
lower (inferior) portions
Oblique plane
some combination of 2 other planes
Planes and Sections of the Brain
(3-D anatomical relationships revealed)
Horizontal Plane
Frontal Plane
Midsagittal Plane
Major Directional Terms
See Definitions page 14
towards the head
The eyes are superior to the mouth.
Inferior
away from the head
The stomach is inferior to the heart.
Dorsal or Ventral
Dorsal or Posterior
at the back of the body
The brain is posterior to the forehead.
Ventral or Anterior
at the front of the body
The sternum is anterior to the heart.
Medial or Lateral
Medial
nearer to the midline of the body
The heart lies medial to the lungs.
Lateral
farther from the midline of the body
The thumb is on the lateral side of the hand.
Proximal or Distal
Proximal
nearer to the attachment of the limb to the trunk
The knee is proximal to the ankle.
Distal
farther from the attachment of the limb to the trunk
The wrist is distal to the elbow.
Dorsal Body Cavity
Near dorsal surface of body
2 subdivisions
cranial cavity
holds the brain
formed by skull
vertebral or spinal canal
contains the spinal
cord
formed by vertebral column
Meninges line dorsal body cavity
Ventral Body Cavity
Near ventral surface of body
2 subdivisions
thoracic cavity above diaphragm
abdominopelvic cavity below
diaphragm
Diaphragm = large, dome-shaped muscle
Organs called viscera
Organs covered with serous membrane
Abdominopelvic Cavity
Inferior portion of ventral body cavity below diaphragm
Encircled by abdominal wall, bones & muscles of pelvis
Thoracic Cavity
Encircled by ribs, sternum, vertebral column and muscle
Divided into 2 pleural cavities by mediastinum
Mediastinum contains all thoracic
organs except lungs
Mediastinum
Midline wall of tissue that contains heart and great
vessels, esophagus, trachea and thymus.
Serous Membranes
Thin slippery membrane lines body cavities not open to the
outside
parietal layer lines walls of cavities
visceral layer covers viscera within the cavities
Serous fluid reduces friction
Pleural & Pericardial Cavities
Visceral pleura clings to surface of lungs --- Parietal
pleura lines chest wall
Visceral pericardium covers heart --- Parietal pericardium
lines pericardial sac
Peritoneum
Visceral peritoneum --- serous membrane that covers the
abdominal viscera
Parietal peritoneum --- serous membrane that lines the
abdominal wall
Abdominopelvic Regions
& Quadrants
Describe locations of organs or source of pain
Tic-tac-toe grid or intersecting lines through navel
Medical Imaging
Allows visualization of structures without surgery
Useful for confirmation of diagnosis
Examples of imaging techniques
Conventional Radiography
A single burst of xrays
Produces 2-D image on film
Known as radiography or xray
Poor resolution of soft tissues
Major use is osteology
Computed Tomography (CT Scan)
Moving x-ray beam
Image produced on a video monitor of a cross-section through
body
Computer generated image reveals more soft tissue detail
kidney & gallstones
Multiple scans used to build 3D views
Digital Subtraction Angiography(DSA)
Radiopaque material injected into
blood vessels
Before and after images compared with a computer program
Image of blood vessel is shown on a monitor
Ultrasound (US)
High-frequency sound waves emitted by hand-held device
Safe, noninvasive & painless
Image or sonogram is displayed on video monitor
Used for fetal ultrasound and examination of pelvic &
abdominal organs, heart and blood flow through blood vessels
Magnetic Resonance Imaging (MRI)
Body exposed to high-energy magnetic field
Protons align themselves relative to magnetic field
Pulse of radiowaves used to
generate an image on video monitor
Can not use on patient with metal in their body
Reveals fine detail within soft tissues
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