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Chapter 1
An Introduction to the Human
Body
1
 Anatomy

science of structure

subdivisions summarized in table 1.1
 Physiology




science of body functions
normal adult physiology is studied in this text
some genetic variations are described
Table 1.1
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Levels of Organization

Chemical

Cellular

Tissue

Organs

System

Organism
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LEVELS OF ORGANIZATION
 Figure
1.1
 The chemical level


Atoms
Molecules
 Cells

Basic structural & functional units of an
organism
 Tissues

Groups of similarly specialized cells that
perform certain special functions
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LEVELS OF ORGANIZATION
 Organs



Structures of definite form
Two or more different tissues
Specific functions
 Systems

Related organs with a common function
 Organism

Collection of structurally & functionally
integrated systems; any living individual
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BODY SYSTEMS
 Integumentary
 Cardiovascular
 Skeletal
 Lymphatic
 Muscular
 Respiratory
 Nervous
 Endocrine
 Urinary
 Digestive
 Reproductive
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Clinical Application
 Noninvasive
techniques used to assess
certain aspects of body structure & function:

Inspection

Palpation

Auscultation

Percussion
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Basic Life Processes
 Metabolism:


Catabolism
Anabolism
 Responsiveness:
 Movement:
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Basic Life Processes

Growth:

hyperplasia, hypertrophy, or both

Differentiation:

Reproduction


formation of new cells for growth, repair, or
replacement
production of a new individual
***Death



Loss of heartbeat
Loss of brain function
Absence of spontaneous breathing
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HOMEOSTASIS

State of balance in body’s internal environment
produced by the ceaseless interplay of all the
body’s regulatory processes



“dynamic equilibrium”
narrow range of conditions compatible w/ life
Recurring theme of textbook
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Body Fluids

Intracellular fluid = fluid inside body cells

Extracellular fluid (ECF) = fluid outside cells
 Interstitial fluid (ISF) = ECF in narrow spaces
between cells of tissues  internal environmt
 Plasma = ECF in blood vessels

Exchange of nutrients across capillaries to/from
ISF/cells & tissues
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Control of Homeostasis

Homeostasis continually disrupted by
 External stimuli
• intense heat or cold
• lack of oxygen

Internal stimuli
• psychological stresses
• low blood sugar

Disruptions are usually mild & temporary

If homeostasis not maintained, death may result
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CONTROL OF HOMEOSTASIS

How do we maintain homeostasis in wake of
internal/external disruptions?


Number of regulatory mechanisms restore
balance
Nervous & endocrine systems
• nervous system rapid response
• endocrine system  slow response

Feedback systems
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Feedback Systems

Information about status of a condition is
continually monitored & reported (fed back)
to central control region
 Monitored variable = controlled condition
 Any disruption that changes a controlled
condition is called a stimulus.
 3 basic components
• Receptors
• Control center
• Effector
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Components of Feedback Loop

Receptor


Monitors Δ in controlled condition
Input to control center
• Nerve impulses
• Chemical signals (hormones)

Control center



Evaluates receptor input
Generates output
Effector


Receives output from control ctr
Produces response that changes
controlled condition
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Negative Feedback Systems
 A negative
feedback system reverses a
change in a controlled condition.
 Homeostasis
of Blood Pressure (BP):
Negative Feedback (Figure 1.3)

The activity of the effector produces a result
(a drop in blood pressure) that opposes the
stimulus (an increase in blood pressure).
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Positive Feedback System
 Reinforces
a change (enhances original
stimulus) in a controlled condition
 Normal
childbirth
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Positive Feedback during Childbirth
receptors in walls of uterus send
signals to brain
 Brain releases a hormone (oxytocin) into
bloodstream
 Uterine smooth muscle contracts more
forcefully
 More stretch  more hormone  more
contraction  etc.
 The cycle ends with birth of the baby &
decrease in stretch
 Stretch
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Homeostatic Imbalances

Disruption of homeostasis can lead to disease
and death.
 Disorder = general term for any derangement or
abnormality of function
 Disease = specific term for illness characterized
by a recognizable set of signs and symptoms



Local disease affects one part or a limited region of
body (rash)
Systemic disease affects either entire body or several
parts (ex: flu)
Cancer begins locally and if left untreated can
become systemic
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Homeostatic Imbalances

Characterizing disease
 Signs
• fever, blood pressure, rash, swelling

Symptoms
• headache, nausea

Diagnosis



Distinguishing one disease from another
Determining the nature of a disease
Medical history & physical examination
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BASIC ANATOMICAL
TERMINOLOGY
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Anatomical Position

When in anatomical position, the
subject is:

standing upright
facing observer, with head level
eyes facing forward
feet flat on floor
arms at sides

palms turned forward (ventral)




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Reclining Position
 If
the body is lying face down, it is in the
prone position.
 If
the body is lying face up, it is in the
supine position.
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Directional Terms
 Used
to precisely locate one part of the
body relative to another
 Commonly



used directional terms:
inferior, superior, medial, and distal
summarized in Exhibit 1.1 and Figure 1.6.
Also see lab manual
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Major Directional Terms

See Definitions page 14
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Superior/Inferior

Refer to placement of structure
along long axis of body


Superior

“Above”

eyes are superior to mouth
Inferior

“Below”

stomach is inferior to heart
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Anterior/Posterior

Anterior (ventral)



At the front of body
Sternum is anterior to heart
Posterior (dorsal)


At the back of body
Brain is posterior to
forehead
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Medial/Lateral

Refers to location of structure in relation
to median plane/midline of body
 Medial



Nearer to midline of the body
Heart lies medial to lungs
Lateral


Farther from midline of the body
Thumb is on lateral side of hand
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Proximal/Distal

Primarily for location of areas of
limbs

Proximal


nearer to attachment of limb to trunk

Knee is proximal to ankle
Distal


farther from attachment of limb to
trunk
Wrist is distal to elbow
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Planes and Sections

Imaginary flat surfaces used to divide
body or organs into definite areas

Principal planes include:





midsagittal (medial) and parasagittal
frontal (coronal)
transverse (cross-sectional or horizontal)
oblique
Sections


flat surfaces resulting from cuts through
body structures
named according to plane of cut
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Sagittal Planes

Sagittal plane


Midsagittal plane


divides the body or
an organ into left and
right sides
produces equal
halves
Parasagittal plane

produces unequal
halves
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Other Planes and Sections

Frontal (coronal) plane


Transverse/cross-sectional/
horizontal plane


front (anterior) & back
(posterior) portions
upper (superior) or lower
(inferior) portions
Oblique plane

some combination of 2 other
planes
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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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Body Cavities
 Body
cavities are spaces within the body
that help protect, separate, and support
internal organs.
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Dorsal Body Cavity
 Located

near dorsal surface of body
Cranial cavity
• formed by the cranial bones
• contains the brain

Vertebral (spinal) canal (Figure 1.9)
• formed by bones of vertebral column
• contains spinal cord
 Lined
by three layers of protective tissue
called meninges

Inflammation of meninges = meningitis
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Ventral Body Cavity

Near ventral surface of
body

2 subdivisions


thoracic cavity above
diaphragm
abdominopelvic cavity
below diaphragm

Organs called viscera
 Organs covered with
serous membrane
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Ventral Body Cavity
 Thoracic


cavity
Contains all chest organs; surrounded by rib cage
Contain fluid-filled cavities surrounding heart/lungs
• Pleural cavities
• Pericardial cavity

Mediastinum
 Abdominopelvic



cavity
Inferior to diaphragm, surrounded by abdominal
wall
Abdominal viscera: mostly digestive organs
Pelvic viscera: urinary bladder, inferior lg intestine,
& internal reproductive structures
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Mediastinum

Partition between lungs that extends from
sternum to vertebral column
 Contains all organs of thoracic cavity except lungs
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Serous Membranes
 Double
layered membrane lining body
cavities not open to outside


parietal layer
visceral layer
 Serous
fluid btwn layers reduces friction
 Serosa
compartmentalize organs

Infection of one organ is contained
 Specific
names of membranes
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Serous Membranes
 Pleural
membrane surrounds lungs
 Pericardium
= serous membrane of
pericardial cavity
 Peritoneum
= serous membrane of
abdominal cavity
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Pleural & Pericardial Cavities

Visceral and Parietal Pleura


Pleurisy = inflammation of pleural membrane
Visceral and Parietal Pericardium
41
Abdominopelvic Cavity

Inferior portion of ventral body cavity below diaphragm
 Encircled by abdominal wall, bones & muscles of
pelvis
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Peritoneum

Serous membrane of abdominopelvic cavity
 Visceral peritoneum


covers abdominal viscera
Parietal peritoneum

lines abdominal wall

Peritoneal cavity = fluid-filled space btwn layers
 Intraperitoneal organs suspended within
peritoneal membranes (most abdom. organs)
 Retroperitoneal organs located behind
abdominal wall (kidneys, colon, adrenal glands)
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**The
blue and
green regions on
this diagram
represent the
peritoneal cavity.
Note that there are
NO organs within
the actual cavity.
It is simply a fluidfilled space as are
the pericardial &
pleural cavities.
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http://www.lab.anhb.uwa.edu.au/hsd212/02weekpages/WK07/week07_5more1.htm
Abdominopelvic
Regions & Quadrants

Describe locations of organs or source of pain
 Tic-tac-toe grid or intersecting lines through
navel
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