introduction to anatomy and physiology 1st sem bsc nursing

CHAPTER 1
The Human Body :
An Orientation
VIVEK SIR

• Anatomy – the study of the structure and shape of the body and body parts
& their relationships to one another. The term anatomy comes from the
Greek words meaning to cut (tomy) apart ( ana) .
• Gross anatomy( macroscopic anatomy) – the study of
large, easily observable structures (by naked eye),
such as the heart or bone.
• Microscopic anatomy (cytology, histology) – the study
of very small structures, where a magnifying lens or
microscope is needed.
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• Physiology – the study of how the body
and its parts work or function
physio =nature , ology = the study of.
• Like anatomy , physiology has many
subdivisions. For example,
neurophysiology explains the working
of the nervous system , and cardiac
physiology studies the function of the
heart.
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Relationship between Anatomy and Physiology
Anatomy and Physiology are always related . Structure
determines what functions can take place. For example, the
lungs are not muscular chambers like the heart and can not
pump blood, but because the walls of lungs are very thin, they
can exchange gasses and provide oxygen to the body.
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Levels of Structural Organization
The human body exhibits 6 levels of structural complexity :
1- Chemical level , the simplest level of structural ladder .At this level atoms
combine to form molecules such as water, sugar, & proteins
2- Cellular level the smallest units of living things .
3- Tissue level , groups of similar cells that have a common function (4 basic
types)
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4- Organ level, an organ is a structure composed of 2 or
more tissue types that performs a specific function .
5- Organ System is a group of organs that work together to
accomplish a common purpose (each organ has its own job
to do)
6- Organismal level , represents the highest level of
structural organization( total of 11 organ systems)
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Body system s: The human body has 11 systems
1-INTEGUMENTARY
ORGANS
• Skin
FUNCTIONS
• Waterproofs, cushions, protects deeper tissue
• Excretes salts & urea; pain, pressure
• Regulates body temp; synthesize vitamin D
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2-SKELETAL
ORGANS
• Bones, cartilages, ligaments, joints
FUNCTIONS
• Protects & supports body organs
• Framework for muscles & movement
• Hematopoiesis; store minerals
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3- MUSCULAR
ORGANS
• Skeletal muscle (attached to bone)
FUNCTIONS
• Contraction & mobility (locomotion)
• Facial expression, posture
• Produce body heat
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4- NERVOUS
ORGANS
• Brain, spinal cord, nerves, & sensory
receptors
FUNCTIONS
• Fast-acting central control system
• Responds to external/internal stimuli
via nerve impulses (electrical
messages)
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5- ENDOCRINE
ORGANS
• Pituitary, thyroid, parathyroids,
adrenals, thymus, pancreas, pineal,
ovaries, testes…..etc.
FUNCTIONS
• Slow -acting control system
• Glands produce hormones that
regulate growth, reproduction,
metabolism,…. etc.
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6- Circulatory
ORGANS
• Heart, blood vessels, capillaries &blood
FUNCTIONS
• Carries O2 nutrients, hormones, & other
substances to and from tissue cells
• White blood cells protect against
bacteria, toxins, tumors
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7- LYMPHATIC
ORGANS
• Lymphatic vessels, lymph nodes,
spleen, tonsils
FUNCTIONS
• Complements circulatory system by
returning leaked fluid back to blood
vessels
• Cleanses the blood; involved in
immunity
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8- RESPIRATORY
ORGANS
• Nasal cavity, pharynx, larynx, trachea,
bronchi, & lungs
FUNCTIONS
• Keeps blood supplied with O2 &
removes CO2
• Carries out gas exchanges through air
sacs in lungs
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9- DIGESTIVE ORGANS
• Oral cavity, esophagus, stomach,
small intestine, large intestine,
rectum, anus (liver & pancreas)
FUNCTIONS
• Breaks food down into absorbable
units that enter the blood;
indigestible food eliminated as feces
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10- URINARY (EXCRETORY)
ORGANS
• Kidney, ureter, urinary bladder,
urethra
FUNCTIONS
• Eliminates nitrogenous waste from
the body (urea & uric acid)
• Regulates water, electrolytes, & acid-
base balance of the blood
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11- REPRODUCTIVE
ORGANS
• Male
• Seminal vesicles, prostate, penis, vas deferens,
testis, scrotum
• Female
• Ovaries, mammary glands, uterus, vagina,
uterine tube
FUNCTIONS
• Primary function for both sexes is to produce
offspring
• Male – testes produce sperm & male sex hormones
• Female – ovaries produce eggs & female sex
hormones; mammary glands for nourishment
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Maintaining Life
I-Necessary Life Functions : All living organisms carry out
certain vital functional activities necessary for life, including :
1-Maintenance of boundaries: Every living organism must
maintain its inside distinct from outside.
-All the cells are surrounded by a selectively permeable membrane.
-The body as a whole is enclosed and protected by the
integumentary system, or skin, which protects our internal organs
from drying out, bacteria, heat, sunlight, and chemicals .
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2-Movement :
-It includes the activities promoted by the muscular system
, the skeletal system provides the bony framework that the
muscles pull on as they work.
-Movement also occurs when substances such as blood,
foodstuffs, and urine are propelled through internal
organs .
- On the cellular level, the muscle cell’s ability to move by
shortening is more precisely called contractility.
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3- Responsiveness or irritability, is the ability to sense
changes (stimuli) in the environment and then respond to them.
-you involuntarily pull your hand away from the painful stimulus .
-When carbon dioxide in your blood rises to dangerously high
levels, your breathing rate speeds up.
Because nerve cells are highly irritable and communicate rapidly
with each other via electrical impulses, the nervous system is most
involved with responsiveness. However, all body cells are irritable
to some extent.
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4-Digestion :is the breaking down of ingested foodstuffs
to simple molecules that can be absorbed into the blood.
The nutrient-rich blood is then distributed to all body cells
by the cardiovascular system.
In a simple, one-celled organism such as an amoeba, the
cell itself is the “digestion factory,” but in the multicellular
human body, the digestive system performs this function
for the entire body.
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5- Metabolism is a broad term that includes all chemical
reactions that occur within body cells. It includes breaking down
substances into their simpler building blocks (catabolism),
synthesizing more complex cellular structures from simpler
substances (anabolism), and using nutrients and oxygen to
produce (via cellular respiration) ATP, that power cellular
activities.
Metabolism depends on the digestive and respiratory systems to
make nutrients and oxygen available to be distributed throughout
the body. Metabolism is regulated largely by hormones secreted by
endocrine system glands.
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6- Excretion is the process of removing excreta or wastes,
from the body. – The digestive system rids the body of
indigestible food residues in feces.
-The urinary system disposes of nitrogen-containing
metabolic wastes, such as urea, in urine.
- Carbon dioxide, a by-product of cellular respiration, is
carried in the blood to the lungs, where it leaves the body
in exhaled air.
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7- Reproduction : is making a whole new person which is the
major task of the reproductive system.
- When a sperm unites with an egg, a fertilized egg forms, which
then develops into a baby within the mother’s body.
- The reproductive system is regulated by hormones of the
endocrine system.
- Because males produce sperm and females produce eggs (ova),
there is a division of labor in the reproductive process, and the
reproductive organs of males and females are different .
- The female’s reproductive structures provide the site for
fertilization of eggs by sperm, then protect and nurture the
developing fetus until birth.
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8- Growth is an increase in size of a body part
or the organism. It is usually accomplished by
increasing the number of cells. However,
individual cells also increase in size when not
dividing. For true growth to occur,
constructive activities must occur at a faster
rate than destructive ones
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II. Survival Needs include:
1-nutrients
Nutrients, taken in via the diet, contain the chemical substances used for
energy and cell building.
-Carbohydrates are the major energy fuel for body cells.
-Proteins, and to a lesser extent fats, are essential for building cell
structures.
- Fats also provide a reserve of energy-rich fuel.
- Selected minerals and vitamins are required for the chemical reactions
that go on in cells and for oxygen transport in the blood. The mineral
calcium helps to make bones hard and is required for blood clotting.
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2- Oxygen : All the nutrients in the world are useless
unless oxygen is also available. Because the chemical
reactions that release energy from foods are oxidative
reactions that require oxygen, human cells can survive for
only a few minutes without oxygen. Approximately 20%
of the air we breathe is oxygen. It is made available to the
blood and body cells by the cooperative efforts of the
respiratory and cardiovascular systems.
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3- Water accounts for 60–80% of body weight and is
the single most abundant chemical substance in the body. It
provides the watery environment necessary for
chemical reactions and the fluid base for body
secretions and excretions. Water is obtained chiefly
from ingested foods or liquids and is lost from the
body by evaporation from the lungs and skin and in
body excretions.
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4- If chemical reactions are to continue at life-sustaining
rates, normal body temperature must be maintained. As
body temperature drops below 37°C (98.6°F), metabolic
reactions become slower and slower, and finally stop.
When body temperature is too high, body proteins lose
their characteristic shape and stop functioning. At either
extreme, death occurs. Most body heat is generated by the activity
of the muscular system.
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5- Atmospheric pressure is the force that air exerts on the
surface of the body. Breathing and gas exchange in the lungs
depend on appropriate atmospheric pressure. At high altitudes,
where atmospheric pressure is lower and the air is thin, gas
exchange may be inadequate to support cellular metabolism.
Notice :The mere presence of these survival factors is not sufficient
to sustain life. They must be present in appropriate amounts; excesses
and deficits may be equally harmful. For example, the food we eat
must be of high quality and in proper amounts; otherwise,
nutritional disease, obesity, or starvation is likely.
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Homeostasis
•Describes the body’s ability to maintain
relatively stable internal conditions even
though the outside world is continuously
changing
•The literal translation of homeostasis is
“unchanging,”( homeo= the same, stasis =
standing still which is not true).
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The term does not really mean a static, or
unchanging, state. Rather, it indicates a
dynamic state of equilibrium, or a balance,
in which internal conditions vary, but
always within relatively narrow limits. In
general, the body is in homeostasis when its needs are
adequately met and it is functioning smoothly.
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Homeostatic Control Mechanisms
Communication within the body is essential for homeostasis.
Communication is accomplished chiefly by the nervous and endocrine
systems, which use neural electrical impulses or blood borne
hormones, respectively, as information carriers.
Regardless of the factor being regulated(the variable)all homeostatic
control mechanisms have at least three interdependent components .
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The first component, the receptor, is some type of
sensor that monitors the environment and responds
to changes, called stimuli, by sending information
(input) to the second component, the control
center. Input flows from the receptor to the control
center along the so-called afferent pathway. The
control center, analyzes the input it receives and
then determines the appropriate response or course
of action.
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The third component, the effector, provides the means
of response (output) to the stimulus. Information flows
from the control center to the effector along the efferent
pathway. The results of the response then feed back to
influence the stimulus, either depressing it (negative
feedback) so that the whole control mechanism is shut off
or enhancing it (positive feedback) so that the reaction
continues at an even faster rate.
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• Homeostatic control mechanisms are TWO:
• Negative feedback mechanisms – the net effect of the
response to the stimulus is the shut off of the original
stimulus or to reduce its intensity
• E.g. – body temp, blood chemical levels
• Positive feedback mechanisms – tend to increase the
original disturbance (stimulus) and push the variable
farther from its original value
• E.g. – ovulation, blood clotting, birth
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Negative Feedback Mechanisms
Most homeostatic control mechanisms are negative
feedback mechanisms. In these systems, the output
shuts off the original stimulus or reduces its intensity. These
mechanisms cause the variable to change in a direction
opposite to that of the initial change, returning it to its
“ideal” value; thus the name “negative” feedback
mechanisms.
VIVEK SIR

A good example of a non biological negative
feedback system is a home heating system connected
to a temperature-sensing thermostat . If the
thermostat is set at 20°C (68°F), the heating system
(effector) is triggered ON when the house
temperature drops below that setting. As the furnace
produces heat and warms the air, the temperature
rises, and when it reaches 20°C or slightly higher, the
thermostat triggers the furnace OFF.
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This process results in a cycling of
“furnace-ON” and “furnace-OFF” so that
the temperature in the house stays very near
the desired temperature of 20°C. Your body
“thermostat,” located in a part of your
brain called the hypothalamus, operates in a
similar fashion.
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Positive Feedback Mechanisms
In positive feedback mechanisms, the result or
response enhances the original stimulus so that the
activity (output) is accelerated. This feedback
mechanism is “positive” because the change that
occurs proceeds in the same direction as the initial
disturbance, causing the variable to deviate further
and further from its original value or range.
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In contrast to negative feedback controls, which
maintain many physiological functions or keep blood
chemicals within narrow ranges, positive feedback
mechanisms usually control infrequent events that do
not require continuous adjustments. However, TWO
familiar examples of their use as homeostatic
mechanisms are the enhancement of labor contractions
during birth and blood clotting.
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The body’s ability to regulate its internal environment is
fundamental, and all negative feedback mechanisms have
the same goal: preventing sudden severe changes within
the body. Body temperature and blood volume are only
two of the variables that need to be regulated. There are
hundreds! Other negative feedback mechanisms regulate
heart rate, blood pressure, the rate and depth of breathing,
and blood levels of oxygen, carbon dioxide, and minerals.
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Homeostatic Imbalance
Homeostasis is so important that most disease can be regarded
as a result of its disturbance, a condition called homeostatic
imbalance. As we age, our body’s control systems become less
efficient, and our internal environment becomes less and less
stable. These events increase our risk for illness and produce the
changes we associate with aging.
Examples of homeostatic imbalance are provided throughout
this course to enhance understanding of normal physiological
mechanisms.
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The Language of Anatomy
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Anatomical Position
• Standing erect
• Feet parallel
• Arms hanging at the sides
• Palms facing forward
Anatomical position – body is erect with the feet parallel
and the arms hanging at the sides with the palms facing
forward. (It’s important to note throughout this course,
most terminology refers to this position regardless of the
position the body happens to be in at the time)
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VIVEK SIR
Anatomical Position
In the anatomical
position, a person:
1. Stands upright
2. Facing forward
3. Feet pointed forward and
slightly apart
4. Arms at sides
5. Palms facing forward

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1. Anatomical position
2. Anatomical planes
3. Anatomical regions
4. Directional terms
Anatomical Terms

Directional terms
• Superior (cranial or cephalad) – toward the head end or upper part
of a structure or body; above
• Inferior (caudal) – away from the head end or toward the lower part
of a structure or body; below
• Anterior (ventral) – toward or at the front of the body; in front of
• Posterior (dorsal) – toward or at the backside of the body; behind
• Medial – toward or at the midline of the body; on the inner side of
• Lateral – away from the midline of the body; on the outer side of
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• Proximal – close to the origin of the body part or the
point of attachment of a limb to the body trunk.
• Distal – farther from the origin of a body or the point
of attachment of a limb to the body trunk.
• Superficial (external) – toward or at the body surface.
• Deep (internal) – away from the body surface; more
internal.
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Body planes and sections
A section is a cut made along a plane
• Sagittal – cut made along the lengthwise or longitudinal plane of
the body dividing it into left and right parts
• Midsagittal (median) plane – right and left parts are of equal size
• Frontal (coronal) plane – cut made along a lengthwise plane that
divides the body into anterior and posterior parts
• Transverse plane (cross section) – cut made along a horizontal plane
dividing the body or organ into superior and inferior parts
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Planes
• Sagittal Plane – divides
body into right and left
parts.
• Midsagittal =median
plane –divides body into
two equal halves.
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Planes
• Frontal = coronal plane –
divides body into anterior
and posterior parts
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Planes
• Transverse plane = cross
Section= horizontal section
divides into upper and
lower parts
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Directional terms
Standardized terms used to describe the
position of one body part relative to
another

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• Proximal
• Nearer to the attachment of a
limb to the trunk
• Eg: the elbow is proximal to
the wrist
• Distal
• Farther from the attachment
of a limb to the trunk
• Eg: the knee is distal to the hip

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• Anterior
• Nearer to or at the front
of the body
• Eg: the sternum is
anterior to the heart
• Posterior
• Nearer to or at the back
of the body
• Eg: the esophagus is
posterior to the trachea

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Directional terms
• Superior
• Toward the head or upper
part of structure
• Eg: the heart is superior to
the liver
• Inferior
• Away from the head or
lower part of structure
• Eg: the stomach is inferior
to the lungs

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• Medial
• Nearer to the midline
• Eg: the bridge of the
nose is medial to the eye
• Lateral
• Farther from the
midline
• Eg: the lungs are lateral
to the heart

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Directional
Term
Definition
Superior Toward the head or upper part of structure
Inferior Away from the head or lower part of structure
Anterior Nearer to or at the front of the body
Posterior Nearer to or at the back of the body
Medial Nearer to the midline of the body
Lateral Farther from the midline of the body
Proximal Nearer to the attachment of a limb to the trunk
Distal Farther from the attachment of a limb to the trunk
Superficial Nearer the surface of the body
Deep Further from the surface of the body

Regional terms
There are many visible landmarks on the surface
of the body:
- Anterior body landmarks
- Posterior body landmarks
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Body Cavities
There are two sets of internal body cavities called the dorsal and
ventral body cavities. These cavities are closed to the outside.
1-Dorsal Body Cavity
Which protects the fragile nervous system organs has two
subdivisions. The cranial cavity, in the skull, encases the brain.
The vertebral, or spinal, cavity, which runs within the bony
vertebral column, encloses the delicate spinal cord. The cranial
and spinal cavities are continuous with one another
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2- Ventral Body Cavity
The more anterior and larger of the closed body cavities is the ventral
body cavity .It has two major subdivisions, the thoracic and the
abdominopelvic cavities. It houses internal organs collectively called the
viscera .
They are separated by the diaphragm, a dome-shaped muscle important in
breathing.
The abdominopelvic cavity, as its name suggests, has two parts not
physically separated by a muscular or membrane wall.
The inferior part, the pelvic cavity, lies in the bony pelvis .
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HOMEOSTATIC IMBALANCE
When the body is subjected to physical trauma (as
often happens in an automobile accident), the
abdominopelvic organs are most vulnerable. This is
because the walls of the abdominal cavity are formed
only by trunk muscles and are not reinforced by
bone. The pelvic organs receive a somewhat greater
degree of protection from the bony pelvis
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Abdominopelvic Regions and Quadrants
Because the abdominopelvic cavity is large and
contains several organs, it helps to divide it into smaller
areas for study.
One division method, used primarily by anatomists,
uses two transverse and two parasagittal planes. These
planes, divide the cavity into nine regions :
-The umbilical region is the centermost region deep to
and surrounding the umbilicus (navel).
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Abdomino pelvic Regions
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-The epigastric region is located superior to the umbilical region (epi = upon, above;
gastri = belly).
-The hypogastric (pubic) region is located inferior to the umbilical region (hypo =
below).
-The right and left iliac, or inguinal, regions (ing′gwĭ-nal) are located lateral to the
hypogastric region (iliac = superior part of the hip bone).
-The right and left lumbar regions lie lateral to the umbilical region (lumbus = loin).
-The right and left hypochondriac regions flank the epigastric region laterally (chondro
= cartilage).
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A simpler scheme to localize the abdomino pelvic cavity
organs is to imagine one transverse and one median sagittal
plane pass through the umbilicus at right angles. The
resulting quadrants are named according to their positions
from the subject’s point of view:
right upper quadrant (RUQ), left upper quadrant
(LUQ),
right lower quadrant (RLQ), and left lower quadrant
(LLQ).
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Abdominopelvic Quadrants
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introduction to anatomy and physiology 1st sem bsc nursing

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