Transcript The Human Body: An Orientation


Classification of Living Things
o Humans and many other animals are vertebrates
• Characterized by a segmented vertebral column
o Common characteristics suggest the same path in evolution

Homeostasis
o The goal of physiological regulation and the key to survival in a changing
environment

Anatomy
o Is the oldest medical science

• 1600 B.C.
Physiology
o Is the study of function
• Biochemistry
• Biology
• Chemistry
• Genetics
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
Anatomy
o Describes the structures of the body
• What they are made of
• Where they are located
• Associated structures

Physiology
o Is the study of:
• Functions of anatomical structures
• Individual and cooperative functions
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
Anatomy
o Gross anatomy, or macroscopic anatomy, examines large, visible
structures
• Surface anatomy: exterior features
• Regional anatomy: body areas
• Systemic anatomy: organ systems
• Developmental anatomy: from conception to death
• Clinical anatomy: medical specialties
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
Anatomy
o Microscopic anatomy examines cells and molecules
• Cytology: study of cells and their structures
• cyt- = cell
• Histology: study of tissues and their structures
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
Physiology
o Cell physiology: processes within and between cells
o Organ physiology: functions of specific organs
o Systemic physiology: functions of an organ system
o Pathological physiology: effects of diseases
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
The Chemical (or Molecular) Level
o Atoms are the smallest chemical units
o Molecules are a group of atoms working together

The Cellular Level
o Cells are a group of atoms, molecules, and organelles working together

The Tissue Level
o A tissue is a group of similar cells working together
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The Organ Level
o An organ is a group of different tissues working together
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The Organ System Level
o An organ system is a group of organs working together
o Humans have 11 organ systems
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The Organism Level
o A human is an organism
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Cellular Level
Chemical and Molecular Levels
Heart muscle
cell
Protein filaments
Complex protein molecule
Atoms in combination
Organ system
level
Organ Level
Tissue Level
Cardiac muscle
tissue
The heart
The
cardiovascular
system
Organism
level

The Organ Systems
o Integumentary
• Major Organs
• Skin
• Hair
• Sweat glands
• Nails
• Functions
• Protects against environmental hazards
• Helps regulate body temperature
• Provides sensory information

The Organ Systems
o Skeletal
• Major Organs
•
•
•
•
Bones
Cartilages
Associated ligaments
Bone marrow
• Functions
• Provides support and protection for other
tissues
• Stores calcium and other minerals
• Forms blood cells
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The Organ Systems
o Muscular
• Major Organs
• Skeletal muscles and associated tendons
• Functions
• Provides movement
• Provides protection and support for other
tissues
• Generates heat that maintains body
temperature
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The Organ Systems
o Nervous
• Major Organs
•
•
•
•
Brain
Spinal cord
Peripheral nerves
Sense organs
• Functions
• Directs immediate responses to stimuli
• Coordinates or moderates activities of other organ systems
• Provides and interprets sensory information about external
conditions

The Organ Systems
o Endocrine
• Major Organs
• Pituitary gland
• Pancreas
• Gonads
• Thyroid gland
• Adrenal glands
• Endocrine tissues in other systems
• Functions
• Directs long-term changes in the activities of
organ systems
• Adjusts metabolic activity and energy use by the body
• Controls many structural and functional changes during
development
other
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The Organ Systems
o Cardiovascular
• Major Organs
• Heart
• Blood
• Blood vessels
• Functions
• Distributes blood cells, water and dissolved
materials including nutrients, waste products,
oxygen, and carbon dioxide
• Distributes heat and assists in control of body
temperature
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The Organ Systems
o Lymphatic
• Major Organs
• Spleen
• Thymus
• Lymphatic vessels
• Lymph nodes
• Tonsils
• Functions
• Defends against infection and disease
• Returns tissue fluids to the bloodstream
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The Organ Systems
o Respiratory
• Major Organs
• Nasal cavities
• Sinuses
• Larynx
• Trachea
• Bronchi
• Lungs
• Alveoli
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The Organ Systems
o Respiratory
• Functions
• Delivers air to alveoli (sites in lungs where gas
exchange occurs)
• Provides oxygen to bloodstream
• Removes carbon dioxide from bloodstream
• Produces sounds for communication
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The Organ Systems
o Digestive
• Major Organs
• Teeth
• Tongue
• Pharynx
• Esophagus
• Stomach
• Small intestine
• Large intestine
• Liver
• Gallbladder
• Pancreas
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The Organ Systems
o Digestive
• Functions
• Processes and digests food
• Absorbs and conserves water
• Absorbs nutrients
• Stores energy reserves
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The Organ Systems
o Urinary
• Major Organs
• Kidneys
• Ureters
• Urinary bladder
• Urethra
• Functions
• Excretes waste products from the blood
• Controls water balance by regulating volume of urine
produced
• Stores urine prior to voluntary elimination
• Regulates blood ion concentrations and pH
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The Organ Systems
o Male Reproductive
• Major Organs
• Testes
• Epididymis
• Ductus deferentia (vas deferens)
• Seminal vesicles
• Prostate gland
• Penis
• Scrotum
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The Organ Systems
o Male Reproductive
• Functions
• Produces male sex cells (sperm), suspending fluids, and
hormones
• Sexual intercourse
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The Organ Systems
o Female Reproductive
• Major Organs
• Ovaries
• Uterine tubes
• Uterus
• Vagina
• Labia
• Clitoris
• Mammary glands
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The Organ Systems
o Female Reproductive
• Functions
• Produces female sex cells (oocytes) and hormones
• Supports developing embryo from conception to delivery
• Provides milk to nourish newborn infant
• Sexual intercourse
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Homeostasis
o All body systems working together to maintain a stable internal
environment
• Systems respond to external and internal changes to function
within a normal range (body temperature, fluid balance)
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
Mechanisms of Regulation
o Autoregulation (intrinsic)
• Automatic response in a cell, tissue, or organ to some environmental
change
o Extrinsic regulation
• Responses controlled by nervous and endocrine systems
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Receptor
o Receives the stimulus
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Control center
o Processes the signal and sends instructions
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Effector
o Carries out instructions
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RECEPTOR
Normal
condition
disturbed
Thermometer
Information
affects
STIMULUS:
Room temperature
rises
Normal room
temperature
RESPONSE:
Room temperature
drops
Normal
condition
restored
EFFECTOR
Air conditioner
turns on
20° 30° 40°
Sends
commands
to
In response to input from a receptor (a thermometer), a thermostat
(the control center) triggers an effector response (either an air conditioner or a heater) that restores normal temperature. In this case,
when room temperature rises above the set point, the thermostat
turns on the air conditioner, and the temperature returns to normal.
Room temperature (°C)
CONTROL CENTER
(Thermostat)
HOMEOSTASIS
Air
Air
conditioner conditioner
turns on
turns off
22
Normal
range
Time
With this regulatory system, room
temperature fluctuates around the
set point.

The Role of Negative Feedback
o The response of the effector negates the stimulus
o Body is brought back into homeostasis
• Normal range is achieved
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RECEPTORS
Temperature
sensors in skin
and
hypothalamus
Normal
temperature
disturbed
Information
affects
CONTROL
CENTER
STIMULUS:
Body temperature
rises
HOMEOSTASIS
RESPONSE:
Increased heat loss,
body temperature
drops
Normal
temperature
restored
EFFECTORS
• Sweat glands
in skin increase
secretion
• Blood vessels
in skin dilate
Sends
commands
to
Events in the regulation of body temperature, which are
comparable to those shown in Figure 12. A control center
in the brain (the hypothalamus) functions as a thermostat
with a set point of 37°C. If body temperature exceeds
37.2°C, heat loss is increased through enhanced blood flow
to the skin and increased sweating.
Body temperature (°C)
Thermoregulatory
center in brain
Normal body
temperature
37.2
37
36.7
Vessels
Vessels
dilate,
constrict,
sweating sweating
increases decreases
Normal
range
Time
The thermoregulatory center keeps
body temperature fluctuating
within an acceptable range, usually
between 36.7 and 37.2°C.

The Role of Positive Feedback
o The response of the effector increases change of the stimulus
o Body is moved away from homeostasis
• Normal range is lost
o Used to speed up processes
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Clotting
accelerates
Positive
feedback
loop
Chemicals
Chemicals
Damage to cells in the
blood vessel wall releases
chemicals that begin the
process of blood clotting.
The chemicals start chain
reactions in which cells,
cell fragments, and
soluble proteins in the
blood begin to form a clot.
As clotting continues,
each step releases
chemicals that further
accelerate the process.
Blood clot
This escalating process
is a positive feedback
loop that ends with the
formation of a blood clot,
which patches the vessel
wall and stops the bleeding.

Systems Integration
o Systems work together to maintain homeostasis
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Homeostasis is a state of equilibrium
o Opposing forces are in balance
o Dynamic equilibrium — continual adaptation

Physiological systems work to restore balance
o Failure results in disease or death
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
Superficial Anatomy
o Locating structures on or near the body surface

Anatomical Landmarks
o Anatomical position: hands at sides, palms forward
o Supine: lying down, face up
o Prone: lying down, face down
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Superficial Anatomy
o Anatomical Landmarks
• References to palpable structures
o Anatomical Regions
• Body regions
• Abdominopelvic quadrants
• Abdominopelvic regions
o Anatomical Directions
• Reference terms based on subject
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Frontal or
forehead
Cranial
or skull
Nasal or nose
Ocular, orbital
or eye
Otic or ear
Cephalic or head
Buccal or cheek
Facial
or face
Cervical or neck
Oral or mouth
Mental or chin
Thoracic or
thorax, chest
Axillary or armpit
Mammary
or breast
Brachial
or arm
Abdominal
(abdomen)
Umbilical
or navel
Antecubital
or front of
elbow
Anterior view
Trunk
Antebrachial
or forearm
Pelvic
(pelvis)
Trunk
Carpal or wrist
Palmar or palm
Manual
or hand
Pollex
Digits
or thumb (phalanges)
or fingers (digital
or phalangeal)
Patellar
or kneecap
Inguinal
or groin
Pubic
(pubis)
Femoral
or thigh
Crural
or leg
Tarsal or
ankle
Digits (phalanges)
or toes (digital or
phalangeal)
Hallux or
great toe
Pedal
or foot
Anterior view
Cephalic
or head
Acromial or
shoulder
Dorsal or
back
Cervical
or neck
Olecranal
or back
of elbow
Upper
limb
Posterior view
Upper
limb
Lumbar
or loin
Gluteal
or buttock
Lower
limb
Popliteal or
back of knee
Sural
or calf
Calcaneal or
heel of foot
Plantar or
sole of foot
Posterior view
Right Upper
Quadrant
(RUQ)
Left Upper
Quadrant
(LUQ)
Right Lower
Quadrant
(RLQ)
Left Lower
Quadrant
(LLQ)
Abdominopelvic quadrants. The four
abdominopelvic quadrants are formed by two
perpendicular lines that intersect at the navel. The
terms for these quadrants, or their abbreviations,
are most often used in clinical discussions.
Right
hypochondriac
region
Right lumbar
region
Right
inguinal
region
Epigastric
region
Umbilical
region
Hypogastric
(pubic)
region
Left
hypochondriac
region
Left lumbar
region
Left inguinal
region
Abdominopelvic regions. The nine abdominopelvic
regions provide more precise regional descriptions.
Liver
Gallbladder
Stomach
Spleen
Large intestine
Small intestine
Appendix
Urinary
bladder
Anatomical relationships. The relationship between
the abdominopelvic quadrants and regions and the
locations of the internal organs are shown here.
Superior
Cranial
Right
Left
Proximal
Anterior
or ventral
Posterior
or dorsal
Lateral
Caudal
Medial
Proximal
Distal
Inferior
A lateral view.
Distal
An anterior view. Arrows
indicate important directional
terms used in this text;
definitions and descriptions
are given in Table 12.

Sectional Anatomy
o Planes and sections
• Plane: a three-dimensional axis
• Section: a slice parallel to a plane
• Used to visualize internal organization and structure
• Important in radiological techniques
• MRI
• PET
• CT
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Frontal plane
Sagittal plane
Transverse plane
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Essential Functions of Body Cavities
1. Protect organs from accidental shocks
2. Permit changes in size and shape of internal organs

Ventral body cavity (coelom)
o Divided by the diaphragm
•
Thoracic cavity
•
Abdominopelvic cavity
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Ventral Body Cavity
• Provides protection
• Allows organ movement
• Linings prevent friction
Subdivides during development into
Abdominopelvic Cavity
Thoracic Cavity
Surrounded by chest wall and
diaphragm
Peritoneal Cavity
Right Pleural Cavity
Mediastinum
Left Pleural Cavity
Surrounds right lung
Contains the
trachea, esophagus,
and major vessels
Surrounds left lung
Pericardial Cavity
Surrounds heart
Extends
throughout
abdominal cavity
and into superior
portion of pelvic
cavity
Abdominal Cavity
Pelvic Cavity
Contains many
digestive glands
and organs
Contains urinary
bladder,
reproductive
organs, last
portion of
digestive tract

Serous Membranes
o Line body cavities and cover organs
o Consist of parietal layer and visceral layer
• Parietal layer — lines cavity
• Visceral layer — covers organ
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
The Thoracic Cavity
o Right and left pleural cavities
• Contain right and left lungs
o Mediastinum
• Upper portion filled with blood vessels, trachea,
esophagus, and thymus
• Lower portion contains pericardial cavity
• The heart is located within the pericardial cavity
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POSTERIOR
ANTERIOR
Pleural
cavity
Thoracic
cavity
Pericardial
cavity
Diaphragm
Peritoneal
cavity
Abdominal
cavity
Pelvic
cavity
Abdominopelvic
cavity
Visceral
pericardium
Heart
Pericardial
cavity
Air space
Balloon
Parietal
pericardium
ANTERIOR
Pericardial
cavity
Pleural cavity
Parietal
pleura
Right
lung
Left
lung
Mediastinum
Spinal cord
POSTERIOR

The Abdominopelvic Cavity
o Peritoneal cavity: chamber within abdominopelvic cavity
• Parietal peritoneum: lines the internal body wall
• Visceral peritoneum: covers the organs
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
The Abdominopelvic Cavity
o Abdominal cavity — superior portion
• Diaphragm to top of pelvic bones
• Contains digestive organs
• Retroperitoneal space
• Area posterior to peritoneum and anterior to muscular body wall
• Contains pancreas, kidneys, ureters, and parts of the digestive tract
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
The Abdominopelvic Cavity
o Pelvic cavity — inferior portion
• Within pelvic bones
• Contains reproductive organs, rectum, and bladder
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