Introduction to
the Human
Body
Lesson 1
How Structure Determines Function
• Human anatomy is the scientific study of the body’s structures.
• The word “anatomy” comes from the Greek root “ana” which means
“to cut apart” and “tomia” which means “to cut”
Areas of Specialization in Anatomy
1. Gross anatomy - the study of the larger structures of the body,
those visible without the aid of magnification.
2. Microscopic anatomy includes cytology, the study of cells, and
histology, the study of tissues.
Type of Approach in studying Anatomical Parts
Regional anatomy
- the study of the interrelationships of all of the structures in a specific
body region
- helps us appreciate the interrelationships of body structures and how
they work together to serve a particular body region
Systemic anatomy
- the study of the structures that make up a discrete body system—that
is, a group of structures that work together to perform a unique body
function.
Structural
Organization
of the
Human Body
Levels of Organization
A.The human body is the sum of its parts and
these parts can be studied at a variety of
levels of organization.
• Chemicals
a.Atoms are the simplest level.
b.Two or more atoms comprise a molecule.
c. Macromolecules are large, biologically important
molecules inside cells.
• Organelles are aggregates of macromolecules
used to carry out a specific function in the cell.
3.Cells are the basic units of structure
and function for living things.
4.Tissues are groups of cells
functioning together.
5.Groups of tissues form organs that
have specialized functions.
6.Groups of organs function together
as organ systems.
7.Organ systems functioning together
make up an organism.
• Fundamental characteristics of life are traits
shared by all organisms.
• Movement – change in position of the body or a
body part; motion of an internal organ
• Responsiveness – reaction to internal or external
change
• Growth – increase in size without change in
shape
• Reproduction – new organisms or new cells
• Respiration – use of oxygen; removal of CO2
• Digestion – breakdown of food into simpler
forms
7.Absorption – movement of substances
through membranes and into fluids
8.Circulation – movement within body fluids
9.Assimilation – changing nutrients into
chemically different forms
10.Excretion – removal of metabolic wastes
B.Taken together, these 10 characteristics
constitute metabolism – the physical and
chemical events that obtain, release, and
use energy.
Maintenance Requirements of organisms to live
• Life depends on the availability of the
of following:
A. Water
Life •
•
Most abundant chemical in the body
Required for many metabolic processes
• Provides the environment for metabolic processes
• Transportation medium
• Regulated body temperature
• Makes up intracellular and extracellular fluid
compartments
b.Food
1)Provides the body with needed nutrients
2)Needed for energy, raw building materials for
growth and repair, and to regulate chemical
reactions
c.Oxygen – releases energy from
food
d.Heat – product of metabolic
reactions that controls reaction
rate; temperature: measure of
the degree of heat
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e.Pressure
1)Force applied to something
2)Atmospheric pressure is needed for breathing
3)Hydrostatic (water) pressure is needed to move blood
through blood vessels
2.Both the quality and quantity of these
factors are important
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Homeostasis
1.Maintenance of a stable internal environment is called homeostasis.
2.Homeostasis is regulated through control systems which have
receptors, a set point, and effectors in common.
a. Receptors are of many types whose job is to monitor for changes
b. The set point is the normal value or range of values
c. Effectors are muscles or glands that respond to the changes to return to stability
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3.Examples include:
a.Homeostatic mechanisms regulate body temperature in a manner similar to the
functioning of a home heating/cooling thermostat.
b.Another homeostatic mechanism employs pressure-sensitive receptors to
regulate blood pressure
4.Each individual uses homeostatic mechanisms to keep body levels
within a normal range; normal ranges can vary from one individual to
the next.
5.Many of the body's homeostatic controls are negative feedback
mechanisms.
a.Responses move in the opposite direction from the change
b.Reduces the amount of change from the set point
c. Includes most control mechanisms in the body
6.Positive feedback mechanisms
a. Response moves further from the set point
b. Change from set point gets larger
c. Many positive feedback mechanisms produce unstable conditions in the body
d. Examples associated with normal health
1) Blood clotting
2) Birth
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Organization of the body
A.Body Cavities
• The body can be divided into an axial portion (head, neck, and trunk) and
an appendicular portion (upper and lower limbs).
• The axial portions contains several cavities that house body organs
a.Cranial cavity – brain
b.Vertebral cavity – spinal cord
c.Thoracic cavity – heart, lungs, mediastinum
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d.Abdominopelvic cavity
1)Abdominal cavity – viscera of digestion and the spleen
2)Pelvic cavity – end of large intestine, urinary bladder, and
internal reproductive organs
e.A broad, thin muscle called the diaphragm separates the
thoracic and abdominopelvic cavities
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3.Smaller cavities within
the head include the oral
cavity, nasal cavity, orbital
cavities, and middle ear
cavities
B.Thoracic and Abdominopelvic Membranes
• Double-layered membranes; the parietal portion attaches to
wall cavity and the visceral portion covers the internal organ.
• The thoracic cavity is lined with pleural membranes; the
parietal pleura lines the cavities while the visceral
pleura covers the lungs. A thin layer of serous fluid
separates the two layers.
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• The heart is surrounded by pericardial membranes. The
parietal pericardium makes up an outer sac and the
visceral pericardium covers the heart. Serous fluid
separates the two layers.
• Peritoneal membranes line the abdominopelvic cavity; a
parietal peritoneum lines the wall while the visceral
peritoneum covers the organs.
Pleural Membrane
Pericardial Membrane
Fig 1.11 30
Fig 1.12 31
C.Organ Systems
• Body Covering
a.The integumentary system,
including skin, hair, nails, and
various glands, covers the
body. It protects underlying
tissues, helps regulate body
temperature, senses changes,
and synthesizes certain
products.
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2.Support and Movement
a.The skeletal system is made up of
bones and ligaments. It supports,
protects, provides frameworks,
stores inorganic salts, and houses
blood-forming tissues.
b.The muscular system consists of
the muscles that provide body
movement, posture, and body
heat.
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3.Integration and Coordination
a.The nervous system consists of the
brain, spinal cord, nerves, and sense
organs. It integrates incoming
information from receptors and sends
impulses to muscles and glands.
b.The endocrine system, includes the
hypothalamus, pituitary, thyroid,
parathyroid, pineal, and thymus
glands, pancreas, ovaries, and testes,
along with other organs that secrete
hormones. It helps to integrate
metabolic functions.
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4.Transport
a.The cardiovascular system, is
made up of the heart and blood
vessels. It distributes oxygen,
nutrients, and hormones
throughout the body while
removing wastes from the cells.
b.The lymphatic system, consists of
lymphatic vessels, lymph nodes,
thymus, and spleen. It drains
excess tissue fluid and includes
cells of immunity.
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5.Absorption and Excretion
a.The digestive system is made up of the mouth,
esophagus, stomach, intestines, and accessory
organs. It receives, breaks down, and absorbs
nutrients.
b.The respiratory system exchanges O2 and CO2
between the blood and air and is made up of the
lungs and passageways.
c.The urinary system, consists of the kidneys,
ureters, bladder, and urethra. It removes wastes
from the blood and helps to maintain water and
electrolyte balance.
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6.Reproduction
a.The reproductive system
produces new organisms.
1)The male reproductive system
consists of the testes, accessory
organs, and vessels that produce and
conduct sperm to the female
reproductive tract.
2)The female reproductive system
consists of ovaries, uterine tubes,
uterus, vagina, and external genitalia.
It produces egg cells and also houses
the developing offspring.
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Fig 1.13 38
Anatomical Terminology
A.Anatomical position : body erect, face forward, upper limbs at sides with
palm forward.
A body that is lying down is described as either prone or
supine. Prone describes a face-down orientation, and supine describes a face up
orientation
A.Directional Terms
• Superior – above another part
• Inferior – below another part
• Anterior (ventral) – toward the front
• Posterior (dorsal) – toward the back
• Median – closer the midline
• Lateral – toward the side
• Bilateral – paired structures with one on each side
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8.Ipsilateral – structures on the same side
9.Contralateral – structures on the opposite sides
10.Proximal – closer to point of attachment or another referenced
body part
11.Distal – further from the point of attachment pr another
referenced body part
12.Superficial – near the surface; peripheral – outward or near the
surface
13.Deep – more internal
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C.Body Planes
A section is a two-dimensional surface of a three-dimensional structure that has
been cut.
A plane is an imaginary, two-dimensional surface that passes through the body.
There are three planes commonly referred to in anatomy and medicine
• A sagittal plane divides the body into right and left portions. If it passes
along the midline and divides the body into equal parts it is a median or
midsagittal section. A section lateral to the midline is parasagittal.
• A transverse (horizontal) plane divides the body into superior and inferior
portions.
• A frontal (coronal) plane divides the body into anterior and posterior
sections.
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Body regions
• The abdominal area can be divided
into nine regions – epigastric, right
and left hypochondriac, umbilical,
right and left lumbar, hypogastric,
and right and left iliac
• The abdominal area can also be
divided into four quadrants – right
and left upper quadrants and right
and left lower quadrants
Regional
Terms
