Chapter 4
Organization of the Body
Identify parts of a cell and the specialized
functions of tissues
Identify the body systems
Describe the functions of the body system
and how they work
Define the anatomical positions of the body
List the body cavities and the organs
Identify nine body regions
Organization of the Human
Body
The body is organized from the smallest
part to the largest part.
 CELL
-simplest structural unit
-basic unit of life
-smallest unit that can live on its own

Cell
Many
cannot be seen with the
naked eye
A cell may be an entire
organism or it may be one of
billions of cells that make up
the organism
Tissue
- a group of cells with common origin,
structure, and function.
- cells within a tissue all work toward a
common goal (i.e.: movement, nutrition,
etc.)
 Organ
- a group of tissues that have a common
function.

Structural units of the body:
Cell:
Body has million of cells that work
together to sustain life
 consist of a nucleus surrounded by
cytoplasm
 It is the fundamental unit of all living
things (basic building block)
 Cells multiply by dividing called mitosis

Contd:
Several types of cells
 Size and shape of cell relates its function
Examples of some cells in the body:

Muscle cells: contract
 Nerve: conduct electrical impulses
 Epithelial: skin and lining
 Fat cell: contain empty spaces to store fat

Nucleus
A spheroid body within a cell
 Consists of a thin nuclear membrane and
genes and chromosomes
 Responsible for metabolism, growth and
reproduction
 Control center of the cell

Chromosomes
Thread like structures in the cell nucleus
 Control growth and repair
 Control the reproduction of the body
 Contain regions of DNA called genes
 There are 23 pairs of chromosomes in
every cell except for the egg and sperm
which contain 23 unpaired chromosomes

Cytoplasm
The substance between the cell
membrane and the nuclear membrane
 Jelly like material that is mostly water
 It is exclusive to the nucleus
 Carries on the work of the cell

Cell membrane
Thin layer of tissue which serves as the
wall of the cell
 Protects the cell
 Selectively allows substances to pass in
and out of the cell

Tissues: groups of similar cells
working together to do a specific
job
For example:
 Muscle tissue contracts
 Epithelial tissue forms linings and
covers i.e. skin
 Connective tissue do just that: fat,
cartilage, bone and blood
 Nerve tissues conduct impulses all over
the body
Tissue
Epithelial tissues
The skin and lining surfaces
 Forms the lining of the internal organs
 It protects, absorbs and excretes

Connective tissue
The fibrous tissue of the body
 Binds together the various parts and
organs of the body
 Eg: bones , tendons cartilage

Muscle tissue
Tissue that contracts
 Consist of striated (striped) cardiac and
smooth muscle
 Voluntary is where the movement is under
conscious control such as arms and legs
 Involuntary is not under conscious control,
such as heart and digestive system

Nerve Tissue

A collection of nerve fibers that conduct
impulses that control and coordinate body
activities
Organ System
- a group of organs with a special
function.
- Digestive System, Nervous System,
etc…
 Organism
- A group of organ systems that at some
point in time is capable of sustaining life.
- All organ systems work together in an
organism.

Organs: structures composed of
several types of tissue
o
An organ (Latin: organum, "instrument, tool")
is a group of tissues that perform a specific
function or group of functions.
o
Usually there is a main tissue and sporadic
tissues. The main tissue is the one that is
unique for the specific organ.
o
For example, main tissue in the heart is the
myocardium, while sporadic are the nervous,
blood, connective etc.
Systems:
A set of body organs that work
together for a common
purpose
systems
Integumentary system
 Musculoskeletal system
 Cardiovascular system
 Gastrointestinal system
 Respiratory system
 Genitourinary system
 Endocrine system’
 Nervous system

Body Cavity: space within the
body that contains internal
organs


The human body consists of the following cavities:
dorsal body cavity
– cranial cavity, enclosed by the Skull and contains the brain,
eyes, and ears.
– spinal canal, enclosed by the spine and contains the spinal
cord.
– ventral body cavity
 thoracic cavity, enclosed by the ribcage and contains the
lungs and heart.
 abdominopelvic cavity
– abdominal cavity, enclosed by the ribcage and pelvis
and contains the kidneys, ureters, stomach,
intestines, liver, gallbladder, and pancreas./pelvic
cavity, enclosed by the pelvis and contains bladder,
anus and reproductive system.
Body cavities and Planes
The body has two main large cavities
 Ventral = front of body includes thoracic,
abdominal, and pelvic cavity
 Dorsal = back of body which includes
Cranial and Spinal cavity

Anatomical Planes

Fixed lines of reference
along which the body is
often divided or
sectioned to facilitate
viewing of its structures

Allow one to obtain a
three-dimensional
perspective by studying
the body from different
views
 Sagittal
 A plane that divides the body into right
and left portions
 Midsagittal
 A plane that vertically divides the body or
some part of it, into equal right and left
portions
 Coronal
 Also called frontal; a plane that divides the
body into anterior and posterior sections
(front and back)
 Transverse
 A plane that divides the body into superior
and inferior sections (top and bottom)
Anatomical
Position
Standing erect, with palms
and feet facing forward
 Is the standard reference
point in which all positions,
movements, and planes are
described

Positions and
Directions
Terms of position and
direction describe the
position of one body
part relative to another,
usually along one of
the three major body
planes
Positions and
Directions
Superior
 Refers to a structure being
closer to the head or higher
than another structure in the
body
Inferior
 Refers to a structure being
closer to the feet or lower
than another structure in the
body
Positions and
Directions
Anterior
 Refers to a structure being
more in front than another
structure in the body
Posterior
 Refers to a structure being
more in back than another
structure in the body
Positions and
Directions
Medial
 Refers to a structure being
closer to the midline or
median plane of the body
than another structure of the
body
Lateral
 Refers to a structure being
farther away from the
midline than another
structure of the body
Positions and
Directions
Distal
Refers to a structure being
further away from the root of
the limb than another
structure in the limb
Proximal
 Refers to a structure being
closer to the root of the limb
than another structure in
that limb