Cell, tissues, organs , systems....

2. This chapter presents the basic
structure and functions in the body, the
terms used to describe planes of the
body, it’s cavities, the quadrants &
regions of the abdominal cavity, and the
divisions of the spinal column; to
provide a greater understand of the
general concepts of pathology (the
study of the nature of diseases, their
causes, development, and
consequences).

3. Our bodies are made up of many different levels of structure and
function, some are more complex than others. Listed below, from
least to most complex, are the levels of organization that make up
our body systems.
1.) Cell
2.) Tissue
3.) Organ
4.) System
5.) Organism

4. 1.) Cell: The structural and functional unit of life. The study of the body at
the cellular level is called cytology. A cell consist of the following:
– Cell membrane: acts as a barrier that encloses the entire cell. It controls the
transport of many substances to and from the cell.
– Cytoplasm: a jellylike matrix of proteins, salts, water, dissolved gases, and nutrients.
Inside the cytoplasm are various structures called organelles that provide socialized
functions for the cell.
– Nucleus: is the largest cell organelle and it is responsible for metabolism, growth,
and reproduction. It carries the genetic blueprint of the organism and is found in a
complex molecule called DNA that is organized into a threadlike structure called
chromatin. When a cell prepares to divide, chromatin forms chromosomes, which
carry thousands of genes that become our genetic blueprint.
Genes pass biological information from one generation to the next. This
biological info. includes traits like hair color, body structure, and metabolic
activity. All cells in the human body, except sperm cells and egg cells contain
23 pairs, or 46 chromosomes. Sperm and egg cells each have 23 unpaired
chromosomes. After fertilization, each cell of the embryo then has all 46
chromosomes.

5. 2.) Tissue: Groups of cells that perform a specialized activity. The study of
tissues is called histology. More than 200 cell types make up four major
tissues of the body; they are as follows:
– Epithelial tissue: is composed of cells arranged in a continuous sheet consisting of
one or more layers.
– Connective tissue: supports and connects other tissues and organs.
– Muscle tissue: provides the contractile tissue of the body, which is responsible for
movement.
– Nervous tissue: transmits electrical impulses as it relays information throughout the
entire body.
This type of tissue covers surfaces of organs, lines cavities and
canals, forms tubes and ducts, provides the secreting portions
of glands, and makes up the epidermis of the skin.
This type of tissue is made up of diverse cell types, including
fibroblasts, fat cells, and blood.
This type of tissue transmits information throughout the body
that allows us to move, think, taste, see and experience all
functions associated with being alive.

6. 3.) Organ: Organs are the body structures that perform specialized functions.
They are composed of at least two or more tissue types.
The stomach is made up of connective
tissue, muscle tissue, epithelial tissue, and
nervous tissue.
•Muscle and connective tissue form the
wall of the stomach.
•Epithelial and connective tissue cover the
inner and outer surfaces of the stomach.
•Nervous tissue penetrates the epithelial
lining of the stomach and its muscular
wall to stimulate the release chemicals for
digestion and contraction for peristalsis
(the rhythmic contraction and relaxation
of the walls of a tubular organ to force its
contents onward).

7. 4.) System: A body system is composed of different numbers of organs and
accessory structures that have similar or related functions.
The organs of the
gastrointestinal system
include the esophagus,
stomach, small intestine,
and bowel.
The accessory structures of
the GI system would be the
liver, gallbladder, and
pancreas. The purpose of
this system is to digest
food, remove and use its
nutrients, and expel
wastes.

8. 5.) Organism: The highest level of organization is the organism. An organism is a
complete living entity capable of independent existence. All complex organisms,
including humans, are made up of several body systems that work together to
sustain life.
The human body is an organism. The systems that keep us
functioning are complex and must maintain a proper balance to
continue to perform successfully.
There are 10 different body systems including the special
senses that keep our bodies going. These systems are:
1.) Integumentary system
2.) Digestive system
3.) Respiratory system
4.) Cardiovascular system
5.) Blood, Lymph, and Immune systems
6.) Musculoskeletal systems
7.) Genitourinary systems
8.) Female Reproductive systems
9.) Endocrine systems
10.)Nervous systems
Special senses

9. Anatomical Position: is a body posture used to locate anatomical parts in relation
to each other.
The body is erect and the eyes are looking
forward. The upper limbs hang to the sides,
with the palms facing forward. The lower
limbs are parallel, with toes pointing
straight ahead.
No matter how the body is actually
positioned– standing or lying down,
facing forward or backward– or how
the limbs are actually placed, the
positions and relationships of a
structure are always described as if
the body were in anatomical
position.

10. Planes of the body: are identified by anatomists by the use of an imaginary flat
surface called a plane. The most commonly used planes are midsagittal (median),
coronal (frontal), and transverse (horizontal).
Because of the advancement
in imaging techniques; we
have current imaging
procedures, such as
magnetic resonance imaging
(MRI) and computed
tomography (CT). These
procedures can produce
three-dimensional images on
more than one plane.
Making it easier to find and
identify structural
abnormalities in the body.

11. Body Cavities: Medical professionals locate structures or abnormalities by
referring to the body cavity in which they are found. The body has two major
cavities.
1.) Dorsal (posterior), including the cranial and spinal cavities.
2.) Ventral (anterior), including the thoracic and abdominopelvic cavities.

12. Abdominopelvic divisions: The abdominopelvic area of the body lies under the
diaphragm. It holds the organs of digestion (abdominal area) and the organs of
reproduction and excretion (pelvic area). Two anatomical methods are used to
divide this area of the body for medical purposes: Quadrants and Regions.
• Quadrants: Four divisions of the lower torso used to show topographical location.
• Regions: Primarily used to identify the location of underlying body structures and visceral organs. (p.46-text)

13. Quadrants: are four divisions of the lower torso used to show topographical
location. They provide a means of locating specific sites for descriptive and
diagnostic purposes. The divisions of quadrants are used in clinical
examinations and medical reports.
An imaginary cross passing through the
identifies the four quadrants.
*Remember: Quadrants are primarily
used to identify relevant sites.

14. Abdominopelvic Regions: are primarily used to identify the location of underlying
body structures and visceral organs.
An example: the stomach is located in
the left hypochondriac and epigastric
region.
Another example: the appendix is
located in the hypogastric region of the
body.

15. Spine: The spine is divided into sections corresponding to the vertebrae located in
the spinal column. These divisions are:
• Cervical spine: 7 vertebrae (C1–C7)
• Thoracic spine: 12 vertebrae (T1–T12)
• Lumbar spine: 5 vertebrae (L1–L5)
• Sacrum: 5 (fused) vertebrae (S1–S5)
• Coccyx: 4 (3–5) (fused) vertebrae
(Tailbone)