Transcript HUMAN BODY - IUST Dentistry

HUMAN BODY
The human body is a remarkable
structure consisting of cells
arranged in an orderly fashion .
Cells are grouped together to form
tissues ,which are grouped to form
organs .
Organs work together as organ
systems ,
CELLS and TISSUES
There are many distinguishable kinds of
cells are present in the body , there are
only four major types of cells :
a – Neurons .
b – Muscle cells .
c – Epithelial cells.
d – Connective tissue cells .
This classifications are based on the
functional differences .
A - Neurons
Neurons or nerve cells are specialized to
transmit information in the form of
electrical signals.
For this purpose, neurons typically
possess a number of branches that
function either to receive signals from
or transmit signals to other cells.
KINDS OF THE Neurons
a – Neurons in the eyes : that respond to light
b – Neurons in the skin : that respond to
touch ,
receive information from the
outside environment and allow us to
perceive the world through our senses .
c - Neurons in the muscles : that respond to
movement .
d - Neurons in the glands : that respond to
hormones secretion .
Neurons
b – Muscle cells
Muscle cells or muscle fibers are specialized
to contract ,thereby generating mechanical
force and movement .it found in muscle of
the arms , legs , and other body parts
whose movements are under voluntary
control(skeletal muscle ) .
Other muscles not under voluntary control,
such as the heart ( cardiac m.) and blood
vessels (smooth m.)
Muscle cells
C – Epithelial cells
Epithelial cells :Are found in tissues
called epithelia ,which consist of a
continuous, sheetlike layer of cells in
combination with a thin underlying
layer of noncellular material called a
basement membrane .
The epithelial layer may be one cell thick
or several cells thick.
Epithelial cells vary in shape from short
and flattened, and in some cases to tall
and oblong in others .
In all cases cells are joined closely
together to form a barrier, prevents
material on one side of the epithelium
from mixing freely with material on the
other side .
Epithelial cells
Certain epithelial cells are specialized to
transport some material such as
inorganic ions ,organic molecules or
water from one location to anther
e.g. cells in lining of the stomach
transport acid into the lumen of the
stomach to aid the digestion of food .
Cells in the lining of the intestine ,
which transport nutrients and water
from the lumen of the intestine into
the bloodstream .
.
Some epithelial cells form glands
,organs specialized in the synthesis
and secretion of a product .
There are tow types of glands .
types of glands :
a- Exocrine glands
secrete a product
into a duct leading
to the external
environment
e.g. sweat gland
and salivary glands
B –Endocrine glands
Endocrine gland
secrete
hormones, which
are chemicals that
communicate a
massage to cells of
the body ,into the
bloodstream.
e.g. pituitary & adrenal
glands .
d – Connective tissue cells
Connective tissue refers to any structure
whose primary function is to provide
physical suport for other stacture ,to
anchor them in place ,or to link them
together .
e.g. tendons : which anchor muscle to bones.
Ligaments : which connect bones together
, and the elastic tissue in the skin that
gives it its toughness & flexibility .
Bones them selves , which provide support for
all the body `s structures .
Connective tissue consists of widely
scattered cells embedded in a mass of
noncellular material called extracellular
matrix .
The most important constituents of the
extracellular matrix are the longe ,
fibrous proteins elastin & collagen .
Blood and lymph also a connective
tiusses
Connective tissue cells
ORGANS AND ORGANS
SYSTESM
When two or more tissues combine to make
up structures that perform particular
functions ,those structures are called
organs .
e.g. The heart , is an organ whose primary
function is to pump blood , Although
composed mostly of muscle tissue , it also
contains nervous tissue , epithelial tissue
and connective tissue
ORGAN SYSTEMS
The various organs are organized into
organ systems , collections of organs
that work together to perform certain
functions .
e.g. cardiovascular system , whose
function Is to deliver blood to all
body`s tiusse .
cardiovascular system includes the
HEART, BLOOD VESSELS & BLOOD .