The Cardiovascular System -- HEART -- Histology -- جهاز الدوران -------------------------------------------------------------------------------

1. The cardiovascular system, also called the circulatory system, is an organ
system that permits blood to circulate and transport gases and nutrients
through the body.
The major functions of the circulatory system are
1. Transport oxygen and carbon dioxide to and from tissues.
2. Transport nutrients, waste products and hormones.
3.Regulates body temperature and pH, and maintain homeostasis.
The Cardiovascular System

2. 4. Play a role in the immune response.
5. Maintain appropriate environment in all the tissue fluids of
the body for optimal survival and function of the cells,
The major components of cardiovascular system are blood,
heart, and blood vessels

3. HEART
The heart is a muscular pump that maintains unidirectional flow of
blood. The heart contains four chambers, the right and left atria and
right and left ventricles, through which blood is pumped. valves guard
the exits of the chambers, preventing 3 backflow of blood.

4. Cardiac Cycle
The term cardiac cycle refers to the repetitive pumping process that
begins with the onset of cardiac muscle contraction and ends with the
beginning of the next contraction. Pressure changes produced within the
heart chambers as result of cardiac muscle contraction are responsible
for blood movement because blood moves from areas of higher pressure
to areas of lower pressure.

5. Atrial systole is contraction of the atria and ventricular systole is
contraction of the ventricles. Atrial diastole is relaxation of the atria
and ventricular diastole is relaxation of the ventricles. when the atria
are relaxed, blood flows from the superior and inferior vena cava to
the right atrium and through the pulmonary veins to the left atrium

6. The following factors affect cardiac output:
 u he basic level of body metabolism
 (2) whether the person is exercising
 (3) the person's age, and
 (4) size of the body.

7. Blood vessels
Blood vessels are an extensive tubular network that transports blood
throughout the human body, carry the blood from and to the heart,
There are five major types where of blood vessels

8. ✔️⭕⭕Arteries, are blood vessels that carry the blood away from the
heart to the e tissues under high pressure. For this reason, it have
strong vascular walls, and blood flows at a high velocity in the arteries
✔️⭕⭕Arterioles, are the last small branches of the arterial system: they
act as control conduits through which blood is released into the
capillaries, The arteriole has a wall that can close the arteriole
completely or can dilate it strong muscular several fold.

9. ✔️⭕⭕capillaries, are tine blood vessels, enable the actual
exchange of water and nutrients between the blood and the
tissues. The capillary walls are very thin and have numerous
minute capillary pores permeable to water and other small
molecular substances,
✔️⭕⭕Venules, collect blood from the capillaries, and they
gradually convene into progressively larger veins.
✔️⭕⭕Veins, are blood vessels that carry blood from the venules
back toward the heart, they serve as a controllable reservoir for
the extra blood. The pressure in the venous system is very low,
and the venous walls are thin.

10. The circulation is divide in to:
1. The systemic circulation: It is also called the greater circulation or
peripheral circulation. It supplies blood flow to all the tissues of the body
except the lungs, and the vessels called the snemic vessels, which transport
blood through all parts of the body from the left ventricle and back to the
right atrium. Blood flowing through Pulmonary croulation systemic vessels
supplies oxygen and nutrients to all tissues of the body and carries away
carbon Sugeror dioxide and waste. vena cava

11. 2. The pulmonary circulation: It is Heart-7% carries blood flow from
heart to the lungs, and their vessels called the pulmonary vessels,
which transport Antanes-131i blood through the lungs from the right
ventricle and back to the left capillanes-7Ni atrium. Blood flowing
through pulmonary vessels takes up oxygen through the lung and
releases carbon dioxide.

12. Two circuits distribute blood in the body
✔️⭕⭕1_. Pulmonary circulating conveys blood from the heart to the
lung and from the lung to the heart
Right Ventricle ➡️Pulmonary artery ➡️Lung ➡️Pulmonary Vein➡️Left
Atrium
✔️⭕⭕2._ Systemic circulating conveys blood from the heart to other
tissues of the body and from other tissues to the heart
Left Ventricle ➡️Aorta ➡️Larage and Small Arteries ➡️Arterioles
➡️Capillaries ➡️Venules ➡️Small and Large Veins ➡️Right Atrium

13. Basic Theory of Circulatory Function
the The function of the circulation is to service the needs of the body
tissues, where heart and circulation are controlled to provide the
necessary cardiac output and arterial pressure to cause the needed
blood flow to tissue, There are three basic principles that underlie the
controlled rate of blood flow through most tissues:

14. 1_The rate of blood flow to tissues of the body is always
controlled in relation to the tissue need.
2. The cardiac output is controlled mainly by the sum of all the
local tissue flows.
.3 The arterial pressure is controlled independently of either local
blood fow control or cardiac output control.

15. The Blood
Blood is a bodily fluid in humans that delivers necessary substances such as
nutrients and oxygen to the cells and transports metabolic waste products
away from those same cells. Blood is a type of connective tissue that
consists of blood cells suspended in liquid matrix (blood plasma); and
accounts for 7% of the human body weight. The average adult has a
blood volume of roughly s liters, which is composed of plasma (constitute
about 54% of whole blood) and several kinds of blood cells (red blood
cells (about 45%), white blood cells, and platelets dess l%), accounts for
the remaining volume