The circulatory system circulates blood and lymph throughout the body using the heart, blood vessels, and lymph vessels. The circulatory system transports gases, nutrients, hormones, wastes and other substances. There are three major types of blood vessels - arteries carry blood away from the heart, capillaries enable exchange between blood and tissues, and veins carry blood from capillaries back toward the heart. Blood flows from the arteries into smaller arterioles and capillaries, then into venules and veins which drain into the heart. Blood pressure is the pressure exerted by blood against vessel walls and is measured using a sphygmomanometer.

2. CIRCULATORY SYSTEM

3. What is Circulatory System?
Circulatory system is the system
that circulates blood and lymph through
the body. Its is a transport system that
carries gases, nutrients, hormones
wastes, and many other substances. This
is composed of the heart, blood vessels,
blood, lymph and the lymphatic vessels.

4. Blood Vessels

5. What is Blood Vessels?
The blood vessels are the part of
the circulatory system that transports
blood throughtout the human body.
The blood is the circulating medium in
the cardiovascular system. It moves in
circles inside the blood vessels.

7. Three major types of blood vessels:
Arteries
- Carry blood away from the heart.
Capillaries
- Enable the actual exchange of water
and chemicals between blood and tissues.
Veins
- Carry blood from the capillaries back
toward the heart.

9. Blood Vessels
The arteries receive the
propelled oxygenated blood from the
ventricles of the heart. The blood from
the arteries goes to the smaller blood
vessels called arterioles, which are
connected to the capillaries in the
tissues.

11. Venules, which are small
veins drain the capillary beds
(interweaving capillary networks),
which empty into veins then into
the great veins that enter the heart.

13. The walls of blood vessels
except those of microscopic capillaries
have coats of tunics:
• Tunica intima (interior of the
vessels)
• Tunica media (bulky central tunic)
• Tunica adventitia (outermost coat).

15. The walls of arteries are
thicker than those of veins. The walls
of arteries are strong enough to
withstand the pressure of blood from
the heart. On the contrary, veins have
low pressure. This is why veins have
thinner walls.

16. Arteries often carry
oxygenated blood, while veins often
carry deoxygenated blood. The flow
of blood in the arteries is away from
the heart, while in veins the blood
goes toward the heart.

17. Because the blood in veins
is directed toward the heart,it is
against gravity. This is the reason
why veins have valves to prevent
the backflow of blood.

19. Capillaries
The transparent walls of
the capillaries are very thin, which
make the exchanges between the
blood and tissue cells easy. A
capillary bed has vessels that
connect an arteriole and a venule.

20. Blood Pressure
Blood pressure is the pressure
that blood exerts against the inner
walls of the blood vessels. It rises and
falls as the heart contracts and
relaxes. The systolic pressure is the
pressure in the arteries during the
contraction of the ventricles.

21. Blood Pressure
On the other hand, the
diastolic pressure is the pressure in
the arteries during the relaxation of
the ventricles. A blood pressure
reading of 120 over 80 means a
systolic pressure of 120 and diastolic
pressure of 80.

23. Sphygmomanometer
A sphygmomanometer is a
device used for measuring blood
pressure. An Inflatable cuff is
warapped around the arm to
constrict the arteries during
measurement.