The circulatory system consists of the heart, blood vessels, and blood. It transports nutrients, waste, hormones, and oxygen throughout the body. There are four main types of circulation: systemic circulation carries oxygenated blood from the heart to tissues and returns deoxygenated blood; pulmonary circulation carries deoxygenated blood to the lungs and returns oxygenated blood; portal circulation transports blood between capillary beds; and collateral circulation forms alternate pathways around blockages. Oxygen is transported primarily by binding to hemoglobin in red blood cells, while carbon dioxide is transported through dissolved gas, binding to hemoglobin, and as bicarbonate ions.

1. PHYSIOLOGY OF
CIRCULATION
(Types)

2. WHAT IS CIRCULATORY SYSTEM ?
• The circulatory system, also called cardiovascular system
or blood vascular system consists of BLOOD, THE
HEART and BLOOD VESSELS.
• In general it maintains appropriate environment in all the
tissue fluids of the body for optimal survival and
functions of the cells.

4.  Transport of nutrients to the body tissues
 To transport waste products away
 Transport of the hormones
Functions of Circulation

5. Role of each part of the Circulation
BLOOD VESSEL FUNCTIONS CHARACTERISTICS
Arteries Transport of oxygenated
blood under high pressure
to the tissues
Strong vascular walls
Blood flow at high velocity
Arterioles Control conduits for blood
release into capillaries
Strong muscular walls
Capillaries Exchange of fluids,
nutrients, electrolytes,
hormones etc
Very thin walls
Have numerous pores
Venules Collect blood from
capillaries and coalesce into
larger veins
Elastic tissues and fibrous
connective tissues are
present
Veins Transport of blood from
venules to the heart
Have thin walls
Blood flows under low
pressure

6. TYPES OF CIRCULATORY ROUTES
(1) Systemic Circulation
(2) Pulmonary Circulation
(3) Portal Circulation
(4) Collateral Circulation

7. Systemic Circulation
• This includes the arteries and arterioles that carry oxygenated
blood from the left ventricle to systemic capillaries.
• It also includes veins and venules that return deoxygenated
blood to the right atrium.
• Because it supplies blood flow to all the tissues of the body
except lungs, it is also called as the greater circulation or
peripheral circulation.

8. Pulmonary Circulation
• The pulmonary circulation carries deoxygenated blood from the right
ventricle to the air sacs (alveoli) within the lungs and returns oxygenated
blood from the air sacs to the left atrium.
• The pulmonary trunk emerges from the right ventricle and then divides
into the right pulmonary artery to the right lung and the left
pulmonary artery to the left lung.
• The pulmonary arteries are the only arteries that carry deoxygenated
blood.
• On entering the lungs the branches divide until they form capillaries
around the alveoli within the lungs.
• The pulmonary capillaries unite to form venules and eventually
pulmonary veins ( only veins that carry oxygenated blood ).

10. Portal Circulation
• In some parts of the body, however, blood passes from
one capillary network into another through a vein called a
portal vein.
• Such a circulation of blood is called a portal system.
• The portal systems are associated with the following
locations –

11. (1) Hypophyseal Portal System
(associated with the pituitary gland)

12. (2) Hepatic Portal System
(associated with the liver)

13. Collateral Circulation
• Collateral circulation
is the alternate
circulation around a
blocked artery or vein
via another path, such as
nearby minor vessels.
• Its formation may be provoked by pathological conditions
such as high vascular resistance or ischaemia.

14. • An example in humans and some other animals is after an
acute myocardial infarction (heart attack).
• Collateral circulation in the heart tissue will sometimes bypass
the blockage in the main artery and supply enough oxygenated
blood to enable the cardiac tissue to survive and recover.

15. OXYGEN TRANSPORT
• Oxygen does not dissolve easily in water, so only 1.5% of inhaled oxygen
is dissolved in blood plasma, which is mostly water.
• About 98.5% of blood oxygen is bound to hemoglobin in RBCs.
• Oxygen and hemoglobin bind in an easily reversible reaction to form
Oxyhemoglobin.
• Partial pressure of oxygen is the most important factor that determines how
much oxygen binds to hemoglobin.
• Factors affecting hemoglobin’s affinity for oxygen are pH, partial pressure
of carbon dioxide, temperature etc.

16. Carbon Dioxide Transport
AS DISSOLVED
CO2
• About 7% dissolved in
blood plasma
• This depends on the
partial pressure of the
carbon dioxide
AS
CARBAMINO
COMPOUND
• About 23% combines
with the globin proteins
of Hemoglobin
• Carbaminohemoglobin
( HbCO2 )
AS
BICARBONATE
ION
• ~ 70% is transported as
HCO-
3 ion
• Some of dissolved CO2
reacts with water
forming carbonic acid
which immediately
breaks down to HCO-
3
and H+
• When arterial blood flows through the tissue capillaries, CO2 diffuses down its
partial pressure gradient from the tissue cells into the blood.
• The transport to the lungs takes place in three ways -

17. References -
• Guyton and Hall (2011) Textbook of Medical Physiology 12th ed.
Philadelphia : Saunders, Elsevier
• Pranav Kumar and Usha Mina (2018) Life sciences fundamentals
and practice 6th ed. New Delhi, India : Pathfinder
• https://socratic.org/questions/what-is-the-difference-between-
pulmonary-and-systemic-circulation
• https://socratic.org/questions/what-is-a-portal-system-what-is-the-
purpose-of-the-hepatic-portal
• https://www.easynotecards.com/notecard_set/84284

18. THANK YOU