The Human Cardiovascular System and Its Functions
Learn the basics of the human cardiovascular system and Its Functions with this simple and
easy-to-follow guide for aspiring
Pharmaceutical Sales Representatives. Here, you’ll discover how the
heart and blood vessels
work together to keep the body running.
Diagram: Cardiovascular system diagram
The explanations use real-world examples and skip the heavy medical jargon.
Even if you’re just starting out, you’ll be able to grasp the concepts
quickly. Step by step, you’ll build confidence and grow your career in
pharmaceutical sales.
Table of contents: The Human Cardiovascular System and Its Functions
What you will get in this blog post-
The Human Cardiovascular System and Its Functions
To learn The Human Cardiovascular System basics, start with how the heart pumps blood
throughout your body. Understand the role of
arteries,
veins, and
capillaries
in blood circulation. This basic knowledge is essential for every
Pharmaceutical Sales Representatives. It helps you explain drug actions to
doctors clearly. Begin with the simple structure and grow from there.
Here you can learn - Contents:
- Description of the Cardiovascular System.
- Physiology of the Cardiovascular System.
- Monitoring and Diagnostic Techniques of the Cardiovascular System.
What is Cardiovascular System?
Cardiovascular system is a transport system that transports important
substances
around the body.
Components of the cardiovascular system are:
- Heart
- Blood
- Blood vessels
Blood and its composition
Blood is a suspension of cells in plasma.
- Blood = Cell + Plasma.
Composition of Blood-
Diagram: Blood vessel diagram
A. Cellular substance (cell):
- Erythrocytes or RBC (Red Blood Corpuscles)
- Leukocytes or WBC (White Blood Corpuscles)
- Platelets or Thrombocytes
B. Liquid substance (Plasma):
- Inorganic substance.
- Organic substance (Proteins, Non protein nitrogenous substances, Fats, Carbohydrates and other).
Plasma, plasma proteins and Serum
Plasma is the liquid part of blood, which is a solution of protein and
salts.
- Plasma = Serum + Coagulation proteins and factors.
Plasma Proteins:
Serum
Serum is the fluid or the watery portion that remains after blood
coagulation.
- Serum = Plasma - coagulation proteins and factors.
Blood cells
Erythrocytes/RBC:
These are nucleus-less cells containing hemoglobin and carry oxygen from
the lung to all the tissues where it is exchanged for carbon dioxide.
Haemoglobin
It is the red pigment of the blood present in the RBC. Haemoglobin binds
with oxygen and is converted to oxyhaemoglobin in the lung.
It is composed of two parts:
- Haemoglobin = Haem (red pigment) + Globin (protein).
Leukocytes/WBC:
Leukocytes are defensive substances of the body, which defend against
microorganisms that enter the body from the environment.
There are two types of WBC:
1) Granular:
- Neutrophil
- Basophil
- Eosinophil
2) Agranular:
- Lymphocyte
- Monocyte
Thrombocytes/Platelet:
Platelets are substances that form plugs with coagulation proteins in
the plasma to stop leaking from the blood vessels.
Diagram: thrombocytes platelets diagram
General Properties of Blood
Blood volume is an average of 56 litres.
Blood pH value
is 7.367.45.
Blood temperature is average 36-38 °C.
The viscosity of blood is 4.5 times more than that of water.
Functions of the Blood:
- Transport function.
- Regulation function.
- Defensive function.
Blood vessels: Types
The blood vessels are hollow tubes that carry the blood to and from the
tissues.
There are three types of blood vessels:
Diagram: types of blood vessels diagram
Artery: Carries oxygenated blood from heart to all over the body.
Vein: Carries deoxygenated blood from all over the body to heart.
Capillary: Capillary are fine vessels that link or or junction the
small arterioles and arterioles and smallest venules.
There are three layers in the blood vessels:
Tunica Intima:
A thin layer of flat epithelial cells. The innermost layer of blood
vessels.
Tunica Media:
The middle layer composed of smooth muscle fibers and elastic fibers.
Diagram: Tunica Adventitia diagram
Blood Circulation
Circulation is a process of blood flow through a closed system of vessels.
Diagram: Blood Circulation diagram
Importance of circulation:
- To supply oxygen, nutrition, vitamins to the tissues.
- To carry different metabolic waste products and carbon dioxide from tissue.
- To prevent intravascular coagulation of blood.
- To maintain an environment for cellular function.
Factors of maintaining Circulation:
- Pumping action of heart.
- Elastic recoil of arteries.
- Pressure gradient.
- Respiration.
- Muscular exercise.
Blood Pressure
Blood Pressure is the pressure lateral exerted by the flowing blood on
the wall of blood vessels.
Systolic Pressure:
The pressure exerted by the blood on the blood vessels during
contraction of the heart. It is 120 Hg for a normal person.
Diagram: blood pressure diagram
Diastolic Pressure:
The pressure exerted by the blood on the blood vessels during
relaxation of the heart. It is 80 Hg for a normal person.
Blood Pressure for Adult
| Category | Systolic (mm Hg) | Diastolic (mm Hg) |
|---|---|---|
| Normal | <130 | <85 |
| High Normal | 130-139 | 85-89 |
| Hypertension | Systolic (mm Hg) | Diastolic (mm Hg) |
|---|---|---|
| Mild | 140-159 | 90-99 |
| Moderate | 160-179 | 100-109 |
| Severe | 180-209 | 110-119 |
| Very Severe | 210 or more | 120 or more |
Heart
The heart is the central blood-pumping organ of the body. It receives and
pumps blood from and to all over the body. It is a hollow muscular organ.
A. Heart Chambers:
The Heart has four chambers:
Diagrame: Heart four chambers
* Receiving Chamber
* Distributing Chamber
Diagrame: Heart chambers diagram
B. Heart Muscles:
The
Pericardium:
Outermost layer surrounding the heart.
The
Myocardium:
Middle muscular layer of the heart.
The
Endocardium:
The Innermost layer of the heart.
Diagram: Heart Muscles diagram
C. Valves of Heart
Valve is a membranous structure that temporarily closes in order to permit
flow of fluid in one direction.
Diagram: Valves of Heart diagram
There are four types of valves in the heart:
- Tricuspid or right atrio-ventricular valve.
- Mitral valve or Left atrio-ventricular valve.
- Pulmonary valve.
- Aortic valve.
D. Heart Conduction System
Special tissues responsible for initiation and propagation of cardiac
impulses.
Diagram: Heart Conduction System diagram
These are:
- Sinoatrial node.
- The Internodal pathway.
- AtrioVentricular node.
- The AtrioVentricular bundle/Bundle of His.
- The left and right bundles of AV brunch.
- The Purkinje fibers.
E. Heart Contraction nerve influences
There are two sets of nerves that influence the rate of contraction of
the heart:
- The Vagus nerve which slows the rate and lessens the strength of the beat.
- The Sympathetic nerves which quickens and increase the strength of the beat.
Diagram: Heart Contraction nerve influences diagram
Effects on Heart
A. Effects on Heart: Potassium-
Excess potassium in the extracellular fluid causes-
- The heart becomes extremely dilated.
- Flaccid and slower heart rate.
B. Effects on Heart: Calcium
Excess calcium ion causes-
- Increased Contraction of heart and blood vessels.
C. Effects on Heart : Sodium
Excess Sodium ion causes-
- Depression of cardiac function.
- Dilate and flaccid the heart.
D. Effects on Heart: Adrenaline
Adrenaline increase the rate and force of contraction as it-
- Stimulates S A Node.
- Increases conductivity, contractility and automaticity.
Important Definitions
Heart Rate:
The number of heart beats per minute is called heart rate.
Normal Heart rate-
- Adult: 60-90/minute
- Average: 72/minute
Cardiac Output:
The amount of blood the heart pumps through the circulatory system in a
minute.
Usually, an adult heart pumps about 5 liters of blood per minute at rest.
But when you run or exercise, your heart may pump 3-4 times that much to
make sure your body gets enough oxygen and fuel.
Tachycardia:
The term tachycardia means a faster heart rate than the normal.
Usually above 100 beats/minute) is called tachycardia.
Bradycardia:
The term bradycardia means slower heart rate than the normal physiological
limit.
Usually below 60 beats/minutes is called bradycardia.
Hypertension
Hypertension is a clinical condition in which the patient has a higher
blood pressure than that judged to the normal.
Diagram: Hypertension diagram
Etiology:
- The actual cause of hypertension is known.
Risk Factor:
- Generic
- Smoking
- High lipid content
- Overweight
Hypertension Types
Two types:
Essential or Primary Hypertension: Hypertension for which no cause
is known is called primary or essential or idiopathic hypertension.
Diagram: Types of Hypertension diagram
Secondary Hypertension: Hypertension for which the cause is known
is called secondary hypertension.
FAQs
Q. What is the full form of RBC?
A. The full form of RBC is Red Blood Corpuscles.
Q. What is the full form of WBC?
A. The full form of WBC is White Blood Corpuscles.
Q. What is another name for Platelets?
A. Another name for Platelets is Thrombocytes.
Conclusion
In conclusion, when you learn the human cardiovascular system,
you’re taking an important first step toward becoming a knowledgeable and
confident Pharmaceutical Sales Representative. This foundation strengthens
your understanding of how the human body works and helps you communicate
more effectively with doctors.
Simple, clear knowledge creates stronger trust. Keep learning, stay curious,
and move forward with purpose—the more you know, the more confident you’ll
feel in your pharmaceutical career.
Sarwar Hossain ✅
I am a travel enthusiast and sports-loving person. Education: BBA & MBA in Accounting.