1. The Circulatory System
Part One – Blood
Part Two – Circulatory System

2. Part One - Blood At the end of this section you should be able to:
Identify the liquid and formed elements of blood.
Identify their functions.
Identify different blood types and their compatibility.

3. What we have learned so far…
Nutrients enter the bloodstream after they have been absorbed by the small intestine.
Oxygen enters the bloodstream through the alveoli.
Together, these elements travel through the blood to enter our bodies trillions of cells so as to nourish them and to allow energy to be created.
Later, we will learn how waste products leave our bodies.

4. Blood
Blood is an incompressible fluid flowing through our bodies. It flows everywhere.
Its main function is the transportation of nutrients and gases from their point of entry to their destination, and vice versa.
Nutrients from the digestive system.
Oxygen from the respiratory system.
Waste made from cellular respiration.

5. Characteristics of Blood
Blood is red, not blue as you may think from looking at your veins.
Salty
Viscous, (thick)
Odourless
Males have 5-6 litres of blood.
Females have 4-5 litres of blood.

6. Components of Blood
Blood may seem homogenous, but is composed of formed elements called blood cells, (white and red), and platelets.
Plasma is what makes it liquid.
The formed elements and the plasma can be separated through a process called centrifugation.
45% - formed elements, 55% plasma.

7. Plasma
Formed
elements

8. Components of Blood Liquid Element Formed Elements Plasma
Red blood cells, (RBC)
White blood cells, (WBC)
Platelets

9. Red Blood Cell
Platelet
White Blood Cell

10. Liquid Element - Plasma
Description:
Yellowish liquid, composed of 90% water. Many substances become dissolved in the plasma as they’re being transported, like nutrients, hormones and waste.
Functions:
Transportation of nutrients to cells.
Transportation of waste from cellular respiration to excretory organs.
Transportation of hormones, antibodies, etc.

11. Formed Elements – RBC’s
Description:
There are 4-6 billion RBC’s in your body.
Red-coloured cells. They are concave, (donut-shaped).
Functions:
Transportation of oxygen using a protein called hemoglobin.
Transportation of carbon dioxide.
Blood carrying oxygen is bright red. Blood carrying carbon dioxide is dark red.

12. Formed Elements – WBC’s
Description:
There are 4-11 billion WBC’s in the body.
They are transparent.
Functions:
Provide immunity and defense against disease. This is why the numbers vary. Someone who is very ill will have a lower count of WBC’s than someone who is healthy.
Phagocytosis: surround and destroy foreign substances.

13. Formed Elements - Platelets
Description:
There are million platelets in your body.
They are irregular fragments coming from large cells in bone marrow.
Function:
Coagulation or blood-clotting. This process allows your skin to scab and heal.

14. Blood Types There are 4 main blood types: A, B, AB and O
Blood types are first categorized by the presence or absence of two substances.
Substance A
Substance B Found on the membrane of RBC
In addition, cells can carry another substance on their membrane: Rhesus Factor, or RH Factor.
Blood types can be either RH positive or RH negative.

15. No substances present Blood Type A+ A- B+ B- AB+ AB- O+ O- Substance A
Substance B
RH Factor

16. Blood Transfusions
An injection or transfer of blood to a person who has undergone an accident, surgery or has a disorder which requires it.
A transfusion requires a donor and a recipient. But, because people have different blood types, the process must be done with care.
Before blood typing was discovered in 1902, many people died as a result of blood transfusions.

17. …
Donation is possible between two people with the same blood type. But some types are rarer than others.
Some blood types are compatible with others.
The rule of thumb for blood donation:
Don’t give what they don’t already have.
Consider the substances in blood, A and B, and the RH factor.

18. DONOR
RECIPIENT O- O+ B- B+ A- A+
AB-
AB+

19. Blood Compatibility Two people are blood compatible when:
They are both of he same blood type.
Type O- blood can donate to anyone, regardless of blood type because they have no substances, nor RH factor. Universal donor.
Type AB+ blood can receive blood from anyone because they have both substances and RH factor. Universal recipient.

20. Part Two – Circulatory System
At the end of this section you should be able to:
Name the parts of the circulatory system, (heart, vessels).
Explain the role of the circulatory system
Describe the function of the main parts, (heart vessels).

21. Anatomy of the Circulatory System
There are three main parts of the circulatory system:
The heart
Blood vessels
Pulmonary and systemic circulation
The heart is the pump that keeps blood circulating in our blood vessels.
The blood vessels are broken down into many types, mainly depending on their size.
There are two ways that blood circulates throughout the body.

22. Blood Vessels The bodies blood vessels form a closed-circuit network.
Blood vessels are divided into three categories:
Arteries
Capillaries
Veins

23. Arteries
A blood vessel that carries blood from the heart to other parts of the body.
They have very thick walls, allowing them to withstand high amounts of pressure.
They branch into smaller arterioles, before becoming small capillaries.

24. Capillaries
A blood vessel that has a small diameter and thin walls. Responsible for exchanges between the blood and cells.
Capillaries are so small that the blood cells must pass one at a time.

25. Veins A blood vessel that carries blood back to the heart.
Once capillaries start to reconnect, they form venules, which become the larger veins.

27. The Heart
The heart is roughly the size of your fist, located between your lungs, protected by the rib cage.
It is composed of four chambers:
Right atrium
Right ventricle directly linked
Left atrium
Left ventricle directly linked
Separated by a partition

28. … There are 5 major blood vessels that are connected to the heart.
Superior and inferior vena cava, (veins)
Pulmonary vein
Pulmonary artery
Aorta, (artery).

30. … Valves are also present in the heart.
Without these valves, blood would flow backwards in the heart. They are called atrioventricular valves.
Several blood vessels are attached to the heart.
Veins, (superior and inferior vena cava, pulmonary veins), attached to both atria.
Arteries, (aorta and pulmonary arteries), are attached to the ventricles.

31. Function of the Heart
The contraction and relaxation of the heart muscles is what circulates blood throughout the body.
For blood to enter the heart:
It must enter the atria from the veins.
It must enter when the heart is at rest, or is relaxed.
The filling of the heart is called diastole.

32. … For blood to leave the heart:
The atria must contract, pushing blood into the ventricles.
Then, the ventricles contract, pushing blood into the arteries attached to the heart, (aorta and pulmonary). This is called systole.
The pulse that you feel corresponds to the contractions of the left ventricle, (it is larger). 75 beats per minute when at rest.

33. Circulation Routes
The heart is a double pump. Because the two sides of the heart are separated, the blood is pumped in and out by different routes.
On the right side of the heart, the mechanism is called pulmonary circulation.
On the left side, it is called systemic circulation.

34. Pulmonary vs. Systemic Pulmonary Systemic Left side. Right side.
Longer circuit.
Blood is rich in O₂.
Blood exits the left ventricle through the aorta.
Aorta divides into arteries and capillaries which shed O₂ at the cells and pick up CO₂.
Now rich in CO₂, blood returns to the left atrium, entering via the Vena Cava.
Right side.
Shorter circuit.
Blood is rich in CO₂
Blood exits the right ventricle and flows to the capillaries of the lungs.
CO₂ exchanges with O₂.
Now rich in O₂, blood returns to the heart and enters the left atrium through a pulmonary vein.

35. Circulation Routes

36. Image Credits