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SS2 WEEK 4 CIRCULATORY SYSTEM

                           


    



Topic: Circulatory System
Subtopics:

1. Definition and types of circulatory systems

2. Components of the circulatory system (blood, heart, blood vessels)

3. Blood circulation in humans (systemic and pulmonary circulation)

4. Importance of the circulatory system

Definition:
The circulatory system is the system in living organisms responsible for transporting blood, nutrients, oxygen, hormones, and waste products throughout the body.

Types of Circulatory Systems:

1. Open Circulatory System: Found in invertebrates (e.g., insects), where blood flows freely in the body cavity.

2. Closed Circulatory System: Found in vertebrates (e.g., humans), where blood flows within blood vessels.

Components of Circulatory system

Blood: A fluid connective tissue responsible for transportation and immunity.

Components:

1. Plasma: Liquid portion containing water, proteins, hormones, and waste products.

2. Red Blood Cells (RBCs): Transport oxygen using hemoglobin.

3. White Blood Cells (WBCs): Defend the body against infections.

4. Platelets: Aid in blood clotting.

Heart:






Structure: Four-chambered muscular organ located in the thoracic cavity.

Functions: 1. Pumps oxygenated blood to the body (left side). 2. Pumps deoxygenated blood to the lungs (right side).

Blood Vessels:

1. Arteries: Carry oxygenated blood away from the heart (except the pulmonary artery).

2. Veins: Carry deoxygenated blood to the heart (except the pulmonary vein).

3. Capillaries: Tiny vessels where exchange of substances occurs between blood and tissues.


DIFFERENCE BETWEEN ARTERIES AND VEINS

Arteries

Veins

Blood  flows away from the heart

Blood  flows towards the heart

Carry oxygenated blood except pulmonary artery

Carry deoxygenated blood except pulmonary vein

Possess thick elastic walls

Possess thin elastic walls

Pressure of blood in arteries is high

Pressure of blood in veins is low

Absence of valves

Presence of valves

 


Blood Circulation in Humans

Double Circulation:

1. Blood passes through the heart twice in one complete circuit.

Pulmonary Circulation:

1. Deoxygenated blood is pumped from the right ventricle to the lungs via the pulmonary artery.

2. Blood is oxygenated in the lungs and returns to the left atrium via the pulmonary vein.

Systemic Circulation:

1. Oxygenated blood is pumped from the left ventricle to the body via the aorta.

2. Blood delivers oxygen and nutrients to tissues and picks up waste products.

3. Deoxygenated blood returns to the right atrium via the vena cava.

Importance of the Circulatory System (10 minutes)

Transport:

1. Delivers oxygen and nutrients to cells.

2. Removes carbon dioxide and waste products.

Regulation:

1. Helps regulate body temperature.

2. Transports hormones for body coordination.

Protection:

1. WBCs protect against pathogens.

2. Platelets prevent excessive bleeding through clotting.

 

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