Questions and Answers
What is the main function of arterioles?
What is the characteristic of cardiac muscle that allows it to contract in response to a stimulus?
What type of muscle is cardiac muscle?
What is the term for the transfer of cardiac impulses from the sinoatrial node to all the cardiac muscle?
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Which of the following is NOT a property of cardiac muscle?
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What is the term for the ability of the cardiac muscle to respond to different stimuli?
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What is the function of venules?
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What is the characteristic of cardiac muscle that allows it to beat regularly?
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What is the primary function of the pulmonary circulation?
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What is the sequence of events in systemic circulation?
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What is the primary function of the arteries?
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What is the function of the circulation system?
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What is the heart?
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What is the weight of the heart in women?
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What is the size of the heart?
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What is the difference between pulmonary and systemic circulation?
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Study Notes
Circulation
- The transport system that circulates blood and lymph throughout the body has two types: pulmonary circulation and systemic circulation.
Pulmonary Circulation
- Carries blood from the right ventricle of the heart to the lungs and back to the left atrium.
- In the lungs, carbon dioxide is excreted and oxygen is absorbed.
- Sequence: Right Ventricle of Heart → Pulmonary Arteries → Pulmonary Arterioles → Pulmonary Capillaries → Pulmonary Venules → Veins → Left Atrium of Heart.
Systemic or General Circulation
- Carries blood pumped out from the left ventricle around the body and returns it to the right atrium of the heart.
- Also known as general circulation or peripheral circulation.
- Supplies all tissues of the body except the lungs.
- Sequence: Left Ventricle of Heart → Aorta → Arteries → Arterioles → Capillaries → Venules → Veins → Vena Cave → Right Atrium of Heart.
Function of Circulation
- Transports nutrients to body tissues.
- Transports waste products away.
- Conducts hormones from one part of the body to another.
- Maintains an appropriate environment in all tissue fluids for optimal survival and function of cells.
Functional Parts of Circulation
Heart
- A roughly cone-shaped hollow muscular organ.
- About 10 cm long and the size of a person's fist.
- Weighs about 225g in women and heavier in men.
Arteries
- Carry oxygenated blood away from the heart (except pulmonary and umbilical arteries).
- Function: transport blood under high pressure to tissues.
- Have strong vascular walls and blood flows at a high velocity.
Arterioles
- Smaller branches of arteries delivering blood to capillaries.
- Play a key role in regulating blood flow from arteries into capillaries.
Capillaries
- Diffuse networks of blood vessels connecting arterioles and venules.
- Found in almost every cell in the body.
- Distribution varies with tissue activity (e.g., rich capillary supply in muscles, liver, kidneys, lungs, and nervous system).
Venules
- Connect capillaries with veins.
- Collect blood from capillaries and gradually combine into larger veins.
Veins
- Carry blood towards the heart (except pulmonary and umbilical veins).
Properties of Cardiac Muscle
- Two groups:
- Beating Heart: Automaticity, Rhythmicity, Contractibility, Excitability, Conductivity, Distensibility, Functional Syncitium, Long Refractory Period, Extrasystole & Compensatory Pause.
- Quiescent Heart: All Or None Law, The Staircase Phenomenon, Length-Tension Relationship, Summation Of Subminimal Stimuli.
Nature of Cardiac Muscle
- Involuntary in function and striated in appearance.
- Automaticity: capability of contracting even in the absence of neural control.
- Rhythmicity: heart beats are extremely regular.
- Contractibility: contracts in response to a stimulus in the presence of ATP and calcium ion.
- Excitability: ability to respond to different stimuli.
- Conductivity: transfer of cardiac impulses from the sinoatrial node to all cardiac muscle.
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Description
Test your knowledge of the circulation system, including pulmonary and systemic circulation, and the path of blood and lymph throughout the body.
