CIRCULATORY SYSTEM

Dr Rita Chávez PuenteCIE-MGA

QUIZZ

• 1. PLEASE WRITE THE PATHWAYS OXGYEN PASSES ON ITS WAY INTO THE ALVEOLI.

• 2. WRITE THE FUNCTION AND ANATOMICAL STRUCTURE OF THE NOSE.

• 3. EXPLAIN THE RESPIRATORY PROCESS IN FISH.• 4. WHAT DOES THE DIAPHRAGM MUSCLE DO?• 5. WHAT IS THE EPIGLOTIS, WHERE IS IT

LOCATED AND WHAT IS ITS FUNCTION?

The System for Transporting Gases

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• Your heart beats with about the strength it takes to squeeze a tennis ball. Squeeze a tennis ball and see how hard that is. Now think what it must be like for your heart to do this 70 times a minute, 60 minutes an hour, 24 hours a day - for a lifetime!

• The Circulatory System • The heart, the blood, and the blood vessels make up a system

for the transport of gases, nutrients, and chemical wastes. The primary functions of the circulatory system are the following:

1. To transport nutrients and oxygen to the cells. 2. To remove waste and carbon dioxide from the cells. 3. To provide for efficient gas exchange.

• Blood vessels allow oxygenated blood and nutrients to reach the tissues and wastes to be removed from the tissues.

• The blood is the medium that carries oxygen and nutrients to the tissue and is also the medium by which waste is transported to the appropriate locations.

The Heart

Blood Vessels

• There are three basic types of blood vessels:• 1. Arteries- these carry "oxygen rich" blood

away from the heart, except in the case of the artery to the lungs.

• 2. Capillaries- these are the sites of gas exchange between the tissues.

• 3. Veins- these return "oxygen poor" blood to the heart, except for the vein that carries blood from the lungs.

• The capillaries have very thin walls and there are many of them.

• Why do you think this is?• Why are the capillaries shown with two

different colors?• Why is the vein shown as blue?

• http://www.youtube.com/watch?v=H04d3rJCLCE

Blood Flow

• For gas exchange to occur in the lungs and the rest of the body's tissues, blood must flow continuously through the tissues.

• The heart pushes blood through the tissues and provides a constant force for blood flow to occur.

• The heart provides enough force to propel the blood through the arteries and veins in the body.

• The arteries entering tissues, called arterioles, can constrict (become more narrow) or dilate (become relaxed and less narrow) to change the amount of blood flowing to an area.

• If an arteriole constricts, less blood is available for the tissues it supplies.

• If an arteriole dilates, more blood reaches the tissues it supplies.

• Why is it useful for the arteries to change size?• Can you think of situations where certain

tissues may need more or less blood flow?

Blood Pressure

• Blood pressure is a measure of the force needed for blood to move through the tissues.

• This pressure depends on the amount of blood in the body, the diameter of the blood vessels, and how hard the heart is pumping blood.

• Resistance in the circulatory system is caused by the blood rubbing against the walls of the blood vessels as it flows through them. This rubbing produces a force, called resistance, opposite the blood flow.

• A large vessel is less resistant than a small blood vessel because relatively less blood rubs against the walls of the blood vessel, while a small blood vessel is more resistant because it has a smaller area for the blood to flow through.

• This means that more blood rubs against the walls of the vessel and it slows blood flow.

• In any one capillary, this resistance is an advantage because the slowed blood flow has more time for gas exchange to occur.

• When an arteriole dilates, the diameter almost doubles.

• When a vessel's diameter increases, the blood flow increases by four times the original amount.

WRITE AND ANSWER

• Is it better for the heart to work less to move blood through the tissues? Why?

• What happens to blood flow if the heart is not working hard enough?

• When the blood pressure in the body is elevated, the heart must work very hard to provide adequate blood flow to the tissues.

• Many people have blood pressure that is too high (called hypertension.)

• One known cause of hypertension is atherosclerosis.

• Atherosclerosis is a condition in which the walls of the blood vessels become thick and stiff, reducing their flexibility and ability to dilate.

• http://www.youtube.com/watch?v=xnyfElxkBlI

ATHEROSCLEROSIS

• http://www.youtube.com/watch?v=M0NF2ODfd9E