The Circulatory System Chapter 16

n Right side of the heart n Lungs (here it gets oxygen) n Left side of the heart n Body (here it drops off the oxygen) Blood moves like this....

Cardiovascular System n Also called the Circulatory System n Made up of: u Heart u Blood u Blood vessels

How Do Blood and Air Travel? n Blood is liquid tissue. n The heart is the main organ that makes up the circulatory system. n You’re not writing anything from this slide.

It is the job of the Circulatory System to move blood through blood vessels to the body’s cells. n You’re not writing anything from this slide.

Blood Carries these things to your body’s cells… n Food n Oxygen n Water

Interesting Facts…..(no you don’t have to write this)… n Sponges and cnidarians don’t have a circulatory system. n Insects and other invertebrates have open circulatory systems.

All vertebrates have a closed circulatory system. n Some invertebrates such as earthworms also have a closed circulatory system. u This means the blood travels through tubes called blood vessels. u The blood vessels carry blood to the heart. n You’re not writing anything from this slide.

Each time the heart beats… It pushes blood through the blood vessels of the cardiovascular system

The most complex animals, mammals, have hearts with four chambers. n Atrium Atrium n Ventricle Ventricle n Get ready to write again…

Upper Chambers n Left and right atrium n There are two n Their job is to receive blood that comes from the body

Lower Chambers Left and right ventricle There are two Their job is to pump blood out of the heart

More Parts of the Heart n VALVES – flaps of tissue that prevent blood from flowing backward n PACEMAKER – group of cells that adjusts the speed of the heart beat u Found in the right atrium

n When blood flows through the heart, the force that pushes blood out of the heart and into the arteries is... the contraction of the ventricles

Two Loops n The three kinds of blood vessels are: u Veins u Arteries u Capillaries

What about the capillaries? This is what connects the arteries and the veins. It is where diffusion happens. Remember diffusion??? The movement of molecules from more to less crowed areas. We’ll talk about this more later.

non-oxygenated Pathway of non-oxygenated blood Blood without oxygen enters the : Vena Cava → Right atrium → Tricuspid Valve → Right ventricle → Pulmonary Valve → Artery → Lungs u In lungs, blood picks up O2 and releases CO2.  Then O2 rich blood returns to the heart

Arteries n Arteries carry blood away from the heart

Arteries Made of Three Layers n inner layer --epithelial cells n middle layer -- muscle tissue outer wall -- flexible connective tissue.

Major Arteries n Aorta – largest artery in the body. Carries blood from the heart to the rest of the body. n Coronary Arteries – bring blood to the heart

More Artery Info n Pulse is caused by the expanding and narrowing of artery walls. n When you count pulse beats, you are also counting heartbeats. n Arteries control the amount of blood that different organs receive.

Capillaries n In capillaries, CO2 and O2 are exchanged between the blood and the body’s cells n This happens by diffusion

Main Job of the Veins… u Veins carry blood back to the ♥ F Since most are carrying waste they are purplish/bluish in color F The walls are very thin which is why you can see the color through your skin.

Main Job of the Veins… u Veins carry blood back to the ♥ F Walls of veins are generally thinner than arteries. F Because of this… you can see the color through your skin Since most are carrying waste they are purplish/bluish in color.

What keeps blood moving? – 3 things… n contraction of nearby skeletal muscles n valves that prevent blood from flowing backward u The vein valves are necessary to keep blood flowing toward the heart, but they’re also necessary to allow blood to flow against the force of gravity. For example, blood that is returning to the heart from the foot has to be able to flow up the leg. Generally, the force of gravity would discourage that from happening. The vein valves, however, provide footholds for the blood as it climbs its way up. n breathing movements that squeeze veins in the chest

Blood Pressure n Blood pressure is the pressure that blood exerts against the walls of the blood vessels. n As blood moves away from the heart, the blood pressure decreases. n The instrument that measures blood pressure is a sphygmomanometer.

Superior vena cava Inferior vena cava septum Pulmonary veins & valves aren’t shown here