Blood and Breathing: circulatory and respiratory systems  Two connected organ systems that depend on each other

Circulatory System is a Transport System: The Bloody Bus  Function of the system: To transport blood carrying oxygen, nutrients, wastes, hormones, proteins, red blood cells (RBCs), white blood cells (WBCs) to and from cells of the body.  How is blood transported?  Where is blood transported?

Function of the Circulatory System  Main function: to transport “stuff”  Circulate oxygen and nutrients to body cells.  Circulate carbon dioxide and wastes out of body.  Circulate hormones and chemicals to body places that need them.  Circulate immune systems components.

What is blood made of? Water: blood is 95% water plasma, a yellowish liquid, mostly water, that carries blood cells, nutrients, hormones, and proteins red blood cells, carry oxygen throughout the body using hemoglobin molecules white blood cells, fight infections platelets, cells that help you stop bleeding if you get a cut

Blood is mostly plasma and RBCs.

Red Blood Cells RBC’s carry oxygen from lungs or gills to all body tissues. Oxygen chemically attaches to hemoglobin molecules in RBC’s.

What’s the best way to transport materials?

Two ways to solve the transport problem  1. “slosh the blood over the organs”  The “open” circulatory system  2. efficiently take blood to exactly where it needs to go  The “closed system” of blood vessels.

Open Systems  Occur in insects, crabs, clams, etc.  Blood dumps into organ-filled spaces in body  Drains back to heart  It’s leaky and there’s little pressure

Closed Circulatory Systems  A system of tubes carries blood under pressure, pumped by heart  No leakage  Blood transported directly to tissues that need it

Mammal Circulatory System  Two vessel “circuits” in one  Pulmonary circulation: heart to lungs  Systemic circulation: heart to body

Pulmonary circulation, Systemic circulation

Where blood goes.

Circulatory System: a network of tubes  Analogy  Super highway, arterial, large street, side street, alley, sidewalk, door

Blood Vessels  Away from heart to body or lungs  Arteries: high pressure, thick walled  Usually it’s oxygenated  Towards heart from body or lungs  Veins: lower pressure, with valves to stop back flow  Usually it’s deoxygenated  Capillaries: connect arteries and veins  Narrow tubes, one RBC at a time  Distribute oxygen and nutrients  Collect carbon dioxide, wastes

Arteries: carry blood away from the heart 1.Arteries carry blood away from the heart, most of it oxygenated. 2. Arteries have thicker and stronger walls than veins. (Why is that? Think Form Follows Function) 3. The main artery coming out of the heart is the AORTA, which then branches to supply other regions and organs. 4. PULMONARY ARTERY carries deoxygenated blood to the lungs. Arteries: not only to the body!

Most is deoxygenated blood. Pulmonary Vein carries oxygenated blood from lungs to heart. Contain one-way valves to prevent backflow and to assist the heart in moving the blood back to the lungs to be oxygenated. E.g., Without valves, blood would flow back down to your feet! Veins are blue in this picture. Veins: carry blood to the heart

The blood pump: the heart  Very muscular organ  Needs to move 4-6 liters of blood, constantly.  The heart beats times per minute at rest and can beat as fast as 200 beats per minute when exercising.  The heart beats about 3 billion times during an average lifetime (100,000 times per day).

Structure and Function of the Heart 1) RIGHT ATRIUM receives blood from all the organs except the LUNGS through two large veins called the SUPERIOR VENA CAVA and INFERIOR VENA CAVA. 2) it passes this oxygen-poor blood to the RIGHT VENTRICLE, which then pumps the blood through the PULMONARY ARTERY. 3) the PULMONARY ARTERY brings the blood to the lungs where it picks up oxygen from the air you breathe in. 4) this oxygen rich blood is returned to the LEFT ATRIUM of the heart by way of the PULMONARY VEINS. 5) this blood passes from the LEFT ATRIUM into the LEFT VENTRICLE to be pumped out to the rest of the body through the AORTA.

Controlling the heart rhythm: The Cardiac Cycle  Controlled by electrical impulses.  The Cycle includes the events from the beginning of one heartbeat to the beginning of the next.  Cycle frequency = heart rate or pulse rate  Diastole (rhymes with potentially): the period when chamber muscles relax and blood flows into atria or ventricles  Systole : the period when chamber muscles contract and blood flows out of atria or ventricles.

Sounds of the heart: lub-dub, lub-dub  “lub” is sound of mitral and tricuspid valve closure  “dub” is sound of aortic and pulmonary valve closure  ml ml

Comparative Anatomy  Fish  Reptiles and amphibians  Mammals

Ways to organize circulatory system: circulation in fish, amphibians, and some reptiles

Gills are inside out lungs!  Gills: oxygen dissolved in water diffuses into blood  Lungs: oxygen from air diffuses into blood

The Three-Chambered Amphibian Heart  How does this function differently from the mammalian four-chambered heart?  Can you think of any problems with this type of circulatory system?