The Circulatory System The Heart Pathway of Blood

The Circulatory System The Heart & Pathway of Blood Chapter 37 -1 pp. 943 - 948

Function of the Circulatory System n Transport of nutrients, oxygen, carbon dioxide, and wastes around your body n The heart, blood, and blood vessels each have a part in accomplishing this.

The Heart n. Hollow organ composed of muscle n. Muscle contractions pump blood around the body

The heart has two halves, the left and the right. The halves are identified if you were looking at someone else’s heart. The septum divides the heart in half. It prevents the blood with oxygen from mixing with the blood with carbon dioxide Each half of the heart has two chambers, so the heart has 4 chambers total.

n Atria (Atrium is singluar) – Top chambers – Take the blood in from the body – Pump blood into the ventricles. n Ventricles – Bottom chambers – Take in the blood from the atria – Pump blood out to the body. – Larger than the atria because they are pumping the blood to the whole body.

Heart Valves n The atria and ventricles are separated by valves, which prevent the blood from flowing into the ventricles prematurely or flowing back into the atria n Valves improve the efficiency of the heart, and allow the blood to flow in only one direction.

Why does the heart need 4 chambers? n The blood flow in the body and the heart is in one direction n Oxygenated blood should not mix with blood carrying carbon dioxide to be efficient The four chambers allow the blood from the lungs (with oxygen) not to mix with blood from the body (with carbon dioxide).

In diagrams: n Blue means the blood has carbon dioxide and no oxygen n Red means that the blood has oxygen and no carbon dioxide

The left and right sides of the heart have different functions n The left side of the heart: – takes in oxygenated blood – pumps it to the body cells. n The right side of the heart: – takes in blood with carbon dioxide (deoxygenated) – pumps it to the lungs to get oxygenated. The blood passes through each side once during each trip through the body. n The left ventricle has a larger area to pump to so it is larger than the right ventricle n

Video Clips: How the heart works (2 min) The heart and its parts (4 min)

Animations n Animation 1 n http: //www. bostonscientifi c. com/templatedata/impor ts/HTML/CRM/heart_ bloodflow. html

Starting with the right atrium, what is the path that blood takes through the heart and body? Does it have carbon dioxide or oxygen in it? Where is it going? Step Part CO 2 or O 2 Where Next? 1 Right Atrium CO 2 Right Ventricle CO 2 Lungs 3 Lungs Exchange Left Atrium 4 Left Atrium O 2 Left Ventricle 5 Left Ventricle O 2 Body 6 Body Exchange Right Atrium

Heartbeat Each cycle of the heart’s contractions is a heartbeat • Each heartbeat consists of two contractions – 1. The atria contacting and squeezing blood into the ventricles – 2. The ventricles contracting and squeezing blood out to the body/lungs • n Heart Contraction Animation

Pulse n Your pulse measures how fast your heart is pumping blood. – Your pulse is the measure of how fast your VENTRICLES are pumping the blood to the body n Your pulse can increase or decrease depending on your body’s need for oxygen -rich blood

Blood Pressure