Circulatory System Facts about the heart n Though

Circulatory System

Facts about the heart n Though weighing only 11 ounces on average, a healthy heart pumps 2, 000 gallons of blood through 60, 000 miles of blood vessels each day. n Every day, the heart creates enough energy to drive a truck 20 miles. In a lifetime, that is equivalent to driving to the moon and back. n 5% of blood supplies the heart, 15 -20% goes to the brain and central nervous system, 22% goes to the kidneys, and the remainder is spread throughout other organs.

Functions 1. Carries needed substances (nutrients/oxygen) to cells and waste products (carbon dioxide/urea) away from cells 1. Blood contains cells to help fight disease ¨ These functions help maintain homeostasis

How it works – Circulatory System - Video

Major Organs Heart (most important) n Blood vessels n Blood n

The Heart It is a hollow organ about the size of your fist made of cardiac muscle. n Located in the center of your chest slightly to the left n Each time the heart beats it pumps/pushes blood throughout the body n

Heart Structure n Atrium ¨ 2 upper chambers that receives blood that comes into the heart n Ventricle ¨ 2 lower chambers that pumps blood out of the heart n Valve ¨ flap of tissue that prevents blood from flowing backwards n Septum ¨ Muscular wall that separates the left & right

Pacemaker n Pacemaker - located in the right atrium; sends out signals that make the heart muscle contract

Three Types of Blood Vessels n Arteries are blood vessels that carry oxygen rich blood AWAY from the heart. Remember: A A - Arteries Away n Veins carry blood BACK toward your heart. n Capillaries are tiny blood vessels as thin or thinner than the hairs on your head. Capillaries connect arteries to veins for gas exchange.

Vena Cavas - Veins n Superior Vena Cava is the large vein which returns blood to the heart from the upper body (head, neck and both upper limbs) n Inferior Vena Cava returns blood to the heart from the lower body.

Did you know? ? ? Blood is actually a connective tissue. n The right atrium holds about 3. 5 tablespoons of blood. The right ventricle holds slightly more than a quarter cup of blood. The left atrium holds the same amount of blood as the right, but its walls are three times thicker. n

Functions of the Atria and Ventricles n Right atrium- receives blood from the body. The blood is low in oxygen and high in waste product carbon dioxide. n Right ventricle- the right ventricle contracts, it pumps oxygen-poor blood to the lungs (to leave CO 2 & get O) n Left atrium-oxygen-rich blood comes from the lungs n Left ventricle- the left ventricle contracts and pumps oxygen-rich blood to all parts of the body through the aorta (the largest artery in the body)

Word Meanings…in Latin Atrium - entrance hall Ventricle - little belly

Superior Vena Cava Blue color represents oxygen-poor blood coming from the body to the heart. Inferior Vena Cava Red color represents oxygen-rich blood coming from the lungs to go out to the body

Order of the Circulatory System 1. Oxygen-poor blood moves from the body through large veins called the Superior Vena Cava or Inferior Vena Cava to the right atrium then through a valve into the right ventricle. 2. It is pumped from the right ventricle into the lungs, where it picks up oxygen and leaves carbon dioxide. 3. The now oxygen-rich blood moves from the lungs into the left atrium. 4. It again passes through a valve into the left ventricle, where it is pumped through the aorta to the rest of the body.

5. The aorta branches off into more and more arteries, which eventually branch off into tiny capillaries to carry the blood to all of the organs. 6. The capillaries leave oxygen and other nutrients behind and pick up carbon dioxide and other wastes. 7. After moving through capillaries, the now oxygen-poor blood moves into larger and larger veins (the Superior Vena Cava or Inferior Vena Cava) , which carry the blood back to the right atrium of the heart to begin the cycle again.