Cardiovascular (Circulatory) System

What is it? It is the network that delivers blood to the body’s tissues With each heartbeat, blood is sent throughout our bodies carrying oxygen and nutrients to all of our cells Every day, 10 pints of blood in your body travel through 60,000 miles of blood vessels that link the cells of our organs and body parts

What makes it up? The heart and blood vessels which include: Arteries Veins Capillaries

The Heart The heart is the key organ in the circulatory system It is a hollow, muscular pump that propels blood throughout the body It usually beats from 60-100 times per minute It beats about 100,000 times a day, more than 30 million times per year, and about 2.5 billions times in a 70-year lifetime

The Heart The heart gets messages from the body that tell it when to pump more of less blood depending on a person’s needs When we sleep, it pumps just enough to give us the lower amounts of oxygen needed by our resting bodies When we’re exercising or frightened, the heart pumps faster to get more oxygen to our bodies

Anatomy of the Heart The heart has four chambers The upper two chambers are the right and left atria They receive the blood entering the heart The bottom two chambers are the right and left ventricles They pump the blood out of the heart

Arteries Blood vessels carrying blood AWAY from the heart are called arteries They are the thickest blood vessels They have muscular walls that contract to keep the blood moving away from the heart and throughout the body There are two main arteries: Aorta: Carries oxygen rich blood Pulmonary Artery: Carries oxygen poor blood because it goes to the lungs to pick up oxygen

Veins Blood vessels that carry blood BACK to the heart are called veins They are not as muscular as arteries but they have valves that prevent blood from flowing backward The two largest veins are the: Superior vena cavae (located above the heart) Inferior vena cavae (located below the heart)

Capillaries A network of tiny capillaries connects the arteries and veins They are one of the most important parts of the circulatory system because they deliver nutrients and oxygen to cells Waste products, like carbon dioxide are removed by the capillaries

Interactions with Other Body Systems The circulatory system touches every organ and system in your body. It is connected to all of your body’s cells so that it can transport oxygen efficiently. When you breathe, the circulatory system carries oxygen to your cells and carries carbon dioxide back to the lungs for removal (exhale)

More Interactions The circulatory system is especially important to the digestive system The digestive system absorbs nutrients that your body needs from the food that you eat using the fluids from the circulatory system Hormones created by your endocrine system are sent through the body using the circulatory system, too!

Pathway of the Circulatory System Blood travels of to the heart (left ventricles), to the aorta which takes oxygen to every organ and tissue in the body then back to the right atrium The arteries, capillaries, and veins are all channels through which the blood flows throughout the body

Pathway In the capillaries, the bloodstream delivers oxygen and nutrients to the body’s cells and picks up waste materials Then it goes into the veins which brings the oxygen depleted blood back to right atrium. From the right atrium the blood fills the right ventricle and is ready to be pumped into the lungs to replenish its oxygen supply

Pathway through the lungs Blood low in oxygen and high in carbon dioxide is pumped out of the right ventricle into the pulmonary artery which has two branches The right branch goes to the right lung, and the left branch goes to the left lung In the lungs the branches divide into capillaries which interact with alveoli (tiny air sacs in the lung) to get oxygen This is called oxygenation!

Oxygenation Oxygen is taken up by the bloodstream Oxygen locks onto a molecule called hemoglobin in the red blood cells The newly oxygenated blood leaves the lungs and heads back to the heart Now it is ready to travel once again to all the organs and tissues of the body