Circulatory System

The Circulatory System Made up of 3 main parts: heart, blood, and blood vessels Functions of the body’s delivery system Delivers oxygen, nutrients, hormones, water, etc. throughout the body, and removing waste.

Components of Blood Plasma: colorless liquid that makes up most of the blood Red blood cells: actually make the blood look red They deliver oxygen to cells throughout the body White blood cells: part of immune system Platelets: help with clotting and repair after injury

Plasma Plasma is the liquid component of your blood Plasma makes up just about half your blood Contains proteins, minerals, and sugars your cells use as nutrients as well Since this is the liquid aspect of your blood, this is what actually carries things like the red blood cells, platelets, white blood cells, etc. Plasma is made in the liver Yet another reason why you don’t want to drink so much you get a cirrhotic liver 

Red Blood Cells AKA Erythrocytes Carry oxygen and carbon dioxide Oxygen from lungs diffuses into hemoglobin of RBC deliver it to all the cells in the body Once O2 is dropped off, RBCs pick up the carbon dioxide waste produced in cellular respiration CO2 is transported back to the lungs where gas exchange occurs and you breathe it out Crazy fact: there are roughly 5,000,000 RBCs in ONE drop of blood!!

White Blood Cells AKA Leukocytes about 1% blood's volume lymphocytes are a major part of the immune system granulocytes and macrophages protect our bodies from infection by surrounding and destroying bacteria, viruses, fungi, or other parasites. They also have the function of getting rid of old, unneeded blood cells as well as foreign matter such as dust and asbestos.

Platelets AKA Thrombocytes Blood cells that help stop bleeding Platelets stick to the sides of ruptured areas in blood vessels to block blood from leaving the vessel This is eventually what forms a scab, which we will learn about next!

Coagulation When a vessel gets ruptured in some way, platelets are the first responders Platelets gather at the opening of the blood vessel These platelets send out a chemical message that attracts other platelets, so the opening of the blood vessel starts becoming filled with platelets This aggregation of platelets attracts other clotting factors like fibrin and thrombin

Scabs The fibrin forms a mesh-like net over the opening and traps red blood cells as they try to leak out of the cut. As the clot hardens, it forms a protective seal over the cut. This is a scab!

Blood Vessels 3 Types: Arteries are blood vessels that carry oxygen rich blood AWAY from the heart. Aorta is the largest, Arterioles are the smallest They contain muscular walls (smooth muscle) that contract to aid in blood movement.

Capillaries are smallest blood vessels as thin or thinner than the hairs on your head. Capillaries connect arteries to veins. Food substances (nutrients), oxygen and wastes pass in and out of your blood through the capillary walls. Veins carry blood back toward your heart. They contain valves to prevent backflow (due to gravity) Vena Cava are largest, Venules are smallest

Human Heart Facts Women hearts beat faster than men. Three years after a person quits smoking, their chance of having a heart attack is the same as someone who has never smoked before. The human heart weighs less than a pound. The human heart can create enough pressure that it could squirt blood at a distance of thirty feet. The right lung of a human is larger than the left one. This is because of the space and placement of the heart. The human heart beats roughly 35 million times a year. In a lifetime, the heart pumps about one million barrels of blood.

Structures of the Heart The heart has 2 sides, a left and a right 4 chambers: 2 atrium and 2 ventricles The atrium are located next to each other in the top half (base) of the heart while the ventricles are located next to each other in the bottom half (apex) of the heart

Valves There are 4 valves in the heart to prevent backflow: tricuspid valve connects the right halves of the heart; bicuspid valve or Mitral connects the left halves of the heart Pulmonary valve leads to the lungs Aortic valve leads to body

Main Veins and Arteries of the Heart Aorta: the large artery coming out of the heart Brings nutrient rich/oxygenated blood from the heart to the rest of the body Pulmonary artery/trunk: connects the heart to the lungs, brings blood from the heart to the lungs to get oxygenated This is the only artery that carries DEOXYGENATED blood!!

Pulmonary veins: bring the oxygenated blood back into the heart Vena Cava: “Heart’s Veins” Superior: brings blood in to the heart from the upper half of the body Inferior: brings blood in to the heart from the lower half of the body; is located beneath the superior

Blood Flow through the Heart Right side: First the deoxygenated blood enters the heart through the inferior and superior vena cava Flows into the right atrium From the right atrium, it passes through the tricuspid valve and then into the right ventricle The blood is then pumped through the pulmonary valve into the pulmonary artery and into the lungs

Once in the lungs, carbon dioxide is removed and oxygen is added to the blood.

Left side: The pulmonary vein empties oxygen-rich blood, from the lungs, into the left atrium. From here, the blood flows from your left atrium into your left ventricle through the open bicuspid valve Finally, it is pumped through the aortic valve into the aorta - the blood vessel that feeds all of the other parts of your body.

This website animates the flow of blood through the heart http://www.heartpoint.com/theheart.html

Lub-Dub “Lub” The atria and ventricles work together by alternately contracting (squeezing) and relaxing to pump blood through your heart Blood initially comes into your right atrium, so this fills with blood This causes the tricuspid valve to open so the blood can flow to the right ventricle At the same time, the oxygenated blood from the lungs is coming into the left atrium This causes the bicuspid valve to open so blood can flow to the left ventricle As soon as the atria are empty, the tri- and bi- cuspid valves must close very quickly This is what makes the “Lub” sound

Lub-Dub “Dub” Once the right ventricle is filled with blood, this causes the pulmonary valve to open so that blood can flow to the lungs At the same time, blood from the left ventricle passes through the aortic valve to go into the aorta and then through the rest of the body Once the blood is out of the heart, either to the lungs or the aorta, these valves must snap close to that blood doesn’t get back into the heart This is the “Dub” sound

Heart Conduction The heart must contract in an orderly manner…have rhythm In the top right atrium, there is a bundle of neurons called the Sinoatrial (SA) node This is the heart’s natural pacemaker that fires at regular intervals, telling the heart when to beat It sends an electrical impulse down the heart, triggering a sequence of electrical events

Heart Conduction cont… The SA node passes this electrical signal through the atria, and then to the Atrioventricular (AV) node, which passes the signal to the ventricles Wave of contraction (electrical event): atria first, then ventricles.