The Circulatory System Unit 2 Notes The Circulatory System

Overview of the Circulatory System Cells need oxygen and nutrients in order to do their work They also need to get rid of waste The circulatory system is what allows the cell to exchange oxygen and nutrients and waste (it’s the body’s transport system)

Overview cont. The circulatory system is made up of: blood, the heart, blood vessels Blood carries substances to all parts of the body The heart pumps blood through a huge network of tubes inside your body called blood vessels

Blood Vessels Think of blood vessels like highways; they are a network of channels that circulate blood through the entire body and help keep the blood flowing to and from the heart There are 3 different kinds of blood vessels: arteries, capilaries, and veins (think – airplanes, cars and vans)

Arteries Arteries carry blood AWAY from the heart They are strong, and thick-walled so they are capable of withstanding high pressures exerted by blood as it’s pumped by the heart

Capillaries Arteries branch into smaller vessels called arterioles, which become smaller in diameter as they grow farther away from the main vessel Capillaries are small blood vessels where the exchange of important substances and waste occurs They are very thin – only 1 cell thick – so it’s easy to exchange materials between the blood and body cells through diffusion They’re so small that red blood cells move single-file through them, but they can expand if needed (when exercising for example)

Veins After blood moves through the capillaries, it enters larger vessels called venules, and then enters the largest blood vessels called veins. Veins carry oxygen-poor blood (deoxygenated) back to the heart (Your blood IS NOT BLUE) The walls of veins are thinner than arteries because there’s less pressure from the heart’s original pushing force *How can you tell if you’ve cut a vein or an artery?

Brain Break Draw the path that blood takes going away from, and then back into your heart, labeling each blood vessel that it travels through

The Heart This is a muscular organ that is about the size of your fist. It pumps blood through your body (pumps oxygenated blood to the body, and deoxygenated blood to the lungs) It’s made of cardiac muscle tissue

The Heart cont. It’s divided into four compartments called chambers The two on the top – left and right atrium or atria – receive blood that’s returning to the heart. Below the atria are the ventricles, which pump blood away from the heart A strong muscular wall separates the left and right side of the heart Valves separate the atria from the ventricles and keep blood flowing in one direction, and are also located between each ventricle and the large blood vessels that carry blood away from the heart

Brain Break Draw and Label the chambers of the heart

How the heart beats The heart acts in two main phases: 1st, the atria fill with blood. The atria contract, which fills the ventricles with blood 2nd, the ventricles contract to pump blood out of the heart and into the lungs, and forward into the body

Heart beat cont. A group of cells in the right atrium, called the pacemaker (or sinoatrial- SA- node) send out signals that tell the heart muscle to contract. (each year 600,000 pacemakers are implanted into people – the battery usually lasts 5 to 8 years and needs to be monitored frequently) Your heart beats about 70 times a minute To calculate your heart beat, find your pulse on your wrist below your thumb. Count the number of beats you feel in 15 seconds, then multiply that number by 4 (to get beats per minute)

Blood Pressure Blood pressure is a measure of how much pressure is exerted against the vessel walls by the blood and can give information about the condition of the arteries The contraction of the heart (systolic pressure) is when your blood pressure is at its highest point The relaxation of the heart (diastolic pressure) is the lowest point Anyone know ideal blood pressure?

Blood flow in the body Blood flows in 2 loops – First, the right side pumps deoxygenated blood from the heart to the lungs and then back to the heart. Then, the left side pumps oxygenated blood in another loop from the heart through the body and back. A detailed list of bloods path: Superior and inferior vena cava –right atrium – through the AV (or tricuspid valve) -right ventricle – through the semilunar valve - pulmonary arteries (away from heart) – lungs – pulmonary veins (returning to heart) – left atrium – left AV valve - left ventricle – aorta – body

To the lungs and back When blood from the body flows into the right atrium, it’s low on oxygen and high in carbon dioxide (this blood is not blue, it’s dark red) The blood flows from the right atrium into the right ventricle and is pumped into the pulmonary arteries that lead to the lungs The blood flows into capillaries in the lungs that are in close contact with the air that enters the lungs The air in the lungs has more oxygen than the blood in the capillaries, so it diffuses into the blood while carbon dioxide diffuses in the opposite direction, into the lungs. The newly oxygenated blood goes to the left atrium of the heart to be pumped out to the body

To the body and back The left atrium fills with oxygenated blood from the lungs, which begins the second loop The blood moves from the left atrium into the left ventricle, which pumps the blood into the largest artery in the body called the aorta Blood flows into the capillaries that branch throughout the body, which are in close contact with body cells Oxygen is released from the blood into the body cells by diffusion and carbon dioxide moves from the cells to the blood by diffusion The deoxygenated blood then flows back to the right atrium through veins

Heart simulation activity AND THEN drawing activity Brain Break Heart simulation activity AND THEN drawing activity

Blood Components Blood is made of plasma, red and white blood cells, and platelets Plasma is a clear, yellowish fluid part of the blood (makes up more than 50% of the blood) 90% of plasma is water, and the rest is dissolved material Plasma carries glucose, fats, vitamins, minerals, hormones, and waste products Plasma is made of proteins (one of your macromolecules) that help regulate water, fight disease, and form blood clots

Blood components cont. Red blood cells carry oxygen to all of the cells in the body Made in the bone marrow They only live about 120 days Made mostly of an iron-containing protein called hemoglobin (it’s what gives blood its taste)

Platelets Platelets are cell fragments that help form blood clots If a blood vessel is cut, then the platelets stick to the vessel at the site of the wound then release chemicals that produce a protein called fibrin Fibrin weaves fibers across the cut These fibers trap blood platelets and red blood cells, which forms a blood clot

White blood cells White blood cells are the body’s disease fighters Also made in the bone marrow Some recognize disease-causing organisms (like bacteria) and alert the body, while others surround and fight them There are fewer of these than red blood cells – about one for every 500 to 1000 They live longer then red blood cells; they can live for many months, or even years

Blood Groups There are marker molecules attached to red blood cells (called blood groups); they determine blood type

Blood groups cont. There are 4 types of blood – A, B, AB, and O If you ever need a blood transfusion, you can only receive certain blood types because plasma contains proteins called antibodies that recognize red blood cells with foreign markers and cause those cells to clump together Ex – if you have blood type B, your blood contains antibodies that cause cells with A marker to clump; this can block blood flow O is the universal donor AB is the universal receiver

Blood groups cont. Rh factor is another marker found on the surface of red blood cells If someone with Rh-negative blood (no Rh factor) receives a transfusion of Rh-positive blood that has the Rh marker, it can result in clumping of red blood cells because of the antibodies against Rh-positive cells It can cause complications during some pregnancies (if the Rh-positive blood of a fetus mixes with the mothers Rh-negative blood, the mother will make anti-Rh antibodies. If the mother becomes pregnant again, these antibodies can cross the placenta dn destroy red blood cells if the fetus has Rh-positive blood) *may have been a problem for Ann Boelyn

Circulatory system disorders Atherosclerosis – blocked arteries caused by blood clots or fat deposits which reduce the flow of oxygen and nutrient-rich blood traveling through the arteries. The heart has to work even harder to pump blood and vessels can burst Can lead to a heart attack or stroke Heart attacks occur when blood doesn’t reach the heart muscle Strokes are caused when clots form in the blood vessels that supply oxygen to the brain, which can lead to ruptured blood vessels and internal bleeding (parts of the brain die because brain cells are deprived of oxygen)