The Circulatory System
Some Fun Facts The left side of the heart contains oxygenated blood whereas the right side has de-oxygenated blood. One drop of blood has about 5 million red blood cells and 12 thousand white blood cells. The heartbeats about 30-35 million times in 365 days. 10 million blood cells die in the human body every second, the same quantity is produced at the same time. Blood circulates the entire body in 20 seconds. An average heart pumps about 450 gallons of blood everyday.
Some Fun Facts One of the surprising circulatory system facts is that the heartbeat is the sound of the valves opening and closing. An average adult's body has about 5 liters of blood in it and a baby's body has about 1 liter of blood in it. A human heart is a muscle which is the size of a clenched fist. Blood cells die every 4 months. The plasma in the blood is made in the liver. One of the amazing facts of circulatory system is that the heart continues to beat even when it is taken out of the body!
The Circulatory System The heart and circulatory system (also called the cardiovascular system) make up 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, the approximately 5 liters of blood in your body travel many times through about 60,000 miles (96,560 kilometers) of blood vessels that branch and cross, linking the cells of our organs and body parts. From the hard-working heart, to our thickest arteries, to capillaries so thin that they can only be seen through a microscope, the cardiovascular system is our body's lifeline.
Components of the Circulatory System Blood Blood Vessels Arteries Veins Capillaries Heart
What is Blood?
What is Blood? Plasma Blood Cells RBC WBC Platelets Blood Types Blood Cell Disorders Blood: http://www.youtube.com/watch?v=r-skzwqsupw&feature=related
Review Last Class Why is the Circulatory System so important? What are the three components of the circulatory system? What are the four components of Blood?
What did we learn? What is Plasma? What are Red Blood Cells? What do they do? What are White Blood Cells? What are Platelets?
Plasma: Primarily made up of water and over 100 dissolved solutes such as nutrients, gases, hormones, ions, and proteins. Erythrocytes: Look like miniature doughnuts (concave shape) Have a plasma membrane but lack a nucleus Carry oxygen and some carbon dioxide Mostly hemoglobin (molecule that binds to and transports gases) The formation of blood cells occurs in red bone marrow.
Leukocytes: White blood cells Complete cells with nuclei and organelles Crucial in defense against diseases Platelets: Essential in clotting process; stick to the damaged site and seal the break
Antigens An antigen is a substance that can stimulate the body to make antibodies. Antigens can be found on the surface of RBCs, or they can enter the body through an infection or transfusion. In this case, the antigen is foreign and will illicit an immune response from the body.
Antibodies An antibody is made by the body in response to an antigen. These are made by the WBCs and are found floating in the plasma of blood. Antibodies generally react with their antigens to agglutinate them (cause antigens to stick together; clump). In the human body, you produce the opposite antibody to your antigen. Example: Type A Blood Carry A antigens, and produce B antibodies (we will see more of this in just a little while!)
Blood Types Blood type is determined by the presence or absence of certain antigens on the red blood cells. There are two kinds of antigens: A and B If antigen A is present, then the individual is said to have Type A blood. Similarly, someone with whose red blood cells have antigen B on them are said to have Type B blood.
Question: What about Type AB? What about Type O?
Antigens and Antibodies The antibodies found in the blood plasma of a person with a particular blood type are always the opposite of their antigen. Example: Type A blood contains the A antigen but the B antibody Type AB blood contains both antigens but neither antibody Type O blood contains no antigens but possesses both the A and B antibody
RECAP: Antibodies and Antigens Your body does not make antibodies to the type of antigen you have because you were born with it. Problems will occur if the antigens on a donor s red blood cells become agglutinated with antibodies in the recipient s plasma. (Does not occur the other way around) Therefore, Type O is the universal donor (no antigens present) Type AB is the universal recipient (no antibodies present)
Types of Blood Antigens Present on RBC Antibodies Present in Blood Plasma Blood Types A A B B B A AB AB --- O -- AB
Why are these combinations so important? If antigens and antibodies of the same type come together, the antibodies cause the RBCs to clump together. If two samples of blood of the same type mix together, no clumping occurs. If incorrect matching of blood during a transfusion occurs, the results could be fatal. Before a transfusion occurs, the recipient s blood is always tested with the donor s blood. This is called typing.
Blood Transfusions Before a Transfusion, you must test for compatibility: Establish that the mixing of blood will not cause clumping, otherwise this can cause a blockage in an artery. Blood Typing: A sample of blood is mixed with a drop of concentrated serum containing A antibodies. Another sample of blood is mixed with a serum containing B antibodies. The presence or lack of clumping will tell you what blood type you have!
Let s try and figure this out: Sample Mixed with Anti-A Antibodies Sample Mixed with Anti-B Antibodies Sample Mixed with Rh Serum No clumping No clumping Clumping No clumping Clumping No Clumping Clumping No clumping Clumping Clumping Clumping No clumping Antigens Present in RBCs Blood Type
Let s try and figure this out: Sample Mixed with Anti-A Antibodies Sample Mixed with Anti-B Antibodies Antigens Present in RBCs Blood Type No clumping No clumping None O No clumping Clumping B B Clumping No clumping A A Clumping Clumping AB AB
Blood Transfusions Check this out: http://www.youtube.com/watch?v=zuhdnt KBBKg
The Rh Factor The Rh factor is an antigen found on the red blood cells of most people. Genetically inherited Present in approximately 85% of the Canadian population
Rh Factor Each of the four blood types is additionally classified according to the presence of another protein on the surface of RBCs that indicates the Rh factor. If you carry this protein, you are Rh positive. If you don't carry the protein, you are Rh negative.
Rh factor and Pregnancy Other than during a blood transfusion, the other time the Rh factor can be a problem is during pregnancy. It is only an issue if the Mom is Rh negative and she becomes pregnant with an Rh positive baby.
Rh Incompatibility The mother s body can recognize the Rh positive factor in the baby s blood as foreign and it can stimulate an antibody response in the mother. This does not normally happen in the first pregnancy because mother and baby s blood do not normally mix until delivery. It will however be an issue for a second pregnancy.
Rh Incompatibility If a woman who is Rh negative and a man who is Rh positive conceive a baby, there is the potential for a baby to have a health problem. A new born whose Rh factor differs from its mother can develop Rh incompatibility or Hemolytic Disease of the New Born (HDN) This can cause clumping of the baby s RBCs, a lose in hemoglobin (cells unable to carry oxygen), massive swelling of tissues, or death. Treatment: Rh immune globulin prevents the formation of Rh antibodies http://www.rhophylac.com/about-hdn/about-hdn.aspx
Are you ready to transfuse? Let s see how much you learned today about blood types and blood transfusions! http://nobelprize.org/educational_games/m edicine/landsteiner/index.html
The Heart and Blood Vessels The heart is a transport system pump that propels blood into the interconnecting blood vessels that move to and past the body cells Blood vessels form a closed delivery system that begins and ends at the heart (the circulatory system!) Dynamic: pulsate, constrict, and relax There are three major types of blood vessels
Moving Blood Throughout the Body: The Circulatory System Arteries Blood vessels that carry oxygen rich blood away from the heart. Capillaries A network of tiny blood vessels that connect the arteries with the veins. Veins Blood vessels that carry oxygen poor blood back to the heart.
Arteries Arteries are vessels that carry oxygen rich blood from the heart to other body tissues/organs. Arterioles are simply small arteries. Arterioles deliver the blood to the capillaries. Structure: The walls of arteries are thick and contain a layer of muscle. When blood is pumped out of the heart, it is forced out under high pressure. These muscular arteries are also elastic and stretch to accommodate this wave of pressure that is being pushed along. Colour of blood in arteries is bright red
Arteries Elastic arteries: Arteries closest to the heart (eg. Aorta) are more elastic, as they expand and recoil to accommodate changes in blood volume. Muscular arteries: arteries closer to other body organs (femoral artery) are more muscular than elastic. Note: Arteries and veins have both elastic and muscular properties.
Although the blood is forced into the arteries under pressure, by the time it reaches the capillaries this pressure is very low Therefore, there must be another mechanism for getting the blood back up to the heart.
Veins Veins carry blood the heart. Venules are smaller veins that connect to the capillaries. Within a vein are tiny valves that are regularly spaced throughout its length. These valves point in the direction in which the blood is flowing. The valves can be pushed open to allow blood to flow toward the heart, but they close to prevent any back flow. Unlike arteries, where blood flows smoothly, the blood in veins travels in small spurts Blood in veins is a dark maroon colour as a result of its low oxygen content
Check this out! http://www.youtube.com/watch?v=hnupw dfjdoc What happens if these valves get weak?
Interesting Note: Varicose Veins Portions of the veins lose elasticity and become extended, preventing their valves from closing completely. This allows the blood to form bulging pools. This swelling, particularly in the legs, causes the veins to appear knotted and blue
Veins versus Arteries Veins also have a muscular coat in their walls, but because the pressure of blood flow is greatly reduced, this coat is much thinner than that found in the arteries. Both arteries and veins have walls that are far too thick to allow any blood plasma, nutrients, or gases to pass out into the surrounding tissue.
Still got it? Blood Composition ABO Blood Types Antigens and Antibodies Blood Vessels
Arteries Take blood away from the heart to the body organs/tissues No valves present Thick muscle walls Blood rich in oxygen Low in CO2 Blood is bright red in colour Veins Take blood to the heart Valves present Thin muscle walls Blood poor in oxygen High in CO2 Blood is maroon red in colour Very high pressure Very low pressure
So where does gas and nutrient exchange occur?
Capillaries Smallest blood vessels Very thin walls A capillary is so narrow that often only one tiny RBC can pass through at a time. It is through the walls of the capillaries, which link the arterioles to the venules that the exchange of oxygen, carbon dioxide, nutrients, wastes, and other substances takes place.
Interstitial Fluid All of the cells and tissues of the body must be continually bathed by fluids. These fluids, called interstitial fluids, enable nutrients to pass from the capillaries across the spaces between the cells to reach cell membranes. They also prevent the cells from drying out.
Check this out! Capillaries http://www.youtube.com/watch?v=q530h1 WxtOw
The System in Action: The Heart Located behind the rib cage, between the lungs, with its lower end slightly toward the left side. About the size of your fist approx. 300g The heart is not attached to surrounding tissue. It is suspended by the large blood vessels that are attached to it. This enables it to move loosely in place as it contracts and relaxes.
The Heart The heart is not one pump, but two separate pumps. Composed of special heart muscle tissue, similar to striated muscle. Incredible stamina
Cardiac Muscle Each cardiac muscle cell is attached to, and pulls against, other cardiac muscle cells during contractions; the muscle is not anchored to bones or other tissues. The muscle cells of the heart have an innate ability to contract and they do so spontaneously. Cells that are connected to each other have the ability co-ordinate their contractions into a common rhythm.
Check this out! http://www.youtube.com/watch?v=_mjnq 67KrAo
Heart Anatomy: The Right Side The right side of the heart is responsible for collecting blood from the body and sending it to the lungs to be oxygenated. The blood flows back, from the head and arms, to this side of the heart by way of a large vein called the superior vena cava. This vein leads into the upper right-side chamber of the heart, the RIGHT ATRIUM.
Heart Anatomy: The Right Side Blood from the trunk and legs enters this same chamber, the RIGHT ATRIUM, via the inferior vena cava. Both the right and left atria (plural of atrium) are thinwalled chambers which lie above the ventricles.
Heart Anatomy: The Right Side The RIGHT VENTRICLE has thicker, more muscular walls than the right atrium and is much larger than the right atrium. The Right Ventricle is connected to the Right Atrium via the TRICUSPID VALVE, which prevents the blood from flowing back into the atrium when the ventricle contracts. When the right ventricle contracts, it pushes blood out through the Pulmonary Valve into the PULMONARY ARTERY.
Check this out! Interactive Heart: http://kidshealth.org/teen/interactive/heart_ it.html
Pulmonary Circulation The pulmonary artery is a vessel that carries the blood to the lungs where its load of carbon dioxide wastes are released and a fresh load of oxygen is absorbed. This newly oxygenated blood then flows into the left atrium via the four pulmonary veins. This portion of the circulatory system, the heart to lungs and back, is called the pulmonary circulation.
Heart Anatomy: The Left Side Contractions of the left atrium push the blood through the BICUSPID VALVE (or Mitral Valve) into the LEFT VENTRICLE. The left ventricle is the largest part of the heart and the most heavily muscled. As the left ventricle contracts, it must force the blood to every part of the body, from the brain to the smallest toe.
Systemic Circulation The blood is pushed out from the left ventricle via the aortic semilunar valve, into the largest blood vessel in the body, the aorta. This portion of the circulatory system, the systemic system, supplies blood to the remaining body system.
Valves of the Heart The tricuspid and bicuspid valves are also known as the atrio-ventricular valves, after the two chambers that they separate, the atrium and the ventricle. Pushing blood through the heart: In the right side of the heart, the tricuspid valve connects the atrium and ventricle.
The tricuspid valve (AV valve) is closed while the atrium is filling with blood. When this is completed, the tricuspid valve opens and a wave of contractions starts at the top of the atrium and squeezes the chamber through the valve into the right ventricle. The valve then closes. Another wave of contractions starts, this time at the bottom of the ventricle. The blood is now squeezed upward through the semilunar valve, which lies at the entrance of the pulmonary artery leading to the lungs. This process is repeated over and over with each beat of the heart. The same sequence of valve action takes place in the left side of the heart.
Heart Sounds The sounds produced by the heart are caused by the vibrations produced when the heart valves close and the blood bounces against the walls of the ventricles or blood vessels. The stethoscope makes it much easier to hear these sounds.
Heart Sounds The first sound: Produced when the valves between the atria and ventricles close and the semilunar valves open. This sound has a lower pitch and makes a lub sound. The second sound: Produced by the closure of the semilunar valves and the opening of the valves between the chambers. The pressure in the arteries is higher and the pitch is also somewhat higher. The sound is a short dub sound.