- Overview of the Cardiovascular System
- Types of Blood Vessels
- Heart is a Double Pump
- Features of the Cardiovascular System
- Two Cardiovascular Pathways
- Exchange at the Capillaries
- Cardiovascular Disorders
Cardiovascular System: Blood
- Blood: An Overview
- Red Blood Cells and Transport of Oxygen
- White Blood Cells and Defense Against Disease
- Platelets and Blood Clotting
- Homeostasis
Lymphatic System and Immunity
- Microbes, Pathogens, and You
- The Lymphatic System
- Nonspecific Defenses
- Specific Defenses
- Acquired Immunity
- Hypersensitivity Reactions
ice to the cells by exchanging substances with tissue fluid which the actual cells are bathed in.- Arteries- these travel from the heart. Three layers make up the arterial wall. Innermost is endothelium (thin layer of cells), then a layer of smooth muscle and elastic tissue, and finally the outer layer of connective tissue. Arterioles are small arteries you are able to see with the naked eye. When their muscle fibers contract the vessel becomes constricted, when they relax, dialation occurs. This regulates blood pressure
- Capillaries- These are a place for exchange. Capillaries are branched of from arterioles. They are a very narrow tube and their wall is made up of only endothelium. Capillary beds are found everywhere in the body. In tissues certain capillaries are open at certain times. If a capillary bed is closed, then the precapillary sphinters will contract
- Veins- travel to the heart. Venules are small veins that drain blood from the capillaries then to join to form a vein. The wall of a vein is the same as an artery, but thinner because there is less smooth muscle and also less connective tissue. Valves are a one way sign for blood. They are found in the veins that blood travels against the flow of gravity and make sure the blood only flows towards the heart.
The Heart is a Double Pump
The heart is a muscle that sits between the lungs, behind the sternum. The myocardium is made of cardiac muscle tissue. The coronary artery and the cardiac vein service th
e myocardium.
- Surrounding the heart is the pericardium -(membranous sac protecting the heart, the inside secretes a lubricating fluid that allows the pericardium to slide over the surface while the heart pumps blood).
- Septum- is a wall that divides the heart into a right and left side (each side has a thin walled atrium on top and a thicker walled ventricle on the bottom).
- Atrioventricular valves- prevent backward movement of the blood. The one on the right side is the tricuspid (three flaps) and the one on the left is the bicuspid (aka mitral, and only has 2 flaps). The other 2 flaps are semi-lunar valves (half moon shape and are located between ventricles and their attatched vessels- pulmonary trunk and aorta
The passage of blood through the heart is as follows: Superior and inferior vena cava(O2 poor) enter the right atrium. Right atrium sends blood through atrioventricular valve to right ventricle. Right ventricle sends blood through pulmonary semilunar valve into pulmonary trunk. The trunk divides into two pulmonary arteries that go to the lungs. Four pulmonary veins (carrying O2 rich blood) enter the left atrium. The left atrium sends the blood through the bicuspid valve to the left ventricle. The left ventricle sends it through the aortic semilunar valve into the aorta.
Each heartbeat is a cardiac cycle. The two atria contract at the same time, then the two ventricles contract at the same time. Then all the four chambers relax. Systole is the working phase (contraction) and diastole is the resting phase (relaxation of chambers). The sinoatrial (SA) node initiates the heartbeat and sends out the excitation impulse causing the atria to contract. The atrioventricular (AV) node receives the impulse for the ventricles to begin contracting and sends it through the atrioventricular bundle and purkinje fibers. The medulla oblongata, can also regulate and change heartbeat through the parasympathetic and sympathetic portions of the nervous system.
We are able to physically see a person's heartbeat by an electrocardiogram (ECG). This records the electrical changes in the myocardium. The ions in body fluids conduct an elec
trical current that can be detected on the skin surface. A P wave is an electrical charge from the atrial fibers that is triggered by the SA node. This shows the atria preparting to contract. The QRS complex is showing the ventricles about to contract. The T wave is showing ventricular muscle fibers recovering.
Features of the Cardiovascular System
A pulse is equal to heart rate. The pulse you can feel on arteries close to the skin surface is the surge of blood entering them, causing their elastic walls to expand briefly. Normal pulse rate for an adult is 60-80 beats per minute.
Blood pressure is critical to homeostasis by making sure hte blood gets moved all the way from arteries down to capillaries where exchange with tissue fluid occurs. Blood pressure is measured using a sphygmomanometer. Systolic pressure is heard during ejection of blood from the heart and diastolic pressure happens when the ventricles are relaxing. Normal blood pressure for a young adult is 120/80.
Because blood flow slows down in the capillaries (gives enough time for the exchange), but the velocity increases in the veins, there are other factors involved in venous return.
- First is the skelatal muscle pump- upon contraction they compress the weak walls of the vein, allowing the blood to flow past a valve.
- Respiratory pump- by inhaling, the pressure is reduced in the thoracic cavity, allowing blood to flow from a higher pressure cavity, to a lower pressure cavity.
- Valves- prevent backward flow of blood from occuring, thus always working to move blood towards the heart
Two Cardiovascular Pathways
The first circuit is the pulmonary circuit, where blood circulates through the lungs. Blood from all regions collects in the right atrium where it then moves to the right ventricle and onward to the pulmonary trunk. From here the trunk is divided into right adnd left pulmonary art
eries that begin to branch upon approaching the lungs. Arterioles deliver blood to pulmonary capillaries (CO2 given, O2 taken). The blood then travels through the pulmonary venules to four pulmonary veins going to the left atrium (O2 rich )
The second circuit is the systematic circuit where the needs of body tissues are served. The aorta receives blood from the heart and teh superior and inferior vena cavaes return blood to the heart. In the systematic circuit blood travels like this :
Left ventricle -> aorta -> common illiac artery -> femoral artery -> lower leg capillaries -> femoral vein-> common illiac vein -> inferior vena cava -> right atrium
Exchange at the Capillaries
Blood pressure along with osmotic pressure ( created by salts and plasma proteins) are the main forces that control fluid movement through the capillary wall. Blood press
ure moves water from the capillaries to tissue fluid, and osmotic pressure moves water from tissue fluid into the capillaries. Water leaves the capillaries(due to blood pressure) at the arterial end. In the middle of the capillaries blood pressure is equal to osmotic pressure and therefore, no net movement of water. This is where oxygen, glucose, and amino acids diffuse out and carbon dioxide and wastes diffuse in. At the venule end osmotic pressure allows water into the capillary.
Cardiovascular Disorders
Hypertension is high blood pressure defined as a systolic number greater than 140 and/or the diastolic number greater than 90. Atherosclerosis (accumulation fatty material in the inner lining of arteries) is a leading cause of hypertension. A low cholesterol and low saturated fat diet can help prevent this. Plaque can cause clots (thrombus if stationary, embolus if dislodged)
A cerebrovascular accident (CVA, stroke) occurs from a small cranial artery bursting or also from embolus' . This blockage prevents oxygen from getting to the brain which can result in death of the brain cells.
A myocardial infarction (MI, heart attack) occurs from parts of the heart muscle dying due to lack of oxygen. A partial blockage of the coronary artery results in angina pectoris which can be temporarily relieved by dialating blood vessels. Coronary bypass operation is when a vein ( most commonly from the leg) is attatched to the aorta and the coronary artery past the obstruction. A different procedure is gene therapy where genes that code for vascular endothelial growth factor are injected into the area of the heart that needs it. This causes new blood vessels to form that will transport around the clogged arteries. People with heart failure can be helped by ICD's, LVAD, heart transplants, bone marrow stem cells, or even total artificial hearts.
Cardiovascular System: Blood
Blood: An overview
Your body contains approximately five liters of blood that is pumped by the heart with every beat. Blood is a liquid tissue composed of formed elements (cells and cell fragment) that is suspended in plasma.
The formed elements ( red and white blood cells, platelets) are produced in red bone marrow that contains stem cells that divide and create many different blood cells.
Plasma (91% water, 9% salts and organic molecules) carries the substances in the blood and distributes heat. Plasma proteins(albumins, globulins, fibrinogen) are produced in the liver and maintain homeostasis by taking and releasing hydrogen ions. Albumins help transport organic molecules. Globulins (alpha, beta, gamma) transport hormones, cholesterol and iron. Gamma help fight disease. Fibrinogen plays a large part in forming blood clots.
There are three main functions blood
- Transport- delivers oxygen and nutrients to the tissues. Takes carbon dioxide and wastes from the tissues to exchange in lungs and kidneys. Hormones that act as signals to influence cellular metabolism are also trasported through the blood.
- Defense- defends against invasion by pathogens. Blood is able to do this by phagocytizing the pathogens and secreting antibodies. Blood is able to clot preventing us from bleeding to death.
- Regulation- can regulate body temperature by transporting heat from active muscles out of the body from blood vessels in the skin. Contains buffers which regulate the body's pH
Red Blood Cells and Transport of Oxygen
Red blood cells (erythrocytes) are specialized for oxygen transport. Copies of hemoglobin replace a nucleus.Each hemoglobin (approx 280 million in one red blood cell) can transport 4 O2 molecules. The hemoglobin is the pigment that gives blood and the cells their red color. Heme is a group in the center of each polypeptide that contains iron. This is able to accept and release oxygen. When the heme is carrying oxygen the shape is oxyhemoglobin, after it is released the shape is deoxyhemoglobin. The oxygen has been diffused into tissue fluid and then cells. Globin is a protein with four "highly folded polypeptide chains"
Red blood cells also transport carbon dioxide. When it is picked up from the tissues it is dispersed as follows: 7% dissolved in plasma, 25% directly transported by hemoglobin(on amino group of globin), 68% transported as bicarbonte ion in plasma (HCO3) See following reaction
Red blood cell only have a life expectancy of around 120 days. When aged they are destroyed in the liver and spleen by macrophages. Upon destruction hemoglobin is released. The globin breaks into amino acids which teh body recycles and the iron is returned to the bone marrow for reuse. The kidneys are able to release erythropoietin to stimulate stem cells to produce more red blood cells when there is not enough oxygen being delivered to the cells.
Anemia (lack of red blood cells and/or hemoglobin), Hemolysis (rupturing of red blood cells
) and Sickle-cell disease are all disorders of the red blood cells. Sickle cell is hereditary and occurs when 2 of the amino acid chains in hemoglobin is abnormal. The cells tend to rupture as they travel through the capillaries. Usually sickle-cell is a bad thing, but in some countries where malaria is present, sickle-cell can actually act as a defense against it. When carriers of sickle-cell are infected with malaria, their blood cells sickle. When these cells circulate through the spleen they are filtered out due to their shape, effectively eliminating the parasite with them.
White Blood Cells and Defense Against Disease
White blood cells have a nucleus (no hemoglobin) and are known as leukocytes. They are produced from stem cell in red bone marrow. Colony-stimulating factor (CSF) is a protein that regulates the production of the different types of white blood cells. These white blood cells are not only found in blood, but also in tissue fluid and lymph due to their ability to squeeze through the capillary wall pores.
White blood cells fight infection by various methods (phagocytosis, production 
of antibodies) and have a life span that can vary from a few days to a few years. There are two groups of white blood cells: granular leukocytes and agranular leukocytes.
- Neutrophils (granular)- most abundant type (50-70 percent of white blood cells). Contain a multilobed nucleus and resist staining. They are usually first on scene to bacterial infections and fight using phagocytosis. Pus is a result of large scale death in neutrophils.
- Eosinophils(granular)- Contain a bilobed nucleus and take up eosin (staining them red). Numbers increase upon parasitic worms and allergic reactions
- Basophils (granular)- contain a lobe nucleus and take up a basic stain (leaving them blue). Found in the connective tissue and release histamine.
- Lymphocytes (nongranular)- (25-35 percent of white blood cells). There are B-cells or T-cells. B-cells produce antibodies. T-cells can directly destroy pathogens.
- Monocytes (nongranular)- largest in size. Live in the tissues and become large macrophages using phagocytosis on pathogens, cellular debris and old cells. Stimulate the other white blood cells to defend the body.
Disoders of white blood cells include: severe combined imunodeficiency disease (SCID), leuemia and infectious mononucleosis. SCID is a lack of enzyme in white blood cells leaving them unable to fight any infections. Gene therapy is on the rise to try and cure this if the new stem cells (injected with the correct gene) settle back into the bone marrow to produce healthy lymphocytes. Leukemia is white blood cell proliferation that is uncontrolled and as a result most are not mature and unable to perform the defense functions needed. Infectious mononucleosis is a virus which symptoms can go away, but it's cells remain dormant in throat and blood cells and can be reactivated by stress.
Platelets and Blood Clotting
When megakaryocytes in the red bone marow fragment, this creates platelets (thrombocytes). If a blood vessel becomes damaged, platelets clump at the site to seal the break. Larger d
amage might also require a blood clot to seal the break. When a blood vessel is punctured, the damaged tissue and platelets release prothrombin activator. This converts prothrombin to thrombin, which severs 2 short amino acid chain from each fibrinogen molecule. These then join to form fibrin which provides the framework for the clot and trap red blood cells. Then blood vessel repair begins and the fibrin is destroyed to restore the fluid plasma.
Disorders of blood clotting include thrombocytopenia (insufficient amount of platelets), and hemophilia (deficiency in a clotting factor, this is an inherited disorder).
Blood Typing and Transfusions
Blood typing is determining the ABO blood group and Rh negative or positive. This must be done prior to transfusion (transfer of blood from one person to blood of another) to assure that agglutination does not occur. This is very important because the plasma membranes on the red blood cells can have glycoproteins that are antigens to other membranes. There are A and B antigens. A has anti-B antibodies, B has anti-A antibodies and O has both antibodies. Antibodies in the plasma should not combine with the antigens on the red blood cell serface. If they combine, this is agglutination.
Rh negative people to not have antibodies to the Rh factor, but their body will make the antibodies if exposed to the factor. If a baby is Rh positive and mom is negative, the Rh positive can leak from the placenta to mom's blood stream. She would then produce anitbodies, which could cause a problem in a second birth if baby was Rh positive. This is hemolytic disease, and hemolysis does not stop when the baby is born. A Rh immunoglobin injection is given to a Rh negative mom after giving birth (up to 72 hours after) to a Rh positive baby so mom does not produce antibodies.
Homeostasis
Homeostasis is only possible if the cardiovascular system delivers oxygen (lungs) and nutrients (digestive) to the tissue fluid and if it also takes away metabolic wastes. Also the lymphatic system has to return tissue fluid to the bloodstream. The muscular system contributes to moving blood through the cardio system by the cardiac and skelatal muscle contracting which moves blood and lymph through veins. Bones contribute calcium which is essential for blood clotting, and the urinary system even contributes by regulating acid-base and salt-water balance in blood and tissue fluid.
Lymphatic System and Immunity
Microbes, Pathogens, and You
Microbes are microscopic organisms and occur throughout the environment. There are good microbes (ones in yougurt, drugs produced by bacteria, decomposers), and harmful ones that can cause infectious diseases. These are called pathogens. The bodies defense to pathogens are: barriers (skin, membranes), first responders (white blood cells), and specified defenses.
Bacteria are single cell prokaryotes that lack a nucleus. They are bacillus o(round), coccus (sphere), and spirillum (curved) in shape. Some can move with flagella, or stick to surfaces with fimbriae. A pilus allows them to transfer DNA between cells. Bacteria are metabolically competent with DNA in one chromosome in the center of the cell. They might also have additional DNA rings (plasmids). Binary fission is bacteria's method of reproduction.
Viruses are like a bridge between living, and nonliving. Without a host, t
hey are essentially chemical, but they gain life once inside a host. Viruses are ace
llular and made up of two parts: outer capsid of protein units and an inner core of nucleic acid. A virus gains entry into a specific host cell utilizing a lock and key manner. Viral nucleic acid enters the cell and begins coding for protein units in capsid. They also use host enzymes and ribosomes for their own reproduction
Prions are proteinaceous infectious particles and cause degenerative diseases of the nervous system. (CJD, scrapie, mad cow disease). Apparently transmitted by ingestion of infected brain and nerve tissue. They start out healthy but become diseased when prion proteins change shape (rogue shape). This shape converts other normal prion proteins, and now they don't function due to the changed shape.
The Lymphatic System
This consists of lymphatic vessels and lymphatic organs. Four functions are: lymph
atic capillaries absorb any extra tissue fluid and then return it to the bloodstream, lacteals (in the small intestine) absorb lipoproteins and transport these to the bloodstream, produces, maintains and distributes lymphocytes, helps the body defend against pathogens.
The lymphatic vessels form an intricite system of capillaries, vessels and ducts that all work to move lymph to the cardiovascular veins in shoulders. The thoracic duct returns lymph from below the thorax, left arm, side of head and neck. The right lymphatic duct returns lymph from right arm, side of head and neck.
Primary lymphatic organs are:
- Red bone marrow- produces all types of RBC's. Produces neutrophils, eosinophils, basophils, lymphocytes and monocytes
- Thymus gland- produces thymic hormones, and immature T lymphocytes mature here.
Secondary lymphatic organs are:
- Spleen- filters bood. macrophages destroy pathogens and debris before blood exits
- Lymph nodes- filter lymph. lymphocytes fight infection, and macrophages clean up pathogens and debris
- Lymphatic nodules- patches of lymphatic tissue arranged around the pharynx
- Peyer's patches-encounter pathogens that enter the body by way of intestinal tract
Nonspecific Defenses
Immunity is the ability to combat diseases and cancer. The first line of defense is barriers.
- Skin and Mucous Membranes
- Chemical Barriers-secretions of oil glands can weaken and destroy some bacteria. Lysozyme in tears and saliva can wash away bacteria and microbes. pH of stomach can also kill many types of bacteria
- Resident Bacteria- they use available nutrients and release their own waste to prevent other pathogens from moving in.
The second line of defense is inflammatory response
Neutrophils and macrophages are main players in this defense. Inflamation is recognized by redness, heat, swelling and pain. Damaged tissue releases histamine causing dialation and greater permeability of the capillaries. This allows greater blood flow which is 
seen by reddened skin. This increased flow brings in the WBC's and lets fluid and blood clotting factors to move into the tissues. The pain normally felt is from this extra fluid pressing on nerve endings.
Neutorphils arrive first destroying debris, dead cells and bacteria. Usually they are enough to localize an infection. When injury is minor inflammatory is short and nearby cells work efficiently to secrete growth factors contributing to new growth and repair of the damaged area. If it is a larger infection and neutrophils need help, they secrete cytokines, which attract monocytes to the area. These become macrophages, which can get lymphocytes to help with defense.
Complement system has complement proteins which work with certain immune responses such as the inflammatory response. Some examples are interferons, and the membrane attack complex.
Specific Defenses
Specific defenses respond to antigens( molecules that have been recognized as a foreign body). Lymphocytes differentiate B-cells or T-cells to recognize these antigens. Each of these lymphocytes has only one type of receptor to combine with a particular antigen, so g
reat diversity is needed and occurs during the maturation process.
B-cells' receptor (BCR). An antigen selects, and binds to only one type BCR and then the B-cell makes multiple copies of itself. This works the same way in T-cells. The B-cells clones become plasma cells which are then able to secrete antibodies to that specific antigen. Some of the clones become memory cells acheiving long term immunity. This defense by the B-cells is antibody-mediated immunity.
T-cells cannot recognize an antigen without help, so an antigen-presenti
ng cell (maybe a macrophage) breaks the pathogen apart and displays it on the MHC protein. By linking a foreign antigen to the self protein, it is showing the T-cell how to recognize "foreign" from "self".
Cytotoxic T-cells look for a specific enemy. When the enemy is found, the T-cell releases 
perforins which puncture the invading cell. Then they release granzymes into the punctures and these kill the invading cell. This is called cell-mediated immunity.
Helper T-cells secrete cytokines to organize and enhance the immune cells response. Memory T-cells remain to jump start an immune reaction if the antigen has been present before.
Aquired Immunity
This occurs through infection or artificially by medical intervention. Active Immunity can develope when someone is infected with a pathogen, or can be artificially introduced by using vaccines. Passive Immunity is when someone is given antibodies or immune cells to combat a diesease, this is temporary because the antibodies have not produced by the indidvidual. There are monoclonal antibodies that that are the same type, produced by the plasma cells that were derived from the same B-cell. Cytokines are signaling molecules that regulate white blood cell production and function.
Hypersensitivity Reactions
These reactions occure when the immune system's response actually harms t
he body
- Allergies- this is a hypersensitive response to allergens (pollen, food, animal hair) caused by the IgE antibodies. Histamine is released along with other substances which cause the common symptoms of allergies (runny nose and eyes, wheezing) Anaphalactic shock is a more serious response to an allergen that has entered into the blood stream (bee stings, penicillin)
- Tissue Rejection- this occurs when the patients immune system sees the transplanted tissue as "foreign" and cytotoxic t-cell procede to attack
- Immune System Disorders- an autoimmune disease is when cytotoxic T-cells or antibodies attack the person's own cells. The cause of this is still unknown. (MS, SLE, and rheumatoid arthritis are some examples)
Works Cited
Mader, Sylvia. Human Biology 10th ed
Frolich Powerpoint
Links for Pictures
1. http://www.nhlbi.nih.gov/health/dci/images/sickle_cell_image_1.jpg 2.http://faculty.etsu.edu/currie/images/clot.jpg
3. http://connection.lww.com/products/stedmansmedict/primal/primal_24.jpg
This is very good picture of lymphatic system that was too big to put in blogger
4. http://universe-review.ca/I10-13-lymphatic.jpg
5. http://images.medicinenet.com/images/illustrations/heart_attack.jpg
6. http://cache.eb.com/eb/image?id=92807&rendTypeId=34
7. http://www.vanth.org/vibes/images/normalECG2.PNG
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