Term
| Identify the components and functions of the circulatory system: |
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Definition
Components-
Cardiovascular- Heart and blood vessels
Lymphatic system- Lymphatic vessesl and lymphoid tissues within the thymus, spleen, tonsils and lymph nodes.
Functions-
Transportation- respiratory, nutritive and excretory
Regulation- hormonal, temperature
Protection- clotting, immune
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Term
| Describe the relationship between interstitial fluid, plasma and lymph: |
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Definition
| The hydrostatic pressure of blood forces plasma fluid out of the capillary walls and into the surrounding tissues, forming interstitial fluid. Some reenters capillaries and some enters into lymphatic vessels, where it is then called lymph. |
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Term
| Distinguish between the different formed elements of the blood: |
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Definition
Erythrocytes- red blood cells- contain oxygen and contain hemoglobin
Leukocytes- white blood cells- may be granular (eosinophils and basophils) or agranular (neutrophils), and function in immunity.
Platelets- thrombocytes- required for blood clotting |
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Term
| Describe the regulation of red and white blood cell production: |
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Definition
| The production of red blood cells is stimulated by the hormone erythropoietin, secreted by the kidneys whenever blood oxygen levels are decreased. The development of the different kinds of white blood cells is controlled by cytokines, autocrine regulators secreted by various cells of the immune system. |
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Term
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Definition
| The major blood-tying groups are the ABO system, and the Rh system. Blood type refers to the kind of antigens found on the surface of red blood cells. When different types of blood are mixed, antibodies against the red blood cell antigens cause the red blood cells to agglutinate (clump together). |
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Term
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Definition
When a blood vessel is damaged, platelets adhere to the exposed subendothelial collagen proteins. 1) Platelets that stick to collagen undergo a release recation in which they secrete ADP, seratonin and thromboxane A2. 2) Seratonin and thromboxane A2 cause vasoconstriction.
ADP and thromboxane A2 attract other platelets and cause them to stick to the growing mass of platelets that are stuck to the collagen in the broken vessel. In the formation of a blood clot, a soluble protein called fibrinogen is converted into insoluble threads of fibrin. This reaction is catalyzed by the enzyme thrombin. Thrombin is derived from prothrombin, its inactive precursor, by either an intrinsic or extrinsic pathway.
1) The intrisic pathway, the larger of the two, requires the activation of more clotting factors. 2) The extrinsic pathway, the shorter of the two, is initiated by the secretion of tissue thromboplastin. The clotting sequence requires Ca2+ as a cofactor and phospholipds present in the platelet cell membranes.
Coagulation is fibrin formation.
The three steps are: prothrombin activator formation (Xa), thrombin formation, and fibrin formation. |
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Term
| Describe the structure of the heart and its components: |
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Definition
| Fist-sized, cone-shaped, it is divided into 4 chambers, the right and left atria and right and left ventricles. The atria receieve blood from the venous sytem, and the ventricles pump blood into the arterial system. The atria and ventricles are structurally and functionally sperated by the fibrous skeleton. |
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Term
| Distinguish between systemic and pulmonary circulation: |
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Definition
Pulmonary- the path of deoxygenated blood from the heart (right ventricle) through the lungs and back to the heart (left atrium) completes one circuit.
Systemic- oxygen-rich blood in the left atrium enters the left ventricle and is pumped through the aorta to all the organ systems. |
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Term
| Describe the different phases of the cardiac cycle: |
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Definition
| The atria contract first, then the ventricles. During diastole, first the atria, then the ventricles fill with blood. The ventricles are 80% filled before the atria contract and add the final 20% to the end-diastolic volume. Contraction of the ventricles ejects about 2/3 of their blood, leaving 1/3 as the end-systolic volume. |
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Term
| Relate the cardiac cycle to the production of heart sounds: |
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Definition
| Closing of the AV valves produces the first heart sound, or "lub" at systole. Closing of the semilunar valves produces the second heart sound, or "dub" at diastole. Abnormal valves can cause abnormal sounds called murmurs. |
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Term
| Describe the pacemaker potential: |
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Definition
| Action potentials originate in the SA node as a result of spontaneous depolarization, which is produced by a hyperpolarization, called the pacemaker potential. When the depolarization reaches a threshold value, opening of the voltage-regulated Na+ gates and fast Ca2+ channels produce an action potential. Repolarization is produced by the outward diffusion of K+, but a stable resting membrane potential is not attained because spontaneous depolarization once again occurs. Other myocardial cells are capable of spontaneous activity, but the SA node is the normal pacemalker due to its fastest rate of depolarization. |
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Term
| Describe the myocardial action potential: |
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Definition
| When the action potential produced by the SA node reaches other myocardial cells, they produce their own action potentials with a long pleatau phase because of the slow inward diffusion of Ca2+. The long action potential and long refractory period in myocardial cells allows the entire mass of cells to be in a referactory period while it contracts. this prevents the myocardium from being stimulated again until after it relaxes. |
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Term
| Describe how different arrythmias affect the ECG: |
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Definition
Arrhythmias - abnormal heart rhythms
Bradycardia (slower than 60 bpm)
Trachycardia (faster than 100 bpm)
Abnormal trachycardia occurs if heart rate increases at rest
Flutter – contractions are very rapid (200 to 300 coordinated bpm)
Fibrillation – contractions of different groups of myocardial fibers occur at different times
Not coordinate beats
Atrial flutter degenerates into atrial fibrillation quickly (600 bpm)
AV node does not respond to all impulses, but ventricles still contract at 150-180 bpm
Atrial fibrillation only reduces the cardiac output by 15%; able to survive for years
Ventricular fibrillation – only live for a few minutes
Fibrillation is caused by continuous recycling of electrical waves (circus rhythms) Normally prevented by refractory period
May be produced by damage to the myocardium
Sudden death progresses from ventricular tachycardia through ventricular fibrillation
Culminates in asystole |
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Term
| Describe the compomnents of the ECG and theircrelationships to the cardiac cycle: |
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Definition
| The regular pattern of conduction in the heart produces a changing pattern of potential differences between two points on the body surface. The recording of this pattern caused by the heart's electrical activity is called an electrocardiogram. The P wave is caused by depolariation of the atria, the QRS wave is caused by depolarization of the ventricles, and the T wave is produced by repolarization of the ventricles. |
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Term
| Compare the structure and function of the arteries and veins: |
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Definition
| Arteries always carry blood away from the heart and are almost always oxygenated (ex. pulmonary trunk). Veins always carry blood to the heart and are almost always deoxygenated (ex. pulmonary trunk). They consist of three layers, tunica interna, media nand externa, but the tunica media in veins are thinner than arteries. Veins have lower blood pressure and a wider lumen than arteries, and many contain valves to prevent backflow of blood. |
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Term
| What is the significance of the skeletal muscle pumps? |
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Definition
| The flow back to the heart is aided by contraction of the skeletal muscles that surround veins. The effect of this action is called the skeletal muscle pump. |
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Term
| Describe the structure and function of capillaries: |
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Definition
| Capillaries function in tyhe exchange of oxygen from the blood to the tissues. Capillary walls consist of one layer of endothelial cells. The flow of blood from arterioles to capillaries is regulated by precapillary sphincter muscles. The capillary wall may be continuous, fenestrated or discontinuous. Continuous capillarries lack intercellular channels and the endothelial cells are closely joined (such as in the blood brain barrier). Fenestrated capillaries are characterized by wide intercellular pores (such as in the kidney tubules) to allow molecule to pass through readily. Discontinuous capillaries have a great distance between the endothelial cells; they look like sinusoids in the organ (ex. spleen). |
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Term
| Explain the causes and dangers of atherosclerosis: |
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Definition
| It is caused by smoking, hypertension and high plasma concentration. Low density lipoproteins (LDL) which carry cholesterol to the artery wall are oxidized by the endothelium and are a major contributor to atherosclerosis. It begins with injury to the endothelium, the movement of monocytes and lymphocytes in to the tunica interna, and the conversion of monocytes into macrophages that engulf lipids. Smooth muscle cells then proliferate and secrete extracellular matrix. It can occlude blood flow to the heart and brain, and is a causative factor in 50% of deaths in the US, Europe and Japan. |
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Term
| Explain the causes and significance of angina pectoris: |
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Definition
| Myocardial ischemia is associated with increased concentrations of blood lactic acid produced by anaerobic metabolism in the ischemic tissue. This condition often causes substernal pain, which may be referred to the left shoulder and arm, as well as to other areas. This referred pain is called angina pectoris. |
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Term
| Explain how the lymph and lymphatic system relate to the blood and cardiovascular system: |
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Definition
| Plasma, leaving blood capillaries is called interstitial fluid and is reabsorbed into the lymphatic capillaries, where it is referred to as lymph. The lymph is is then carried to into lymphatic vesselsd called lymph ducts, where it is filtered through lymph nodes. It is then emptied into the thoracic duct and right lymphatic duct, which drain into the left and right subclavian veins, and then reentered into the circulatory system. |
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Term
| Describe the function of lymph nodes and lymphoid organs: |
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Definition
| The lymph nodes contain phagocytic cells which help remove pathogens, and germinal centers which are the site of lymphocyte production. The tonsils, thymus and spleen are lymphoid organs, which also contain germinal centers and are the site of lymphocyte production. |
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