BSC216 Week of 2/1
BSC216 Week of 2/1 216
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This 11 page Class Notes was uploaded by Alexandra on Wednesday February 3, 2016. The Class Notes belongs to 216 at University of Alabama - Tuscaloosa taught by Jason Pienaar in Winter 2016. Since its upload, it has received 27 views. For similar materials see Human Anatomy and Physiology II Lecture in Biological Sciences at University of Alabama - Tuscaloosa.
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Date Created: 02/03/16
Heart & Blood Vessels 02/02/2016 ▯ Learning outcomes Interpret electrocardiogram waveforms for various dysrhythmias o Disturbances in heart rate Probable explanations Increased parasympathetic tone Impulses originate at S-A node at slow rate Response to exercise or congestive heart failure Impulses originate at S-A node at rapid rate o Disturbances in conduction pathways Probable explanations Heart block at AV node or AV bundle Requires pacemaker if severe o Fibrillation Probable explanations Irregular, chaotic atrial activation Rheumatic disease, atherosclerosis, hyperthyroidism, pericarditis Irregular, chaotic ventricular activation Extremely serious (no pumping), cardiac arrest Requires CPR and defibrillation Describe the cardiac cycle and explain how the heart valves and pressure changes result in one way blood flow o Heart beat Coordinated contraction of cardiac cells in a “wringing” motion that generate pressure changes in the chambers o Cardiac cycle Sequence of events that take place between one heart beat and the next o Diastole Period of relaxation for a heart chamber o Systole Period of contraction for a heart chamber o Cycle of blood flow 1. Ventricular filling ventricles in diastole pressure higher in atria, pulmonary trunk and aorta blood drains from atria into ventricles atrial systole begins 2. Isovolumeric contraction ventricular systole begins atrioventricular valves close pressure not high enough yet to open semilunar valves (isovolumetric) atrial diastole begins 3. Ventricular ejection ventricular systole continues pressure in ventricle exceeds pressure in pulmonary trunk and aorta atria diastole continues 4. Isovolumetric relaxation ventricular diastole begins pressure not high enough yet to open AV valves atria diastole continues What are the common structural components of blood vessels o Efferent pathways Heart, elastic arteries, muscular arteries, arterioles, Capillaries o Afferent pathways Venules, small veins, large veins, heart o Only capillaries and venules exchange gas and nutrients with tissues o Tunica externa (adventitia) Dense, irregular collagenous connective tissue Protection & anchoring o Tunica media Smooth muscle & elastic fibers Vasoconstriction & dilation o Tunica intima Endothelium, elastic fibers Minimizes friction, selectively permeable barrier, produce signaling chemicals and proteins Describe the structure and functions of the different types of arteries and veins o Elastic arteries Thick walls, near heart (aorta & branches), distributes blood Elastin fiber present in all 3 tunics, allows blood pressure alleviation o Muscular arteries Controls blood flow to organs More smooth muscle, less elastin, better at controlling blood pressure o Arterioles All 3 tunics, thin walls, control blood flow to capillary beds in tissues o Venules Drain blood from capillary beds Postcapillary venules = mostly endothelium o Veins Result from venule convergence Large lumens, low blood pressure Venous valves Ensure flow back to heart What are vascular anastomoses o Anastomosis Convergence between blood vessels other than capillaries Arteriovenous anastomosis Blood bypasses the capillary network (shunt) Fingers, toes, ears (e.g. in cold weather, bypass areas close to surface) Venous anastomosis Alternative drainage routes for an organ Vein blockages are rarely life-threatening Arterial anastomosis Alternative supply routes for an organ Coronary circuit, brain joints ▯ ▯ Learning Outcomes Define blood flow, blood pressure and peripheral resistance o Blood pressure Outward force blood exerts on vessel walls Expressed in units of mmHg 1 mmHg = force required to raise mercury 1 mm in a column Usually measured for brachial artery (arms, convenient) o Blood flow Volume of blood that moves past a fixed point per minute Expressed as liters/min Average in body is (5-6 l/min) o Peripheral resistance Any factors that slow blood flow Mostly generated in peripheral arteries Explain how vessel diameter relates to blood flow and pressure o Blood flow is laminar Flows in parallel layers Center is fastest Less resistance o Flow 4 Radius Ex: r=3mm, flow=3 = 81 mm/s o Arterioles can constrict to 1/3 original radius 4 Ex: r=1 mm, flow=1 = 1 mm/s Significant reduction Explain how cross sectional area relates to blood flow and pressure o Greater cross sectional area = slower flow Why does blood pressure differ in various parts of the systemic and pulmonary circuits and what do we measure o pulmonary Arteries= 15 mmHg Veins= 5 mmHg big difference o Systemic Arteries: 120 mmHg (systolic), 80 mmHg (diastolic) Pressure is much higher because it needs to pump it through your entire body As you get to capillaries, venules the pressure decreases Capillaries= 35-15 mmHg Venules= 15-5 mmHg Veins= 5-0 mmHg o Systolic pressure Cuff around arm squeezes brachial artery shut Pressure is slowly released from cuff Listen for blood flow resuming when systolic pressure is high enough to overcome declining cuff pressure Turbulent Korotkoff sounds (usually at 120 mmHg) o Diastolic pressure Occur when turbulent Korotkoff sounds disappear (usually at 80 mmHg) o **Mean arterial pressure (MAP)** (know formula) Diastolic pressure + 1/3 (systolic – diastolic pressure) Ex: 80 + 1/3(120-80) = 80+13.3 so about 93.3 Heart spends more time in diastolic hence 2/3 weight Which mechanisms assist venous flow back to the heart o Pressure from veins to right atrium ranges from 5-0 mmHg Why Veins are compliant (floppy, not a lot of muscular tissue) Low resistance Flow is very slow, veins have bigger radius than arteries Large cross sectional area A lot more veins than arteries o 1. Venous valves o 2. Smooth muscle allows for vasoconstriction o 3. Skeletal muscle pump o 4. Respiratory pump How do local, neutral and hormonal factors affect blood pressure o Factors that affect blood pressure Cardiac output Heart rate (short & long term effects) Blood volume Kidneys (long term) Resistance to flow Blood viscosity (long term) Blood vessel length (long term) Blood vessel radius (short term) o Sympathetic division of ANS Increasing blood pressure overall Most is being diverted to skeletal muscles Away from digestive and urinary systems Starts with sympathetic chain Sympathetic neurons stimulate brain Causing vasoconstriction o Norepinephrine and epinephrine neurotransmitters are used o Parasympathetic division of ANS Decreases blood pressure overall Vagus nerve Job is to decrease heart rate Uses acetylcholine Inhibits sympathetic nerves o Make them stop firing to stop constriction Blood typing o Blood types refer to variation in glycoproteins embedded in Erythrocyte membranes Unique identifiers Genetically inherited Self vs. non-self recognition by immune cells Problematic in blood transfusions, organ transplants & sometimes fetal development Agglutination= Non-self interaction o One type of antibody action Each antibody binds multiple antigens, sticks them together o parts Antigen (agglutinogens) Any molecule that allows the immune system to distinguish self from non- self Antibodies (agglutinins) Y globulins secreted by plasma cells Recognize and bind to non-self antigens Marks for destruction o ABO blood group Glycoproteins attach to erythrocyte determining group Your body doesn’t form antibodies against your own antigens Type A Anti-B antibodies Type B Anti-A antibodies Type AB No AB antibodies “universal recipient” wont agglutinate any Donor type transfusion o BUT donor antibodies can agglutinate recipients erythrocytes Type O Anti-A & Anti-B antibodies “universal donor” no antibodies against O antigen BUT donor antibodies can agglutinate recipients erythrocytes Transfusion mismatch: minimize plasma to minimize agglutination risk o Rh group Only D antigen matters Strongest immunogen Rh factor (Rh+[presence]/Rh-[absence]) Rh factor antibodies only produced in Rh- individuals when exposed to “foreign” Rh factor First mismatched transfusion is not a problem Second transfusion is a problem Severe anemia (hemolytic disease of the newborn) ▯ ▯
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