Circulatory System PDF
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Tamethia Perkins
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These notes provide an overview of the circulatory system, including pulmonary and systemic circulation, the neural controls, baroreceptor reflexes, pressures within the system, the cardiac cycle, arterial pulses, and the effects of blood volume on blood pressure. The document includes diagrams illustrating different aspects of the circulatory system.
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CIRCULATORY SYSTEM Tamethia Perkins MS, RRT-NPS, RRT-ACCS RT 3005/6005 PULMONARY AND SYSTEMIC VASCULAR SYSTEMS Major circulation: – Pulmonary system: from PA to LA – Systemic system: from aorta to RA ARTERIES: strong, elastic vessels. ARTERIOLES: smaller vessels. Dis...
CIRCULATORY SYSTEM Tamethia Perkins MS, RRT-NPS, RRT-ACCS RT 3005/6005 PULMONARY AND SYSTEMIC VASCULAR SYSTEMS Major circulation: – Pulmonary system: from PA to LA – Systemic system: from aorta to RA ARTERIES: strong, elastic vessels. ARTERIOLES: smaller vessels. Distribution and regulation of blood P.(resistance vessels) CAPILLARIES: where gas exchange occurs. – Internal respiration: blood and tissues. – External respiration: blood and air. VENULES: continuation of capillaries… veins (capacitance vessels)… heart Pulmonary and Systemic Circulation Neural Control of Vascular System Sympathetic fibers found in the arteries and arterioles. VASOMOTOR CENTER regulates the number of impulses sent to the vascular system. – Continual stream of impulses that keep the vasomotor tone. BARORECEPTORS are P receptors that help, along with the vasomotor center, the BP. Neural Control Baroreceptor Reflex Located in the walls of the carotid arteries (carotid sinuses) and aorta (aortic arch). Nerve endings very sensitive to stretch or distortion. Afferent fibers travel with the IX cranial nerve (carotid) and with the X (aortic). Feedback: – Low BP causes decrease number of neural impulses to the centers in the medulla( from the baroreceptors) = medulla responds by increasing sympathetic activity = increasing: HR Arterial and venous constriction Myocardial force of contraction Baroreceptor Reflex Net result of sympathetic stimulation: – Increased CO (HR and SV) – Increased peripheral resistance – Return of BP to normal Vascular constriction occurs primarily in the abdominal region. (not vital organs) Other baroreceptors: – Large arteries, large veins, pulmonary vessels and cardiac walls. – Similar response to sympathetic stimulation. – They send info to brain in response to increased pressure Baroreceptors PRESSURES IN THE CIRCULATORY SYSTEM INTRAVASCULAR P – Actual BP in the lumen of any vessel at any point, relative to the PB. TRANSMURAL P – Difference between the intraluminal P and the P surrounding the vessel. DRIVING P – Difference in P between two points. Pressures CARDIAC CYCLE AND BP Systole = ventricular contraction = systolic P. Diastole= ventricular relaxation = diastolic P. BPs = 120/80 BPp = 25/8 (PAP) Pulmonary System (low P system) – Mean PAP = 15 mmHg – Mean LA P = 5 mmHg Systemic System (high P system) – Mean Aortic P = 100 mmHg – Mean RA P = 2 mmHg Sequence of Cardiac Contraction Diastolic and Systolic P Mean Intraluminal P Hemodynamic Events Systole RA LA X X RV LV Hemodynamic Events Diastole RA LA X X RV LV Hemodynamics Events Dynamic Arterial Pulse Rushing of blood into arterial system after each ventricular contraction. It causes expansion of arterial walls. When ventricular contraction stops = arterial walls recoil. Expansion and recoil of the walls can be felt as a pulse in those arteries that run close to the skin. Pulse sites BLOOD VOLUME AND EFFECT ON BP Stroke volume: volume ejected on each ventricular contraction. (40-80mL) Cardiac Output: volume per minute. CO= SV x HR – CO 5 LPM BP varies proportional to CO. – Low CO = Low BP = Low perfusion – Decreased UO, Decreased O2 levels, Decreased Mentation