Circulatory System PDF

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