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Chapter 14

Chapter 14. Cardiac Output, Blood Flow, and Blood Pressure. Cardiac Output (CO). Volume of blood pumped/min. by each ventricle. Pumping ability of the heart is a function of the beats/ min. and the volume of blood ejected per beat. Total blood volume averages about ________.

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Chapter 14

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  1. Chapter 14 Cardiac Output, Blood Flow, and Blood Pressure

  2. Cardiac Output (CO) • Volume of blood pumped/min. by each ventricle. • Pumping ability of the heart is a function of the beats/ min. and the volume of blood ejected per beat. • Total blood volume averages about ________. • Each ventricle pumps the equivalent of the total blood volume each min. (resting conditions).

  3. Regulation of Cardiac Rate • Without neuronal influences, the heart beats according to the rhythm set by ___________________. • Autonomic control: • Sympathetic and parasympathetic nerve fibers to the heart modify the rate of spontaneous depolarization. • Innervate the SA node. • NE and Epi stimulate opening of __________ channel. • _________ promotes opening of K+ channel. • Major means by which cardiac rate is regulated. • Cardiac control center (medulla): • Coordinates activity of ___________ innervation.

  4. TPR • Total Peripheral Resistance: • Impedance to the ejection of blood from ventricle.

  5. Venous Return • Return of blood to the heart via _______ • Venous pressure is driving force for return of blood to the heart. • Veins have thinner walls, thus higher compliance. • Capacitance vessels. • 2/3 blood volume is in _________.

  6. Exchange of Fluid between Capillaries and Tissues • Distribution of ECF between plasma and interstitial compartments is in state of dynamic equilibrium. • Balance between tissue fluid and blood plasma. • __________________pressure: • Exerted against the inner capillary wall. • Promotes formation of tissue fluid. • Net filtration pressure. • ________________osmotic pressure: • Exerted by plasma proteins. • Promotes __________ reabsorption into circulatory system.

  7. Fluid Movement (continued)

  8. Causes of Edema • Excessive accumulation of tissue fluid. • Edema may result from: • _____________arterial blood pressure. • Venous _____________ • Leakage of plasma __________ into interstitial fluid. • Myexedema. • Decreased plasma [protein]. • Obstruction of ___________ drainage.

  9. Regulation of Blood Volume by the Kidney • Formation of urine begins by filtration of plasma through capillary pores. • Volume of urine excreted can be varied by changes in reabsorption of filtrate. • Adjusted according to needs of body by action of hormones.

  10. Regulation by ADH • Released by ______ pituitary when osmoreceptors detect an increase in plasma osmolality. • Dehydration or excess salt intake: • Produces sensation of _________. • Stimulates water reabsorption from filtrate.

  11. Regulation by Aldosterone • ___________ hormone secreted by adrenal cortex. • Mechanism to maintain blood volume and pressure through absorption and retention of __________ and Cl-. • Stimulates reabsorption of NaCl. • Indirectly increases H20 reabsorption. • Does not dilute osmolality. • Release stimulated: • During salt deprivation. • Reduced blood _________ and pressure.

  12. Renin-Angiotension-Aldosterone System • When blood pressure and flow are reduced in renal artery, juxtaglomerular apparatus secretes renin. • Renin converts angiotensinogen to angiotensin I. • Angiotensin I is converted to angiotensin II • Angiotensin II: • Raises blood ________________ • Powerful vasoconstrictor. • Stimulates production of aldosterone (more salt and water retention in kid). • Stimulates ____________________

  13. Renin-Angiotension-Aldosterone System

  14. Atrial Natriuretic Peptide (ANP) • Produced by the _______of the heart. • Stretch of atria stimulates production of ANP. • Antagonistic to aldosterone and angiotensin II. • Promotes Na+ and H20 excretion in the urine by the kidney. • Promotes _________________.

  15. Extrinsic Regulation of Blood Flow (continued) • Parasympathetic nervous system: • Parasympathetic _________ limited. • Promotes vasodilation to the digestive tract, external genitalia, and salivary glands. • Less important than sympathetic nervous system in control of TPR. • Parasympathetic endings in arterioles promote vasodilation.

  16. Paracrine Regulation of Blood Flow • Endothelium produces several paracrine regulators: • Nitric Oxide, Bradykinin, prostacyclin • Cause vaso-relaxation

  17. Intrinsic Regulation of Blood Flow (Autoregulation) (continued) • Metabolic control mechanism: • Intrinsic receptors sense chemical changes in environment. • Vasodilation: • Decreased 02: • Increased _________________. • Increased C02: • Decreased ventilation. • Decreased pH: • ________________. • Increased adenosine or increased K+: • From tissue cells.

  18. Regulation of Coronary Blood Flow • Sympathetic nervous system: • a receptors: • ____________________ at rest. • b receptors: • ______________________.

  19. Regulation of Blood Flow Through Skeletal Muscles • Decreased blood flow when muscles contract and constrict arterioles. • Sympathetic: • a-adrenergic receptors: • Vasoconstrict at rest. • Cholinergic and b-adrenergic receptors: • Vasodilate.

  20. Cutaneous Blood Flow • Thermoregulation: • Blood flow through the skin is adjusted to maintain deep-body temperatures at about 37o C. • Occurs due to: • Vasoconstriction/vasodilation arteries. • Bradykinin: • Sweat glands secrete bradykinin which increases blood flow to skin and sweat glands. • Changes in ___________ blood flow, occur as a result to changes in sympathetic nerve activity; which is controlled by the brain.

  21. Blood Pressure (BP) • Pressure of arterial blood is regulated by blood volume, TPR, and cardiac rate. • ________________________. • Arteriole resistance is greatest because they have the smallest diameter. • Capillary BP is reduced because of the total cross-sectional area. • 3 most important variables are HR, stroke volume, and TPR. • Increase in each of these will result in an increase in _____. • BP can be regulated by: • Kidney and sympathoadrenal system.

  22. Baroreceptor Reflex • Stretch receptors located in the aortic arch and carotid sinuses. • An increase in pressure causes the walls of these regions to stretch, increasing frequency of APs. • Baroreceptor reflex activated with changes in BP. • More sensitive to decrease in pressure and sudden changes in pressure.

  23. Atrial Stretch Reflexes • Located in the ________ of the heart. • Receptors activated by increased venous return. • Stimulate reflex tachycardia. • Inhibit ____________ release. • Promote secretion of _________________.

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