BSC 2086 1st Edition Lecture 13 Outline of Last Lecture I Capillaries Continued II Veins III Blood Distribution in Vessels IV Pressure and Resistance V Arterial Blood Pressure VI Venous Pressure and Return VII Capillary Pressures Outline of Current Lecture I Pressure and Reabsorption II Cardiovascular Regulation III IV Cardiovascular Response to Exercise and Hemorrhaging Other Cardiovascular Adaptations V Pulmonary and Systemic Patterns VI Effects of Aging Current Lecture I Pressure and Reabsorption a Filtration and Reabsorption i Makes sure that plasma and IF are in constant communication and are mutually exchanging 1 Enters lymphatic system which drains extra fluid from tissues ii Accelerates the distribution of nutrients hormones and dissolved gases in tissues iii Assists with the transportation of tissue proteins and insoluble lipids that cant cross capillary walls to enter the bloodstream II iv Carries bacterial toxins and chemical stimuli to the lymphatic tissues and those organs responsible for disease immunity b Net hydrostatic pressure i P between the inside and the outside of a capillary ii Forces water out of solution iii Pushes blood out of capillaries and into IF iv Factors that contribute 1 Capillary hydrostatic pressure CHP 2 Interstitial fluid hydrostatic pressure IHP c Net osmotic pressure i Forces water into solution ii Pushed blood into the capillaries d Net Capillary Colloid Osmotic Pressure i Difference between blood colloid osmotic pressure BCOP and interstitial fluid colloid osmotic pressure ICOP 1 Usually see that BCOP is higher than ICOP ii Pushes water and solutes into capillary from IF e Net Filtration Pressure NFP i Difference between net hydrostatic pressure and net osmotic pressure ii IHP and ICOP is usually 0 mmHg iii NFP CHP BCOP f Capillary Exchange i At the arterial end of a capillary NFP 0 1 Fluid moving from the capillary into IF ii At the venous end of a capillary NFP 0 1 Fluid moving from IF into capillary iii The transition point between filtration and reabsorption is closer to the venous end of the capillary iv Filter more than they reabsorb 1 Excess fluid enters lymphatic vessels g Capillary Dynamics i Hemorrhaging will reduce CHP and NFP and increase reabsorption of IF 1 Fluid recall ii Dehydration will increase BCOP because proteins will remain stuck in the blood 1 Accelerate reabsorption because you now have a larger component drawing liquid back into the capillary iii Increase in CHP or decrease in BCOP will move fluid out of blood and cause a build up in peripheral tissues edema 1 Edema results from starvation or liver disease due to no production of plasma proteins Cardiovascular Regulation a Tissue Perfusion i Blood flow through tissues that involves carrying O2 and nutrients to the tissues and organs while carrying CO2 and wastes away ii Affected by 1 How much blood is reaching tissues cardiac output 2 Peripheral resistance the greater the peripheral resistance the less blood reaches tissues 3 Blood pressure depends on cardiac output b Regulation changes the amount of blood flowing to a specific area at an appropriate time and in the right area without changing blood pressure and blood flow to vital organs c Cardiac output and blood pressure regulated by i Autoregulation immediate localized homeostatic adjustments 1 Don t need stimulation of neural system 2 Adjusted by peripheral resistance while the cardiac output stays the same a Functions of local vasodilators Accelerate blood flow at tissue level due to i Low O2 or high CO2 ii Low pH when cell is metabolically active the pH becomes more acidic iii Nitric oxide NO iv High K or H concentrations 1 The higher the H the lower the pH v Chemicals like histamine that are released due to inflammation vi Elevated local temperature 1 Associated with increase metabolic activity b Local vasoconstrictors i Will only affect local single capillary beds ii Released by damaged tissues and contrict precapillay sphincters iii Examples prostaglandins and thromboxanes ii Neural mechanisms 1 Quick responses to changes at specific sites 2 Short term 3 Cardiovascular CV centers a Medulla oblongata b Cardiac centers i Cardioacceleratory centers increase cardiac output ii Cardiacinhibitory center reduces cardiac output c Vasomotor centers i Vasoconstriction is controlled by stimulation of smooth muscle contraction in arteriole walls ii Vasodilation controlled by relaxing smooth muscle d Monitor arterial blood through i Baroreceptor reflexes respond to blood pressure changes 1 Stretch receptors found in the walls of a Carotid sinuses i Maintains flow of blood to brain b Aortic sinuses i Monitors the start of the systemic circuit c Right atrium i Monitors end of systemic circuit ii Used in Bainbridge reflex to increase heart rate 2 When blood pressure rises cardiac output decreases and vasodilation begins 3 When blood pressure falls cardiac output increases and vasoconstriction begins ii Chemoreceptor reflexes respond to chemical composition changes especially due to pH and gases 1 Peripheral chemoreceptors found in carotid bodies and aortic bodies a Monitor blood 2 Central chemoreceptors found below medulla oblongata a Monitor CSF b Control flow of blood to brain 3 Reduce changes in pH O2 and CO2 concentrations 4 Thought processes and emotional states will cause cardiac stimulation and vasoconstriction due to elevated blood pressure iii Endocrine mechanisms long term changes 1 Some have short term effects while others are long term 2 E and NE stimulate vasoconstriction and cardiac output 3 Antidiuretic hormone ADH a Released by posterior pituitary neurohypophysis b Elevates blood pressure and reduces water loss at kidneys c Responds to i Low blood volume ii High plasma osmotic pressure iii Circulating angiotensin II III 4 Angiotensin II a Responds to fall in kidney blood pressure b Stimulates i Aldosterone production from adrenal cortex ii ADH production iii Thirst causes an increase in fluid intake and raise in blood volume iv Cardiac output and vasoconstriction 5 Erythropoietin EPO a Released at kidneys and responds to low blood pressure and low O2 content in the blood b Stimulates RBC production iv Natriuretic peptides 1 Atrial natriuretic peptide ANP produced by cells in right atrium 2 Brain natriuretic peptide BNP produced by ventricular muscle cells 3 Respond to excess stretching in diastole 4 Lowers blood pressure and blood volume by promoting water loss inhibiting ADH aldosterone NE and E 5
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