Lesson 10 Exam 3 Study Guide 1 The concentration gradient regulates the diffusion of materials across the capillary walls from an area of high concentration to an area of lower concentration Diffusion routes a Water ions small molecules diffuse between adjacent endothelial cells or through fenestrated capillaries b Some ions Na K Ca2 Cl diffuse through channels in the plasma membrane c d Large water soluble compounds pass through fenestrated capillaries Lipids and lipid soluble materials such as O2 and CO2 diffuse through endothelial plasma membranes e Plasma proteins cross endothelial lining in sinusoids 2 Diffusion is the movement of ions or molecules from an area of high concentration to an area of lower concentration along a concentration gradient Substances that are able to diffuse across capillaries enter or leave the bloodstream through endothelial cell fenestrated capillaries or channels in the plasma membranes Filtration is driven by hydrostatic pressure and water and small solutes are forced through the capillary wall This leaves larger solutes in the bloodstream Reabsorption is the result of osmotic pressure Blood colloid osmotic pressure BCOP is caused by suspended blood proteins that are too large to cross the capillary walls BCOP equals the pressure required to prevent osmosis and it draws fluid back into the capillaries 3 Filtration and reabsorption a Ensure that plasma and interstitial fluid are in constant communication and mutual exchange tissues b Accelerate the distribution of nutrients hormones and dissolved gases throughout c Assist in the transportation of insoluble lipids and tissue proteins that cannot enter the bloodstream by crossing capillary walls d Has a flushing action that carries bacterial toxins and other chemical stimuli to lymphatic tissues and organs responsible for providing immunity to disease Fluid that does not get absorbed enters lymphatic vessels 4 The capillary hydrostatic pressure and the interstitial fluid hydrostatic pressure make up the net capillary hydrostatic pressure This pushes water and solutes out of the capillaries and into the interstitial fluid The blood colloid osmotic pressure and the interstitial fluid colloid osmotic pressure make up the net capillary colloid osmotic pressure which pulls water and solutes into a capillary from the interstitial fluid 5 Net filtration pressure NFP CHP IHP BCOP ICOP Usually the IHP and ICOP are 0mmHg so these two factors can be eliminated and the equation will be NFP CHP BCOP If NFP is negative reabsorption occurs If NFP is positive filtration occurs 6 Hemorrhaging reduces the CHP and the NFP but increases reabsorption of interstitial fluids because the NFP is less than the BCOP Dehydration increases the BCOP because since there is less fluid the concentration of blood is greater This accelerates reabsorption Edema occurs when fluid moves out of the blood and builds up in the peripheral tissues because an increase in CHP or a decrease in BCOP increases NFP Edema can result from starvation or liver disease because plasma proteins are not made 7 Tissue perfusion is when blood flow through the tissues carries O2 and nutrients to tissues and organs and carries CO2 and wastes away It is affected by cardiac output peripheral resistance and blood pressure Cardiovascular regulation changes blood flow to a specific area at an appropriate time in the right area without changing blood pressure and blood flow to vital organs 8 Mechanisms to control cardiac output and blood pressure a Autoregulation causes immediate localized homeostatic adjustments by opening and closing precapillary sphincters due to the local release of vasodilator or vasoconstrictor chemicals in the tissue i Local vasodilators accelerate blood flow at the tissue level and include low O2 or CO2 levels low pH NO high K or H concentrations chemicals released by inflammation histamine and elevated local temperature ii Local vasoconstrictors include prostaglandins and thromboxanes that are released by damaged tissues to constrict a precapillary sphincter to affect a single capillary bed b Neural mechanics respond quickly to changes at specific sites through the cardiovascular centers i The cardiac centers include the cardioacceleratory center which increases cardiac output through sympathetic innervations and the cardioinhibitory center which decreases cardiac output through parasympathetic innervations ii The vasomotor center includes the control of vasoconstriction to stimulate smooth muscle contraction in arteriole walls and the control of vasodilation to relax smooth muscle c Endocrine mechanics direct long term changes 9 Baroreceptors reflexes respond to changes in blood pressure Stretch receptors in the walls of the carotid sinus maintain blood flow to the brain Stretch receptors in the aortic sinus monitor the start of the systemic circuit Stretch receptors in the right atrium monitor the end of the systemic circuit and are used in the Bainbridge reflex to increase heart rate When blood pressure rises the cardiovascular centers decrease cardiac output and cause peripheral vasodilation When blood pressure falls the cardiovascular centers increase cardiac output and cause peripheral vasoconstriction Chemoreceptor reflexes respond to changes in chemical composition particularly pH and dissolves gases Peripheral chemoreceptors in the carotid bodies and aortic bodies monitor blood The central chemoreceptors below the medulla oblongata monitor cerebrospinal fluid control blood flow to the brain and control respiratory function This reflex coordinates cardiovascular and respiratory activities to reduce changes in pH O2 and CO2 concentration 10 Hormones important in regulating cardiac output and blood pressure a Antidiuretic hormone ADH released by the neurohypohysis posterior lobe of the pituitary elevates blood pressure reduces water loss at the kidney ADH responds to low blood volume high plasma osmotic concentration and circulating angiotensin II b Angiotensin II responds to a fall in renal blood pressure at the kidneys stimulates aldosterone production from the adrenal cortex ADH production thirst cardiac output and peripheral vasoconstriction c Erythropoietin EPO released at the kidneys to respond to low blood pressure and low O2 content in the blood stimulates red blood cell production d Natriuretic peptides atrial natriuretic peptide ANP is produces by cells in the right atrium brain natriuretic peptide BNP is produced by
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