BIOL 244 1nd Edition Lecture 9Outline of Last Lecture I. Cardiac OutputII. Regulation of Cardiac OutputIII. Sympathetic and Parasympathetic Nervous System Regulation of COIV. Factors that influence Cardiac OutputV. Three Main Types of Blood VesselsVI. Structure of Blood Vessels Outline of Current Lecture I. Arterial SystemII. CapillariesIII. Venous SystemIV. Physiology of CirculationV. Systemic Blood PressureVI. Maintaining Blood Pressure Current LectureI. Arterial Systema. Elastic arteriesi. Arteries closest to the heart ii. Conducting Vessels iii. Contain elastin1. Helps to conduct blood away from the heartiv. Pressure reserves1. Stretch and recoilThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.2. Maintains pressure that keeps blood moving in a continuous manner away from the heart3. Keeps flow continuous b. Muscular arteriesi. Tunica Media is thickest than that of any other blood vesselii. Important for vasoconstriction c. Arteriolesi. Small in diameterii. Higher resistance iii. Feed into the capillaries1. Essentially just tunica interna2. Pericytea. Smooth, muscle-like cell b. Short with a small diameterc. Helps stabilize wall of capillaryII. Capillariesa. Most capillaries in the body are continuousb. Fenestrated capillariesi. Perforated by a windowii. Allows larger solutes to pass throughc. Sinusoidsi. Located in red marrowii. Large holesiii. Are very leakyiv. Allows for movement of cells 1. Allows blood cells into the circulatory system from the red marrowd. Capillary bedsi. Vascular Shunt1. Consists of metarteriole and the thoroughfare channel2. Connects terminal arteriole to the postcapillary venulee. Most tissues have very rich capillary suppliesf. Pre-capillary sphinctersi. At the base of some of the true capillariesii. Rings of smooth muscleiii. Relaxed: sphincter is open 1. Blood delivered to capillary bed2. Blood returned to thoroughfare channels iv. Contracted: shut1. Blood is delivered into capillary bed from terminal arteriole but bypasses all of the true capillaries2. Goes directly through the shunt to the postcapillary venule3. Bypassed so that we can bypass to other areas of the body that need it more III. Venous Systema. Postcapillary venulei. First component of systemb. Venulesi. Join together to form larger venules1. Eventually converge to veins c. Veinsi. Blood reservoirsii. Capacitance vessels1. At any given time, over half of the blood in your body is in your veins iii. Adaptations of veins to help return blood to heart1. Large lumensa. Lumen of vein much larger than lumen of arteryb. Blood along blood vessel wallslowed down by frictioni. Making it bigger increases the amount of blood that is against the wall and being slowed down by friction c. Relative to their overall size or compared to arteries2. Venous valvesa. Made up of folds of the tunica intima b. When blood is moving towards the heart, at some point it wants to go backwards (gravity)i. Pulls against venous valves and shuts them1. Blood cant go very far away from heartd. Vascular Anastomosis i. Arterial anastomoses1. Major arteries come together and form a network that give rise tolarger branchesa. Provides collateral channels to ensure adequate blood supply to rest of bodyi. Contains blood from multiple original arteries ii. In case of original vessels getting blocked or damagedii. Atriovenous anastomoses 1. See image iii. Venous anastomoses IV. Physiology of Circulation a. Blood flowi. The volume of blood moving through vessel, organ, or entire circulation ina given period of time1. Measured in mL/minute b. Blood pressure i. The pressure that is exerted on a vessel by the contained blood 1. Measured in mm Hgii. The flow of blood through the body is incredibly dependent on difference in blood pressure between one area and another c. Resistance (R)i. The opposition to flowii. Produced by friction iii. Peripheral resistanceiv. Determined by1. Blood viscositya. How thick is bloodb. Higher viscosity=increased thickness=increased resistance c. Directly proportional to resistance d. Tends to remain fairly stablei. Can change but will take 5-7 days under normal circumstances2. Total blood vessel lengtha. Increases resistanceb. Takes longerc. Directly proportional to resistance 3. Blood vessel diametera. Increased diameter leads to a decrease in resistanceb. Inversely proportional to resistance d. F= (deltaP)/Ri. deltaP: the difference in blood pressure between 2 points 1. The steeper BP gradient, the greater flow will be V. Systemic Blood Pressurea. Systolic pressurei. Blood pressure during systole 1. Focus on left ventricle systoleii. Approximately 120 mm Hgiii. Systolic pressure is highest pressure experienced in aorta during ventricular systole b. Diastolic pressurei. Pressure within the aorta during ventricular diastole ii. Helps to keep blood moving away from the heartiii. Approximately 70-80 mm Hgc. Pulse Pressurei. Systolic pressure-diastolic pressure1. Difference between systolic and diastolic pressured. Mean arterial pressure (MAP)i. Diastolic pressure + (pulse pressure/3)ii. Important for maintaining flow of blood through systemic circuit as blood gets farther from the heart e. Respiratory “pump”i. External to veinsii. Inspiration and expiration change volume of thoracic cavity 1. Helps to pump blood towards heartf. Muscular “pump”i. External to veins ii. Skeletal muscles contract around the veins and squeeze blood towards the heart VI. Maintaining Blood Pressure a. Cardiac Output (CO)i. CO=(SV)(HR)ii. mL/minb. Peripheral resistance i. Resistance to flowc. Blood Volumei. Amount of blood in the entire circulatory system d. Derivations i. F= (deltaP)/Rii. CO=(deltaP)/Riii.