Chapter 21 - Blood Vessels and Circulation (Lecture) PDF

Part 1: Intro to the Main Types of Vessels and the 3 Layers of a Blood Vessel Part 2: A Deep Dive into the 3 Arteries, 3 Capillaries, and 3 Veins How does the vessel anatomy allow for the differences in functionality of the 3 vessel types? Part 1:  Identify and describe the 5 types of vessels and i...

Part 1: Intro to the Main Types of Vessels and the 3 Layers of a Blood Vessel Part 2: A Deep Dive into the 3 Arteries, 3 Capillaries, and 3 Veins How does the vessel anatomy allow for the differences in functionality of the 3 vessel types? Part 1:  Identify and describe the 5 types of vessels and identify the largest vessels + there locations.  Describe the 3 layers within vessels, and differentiate between arteries, capillaries, + veins. Part 2:  Compare and contrast the 3 types of arteries, capillaries, and veins.  Explain what vasomotion of capillaries is and its role.   1) Arteries – carry blood away from heart. 2) The smallest branches of arteries? ◦ Arterioles  3) Smallest blood vessels & site of exchange b/n blood and interstitial fluid. ◦ Capillaries  4) The caps. drain blood into the smallest veins? ◦ Venules   5) The veins – return blood to the heart. MPs: Heart → Arteries → arterioles → Capillaries (exchange) → venules → veins → heart.   The vessels attached to heart. 1) Pulmonary trunk, receives blood from? (21.2) ◦ Right ventricle passing to pulmonary circulation.  2) Aorta, sends blood? ◦ to systemic circulation – circulation throughout body.  The smallest BVs? ◦ Capillaries – anatomy allows for exchange. ◦ Bridge between arteries & veins.  1) Tunica intima/interna = Aka endothelial lining. ◦ internal layer of simple squamous + elastic CT. ◦ Arteries have internal elastic membrane – thick elastic fibers separate internal layer from next layer  2) Tunica media – middle layer of smooth muscle. ◦ Loose CT of collagen + elastic fibers. ◦ Function = controls diameter of vessel. ◦ Arteries = external elastic membrane – separates...  3) Tunica externa – outer layer – sheath of CT + elastic fibers that anchors vessels to other tissues.   As and Vs run side by side. Which is thicker? Why? (21.1) ◦ Arteries, deal with high BP.  Which has larger diameter? ◦ Veins = holds largest volume of blood.  More elastic/flexible? ◦ Arteries - extra elastic membranes (high pressure)  Veins have valves that function to? ◦ Prevent backflow. 1. 2. 3. 4. 5. 6. List the order in which blood flows through the next 4 vessel types starting at venules. What’s the middle layer within vessels called, + which vessel has the largest middle layer & why? What are the characteristics that make arteries, capillaries, and veins unique to one another? How do muscular + elastic arteries differ, give examples, + what are arterioles and aneurysms? How do continuous, fenestrated, and sinusoid capillaries differ and where are they commonly located. What BVs have highest percent of blood? How do precapillary sphincters respond to low levels of O2 versus normal nutrient + O2 levels? Part 1: Intro to the Main Types of Vessels and the 3 Layers of a Blood Vessel Part 2: A Deep Dive into the 3 Arteries, 3 Capillaries, and 3 Veins What are the 3 variations of arteries, capillaries, and veins, and what does this variation allow? Part 1:  Identify and describe the 5 types of vessels and identify the largest vessels + there locations.  Describe the 3 layers within vessels, and differentiate between arteries, capillaries, + veins. Part 2:  Compare and contrast the 3 types of arteries, capillaries, and veins.  Explain what vasomotion of capillaries is and its role.  Artery elasticity absorbs pressure waves from each heart beat via? (21.1) ◦ Internal + External elastic membrane (unique to As).  Arteries capable of contractility, meaning? ◦ Has smooth muscle that can change diameter via ANS stimulation. 2 potential changes?    1) Vasoconstriction = ? Contraction ➔ decrease of lumen size. 2) Vasodilation = relaxation, that enlarges the lumen.   Arteries change in A&P from heart to capillaries - diameter shrinks. Starts as elastic arteries - more elastic than muscular arteries. ◦ Absorbs pressure changes readily.  Stretches during systole, relaxes during diastole. Examples? ◦ Aorta, pulmonary trunk, + major branches (1st branches off aorta).  Next, muscular arteries have more? ◦ Tunica media w/less elastic fiber. ◦ Ex: most arteries (external carotid, axillary, brachial, femoral). AKA distribution arteries. ◦ Contract when low demand for blood, relax when high demand.  Arterioles – deliver blood to capillaries. ◦ Thin tunica media (1-2 layers of incomplete smooth muscle) ◦ Poorly defined tunica externa.    Precapillary Sphincters – surround entrance to capillary & control blood flow to capillaries. What’s an aneurysm? Bulge in arterial wall due to weak spot in elastic fibers. ◦ Pressure may rupture vessel ◦ Worst case in brain or heart.    Permit exchange b/n blood and interstitial fluid. tunica interna only = ie: endothelial cells w/basement membrane – branch through CT. Anatomy ideal for diffusion ◦ ◦ ◦ ◦ Thin walls = short travel distance Small diameter = slowed flow promoting exchange. Large surface area due to large capillary beds. Decent Pressure for size  Most common (muscles) = continuous capillaries. ◦ complete endothelial lining; ◦ Permit diffusion of water, small solutes, + lipid soluble materials.  Cells + plasma proteins cannot escape. ◦ Large exchange via vesicular transport.  Fenestrated: have pores in endothelial lining. ◦ rapid exchange + larger solute exch.  Ex: endocrine organs, choroid plexus, kidneys, absorptive area of SI.  Least common = fenestrated w/gaps w/in adjacent endothelial cells. ◦ Permit free exchange, important for plasma proteins. ◦ Found where?    Liver, spleen, bone marrow + endocrine organs. Capillary beds (21.4) = interconnected network of caps. that connect 1 arteriole to one venule. Entrance regulated via precapillary sphincter. ◦ Relaxation = more flow; contraction = less flow. ◦ Dense regions where O2 demands are high. c)   Contraction/relaxation cycle of sphincters. What influences this “control”? ◦ Chemical and oxygen demands. ◦ High demand ➔ relaxation ➔ large diameter for exchange. ◦ Low demand ➔ constriction ➔ shunt blood flow   What vessel is after capillaries? Venules = smallest veins that collect blood from capillaries; (similar to capillaries but larger diam.) ◦ some lack tunica media  Blood distribution throughout cardiovascular sys. ◦ 60-65% in venous system = veins. ◦ 30-35% in heart, arteries, and capillaries   Return blood back to heart. After venules, blood enters into medium sized veins. ◦ Thin tunica media w/few smooth muscle layers. ◦ Limbs have valves that prevent backflow going against gravity.  Large veins – have large diameter + thinner walls than arteries due to low pressure.  Superior + inferior venae cavae + branches w/in abdominopelvic & thoracic cavities. 1. 2. 3. 4. 5. 6. List the order in which blood flows through the next 4 vessel types starting at venules. What’s the middle layer within vessels called, + which vessel has the largest middle layer & why? What are the characteristics that make arteries, capillaries, and veins unique to one another? How do muscular + elastic arteries differ, give examples, + what are arterioles and aneurysms? How do continuous, fenestrated, and sinusoid capillaries differ and where are they commonly located. What BVs have highest percent of blood? How do precapillary sphincters respond to low levels of O2 versus normal nutrient + O2 levels? Part 1: Various Pressures, Vessel Characteristics, and Capillary Exchange. Part 2: Blood Tracing and Identifying Blood Vessels. What causes substances to enter & leave capillaries? What kinds of pressures exists and how does this impact exchange? Part 1:  Define pressure, resistance, and flow, and explain how they are correlated.  Differentiate between hydrostatic and osmotic pressure, and identify what factors contribute to capillary exchange.  Identify which vessels have the greatest pressure, surface area, diameter, velocity, and volume.  Explain capillary hydrostatic pressure & blood colloid osmotic pressure, their role in capillary exchange, + relate to net filtration pressure + exchange. ◦ Relate pressures to arterial & venous ends Part 2:  Identify the various vessels blood would pass through given a start and end location.  Identify the various blood vessels using images and relate it to models within the classroom    Force exerted on vessel wall Resistance – friction of vessel wall pushing back on blood’s outward pressure. Blood flow = P divided by R (P/R) = velocity ◦ More P (heart contraction) = more flow; More R (vessel contraction) = less flow.   2 Types of Pressure related to exchange: 1) Hydrostatic pressure (HP) – pressure due to force of fluid against vessel wall. “pushing force” ◦ Capillary HP = force exerted by blood inside capillary wall forcing substances out. ◦ Interstitial fluid HP = force exerted on outside of capillary wall via interstitial fluid forcing fluid back in  2) Osmotic Pressure (OP) – pressure due to force of solids “sucking/pulling” fluid towards solids. ◦ Blood Colloid OP = force due to proteins in plasma (albumins) = pulls liquid + substances into caps. ◦ Interstitial fluid OP = due to proteins in interstitial fluid (almost 0, doesn’t impact flow much).  Factors the impact pressure/exchange: ◦ Vessel Diameter (smaller = more pressure) ◦ Amount of solutes (greater = more pressure)  Impacts viscosity (more = more viscous) ◦ Blood pressure = measured via arteries = more pressure = more exchange. Normal BP? Hypertension?  ◦ 120/80; 140/90 or greater      A) B) C) D) E) Veins have largest diameter. Capillaries = largest cross-sectional area. Arteries = highest BP. Velocity = highest at arteries; lowest in caps Volume = Greatest in veins.  Movement of materials across capillary walls ◦ Critical for homeostasis   Movement occur 3 ways: Diffusion – solutes moving from high to low concentrations (along conc. gradient). ◦ O2, CO2, + lipid solubles move through cells. ◦ glucose, AAs, and water-solubles move b/n cells or through proteins.  Filtration – movement of? ◦ water and small solutes out of blood (leaves large substance in blood)  Reabsorption –movement of? ◦ water and solutes INTO blood from interstitial fluid (IF)     Movement of water + small solutes out of blood driven by capillary hydrostatic pressure (CHP). Movement of water and solutes INTO blood driven by blood colloid osmotic pressure (BCOP) MPs: CHP = pressure of plasma + solutes push substances out of the capillaries = filtration. BCOP = created by albumins = “pulls/sucks” water + solutes back = Reabsorption  Result from differences b/n CHP and BCOP ◦ When (+) = filtration;   When (-) = reabsorption. MPs: CHP + BCOP control filtration + reabsorption. Is CHP higher at arteriole OR venule end? Why? ◦ Arteriole = blood is full of solutes = high CHP = results in filtration = removal of solutes from capillary into IF.  CHP decreases as blood travels due to exchange; eventually drops below BCOP resulting in? Reabsorp. occurs, but less solutes are picked up.  Effects of Dehydration on CHP?    Water loss = decrease CHP = accelerates reabsorb. Impact of water consumption? ◦ Increase in BP + CHP resulting in more fluids leaving; ◦ Fluid build up in peripheral tissues = edema [a-de-ma] 1. 2. 3. 4. 5. 6. 7. 8. What is pressure, how do pressure & resistance impact flow, and what vessel is used to test one’s BP? What effect does an increase in pressure have on exchange? How would more solutes in blood impact BP? larger vessel diameter? Distance from the heart? Which vessels hold the greatest volume of blood? Greatest surface area? Highest/Lowest velocity? Highest/lowest pressure? Largest/smallest diameter? What 2 factors impact net filtration pressure, how does it normally change from arterial vs venous end, and why does this change happen? How does drinking water impact CHP + BCOP? How does dehydration impact CHP + BCOP and relate these impacts to exchange! When starting blood tracing, which vessel do we start in first and why? If you started at the intestines, what’s the other blood vessels blood passes through to get to the heart? If you started at the brain, what route would blood travel to get to the stomach? What about to get to the legs? If you started at the bladder, what route would blood travel to get to the stomach? What about to get to the right arm? Part 1: Various Pressures, Vessel Characteristics, and Capillary Exchange. Part 2: Blood Tracing and Identifying Blood Vessels. How are blood vessels named, how can we identify them, and what is blood tracing? Part 1:  Define pressure, resistance, and flow, and explain how they are correlated.  Differentiate between hydrostatic and osmotic pressure, and identify what factors contribute to capillary exchange.  Identify which vessels have the greatest pressure, surface area, diameter, velocity, and volume.  Explain capillary hydrostatic pressure & blood colloid osmotic pressure, their role in capillary exchange, + relate to net filtration pressure + exchange. ◦ Relate pressures to arterial & venous ends Part 2:  Identify the various vessels blood would pass through given a start and end location.  Identify the various blood vessels using images and relate it to models within the classroom       Tracking the vessels in which blood moves starting at one location (organ) moving to the next! For LEAST number of steps, we start at arteries or veins? Start with Veins, why? If we start with arteries, we are beginning by moving AWAY from the heart, which would add extra destinations. Since veins move towards the heart, we start with veins. Although the vessels are names differently, they are primarily based along a “highway” of main vessels related to organ or location in the body! ◦ IE, the vessel rarely is a new branch, rather the “next destination” of the vessel.  Must take most direct route AND cannot change “turnaround” once going through specific vessel.  Start at Arm = ◦ L. or R. brachial Vein  #’s 5 and 11  Start at Brain ◦ L. or R. Internal Jugular Vein  #’s 7 and 12  Start at Face ◦ L. or R. External Jugular Vein  #’s 6 and 13  Start at Legs ◦ L. or R. Femoral Veins  #26 or 30  Start at reproductive organs/bladder = ◦ L. or R. Internal Iliac Vein  #’s 25 and 29  Start at Spleen, Stomach, or intestines ◦ Splenic ◦ Gastric ◦ Superior or inferior mesenteric veins  #’s 20, 17, or 18/19  Spleen, stomach, and intestine blood flow passes through “Hepatic Portal Vein” → Liver → Hepatic Vein → Inferior Vena Cava  End at Arm = ◦ L. or R. brachial Artery  #’s 4 and 13  End at Brain ◦ L. or R. Internal Carotid Artery  #’s 7 and 9  End at Face ◦ L. or R. External Carotid Artery  #’s 6 and 10  End at Legs ◦ L. or R. Femoral Arteries  #25 and 29  End at reproductive organs/bladder = ◦ L. or R. Internal Iliac Artery  #’s 24 and 28  End at Spleen, Stomach, or Liver ◦ Splenic Artery ◦ Gastric Artery ◦ Hepatic Artery  #’s 16, 17, or 18  Spleen, stomach, and liver blood flow passes through Celiac Artery (15), which ends at 1 of those 3 destinations! NOT ALL  Start at Right Arm → End at R. Leg =  Start at Left Side of Brain → End at Stomach  Start at Spleen → End at Spleen  Start at Intestines → End at Left Arm  Start at Lungs → Stomach → End at Right Arm 1. 2. 3. 4. 5. 6. 7. 8. What is pressure, how do pressure & resistance impact flow, and what vessel is used to test one’s BP? What effect does an increase in pressure have on exchange? How would more solutes in blood impact BP? larger vessel diameter? Distance from the heart? Which vessels hold the greatest volume of blood? Greatest surface area? Highest/Lowest velocity? Highest/lowest pressure? Largest/smallest diameter? What 2 factors impact net filtration pressure, how does it normally change from arterial vs venous end, and why does this change happen? How does drinking water impact CHP + BCOP? How does dehydration impact CHP + BCOP and relate these impacts to exchange! When starting blood tracing, which vessel do we start in first and why? If you started at the intestines, what’s the other blood vessels blood passes through to get to the heart? If you started at the brain, what route would blood travel to get to the stomach? What about to get to the legs? If you started at the bladder, what route would blood travel to get to the stomach? What about to get to the right arm? Part1: Intro to Perfusion & Cardiovascular regulation, and Neural Regulation. Part 2: Deeper look into System Regulation via Neural and Endocrine Control. How and why does blood go where it goes? Think – nutrients to liver, CO2 to lungs, O2 to active tissue! Part 1:  Define tissue perfusion, and identify and explain the 3 factors that play a role in perfusion.  Define autoregulation and describe the 2 autoreg. responses and conditions in which they occur.  Identify the 2 ways the body controls widespread perfusion.  Explain the neural control related to perfusion + which part of brain, and differentiate between cardiac centers vs vasomotor centers. Part 2:  Differentiate baro- vs chemo-receptors, know their locations, and what environmental factors cause a response.  Identify and describe ALL the hormones related to systemic blood flow control.  Tissue perfusion= regulation of blood flow sending substances to appropriate tissue for exchange.  Ex: O2 + nutrients to tissues; CO2 towards lungs; wastes to kidneys; toxins to liver.  Vasomotion – adjustment of blood flow through capillaries for exchange w/in tissues in need. 3 various levels ◦ Autoregulation – immediate, localized homeostatic adjustments via precapillary sphincters. ◦ Neural mechanisms – quick changes at specific sites for fast homeostasis maintenance. ◦ Endocrine mechanism – enhance short term changes ultimately maintaining long-term homeostasis.  localized adjustments via pre-cap sphincters? ◦ 2 responses?  1) Local vasodilators = increased blood flow via sphincter dilation/relaxation due to: ◦ Low O2 or high CO2 + acidic pH, ◦ Nitric oxide (NO) via endothelial cells; ex: [Viagra] ◦ Histamines & elevated local temperature  2) Local vasoconstrictors = decrease blood flow via sphincter contraction due to: ◦ Injury leading to prostaglandins ◦ Chemicals released by platelets ◦ Heparin via mast cells.  Constrictors are released during injury or damage!   B) Neural vs C) Endocrine (TBD) B) Neural input via cardiovascular “centers” of medulla oblongata which include:  (anatomy of centers is indistinguishable). ◦ I) cardiac centers: regulate cardiac output  a) Cardioacceleratory centers increase CO via sympathetic nerves innervating the heart.  b) cardioinhibitory centers: reduce CO via parasympathetic input. ◦ II) Vasomotor centers: functionally control widespread autoregulation via neurons.  FYI: BOTH CENTERS COMBINED = (general term) Cardiovascular centers 1. 2. 3. 4. 5. 6. What is perfusion and how is it regulated? Where does autoregulation occur and what occurs when O2 levels drop vs a local injury vs when tissues need nutrients vs when CO2 builds up? How is neural and endocrine control related to autoregulation, and how do they differ from each other and differ from autoregulation? What part of the brain elicits neural BP control, and how do cardiac vs vasomotor centers differ? What are baro- + chemo-receptors, where are they located, and how does high BP impact cardiovascular centers? Low O2? Low BP? What’s the role of renin related to perfusion? EPO? ADH? BNP + ANP? E and NE? Aldosterone? Part1: Intro to Perfusion & Cardiovascular regulation, and Neural Regulation. Part 2: Deeper look into System Regulation via Neural and Endocrine Control. Details of the reflex control that helps regulate and maintain perfusion! Part 1:  Define tissue perfusion, and identify and explain the 3 factors that play a role in perfusion.  Define autoregulation and describe the 2 autoreg. responses and conditions in which they occur.  Identify the 2 ways the body controls widespread perfusion.  Explain the neural control related to perfusion + which part of brain, and differentiate between cardiac centers vs vasomotor centers. Part 2:  Differentiate baro- vs chemo-receptors, know their locations, and what environmental factors cause a response.  Identify and describe ALL the hormones related to systemic blood flow control.    Neural input of medulla oblongata that causes widespread autoregulation/changes to vascular tone. 2 Sets of neurons release key neurotransmitters: ◦ a) adrenergic nerves release norepinephrine to cause vasoconstriction of arterioles (most tissues) ◦ b) cholinergic nerves ACh release stimulates release of NO by endothelium to dilate artery (skeletal muscle and brain). Reflex control occurs via sensors (receptors) that sense pressure? and gas? changes ◦ baroreceptor reflexes sense changes to pressure. ◦ chemoreceptor reflexes sense chemical changes; which 3 key chemicals?  pH, O2, and CO2 levels    baroreceptors = carotid and aortic “sinuses” chemoreceptors = carotid and aortic “bodies” When BP rises, 3 cardiovascular centers responses? (Baroreceptor signaling) ◦ 1)Cardioacceleratory center inhibited (heat rate down) ◦ 2)Cardioinhibitory center stimulated (heart rate down) ◦ 3)Arteriole dilation (pressure decrease)  IE: “parasympathetic stimulation” occurs AFTER baroreceptor stimulation!  low O2 levels (↑CO2 levels)? (Chemo-signaling)? ◦ 1)Cardioacceleratory center stimulated (heart rate up) ◦ 2)Cardioinhibitory center inhibited (heart rate up) ◦ 3)Arteriole constriction (pressure increase)  IE: low O2 = high O2 usage = increased energy demand = sympathetic stimulation!  Baroreceptor response (left); chemo (right)    Hormones are for “longer-term”, sustained control. Which hormones help with BP or low O2? ADH, renin (Details in 2 slides), EPO, Epi- and norepinephrine, + natriuretic peptides (next slide). ◦ Secreted by what gland, target’s what gland, released in response to, and end effect of each?    Released from posterior pituitary → target kidney → released due to low blood volume OR high solute concentration → causes water reabsorp. Released by kidneys → targets red bone marrow → release due to low O2 (mostly) or low BP (rare) → increases RBC formation + overall BP. Adrenal medulla → targets heart → low BP OR sympathetic stimulation → increase heart rate  Released when BP too high; causes reduction in blood volume = reduces stress of heart. ◦ Release from right atrium = atrial NP ◦ Release from ventricles (of brain) = brain NP.  What causes Renin release?+ organ that releases it? ◦ Decreased BP & blood volume; released by kidneys. Effects?    Renin converts Angiotensinogen → Angiotensin I ACE converts Angiotensin I → Angiotensin II Angiotensin II stimulates aldosterone secretion (adrenal), ADH secretion (PP), + stimulates thirst.  Autoregulation = local control via precap. sphincters ◦ Dilate/constrict.  Neural control via baro + chemoreceptors that stimulate cardiovasc. centers. ◦ Speed-up/slow-down heart rate + dilate or constrict vessels.  Hormonal control via ADH, Epi & Nor-epi, EPO, Renin, and natriuretic peptides. 1. 2. 3. 4. 5. 6. What is perfusion and how is it regulated? Where does autoregulation occur and what occurs when O2 levels drop vs a local injury vs when tissues need nutrients vs when CO2 builds up? How is neural and endocrine control related to autoregulation, and how do they differ from each other and differ from autoregulation? What part of the brain elicits neural BP control, and how do cardiac vs vasomotor centers differ? What are baro- + chemo-receptors, where are they located, and how does high BP impact cardiovascular centers? Low O2? Low BP? What’s the role of renin related to perfusion? EPO? ADH? BNP + ANP? E and NE? Aldosterone?