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Blood Vessels
A&P II ch 21
| Term | Definition |
|---|---|
| Systemic Circulation | blood vessels that extend to & from the body tissues |
| Pulmonary circulation | vessels that take the blood back to the the lungs for gas exchange |
| Vessels form | closed looped system, blood continuously pumped to & from lungs |
| Vessels can | pulsate and change shape in accordance w/ the body needs |
| NAV complex | arteries and veins run side by side combine with a nerve to form a NAV complex |
| Largest blood vessels | Aorta & pulmonary trunk -attach to heart and have thick walls w/ large diameter |
| Pulmonary Trunk | carries blood from R. Ventricle to pulmonary circulation |
| Aorta | carries blood from L. Ventricle to systemic circulation |
| Capillaires | smallest blood vessels -thin walls -chems and gases diffuse across walls |
| 3 types of Blood Vessels | 1.Arteries-blood away from the heart 2.Veins-blood to the heart 3.Capillaries-connect smallest arteries and smallest veins *Arteries away, Capillaries connect |
| 3 layers of Vessel Walls | 1.Tunica intima (interna)-produces vasoconstriction/dilators 2.Tunica Media (muscular)-smooth muscle, thick layer 3.Tunica externa (adventa)- simple squamous epithelium |
| Structure of Artery Wall | Internal- elastic membrane behind tunica intima/adevnta External- elastic membrane behind tunica media |
| Vasa Vasorum | vessels of vessels small arteries and veins in walls of large arteries & veins supply tunica media & externa helps with formation of atherosclerotic plaques (atheroma) |
| If no Vasa Vasorum | thinner and more prone to aneurysm, abnormal aorta below renal arteries |
| Atheroma | reversible accumulation of degenerate material which narrows walls & restricts flow form between tunica intima |
| "fatty streaks" | WBCs (inflammation) made of macrophages that become foam cells liquid core w/ calcified coating (cracks) |
| Aneurysm | weakened arterial wall force of blood causes wall to bulge MC cause-atherosclerosis & high BP MC sites- aorta, renal arteries, circle of Willis (base of brain) Result of rupture = massive bleeding pain &/or death due to pressure on nerves, tis, organ |
| Arteries | thicker walls & higher BP collapsed artery has small round lumen (internal space) more elastic and contractile (vasoconstriction/dilation) must withstand forceful card. contractions resilient and strong largest closest to heart, smallest far away |
| Veins | large, flat lumen has lining that contracts have valves can stretch= large pool of blood in body not subjected to high pressure = thinner walls |
| 3 types of Arteries | 1. Conducting 2. Distributing 3. Arterioles |
| Conducting Arteries | elastic due to large amount of elastic fibers (expansion fibers) largest, closest to the heart ex. Aorta, common carotid, subclavian |
| Distributing Arteries | med. sized muscular arteries ex. brachial, femoral, renal "Swiss cheese" of internal and external elastic lamina |
| Arterioles | resistance bc resist flow of blood using smooth muscle. contraction in walls smallest arteries regulates BP & control how much blood enters organ connected to capillaries by metarierioles |
| Capicatance | storage vessels- can carry varying amnts of blood smallest @ beginning, larger as approaches heart |
| 3 types of Capicance | 1. Venules 2. Medium- sized veins 3. Large Veins |
| Venules | smallest veins that collect blood from capillaries -thin walls, few endothelial cells -porous & can exchange fluid w/surrounding tissues |
| Medium sized veins | Valves where venues converge, have thicker more elastic walls fights gravity in legs ex. radial/unlar veins of forearm, great saphenous veins in legs |
| Large Veins | formed as medium sized veins converge on the heart thick tunica externa (fibrous) ex. vena cavae, pulmonary veins, internal/external jugulars |
| Capillary exchange | site of gas, nutrients, hormone and waste exchange small diameter- one blood cell @ a time cells in body </= 4-6 cell widths away from a cap |
| Tissue w/ high metabolic rates | liver, kidneys, myocardium more capillaries |
| Fibrous Tissues | tendons have few capillaries |
| Epidermis, cartilage, lens of cornea of eye | no capillaries |
| 3 types of capillaries | 1. Continuous 2. Fenestrated 3. Sinusoid |
| Continuous capillaries | uninterrupted lining small molecules lipid soluble, passively diffuse via concentration gradient Block RBCs & proteins from leaving lumen of vessel |
| Fenestrated capillaries | tiny opening (windows) in endothelial lining small molecules & some proteins allowed permit fast exchange of water & solutes between vessel & interstitium -choroid plexus, kidneys, intestines |
| Sinusoid Capillaries | MOST PERMEABLE open-pore capillaires endothelial cells w/incomplete basement membrane Allows RBCs, WBCs and blood proteins to pass RBC from Red Bone Marrow & clotting from liver enter bloodstream liver, bone marrow, spleen |
| Capillary Beds | use microcirculation plexuses (arterioles->venules) |
| Microcirculation | circulation of the blood in the smallest blood vessels, present in the vasculature embedded within organ tissues contrast is macro circulation- circulation of blood to & form the organs |
| Where is the blood? | venous system holds 60-65% of the blood of the circulation heart, arteries & capillaries contain 30-35% |
| Pre-capillary Sphincter | band of smooth muscle that adjusts blood flow into network capillaries during exercise (more O2)- open during rest (less O2)- close -allows blood to bypass the network & head straight to venule on the thoroughfare channels |
| Throughfare Channels | Direct capillary connections between arterioles & venules -controlled by metarartierles (smooth muscle segements) |
| Collaterals | atreriovenules anastomoses- direct connections between arterioles & venules bypass capillary bed |
| Vasomation | contraction & relaxation cycle of capillary sphincters causes blood in capillary beds to constantly change routes |
| Angiogenesis | formation of new blood vessels due to hypoxia Vasucular Endothelial growth factor (VEGF) |
| Waste involved with capillary exchange | O2, glucose, nutrients out moves waste to other parts of the body -glucose (liver) -calcium (bones) -Antibodies (immune cells) -Hormones (endocrine glands) |
| 3 Mechanisms of capillary exchange | 1. Diffusion 2. Filtration 3. Osmosis |
| Diffusion | gases only gases move from high to low concentration O2 out, O2 into capillary |
| Filtration | Hydrostatic Pressure occurs close to arterial side of capillary bed higher pressure in capillary pushes glucose, amino acids, plasma out |
| Osmosis | (Osmotic pressure) occurs towards venous side as pressure drops @ venous end Albumin exerts colloid osmotic pressure, pulling tissue fluid in along w/waste |
| Edema | fluid filters out of capillaries taste than it can be absorbed that builds up in tissues |
| 3 main causes of edema | 1.Increased capillary filtration- kidney failure, venous status, RSHF 2.Reduced capillary reabsorption-Albumin deficiency to burns or liver disease (made in liver 3.Obstructed lymphatic drainage-includes surgical removal of lymph due to disease (cancer |
| Principles of Circulation | Oxygen & nutrients to tissues & wastes removed deficiency & accumulation of wastes= tissue necrosis & possible death blood flows due to differences in pressure between 2 structures |
| Vasodilation & Vasoconstriction | active change in diameter of arterial wall controlled by Sympathetic Nervous System |
| Vasodilation | smooth muscles in arteries relax increase diameter of lumen promotes more O2 to cells & CO2 removal can be used to cool body |
| Vasoconstriction | Constriction of arterial smooth muscle decrease diameter of lumen can reduce bleeding during hemostasis |
| Flow, Pressure, and Resistance | blood moves away from heart- BP drops until in vena cava (pressure= 1mm Hg) higher pressure difference between 2 points= high tendency to go from high to Low more resistance= slower flow pulse pressure = systolic pressure - diastolic |
| Blood Flow | degree of a motion in the blood vessel |
| Blood Pressure | force exerted by blood against a vessel wall generated by heart to overcome resistance from pulmonary and systemic circuits |
| Resistance | aka peripheral resistance opposition to blood flow from friction or constriction more resistance, slower blood flow due to upset of laminar blood flow which creates whirling turbulence |
| Pressure gradient | pressure in arterioles & arteries of kidneys MUST be > in the capillaries & veins of the kidney to push blood thru so it may be filtered -if hypotension, filtration will not occur -if hypertension in capillaries, cap walls will burst |
| Arterial Blood Pressure | Systolic Pressure-peak arterial pressure during vent. systole Diastolic Pressure- minimum arterial pressure during diastole Pulse Pressure can be used as a predictor of compliance in the aorta= lower elasticity over time creates widened Pulse Pressure |
| Pressures affecting Blood Flow | Blood Pressure Blood Colloid osmotic pressure Capillary Hydrostatic Pressure Venous Pressure |
| Blood Pressure- arterial pressure | starts at 120 mmHg @ aorta, drops to 35 mmHg @ start of capillaries |
| Blood Colloid Osmotic Pressure | caused by suspended blood proteins that are too large to cross capillary walls, esp. albumin (80% responsible for BCOP) |
| Capillary Hydrostatic Pressure | pressing force of fluid against a vessel wall |
| Venous Pressure | pressure of blood in the venous system: very low |
| Factors affecting Overall Blood Pressure | Cardiac Output, High CO= High BP, Low CO= Low BP Blood Volume, low volume= low BP, High volume=High BP Resistance, High resistance= low flow + high BP, low resistance = high flow and low BP |
| Systemic Vascular Resistance | Resistance of entire cardiovascular system heart must overcome SVR so blood can flow thru body aka Total Peripheral Resistance Vasoconstriction (push back)= high SVR Vasodilation (wide open) = lower SVR |
| Vascular Peripheral Resistance | forces opposing blood flow in vessels Friction between blood & vessel walls Blood viscosity Turbulence |
| Friction | depends on length and diameter longer length + friction = more resistance larger diameter+ friction = less resistance |
| Blood Viscosity | suspended materials slow flow of liquid |
| Turbulence | swirling action that disturbs smooth flow of liquid plaque can increase turbulence & irregular surfaces |
| Diameter affects blood flow velocity | Higher Diameter of vessel= faster blood flows Aorta = 1200mm/sec Capillaries 0.4mm/sec small diameter= more resistance # of vessels >= higher cross-sectional total area resistance bc needs time to exchange |
| Mean Arterial Pressure | avg. pressure in arteries during 1 cardiac cycle better indicator of perfusion to vital organs than systolic- accounts for flow, pressure, resistance can be used w/SVR & central venous pressure to calculate cardiac output |
| Venous Pressure & return | Venous return = amnt of blood arriving at r. atrium each min low effective pressure in venous system so use muscle & resp 1. Muscle compression of peripheral veins 2. Respiratory Pump |
| Muscular compression of peripheral veins | compression of skeletal muscles pushes blood towards heart (one-way valves) |
| Respiratory pump | thoracic cavity action inhaling lowers thoracic pressure =vacuum in R. atrium exhaling increases thoracic pressure = blood flows into R. Atrium |
| Capillary Pressures & Capillary exchanges | vital to homeostasis only blood vessels whose walls permit a two-way exchange of material Blood flow= fast across capillary wall moves materials across cap walls by Diffusion, filtration, reabsorption |
| Diffusion of capillaries | movement of ions/molecules high to low concentration |
| Filtration of capillaries | driven by HP from heart heart-aorta-interstitial water & small solutes forced thru cap wall fluid out of capillaries larger solutes stay in bloodstream |
| Reabsorption | result of special OP due to pull of trapped proteins on water call oncotic BCOP pulls fluid into caps like a vacuum= creates neg pressure opposing force to hydrostatic pressure |
| Capillary exchange at Arterial end | Fluid Moves out into interstitial fluid due to hydrostatic pressure |
| Capillary exchange at Venous End | fluid moves in out of interstitial fluid due to colloidal osmotic pressure |
| Net Filtration Pressure | Net Hydrostatic pressure (push out) - Net Osmotic Pressure (Pull in) push out from heart contraction pull in due to colloids trapped in vein |
| Tissue perfusion | blood flow thru tissue O2 & nutrients go to tissues and organs CO2 and wastes away Affected by: Cardiac Output Peripheral Resistance BP |
Created by:
treylowrey1
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