984093
Descrição
FlashCards por rachel-chads, atualizado more than 1 year ago
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Criado por rachel-chads
mais de 10 anos atrás
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| Questão | Responda |
| Structure of blood vessels: Inner layer - Tunica initima | Endothelium Basement membrane |
| Structure of blood vessels: Middle layer - Tunica media | Elastic laminae/tissue Muscle |
| Structure of blood vessels: Outer layer - Tunica externa (adventitia) | Most complex region Collagen - secreted structural proteins to provide mechanical support Nerves Vaso vasorum - the blood vessels that supply blood to the larger vessels Lymphatics - help to drain away fluid |
| Capillary | Wall made of endothelial cells only that are in contact with blood Cells are attached to the basement membrane - same as intima in other vessels |
| Elastic Arteries (Aorta) | Elastic tissue in the media (rather than smooth muscle) Elastic to cope with peak ejection pressure (highest pressure changes) Stretches and recoils Windkessel effect |
| Muscular Arteries | Media is mostly muscle rather than mostly elastic tissues Reflects change in function -> pressure lower-> muscle to maintain pressure |
| Arteriosclerosis | Thickening/toughening of arterial walls Focal calcification: Ca2+ deposition post muscle degeneration Damage to cell -> Ca2+ -> precipitation of proteins High blood pressure |
| Atherosclerosis | Lipid and monocyte deposition in tunica media Associated with: Cholesterol Low ApoE High LDL's Restriction in lumen -> increase in blood pressure |
| Arterioles | Arterioles and venules commonly found next to each other Arterioles have smooth muscle Key target area for control Innervation -> causes them to constrict or dilate therefore are major targets for drugs |
| AG and ACE inhibitors | Angiotensin II -> cardiovascular - vasoconstriction (powerful) -> Hypothalamus - thirst and drinking -> kidney - salt and water retention => Elevated blood pressure ACE inhibitors reduce blood pressure Eg. Ramipril, Perindopril |
| Capillaries | Capillary beds are the place where O2/CO2 exchange, waste removal and hormones take place Simplest vessel Smaller diameter than RBC -> RBCs need to be flexible (problems - SCA) Variable structure - leaky (liver) or tight (brain - BBB) Fenestrations (pores) and gaps Formation of tissue fluid |
| Venules | Less muscular than arterioles More prone to collapse/being compressed |
| Veins | Less muscular and more distensible (opens up more when under pressure) than arteries Can "store" blood - not static About the distribution of total blood volume Greater amount of blood in venous circulation than arterial |
| Large Veins | More muscular than venules More elasticity Contain pocket valves -> prevent backflow of blood due to low pressure Varicose veins -> when valves stop working properly |
| Lymphatic system | Diffuse system Close association with the immune system Delivers excess tissue fluid to CVS Impaired flow (if this stops) -> oedema can occur |
| Lymphatics | Close association with the capillary beds Blind-ended, freely permeable Flap valves -> vessel wall can open "Pocket valves" in larger lymphatics -> larger lymphatics are vein-like |
| Lymphatic system: Immune role | Lymph nodes -> areas where specialised immune cells are Wuchereria bancrofti: Parasitic worms Disturbances in fluid flow Elephantiasis |
| Blood pressure | Blood volume (4-6L related to body size) is a continuous column contained in a flexible closed system It has pressure without the heart pumping |
| Blood pressure waves - The action of the heart | Ejects blood (roughly 70bpm @ 70ml, CO ~ 5L/min) Increases pressures from venous to arterial pressure Induces a waveform in the arterial pressure |
| System blood pressure diagram |
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| Blood pressure waves | The wave has a maxima (systolic) and minima (diastolic) pressures Incisura and dicrotic notch |
| Blood pressures in the pulmonary circuit | Systolic - 25 mmHg Diastolic - 8 Capillary - 10 Left atrial ~1-2 |
| Blood pressures in the systemic circuit | Systolic ~ 120 mmHg Diastolic ~ 75 Capillary ~ 15 Right atrial ~ few |
| Mean arterial pressures | MABP = diastolic + 1/3 PP Pulse pressure = systolic - diastolic BP Pulmonary ~ 16 mmHg Systemic ~ 90 mmHg |
| Measurement of arterial BP | Inflatable cuff, pressure meter, stethoscope Attach on arm at heart level Cuff inflated above expected systolic pressure -> squashes artery shut Pressure released Listen for sounds in brachial artery |
| Diagram of BP & Korotkoff sounds |
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| Korotkoff sounds | First sound -> loud tapping = systolic pressure Muting Pounding Muffling (Diastolic UK) Silence (Diastolic US) |
| Systemic pressure is mainly affected by: | Ejection velocity (EV) - how fast Stroke volume (SV) - how much |
| Diastolic pressure is mainly affected by: | Total peripheral resistance (TPR) -> determined by diameter (and therefore resistance) of arterioles Blood flow from arterial to venous sides through capillary beds |
| Arterial BP is under short and long-term control | Short term by baroreceptors: Embedded in the chamber of heart and also in vessels Aortic arch, carotid artery - feed back into CNS Long term by control of blood volume: Involves hypothalamus and kidneys |
| Eg. of baroreceptor control Orthostasis when standing up | Reduced blood to the brain so the body has to compensate To raise the MABP the reflex: Increases sympathetic outflow to the heart (and decreases parasympathetic) -> Rate and force of contraction both increase -> CO increases Increased sympathetic flow to vessels = constriction = increased resistance As MAPB = CO x TPR => it increases |
| Drugs and BP: 1) Increase TPR by vasoconstricting | Angiotensin II Sympathetic agonists at alpha-1 receptors -> phenylephrine |
| Drugs and BP: 2) Increase CO by increasing HR or SV | Sympathetic agonists at beta-1 receptors Dobutamine (rate and volume) Digitalis Na+/K+ ATPase pump inhibitor Na+ builds up, Na+ is exchanged for Ca2+ Ca2+ builds up -> improves contractability of the muscle |
| Drugs and BP: 3) Decrease TPR by vasodilating | Sympathetic antagonists at beta-1 receptors eg. Prazosin |
| Drugs and BP: 4) Decrease CO by decreasing HR or SV | Sympathetic anatagonists at beta-1 receptors eg. Atenolol Reduce rate and volume Beta blockers are being phased out because side effects Ca2+ channel blockers: eg. Verapamil Reduces force of muscle contraction Reduces amount of blood being pumped out of heart |
| Exercise changes: Supply changes | As you exercise the cardiac output increases Brain always gets 70ml of blood per minute Coronary blood flow increases Major shift is the amount of blood going to the skeletal muscle Amount to skin increases to lose heat, but at higher levels of exercise decreases significantly -> body temperature is a major factor in how intense we can exercise |
| Exercise changes: Blood pressure changes | BP changes minor during light exercise Diastolic decreases as TPR decreases Systolic increases as SV and EV increases |
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