Notes in 6. Exchange and Control of Peripheral Circulation

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Published	02/10/2024	Features of Capillaries[1] {{c1::Large total cross-sectional area}}  [2] {{c1::Thin-walled (small diffusion barrier)}}[3] {{c1::Sm…
Published	02/10/2024	Different Structures of the Capillaries This relates to their function[1] {{c1::Continuous}}[2] {{c1::Fenestrated}}[3] {{c1::Discontinuous}}
Published	02/10/2024	Continuous Capillaries Features:[1] {{c1::Have no clefts or pores (e.g. blood brain barrier)}} [2] {{c1::Have only clefts (e.g. muscle.…
Published	02/10/2024	Fenestrated Capillaries Features:{{c1::Have clefts and pores (e.g. intestine and kidney for fluid exchange)}}
Published	02/10/2024	Discontinuous Capillaries Features:{{c1::Have clefts and massive pores (e.g. liver)}}
Published	02/10/2024	Most exchange that occurs in capillaries is by Diffusion. Why?[1] {{c1::Self-regulating: diffusion across concentration gradients changes on demandThe…
Published	02/10/2024	{{c1::Non-polar}} substances (e.g. O2) can diffuse across the phospholipid membrane{{c1::Polar}} substances have to diffuse through clefts/pores
Published	02/10/2024	{{c1::Carrier-mediated}} transporters are required to transport glucose to the brain because of the {{c2::blood brain barrier}}.
Published	02/10/2024	Bulk flow, i.e. movement of fluid across membranes, is determined by {{c1::Starling}} forces
Published	02/10/2024	{{c1::Hydrostatic pressure}} is the pressure that {{c2::favours the movement of fluid out of the capillaries. This depends upon the blood pressure}}
Published	02/10/2024	{{c1::Net filtration}} pressure = {{c2::OUT Hydrostatic pressure - IN Oncotic/Osmotic pressure}}
Published	02/10/2024	In the body, overall {{c1::~20L}} of fluid is lost and {{c1::~17L}} are regained each dayThe remaining {{c1::3L}} are drained into the lymph…
Published	02/10/2024	{{c1::Oedema}} is the accumulation of excess fluid in tissues which leads to swelling.
Published	02/10/2024	Oedema can occur due to {{c1::lymphatic obstruction e.g. filariasis (parasitic) or surgery}}
Published	02/10/2024	Oedema can occur due to {{c1::raised central venous pressure/raised hydrostatic pressure}} because of ventricular failure.
Published	02/10/2024	Oedema can occur due to {{c1::Hypoproteinaemia/Low osmotic pressure}} as a result of {{c2::nephrosis}}, {{c2::liver failure}}, or {{c2::nutrition}}.
Published	02/10/2024	Oedema can occur due to {{c1::increased capillary permeability}} in the case of inflammation e.g. rheumatism.
Published	02/10/2024	The colloid osmotic or oncotic pressure is created by the presence of {{c1::proteins e.g. albumin}} in plasma.
Published	02/10/2024	If the net filtration pressure is {{c1::positive}} then fluid is flowing out of the capillary (Filtration).
Published	02/10/2024	If the net filtration pressure is {{c1::negative}} then fluid is flowing into the capillary (Absorption)
Published	02/10/2024	Changing the {{c1::radius}} of resistance vessels is used to control {{c2::total peripheral resistance}} and therefore regulate {{c1::mean arterial pr…
Published	02/10/2024	Extrinsic mechanisms that control Flow are concerned with regulating {{c1::total peripheral resistance (TPR)}} and therefore {{c1::mean arterial …
Published	02/10/2024	Intrinsic mechanisms to match blood flow with metabolic needs and their triggers:[1] {{c1::Active metabolic hyperaemia (increase in local metabolism)}…
Published	02/10/2024	Active (metabolic) hyperaemia is triggered by an increase in {{c1::local metabolism}}[1] {{c2::A rise in metabolic activity leads to an increase …
Published	02/10/2024	{{c1::Endothelium-derived relaxing factor (EDRF)}} is an endogenous vasodilator that endothelial cells produce.
Published	02/10/2024	Pressure autoregulation is triggered by a decrease in {{c1::perfusion pressure}}[1] {{c2::A reduction in mean arterial pressure causes a decrease…
Published	02/10/2024	Reactive hyperaemia is triggered by an {{c1::occlusion}} of blood supply.{{c2::For example, when putting a BP cuff (i.e. sphygmomanometer), it le…
Published	02/10/2024	An intrinsic response (Wheal and Flare) to injury:{{c1::C-fibres}} which release {{c1::Substance P}}. This affects {{c1::Mast cells}} that releas…
Published	02/10/2024	Neural central control of blood flow involves the {{c1::sympathetic}} innervation, releasing noradrenaline, to most areas of the body except the {{c2:…
Published	02/10/2024	Hormonal Control of Blood Flow The release of adrenaline which acts on α1 receptors on the arteries causing vasoconstriction.Vasoconstrictio…
Published	02/10/2024	Hormonal Control of Blood Flow The release of adrenaline which acts on ß2 receptors on the arteries causing vasodilation.This occurs in two …
Published	02/10/2024	Coronary Circulation is interrupted by {{c1::systole}} and resumes in {{c1::diastole}} which is the opposite of Systemic Circulation.
Published	02/10/2024	How does the coronary circulation cope with increased demand during exercise?[1] {{c1::The coronary circulation shows excellent active hyperaemia…
Published	02/10/2024	Cerebral circulation must be stable at all time, which is why it has an excellent intrinsic mechanism to control blood flow known as {{c1::p…
Published	02/10/2024	In pulmonary circulation when there is hypoxia, the response is {{c1::constriction}} of vessels to ensure that blood is directed to the well ventilate…
Published	02/10/2024	Renal circulation is dependant upon pressure to do filtration, which is why it has an excellent intrinsic mechanism to control blood flow known as&nbs…
Published	02/10/2024	{{c1::Osmotic/Oncotic pressure)}} is the pressure that {{c2::favours the movement of fluid into the capillaries. This depends upon the prote…
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