95059
Descripción
Fichas por alexlpeart, actualizado hace más de 1 año
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Creado por alexlpeart
hace alrededor de 11 años
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| Pregunta | Respuesta |
| Give 5 methods of measuring skeletal muscle blood flow. Briefly explain what each of them are. | Venous occlusion plethsmography: clam veins to limb meaning the limb swells and the rate of swelling indicates the rate of flow. Xeon clearance: radioactive element injected into muscle and rate of clearance used to examine flow. Femoral vein dilution: inject cold saline, look at warming after a set distance using a thermometer. Doppler ultrasound: visually count flow. Micro-dialysis: measure clearance and recovery of substances e.g ethanol clearance. |
| At the start of measuring skeletal blood flow we recorded lower values. What kind of values were recorded at this time? | 50-70 ml/100g/min |
| What kind of values would we expect to see when using micro-dialysis as a method of measuring skeletal blood flow? Give some problems with this method of measurement. | 500 ml/100g/min. Damage may be caused by inserting the needle which causes increased blood flow anyway. |
| Give some potential reasons for the sudden increase in blood flow at the onset of exercise. | Sympathetic nerve activity withdrawal, acetylcholine release (not proven in humans), acetycholine spill over from motor nerves, mechanical factors such as muscle pump or movement alone causing increased perfusion, Metabolites although thought to not be quick enough (1-2 seconds instead of under 1s). No one factor can fully explain the increase. |
| What is sympatholysis? | The inhibition of impulses from the sympathetic nervous system. |
| Describe the process of functional sympatholysis. | Where local factors take over the control of vessel resistance in order to control a specific area. |
| Explain why we need a balance of vasoconstriction and vasodilation. | We need to balance the ability for oxygen delivery with blood pressure regulation. |
| Explain what happens to blood flow during a isometric contraction. How does this effect time until fatigue? | Isometric contractions block blood flow, only when we relax does blood flow increase again. this mean time till fatigue is decreased as less waste clearance and fuel delivery. |
| Out of isometric contraction and intermittent contraction which allows us to sustain the contraction longest before fatigue. Explain why this is a case. | Intermittent, because we allow blood flow to the muscle when the muscle relaxes clearing the waste products and bring oxygen to the muscles. |
| Describe what can happen when we contract our muscles and also try to vasodilate the vessels. | Active vasodilation and mechanical compression of the vessels due to the muscle contraction compete and a compromise is reached. |
| Describe the differences in blood perfusion of different muscle types. | slow, oxidative muscles will receive higher blood perfusion than fast glycolytic muscles. |
| What does tortuous mean? | the way capillaries don't just lie parallel to the muscle fiber, they wrap round for increased oxygen delivery. |
| We match capillary density to ______ content of the cell. | Mitochondria |
| If we increase blood flow we _____ transit time. The higher the transit time the ____ gas exchange can take place | Decrease, Less |
| Explain what is meant by capillary recruitment. Describe the slight controversy with this concept. | we recruit more capillaries when we need to increase blood flow, however some evidence to suggest that we don't stop flow to capillaries we just reduce the flow of to them. |
| Give some determinants of oxygen delivery in exercise. | Blood flow, blood distribution in microcirculation, surface contact area, capillary perfusion, red blood cell transit time, hemoconcentration (due to plasma volumes) |
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