Rock climbers are at risk of serious injury, including head injuries that result in cranial hemorrhages. When this happens, the body may compensate by increasing its total peripheral resistance via smooth muscle contraction. Explain how doing so impacts the following variables. Describe the physiological relationship between total peripheral resistance and each variable, not just whether that variable increases or decreases during hemorrhage venous pressure: mean arterial pressure: cardiac output:

As a result of heart failure, compensatory mechanisms become activated and ultimately lead to further harmful consequences in the long term. Which of the following is NOT one such compensatory mechanism? O Baroreceptor-mediated activation of the sympathetic nervous system that leads to increased heart rate and contractility The activation of renin-angiotensin-aldosterone system (RAAS) that leads to increased blood pressure increased cardiac preload A reduction in both heart rate and blood pressure O Myocardial hypertrophy resulting in the thickening of the ventricular wall

Please use the word bank below (Terms can be used more than once, or not used at all): Pressure volume lower higher preload afterload The contraction and relaxation of heart chambers results in blood movement because fluids flow from high to low If there is a fixed amount of liquid in a sealed chamber and the of that chamber is decreased (such as in contraction), the pressure in that chamber will increase. The blood will only move if the pressure in the next chamber is than the pressure in the current chamber. Pressure can be reduced in a chamber by relaxing its walls and increasing its Following this logic, hypertension limits blood flow out of the ventricles because the high requires the ventricles to raise their own pressure to extreme levels in order for blood to leave and enter the arteries.

Consider a person standing up from a supine position. How do each of the following parameters change in the first seconds after standing compared to what they were at rest, before they return to normal set point? Total Peripheral Resistance (TPR) Venous Return End Diastolic Volume (EDV) Stroke Volume Heart Rate Mean Arterial Pressure (MAP) [Choose ] ✓ [Choose ] No change Decrease Increase [Choose ] [Choose ] [Choose ]

Critically ill patients in a cardiovascular intensive care unit must be intensely monitored for any number of conditions. One of these conditions is hypoperfusion, which is an overall decrease in blood flow throughout the body. Low stroke volume is one indicator of hypoperfusion. The pressure-volume (PV) graph below shows three possible loops for the heart. The control loop shows a healthy heart while the other two loops show reduced or increased preload (assuming that afterload and contractility remain fixed). 200 LV Pressure (mmHg) 100 Preload Control ↑ Preload 100 LV Volume (ml) (a) What is the stroke volume for the control patient? RK '15 200 (b) A healthy heart rate (HR) is measured as 80 beats per minute. What is the control patient's cardiac output CO? Control patient's CO: mL min

A 43-year-old woman has congestive heart failure after a myocardial infarction. Before the myocardial infarction, she had a cardiac output of 5 L/min and a right atrial pressure of 0 mm Hg at rest. The solid curve in the graph shows the relationship between right atrial pressure and cardiac output in a normal heart. Which of the following lettered points best represents the change in this relationship after the development of congestive heart failure?

Which of the following statements best describes the differences in the regulation of cardiac and skeletal muscle contraction?     The amount of contractile force actively generated by muscle cells is increased by stretch in skeletal muscle and decreased by stretch in cardiac muscle.     Cardiac muscle is stimulated by motor neurons and skeletal muscle by neurones from the autonomic nervous system.     Skeletal muscle contractile force is augmented by increasing the firing frequency of action potentials whereas cardiac muscle contractile force is enhanced by noradrenaline increasing calcium influx through ion channels.     Ryanodine receptors in skeletal muscle are opened by a mechanism that requires calcium influx whereas in cardiac muscle membrane depolarisation alone without calcium influx is sufficient to open ryanodine receptors.

Describe the mechanisms that increase the cardiac output during exercise and that increase the rate of blood flow to the heart and skeletal muscles.

Blood doping (using injected substances to artificially enhance performance) is illegal in many sports. Two substances used are erythropoietin and hypoxia-inducible factors (HIF). One of the actions of HIF is to increase formation of new blood vessels (angiogenesis). Explain how administering erythropoietin can increase performance and how HIF can increase performance through angiogenesis.

There are three major factors that affect stroke volume and therefore affect cardiac output: afterload, preload, and contractility. Select two of these factors and explain how and why each affects cardiac output.