Physiological Changes with Aging
Physiological Changes with Aging ( 10 Questions)
A nurse is assessing a client who is 75 years old. Which of the following findings is most likely related to the decreased contractile strength of the myocardium in older adults?
This is wrong because increased heart rate is not related to the decreased contractile strength of the myocardium, but rather to the decreased responsiveness of the baroreceptors, which regulate blood pressure. Older adults may have higher resting heart rates and lower maximum heart rates than younger adults.
Stroke volume is the amount of blood pumped by the left ventricle of the heart in one contraction.
The contractile strength of the myocardium determines how much blood is ejected with each beat. As people age, the myocardium becomes less elastic and less responsive to catecholamines, which can reduce the contractile force and lower the stroke volume.
This is wrong because increased cardiac output is not related to the decreased contractile strength of the myocardium, but rather to the increased blood volume and cardiac workload that may occur with aging. Cardiac output is the product of stroke volume and heart rate, so a lower stroke volume would tend to decrease cardiac output.
This is wrong because decreased peripheral resistance is not related to the decreased contractile strength of the myocardium, but rather to the decreased elasticity and increased stiffness of the arterial walls that may occur with aging.
The correct answer is B. Decreased stroke volume.
Stroke volume is the amount of blood pumped by the left ventricle of the heart in one contraction.
The contractile strength of the myocardium determines how much blood is ejected with each beat. As people age, the myocardium becomes less elastic and less responsive to catecholamines, which can reduce the contractile force and lower the stroke volume.
Choice A is wrong because increased heart rate is not related to the decreased contractile strength of the myocardium, but rather to the decreased responsiveness of the baroreceptors, which regulate blood pressure. Older adults may have higher resting heart rates and lower maximum heart rates than younger adults.
Choice C is wrong because increased cardiac output is not related to the decreased contractile strength of the myocardium, but rather to the increased blood volume and cardiac workload that may occur with aging. Cardiac output is the product of stroke volume and heart rate, so a lower stroke volume would tend to decrease cardiac output.
Choice D is wrong because decreased peripheral resistance is not related to the decreased contractile strength of the myocardium, but rather to the decreased elasticity and increased stiffness of the arterial walls that may occur with aging.
Peripheral resistance is the opposition to blood flow caused by friction between the blood and the vessel walls. A higher peripheral resistance would increase the afterload on the heart and reduce the stroke volume.
Normal ranges for stroke volume are 60 to 100 mL/beat for men and 50 to 90 mL/beat for women.
Normal ranges for heart rate are 60 to 100 beats per minute for adults.
Normal ranges for cardiac output are 4 to 8 L/min for adults.
Normal ranges for peripheral resistance are 800 to 1200 dynes/sec/cm- for adults.