Anatomy & Physiology Flashcards

A client at rest has a heart rate of 75 bpm and a stroke volume of 70 mL per beat. What is the resting cardiac output?

Answer: 5.25 L/min

Cardiac output = HR x SV = 75 x 70 mL = 5,250 mL/min, or about 5.25 L/min.

During maximal exercise a client has a heart rate of 180 bpm, a stroke volume of 100 mL, and an arteriovenous oxygen difference of 15 mL O2 per 100 mL blood. Using the Fick equation, what is the approximate VO2?

Answer: 2.7 L/min

Q = 180 x 0.100 L = 18 L/min; VO2 = Q x a-vO2 diff = 18 x 0.150 L/L = 2.7 L/min.

What is the primary physiological reason a highly trained endurance athlete has a higher VO2max than a sedentary peer of the same age?

Answer: A greater maximal stroke volume and cardiac output

Maximal heart rate is similar between the two, so the higher VO2max is mainly due to a larger maximal stroke volume and cardiac output.

According to the size principle of motor unit recruitment, which motor units are recruited first as force demands increase?

Answer: Smaller, slow-twitch units with low thresholds

The size principle states that small, low-threshold slow-twitch motor units are recruited first, with larger fast-twitch units added as force demands rise.

Which energy system is the predominant source of ATP during the first 10 seconds of a maximal-effort sprint?

Answer: Phosphagen (ATP-PC) system

The phosphagen (ATP-PC) system supplies most ATP for maximal efforts lasting up to about 10 seconds.

During 45 minutes of moderate-intensity steady-state exercise, which hormonal response is expected?

Answer: Decreased insulin and increased glucagon and catecholamines

Insulin falls while glucagon, epinephrine and norepinephrine rise to mobilize glucose and fatty acids.

In the sliding filament mechanism, which event directly allows myosin heads to bind to actin and form cross-bridges?

Answer: Calcium binding to troponin, which moves tropomyosin off the active sites

Calcium released from the sarcoplasmic reticulum binds troponin, shifting tropomyosin and exposing actin binding sites.

Which blood pressure response is expected during a graded dynamic exercise test in a healthy adult?

Answer: Systolic rises progressively while diastolic stays the same or decreases slightly

During dynamic exercise systolic BP rises with workload while diastolic BP stays about the same or falls slightly.

During a graded exercise test, the point at which minute ventilation begins to rise disproportionately faster than oxygen uptake is called the:

Answer: Ventilatory threshold

The ventilatory threshold marks the nonlinear rise in VE relative to VO2 as buffering of lactate adds CO2.