Medical Physiology Quiz

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Questions and Answers

What is the approximate normal range for young adults' blood pressure?

120-150/70-100 mmHg

90-120/60-80 mmHg (correct)

100-140/70-90 mmHg

110-130/80-90 mmHg

Which statement accurately describes the action potential in cardiac nodal cells?

Purkinje cells are the largest cardiac cells

The action potential in nodal cells is produced by slow channels (correct)

The speed of conductivity in the whole conductive system is very high

The amplitude of action potentials in nodal cells is very steep

What effect does the sympathetic nervous system have on cardiac activity?

Positive dromotropic effect

Positive chronotropic effect (correct)

Positive bathmotropic effect

Positive inotropic effect

What happens during the isovolumic relaxation phase of the cardiac cycle?

$0mmHg/125mmHg$ ventricular blood pressure Signup and view all the answers

Which statement accurately describes cardiac output in a healthy 70kg man at rest?

$4.0 - 6.0 L / minute$ Signup and view all the answers

"Starling's law of the heart" describes:

$\text{Dependence of power on ventricular fibre length}$ Signup and view all the answers

Which statement accurately describes brain autoregulation?

Constant blood flow during gravitation Signup and view all the answers

What effect does tachycardia have on oxygen consumption?

Increases oxygen consumption Signup and view all the answers

What is the typical resting membrane potential in myocardial working cells?

-85 mV Signup and view all the answers

Which phase of the action potential is important for the duration of the action potential and can exhibit a slow diastolic depolarization?

Phase 2 Signup and view all the answers

What is the typical systolic volume in a healthy 70-kilogram man?

70 mL Signup and view all the answers

What causes myocardial contraction?

Action potential and calcium influx from extracellular fluid to sarcomeres Signup and view all the answers

Which structure prevents significant loss of fluid volume from the blood in capillaries?

Plasma colloid osmotic pressure Signup and view all the answers

Which of the following factors influences contractility of the heart?

Sympathetic stimulation Signup and view all the answers

What is the normal upper limit for blood pressure values?

145/85 mmHg Signup and view all the answers

Which of the following influences heart rate by increasing myocardial contractility?

Epinephrine Signup and view all the answers

What is the typical characteristic of the T wave in lead aVR in healthy individuals?

Negative Signup and view all the answers

What is the range for normal heart rate in an ECG evaluation?

60-100 beats per minute Signup and view all the answers

Which factor decreases arterial pressure, stimulating the vasomotor center to raise arterial pressure back towards normal?

Lack of oxygen Signup and view all the answers

What controls the fetal circulation by connecting the pulmonary artery and aorta?

Ductus arteriosus Signup and view all the answers

Which phase correlates with the vulnerable period of the heart?

Absolute refractory period Signup and view all the answers

What are the basic physiological properties of myocardium?

Conductivity, rhythmicity, automaticity Signup and view all the answers

What influences sinus node activity during supranormal phase?

Sinocarotid reflex Signup and view all the answers

At which point does excitation occur between two cardiac cells?

Bundle of His and Purkinje cells Signup and view all the answers

Which of the following is true about the Anrep mechanism?

It is dependent on the aortic blood pressure Signup and view all the answers

What effect does tachycardia have on Bowditch steps?

Increases the contraction force Signup and view all the answers

In coronary hemodynamics, where is most of the blood flow during a cardiac cycle?

In diastole Signup and view all the answers

What happens to coronary blood flow during tachycardia?

It decreases Signup and view all the answers

What is a vectorcardiogram a record of?

Cardiac electric field Signup and view all the answers

What do thyroid hormones produce in terms of heart rate?

Tachycardia Signup and view all the answers

During absolute refractory period, are the cells excitable?

No, cells are not excitable Signup and view all the answers

Which of the following is true about actin and myosin?

They are contractile proteins in myocardium Signup and view all the answers

What do adenosine produce in terms of heart rate?

Bradycardia Signup and view all the answers

Which part of the nervous system is prevailing at rest?

Parasympathetic nerves Signup and view all the answers

What type of neurotransmitter do parasympathetic postganglionic nerves release?

Acetylcholine Signup and view all the answers

Study Notes

Normal heart rate is between 60-100 beats per minute in an ECG evaluation.
T wave in lead aVR is typically negative in healthy individuals.
Lack of oxygen decreases arterial pressure, signaling the carotid and aortic chemoreceptors to stimulate the vasomotor center, raising arterial pressure back towards normal.
High potassium levels decrease myocardial contractility and epinephrine increases heart rate.
The heart's control is influenced by various factors and mechanisms including Poiseuille's law, reflexes, and hormones.
The electrical manifestations of cardiac activity (ECG) include the PQ interval, action potential phases, and various sounds.
The cardioinhibitory center produces bradycardia and inspirium increases the sympathetic activity on the heart.
The cardiac conductive system has a gradient of automaticity and extracardiac nervous mechanisms control heart function.
The fetal circulation is connected by the ductus arteriosus and the circulation is controlled by humoral and extracardiac mechanisms.
The ECG is recorded in 12 leads, with the leads aVR, aVL, and aVF being unipolar, and the AP of the myocardial cells has distinct phases.
The myocardium has basic physiological properties including conductivity, rhythmicity, and automaticity.
Blood pressure is usually measured with a sphygmomanometer and capillaries allow for the diffusion of lipid-soluble substances.
Autoregulation of blood flow occurs through vasodilator substances and vasoconstriction.
Certain sounds are heard during heart function, such as the sounds of cuspid and semilunar valves closing.
Preload factors include venous return, fluid volume, and atrial contraction and occur during diastole.
Afterload is the resistance the ventricles must overcome to circulate blood and occurs during systole.
Contractility is influenced by iontropic factors, such as sympathetic stimulation or noradrenaline, and negative iontropes, such as acetylcholine or beta blockers.
The vulnerable period of the heart correlates with the absolute refractory period and supranormal phase.
The heart's oxygen consumption is larger than other cells and is increased during pressure work, tachycardia, and decreased blood pressure.
Sinus node activity is influenced by the sinocarotid reflex during supranormal phase, and the slow diastolic depolarization correlates with phase 4 of the action potential.
Excitation between two cardiac cells occurs at the conduction system, specifically the bundle of His and Purkinje cells.
The heart's hemodynamics are influenced by the large distensibility of vessels, presence of venous valves, breathing, and muscle activity.
The lung hemodynamics have small pressure gradients and pulsative blood flow in capillaries, and oxygen debt occurs in skeletal muscle.
The sinus node, AV node, and pacemaker's cells have peculiarities, such as the presence of only slow Na-Ca inward channels.
Tachycardia is produced by orthostatic rest or action of hormones and electrolytes on the heart.
The myocardium has rhythmic formation of impulses, conduction of stimuli, automatic formation of impulse, and hemodynamic function.
Blood pressure values have upper limit normal values, which is 145/85 mmHg.

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Test your knowledge of medical physiology with questions on blood pressure, cardiac activity, and the cardiac conductive system.