Heart
Which side of the heart pumps blood to the lungs, and which side pumps blood to the body?
Right → lungs; left → body.
Name the three layers of the heart wall
Epicardium, myocardium, endocardium.
What is the sac surrounding the heart called?
Pericardium.
What is the innermost layer of a blood vessel that directly contacts the blood?
Tunica intima.
What is the main function of capillaries, and why are their walls so thin?
Exchange of gases, nutrients, wastes, and fluid between the blood and tissues. Their walls consist primarily of a single layer of endothelial cells, creating a short diffusion distance.
What doest the pericardial fluid do and where exactly is it located
Pericardial fluid reduces friction as the heart beats and in the pericardial cavity between the parietal and visceral layers of the serous pericardium.
What valve is located between the right atrium and right ventricle?
Tricuspid valve.
What causes the first heart sound, S1 ("lub")?
Closure of the AV valves—the tricuspid and mitral valves.
What hormone promotes water reabsorption by the kidneys, helping increase blood volume?
ADH (antidiuretic hormone).
Name three mechanisms that help return venous blood back to the heart, especially because veins operate under relatively low pressure.
Skeletal muscle pump, respiratory pump, and venous valves.
Bonus: Sympathetic venoconstriction can also increase venous return.
During depolarization of an SA node pacemaker cell, which ion moves into the cell through voltage-gated channels to produce the action potential?
Ca²⁺ (calcium)
Which chamber has the thickest myocardium?
Left ventricle.
What is stroke volume?
The amount of blood ejected by one ventricle during one heartbeat.
Which blood vessels are considered the major resistance vessels because changing their diameter strongly affects blood pressure and blood flow?
Arterioles.
What happens to a blood vessel during vasoconstriction?
Its diameter decreases because vascular smooth muscle contracts.
What is the main purpose of the cardiac conduction system, and describe the pathway an electrical impulse follows through the heart.
The conduction system coordinates the timing of atrial and ventricular contractions so the heart pumps blood efficiently. The impulse travels:
SA node → AV node → AV bundle (Bundle of His) → Right & left bundle branches → Purkinje fibers
A patient has a resting heart rate of 52 beats per minute. What term describes this heart rate?
Bradycardia — a resting heart rate below 60 bpm in an adult.
During which phase of the cardiac cycle do ventricular pressure and volume increase as the ventricles receive blood?
Ventricular filling.
During inspiration, pressure changes in the thorax and abdomen help move venous blood toward the heart. What mechanism is this?
Respiratory pump.
What is autoregulation of blood flow?
The ability of a tissue to locally adjust its own blood flow according to its metabolic needs.
Explain why the ventricles do not eject blood during isovolumetric contraction even though they are contracting.
All four valves are closed. Ventricular pressure is increasing, but it has not yet become high enough to open the semilunar valves.
During which two phases of the cardiac cycle are all four heart valves closed, and what is happening to ventricular pressure during each phase?
sovolumetric contraction and isovolumetric relaxation. During isovolumetric contraction, ventricular pressure increases; during isovolumetric relaxation, ventricular pressure decreases. Ventricular volume does not change during either phase because all valves are closed.
Blood pressure suddenly falls. Name two hormones that promote water retention and help restore blood volume and pressure.
ADH and aldosterone.
Compare diffusion and osmosis during capillary exchange. What moves in each process?
Diffusion is movement of solutes such as O₂ and CO₂ down their concentration gradients. Osmosis is movement of water across a selectively permeable membrane.
If blood pressure becomes too high, how does ANP help bring it back down?
ANP promotes sodium and water loss by the kidneys, decreasing blood volume and helping decrease blood pressure.