mammalian circulation characteristics Flashcards
What are the two main types of circulation in mammals?
Pulmonary Circulation – Heart → Lungs → Heart
Systemic Circulation – Heart → Body → Heart
What are the two atrioventricular (AV) valves, and where are they located?
Tricuspid valve – Between the right atrium and right ventricle.
Bicuspid/Mitral valve – Between the left atrium and left ventricle.
What are the two semilunar valves, and what do they control?
Aortic semilunar valve – Controls blood flow from the left ventricle into the aorta.
Pulmonic semilunar valve – Controls blood flow from the right ventricle into the pulmonary artery.
What is a heart murmur?
A heart murmur is an abnormal sound caused by blood backflow through a defective valve.
What are the two phases of the cardiac cycle?
Diastole – Relaxation phase; heart fills with blood.
Systole – Contraction phase; heart pumps blood
What are the two factors that determine cardiac output?
Heart rate (bpm) – Number of beats per minute.
Stroke volume – Amount of blood pumped per contraction.
What is the function of the Sinoatrial (SA) node?
sets the rate and timing of cardiac muscle contractions by producing electrical signals.
How do electrical signals spread from the SA node? (4 steps)
Signals spread rapidly through the atria, causing coordinated contraction.
They reach the Atrioventricular (AV) node, where there is a 0.1-second delay.
The signals then travel to the heart apex and ventricular walls.
Purkinje fibers ensure coordinated ventricular contraction, forcing blood out through the semilunar valves
What is the atrioventricular (AV) node, and why is there a delay?
The AV node is a relay point between the atria and ventricles. The 0.1-second delay ensures the atria contract before the ventricles.
Where is the heart apex, and why is it important?
The apex is the pointed tip of the heart that faces downward and to the left. It is where signals spread to the ventricular walls for contraction.
What are Purkinje fibers, and what do they do?
Purkinje fibers help coordinate ventricular contraction, ensuring blood is efficiently pumped through the semilunar valves.
How do physiological cues regulate heart rate?
The SA node’s pacemaker function is influenced by:
Sympathetic nervous system – Acts as an accelerator (fight or flight).
Parasympathetic nervous system – Acts as brakes, slowing the heart.
Hormones (e.g., epinephrine) ,Norepinephrine, body temperature
