Cardiovascular System Flashcards
Describe the valves of the heart
Two atrioventricular valves: the right (tricuspid) and left (bicuspid/mitral). Two semilunar valves preventing ventricle backflow: the right (pulmonic) and left (aortic)
What is cardiac output?
Volume of blood pumped in one minute (heart rate x stroke volume). Typically ≈ 5 L/min
Describe the electrical pathway of the heart
Initiation at SA node (myogenic activity), signal delayed at AV node to allow ventricle filling, Bundle of His, Purkinje fibers distribute signal throughout ventricles
How do the sympathetic and parasympathetic systems influence the heart?
PS slows heart via vagus nerve, S via neurotransmitters
Where does the largest drop in BP occur?
Across arterioles. Assures caps aren’t overpressurized
What the composition of blood (% liquid, % cells)
55% liquid, 45% cells
How many molecules of O2 can each hemoglobin bind?
4
Describe the cellular characteristics of RBC’s
No nucleus or organelles, anaerobic, 250M molecules hemoglobin
What are the two classes of WBC’s?
Granulocytes and agranulocytes
What are granulocytes?
Neutrophils, eosinophils, basophils contain granules (bombs) full of toxic compounds for destroying invaders
What are agranulocytes?
Lymphocytes and monocytes.
Lymphocytes = specific immune response = B-cells (antiBody), T-cells (made in Thymus, killers).
Monocytes = macrophages (phagocytose), called microglia in brain.
How does blood carry CO2
It’s very soluble in plasma, and hemoglobin has lower affinity than for O2, so it’s converted into carbonic acid by RBC carbonic anhydrase
Explain the Bohr effect and why it makes sense physiologically
Decreased pH (more H+) = makes hemoglobin lose affinity (curve shifts right). During times of high O2 demand, more CO2 is being produced ==> decrease in blood pH ==> less hemoglobin affinity to for O2 ==> greater O2 delivery to tissue
Explain the balance between oncotic and hydrostatic pressure
At arteriole end, hydrostatic pressure is higher. Oncotic pressure stays about constant from arteriole to venule. Thus at arteriole end, net pressure is out into tissue. Hydrostatic pressure drops along capillary ==> oncotic exceeds hydrostatic and fluid flows back into circulation.
