[BIOL 222] - Midterm Exam Guide - Everything you need to know! (17 pages long)

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7 Feb 2017
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BIOL 222
MIDTERM EXAM
STUDY GUIDE
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EXAM 2 REVIEW NOTES
Chapter 20: Heart
1) Systemic circuit: blood flow from left heart to the body and back to right heart
Pulmonary circuit: blood flow from right heart to the gas exchange surface of lungs.
Blood becomes oxygenated and travels through pulmonary veins to the left heart to
go the systemic circuit
Arteries: carry blood from the heart to capillary beds for gas, waste, nutrient, fluid
exchange
Veins: carry blood leaving capillary beds back to the heart to be re-pressurized
Cardiac output: flow in each circuit, approx. 5L/min for each circuit
Atria: heart chambers that receive blood from veins and deliver to ventricles, do not
add to pressure developed
Ventricles: heart chambers that receive blood from atria and pressurize it to generate
flow to the lungs (right ventricle) or body (left ventricle)
Left ventricle is significantly larger (more mass) than right because it has to
generate more pressure goes to the rest of the body
2) Cardiac muscle characteristics (Cardiac Myocytes)
-Striated (striped), Gap Junctions (communicative pores between adjacent cells
electrical stimuli) and Desmosomes (mechanical strongly attach cells to one
another so don’t pull apart during contraction) (both form a function syncytium
performs as a single unit)
-Myoglobin protein that binds and retains oxygen, reduces possibility of myocytes
becoming reliant on highly inefficient anaerobic metabolism to function
-Lots of mitochondria aerobic ATP production
-Large energy stores of glycogen and lipids cells demonstrate almost no anaerobic
metabolism (no lactic acid formed)
-Contract in response to action potentials generated by pacemaker cells found in
specialized regions, especially the sinoatrial node (SA node)
3) Connective tissues of the heart, especially the fibrous skeleton
-Heart contains many connective tissue fibers, prevents overstretching, maintain
shape of heart (because not attached to anything but itself), and distribute more forces
throughout muscle, increases elasticity
-Fibrous Skeleton (Bundle of His): plate-like layer found at the base of the large
arteries (pulmonary and aortic) and surrounding the AV valves, separates atria and
ventricles electrically, “insulator” (limits action potential propagation from atria (and
SA node) to ventricles. Atria needs to contract prior to ventricular contraction
4) Innervation of the heart, cardiovascular control centers
-Autonomic nervous system parasympathetic and sympathetic
-Parasympathetic and sympathetic innervate the nodes and muscle itself
-Nodes = heart rate, cardiac muscle that does not adapt to contract
-Innervation of nodes is almost entirely sympathetic adjusts AP output
-Muscle = contractility (how strong muscle contracts)
-Medulla Oblongata is autonomic control center controls respiration, cardiac
control, vasomotor control, and numerus reflexes
-Contains cardioacceleratory center and cardioinhibitory center
-Cardioacceleratory: output to sympathetic neurons to increase HR
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-Cardioinhibitory: output to parasympathetic neurons that release ACH to
reduce HR
5) Coronary circulation- system of systemic vessels that provide blood flow to heart
muscle itself different from flow through chambers. Two main coronary arteries (L
and R) supply entire heart. Coronary blood returns directly to heart via coronary
sinus (into right atrium) for re-oxygenation in pulmonary circuit
Coronary artery disease (CAD) decreased function due to lipid plaques or blood
clot formation. May result in ischemia (inadequate blood flow) leading to hypoxia
(low oxygen levels) or anoxia (no oxygen). Region damaged due to ischemia is called
infarction myocardial infarction (MI)= heart attack. Symptoms: angina pectoris
(chest pain during exertion), dyspnea (shortness of breath), diaphoresis (excessive
sweating), nausea
6) Cardiac electrophysiology; nodal versus myocyte action potentials (ion movements,
phases of each, role of the conducting system, refractory periods and their effects)
-Funny current: sodium in, potassium out
-Pre-potential (pacemaker potential): slow depolarization phase, depolarizes cell to
the point that calcium channels
open and fully depolarize cell. It
opens in response to more
negative membrane channel,
allows sodium and potassium to
pass through but sodium is great
so the influx wins
-Basis of skeletal muscle
twitches (tension) wave
summation to tetanus
-Do not want heart to
continuously contract (wave
summation to tetanus) because
you would die. Have a refractory
period: period where can’t get AP
-SA node determines HR
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