Cardiac & Pulmonary Review For Human Physiology 1 (Intro) Key Concepts

1. Review for Test 2:
Cardiac:
Remember that the test questions start on material after the vascular section.
-Make sure you know your definitions!
-Know that in terms of feeding the heart tissue, the greatest amount of blood
is delivered to the heart tissue during diastole through the open cardiac
arteries but that during systole, there is no delivery of blood through the
cardiac arteries as they are often occluded during systole
Pacemakers:
-Be very aware of the ions that control depolarization/action potentials in
both the pacemaker/slow-response cells and the pacemaker/fast-response
cells.
1) Pacemaker Action potentials = initiated by closure of any open potassium
channels and opening (briefly) of T-type calcium channels and F-type
sodium channels
2) Pacemaker Depolarization = phase 0 = opening of loner-lasting calcium
channels
(NOTE: remember, the initiation of the action potential and depolarization
requires inward flux of different ions through different channels in the
pacemaker cells due to the intrinsic activity (i.e. spontaneous activity) of
these cells)
3) Pacemaker Repolarization = closure of calcium channels and opening of
outward potassium channels (NOTE: full return to “resting” potential
requires activation of the ion ATPases and transfer of sodium and calcium
out of the cell and potassium into the cell)
4) Non-pacemaker Action Potentials and Depolarization = opening of fast
sodium channels
5) Non-pacemaker Plateau Phase = opening of calcium channels resulting in
a halt in depolarization as positive calcium ions are entering the cell

2. 6) Non-pacemaker Repolarization = closure of open calcium channels and
opening of outward potassium channels
7) Non-pacemaker Resting Potentials = return to the resting state requires
activation of the ion ATPases to move sodium and calcium out of the cell
and potassium into the cell
-Know conduction pathway
i.e. SA node to AV node to Bundle of His to the left and right bundle
branches to the Purkinje Fibres
-Also know the rates/timing of the various parts of the conduction pathway.
ie: Where is the fastest rate for electrical conduction and where is the
slowest
-ECG: Know what all the waveforms and complexes represent in terms of
cardiac activity
Make sure you know your equation for cardiac output and understand all the
factors that can impact CO such as stroke volume (SV), venous return,
preload, afterload, contractility.
Remember that although HR and SV will both increase CO, there is a
limit to how much CO can be increased.
In terms of HR, too high a HR means less time spent in diastolic filling
of the heart chambers and therefore decreased SV and decreased CO.
In terms of SV, there is a limit to how much stretch and contractility the
heart muscle can have, so SV will only increase up a point
Venous return to the heart relies on activity of the skeletal muscles and
the respiratory pump, so decrease in activity of either will decrease the
volume of blood returning to the heart and therefore decrease how
much blood can be pumped back out in terms of CO

3. -Hemodynamic Section; for resistance to blood flow, the important part of
the equation, (ηL8)/(r4π) is r which is the inside vessel radius because in a
healthy adult, that is the only factor that can be altered.
-Alteration of radius is through vasoconstriction or vasodilation;
Vasoconstriction: the radius becomes smaller which results in an increase
in resistance and a decrease in blood flow through that vessel
Vasodilation: the radius becomes larger which results in a decrease in
resistance and an increase in blood flow through that vessel
-Know the definitions for;
Inotropy
Dromotropy
Chronotropy
Lusitropy
- Autonomic nervous system control:
Sympathetics is through the release of norepinephrine from neural fibres
within the heart
Parasympathetic control is through the release of acetylcholine which is
controlled by the vagus nerve
-Know what cardiac effects (i.e. HR, CO, contractility, etc) will be seen with
the;
Release of acetylcholine, and what will happen with the release of
norepinephrine
- Bloodborne regulation: bloodborne regulation primarily will affect
vasoconstriction or vasodilation and BP in term of cardiovascular activity.
-Remember that;
ADH and angiotensin II will increase BP through increases in
plasma volume
ANP will decrease BP through increased loss of plasma volume
*Most local factors such as the kinins, histamine and NO will cause local

4. vasodilation = decreased BP
-Changes to BP will affect afterload and will therefore affect cardiac activity
-Responses to exercise: You must know the changes to mechanical,
metabolic and autonomic control and hormonal release during exercise
As well, remember that there are various compensations that occur
during exercise to maintain high CO (i.e. resetting of arterial
baroreceptors so that higher BP does not result in a reflex decrease in
HR)
Also, know how CO is maintained at high levels during exercise even
though HR is high enough that filling time is reduced
Capillary Regulation:
*I will not ask you to know the equation for Starling’s Hypothesis. What
you do need to remember is that fluid moves (usually) from the interstitial
tissues into the capillaries and that changing the direction of flow such that
fluid/water moves from the capillaries into the interstitium usually only
occurs with changes to venous or arterial pressure and is not the normal
direction

5. PULMONARY:
-Know all the functions of the lungs
-Know the 2 circulations that are part of the lungs:
1.) The pulmonary circulation is the gas exchange circulation and is a high
compliance, low resistance system
2.) The bronchial circulation is the circulation that feeds the lung tissue and
is a high pressure, high resistance system
Gas Exchange:
Oxygen Concentrations:
Oxygen Concentrations are highest in the alveoli and lower in the
blood which allows for diffusion of oxygen from the alveoli into the
blood and at the tissue level, oxygen concentrations are highest in the
blood and lowest in the tissues again allowing for diffusion of oxygen
from the blood into the tissues
Remember that the majority of oxygen travels bound to hemoglobin
(98.5%)
Oxygen Saturation:
i.e. 2,3-diphosphoglycerate, temperature and acidity and how they
affect hemoglobin’s ability to carry oxygen
Carbon Dioxide:
Know how and where carbon dioxide is produced and the 3 ways
(including percentages of each) that carbon dioxide is carried in the
blood