* trace the path of a drop of blood starting at the left atrium and
passing through both the systemic and pulmonary loops. Also indicate
the oxygen content of the blood in each part of the system.
Blood enters the left atrium from the pulmonary vein in an oxygenated
state. It is then pumped down to the left ventricle, which then pumps
the blood into the systemic loop through the aorta.
Deoxygenated blood then arrives to the right atrium through the
inferior and superior vena cavae. From the right atrium, the
deoxygenated blood is pumped down to the right ventricle. From the
right ventricle it is pumped into the pulmonary artery (in a
deoxygenated state) and enters the pulmonary loop.
* Describe the conduction system of the heart and explain how it
regulates the cardiac cycle?
http://your-doctor.com/healthinfocenter/medical-conditions/cardiovascular/conductiontutorial.html
The sinoventricular node (SVN)
" The sinoatrial node (SAN), located within the wall of the right
atrium (RA), normally generates electrical impulses that are carried
by special conducting tissue to the atrioventricular node (AVN).
Upon reaching the AVN, located between the atria and ventricles, the
electrical impulse is relayed down conducting tissue (Bundle of HIS)
that branches into pathways that supply the right and left ventricles.
These paths are called the right bundle branch (RBBB) and left bundle
branch (LBBB) respectively. The left bundle branch further divides
into two sub branches (called fascicles).
Electrical impulses generated in the SAN cause the right and left
atria to contract first. Depolarization (heart muscle contraction
caused by electrical stimulation) occurs nearly simultaneously in the
right and left ventricles 1-2 tenths of a second after atrial
depolarization. The entire sequence of depolarization, from beginning
to end (for one heart beat), takes 2-3 tenths of a second.
All heart cells, muscle and conducting tissue, are capable of
generating electrical impulses that can trigger the heart to beat.
Under normal circumstances all parts of the heart conducting system
can conduct over 140-200 signals (and corresponding heart beats) per
minute. "
* describe the anatomy of arteries and veins. How are arteries different
in construction [from] veins?
Briefly, the arteries have thicker, less elastic walls than the veins.
This is because arteries need to withstand high blood pressure. The
lumen of the veins is larger than that of the arteries. Also, veins
contain valves whereas arteries do not.
* How is the red blood cell structure related to it function?
OK, first of all the size of the RBC is important, because it allows
it to squeeze through narrow capillaries in the body.
The disc-shaped structure of RBCs and opposed to a large blob is
important because of the surface area to volume ratio. Having a
disc-shape instead of a sphere shape means that there is a higher
ratio of surface area to volume. RBCs as you already know, are
important for binding oxygen and carbon dioxide, hence having a
disc-shape allows this to occur with greater efficiency. |
