6 Feb, 2011
What does the Circulatory System Do?
Blood is made up of 3 components
1.Plasma ( liquid water , few proteins in it 55% of the total)
2.Red Blood cells (45% of the total; % of hematocrit ;
3.Buffy Coat (platelets, white blood cells , very small portion )
CO 2nd O 2
Immunological agents (things that fight infection)
2. Regulates temperature
- The way we get rid of increase in temp, is by taking blood from our core and
putting it to our skin and allowing it to interact with environment to cool off.
The Design of the System
Heart is the central pump of everything; we have 2 systems
Pulmonary circulation and Systemic Circulation
Pulmonary: when the blood goes from the heart into the lungs and becomes oxygenated
comes back to the heart and gets sent rest to the body.
Pulmonary artery has deoxygenated blood
-Arteries take blood away from heart, Veins bring blood back to the heart.
Arterial System: Oxygenated blood comes from the lungs, into the left side of the heart;
it goes out through aorta into the arteries.
-Arteries take blood away from heart.
-Very high pressure because we have to take blood from our heart to circulate to our
entire body (height of the person more pressure)
-120mmHg/ 80mmHg is your blood pressure
-10-15% of our blood is in our arteries (low volume)
-The blood goes form the heart to where we need it in our organs our tissues.
- Branching out slows the pressure ( allows us to offload oxygen and picks up waste
products which takes time)
-Blood goes back to the heart with a fairly low pressure
-60-70% blood is in our veins, after its gone through the tissues -Pseudopumping system is on the venous side
Blood Flow at Rest
Heart 4% (cardiac output pumps 5L/min)
Brain ( only uses 13%)
Skin (9% in a normal room, but it was hot more than 9%)
Kidneys 20% (1/5 of the blood volume is going to kidneys because it’s a purification
system and regulator of blood pressure)
Skeletal muscle ( 1/5 of the blood is skeletal muscles because they are metabolic
tissuses, even when you are resting they are producing Co2 and O2)
Athletes can pump 30-33 L/min
Heart pumps 72 beats perminute
Anatomy of the Heart
Heart is made up of myo(muscle) cardium(heart) walls( ball of muscles) with 4 holes
2 Atria (right & left) ---TOP
2 Ventricles (right & left)—BOTTOM
Moves via bulk flow, we need pressure gradients to move.
We create pressure gradients via muscle contraction. Contract the muscles increases pressure
in the heart.
The direction of blood flow within the heart regulated by valves.
- They are one way, and prevent back flow.
-Valves are also in the veins that prevent blood from going backwards.
-Opened passively by pressure gradients.
- Picture (Atria blue) Ven (Red)
-Ventricle contracts, makes the container smaller ( pressure increases; Boyles law)
-Pressure is greater in Ventricle than it is in the atria; it pushes back on the valves and
closes them and blood can’t go that way. The blood will go out where we want it to ( if these
valves are not there the valves will go back and forth continuously)
-Ventricles relax, pressure comes back to normal, atria contracts, pressure gets bigger in the
atria( bigger in left side) opens valves blood flows through it.
Valves Close (REPEATS)
Atria relax; ventricles contract; valves closes ; blood does not back into the atria, it goes out to
the pulmonary artery or aorta. Two things depend on pressure
-Vol of blood
-Size of container
TOP VIEW OF THE HEART
-Between the right atrium and right ventricle valve (Right Atrial Ventricular –sep atrial from
-Tricuspid Valve (3 cusps/flaps)
-Left AV valvue ( only 2 therefore Bicuspid valve)
-When the pressure builds up there is always a chance that the press gets too great in the
ventricles ( you could break the valves) ; if you do that valves don’t close, system becomes
-In the wall of the ventricle, connected to these valves there are papillary muscles (prevent AV
-Sometime the muscles get torn or ruptured then you have to fix them, (use pig valves)
- 3 cusps valves ( semilunar valves since they look like half-moons)
-All valves prevent blood backflow during pressure.
-Similar to skeletal muscle ( since it has actin and myosin since it makes cross-bridges; when
muscle contracts it gets shorter)
-Unlike skeletal muscles (cardiac muscle has sheets and connect end to end that makes heart
-Skeletal muscle does not connect end to end (all independent)
-Contraction makes heart “Smaller” ; increasing pressure and squeezing the blood out
-The pressure is increased in all 4 chambers
-One of the difference between the cardiac muscle and Skeletal muscle is
-The cells are joined by intercalated disks ( it allows transmission of action potential)
-Can’t do this in skeletal muscl