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#2
LECTURE NAME:Organization of CVS
WRITTEN BY: Laith Sorour
CORRECTED BY:Ahmad Al-Masri
*The function of heart is mainly to pump blood\generate force
*Vessels:
1-Arteries take blood from Heart to tisue
2-veins return blood from tissue to heart
min 12
*Cappilaries:
exchange materials between blood and tissue
The main function of CVS is mainy to generate force(force) and that force will
push the blood*without pressure there is no pump
The flow depends on the pressure gradient (from high pressure to low)
and the maximum pressure is the heart(left ventricle to be more correct) and
least pressure in the right atrium and to make flow there must be a pressure
defference
so the maximum pressure is in the heart(left ventricle) then the blood will flow to
aorta wich have less pressure and then to the rest of the arteries which have lower
pressure than aorta so it will make blood flow and the small arteries
arterulescapillariesvenules veinsheart(right atrium)
CVS is a closed sytem its function is to generate pressure(force) but not
exchange materials,exchanging is related to the blood itself in the cappilaries
min 18.40
CVS is made of two units(circulations)
1-Systemic(peripheral) circulation
(blood flows from left ventricleaortaarteriessmall
arteriesarteriolescappilarriesvenulesveinsright atrium)
2-Pulmonary circulation
(right ventriclepulmonary arterypulmonaryy cappilariespulmonary veins
left atrium)
What is the differnce between the two circulations?
Min 20
-Systemic circulation(left side/ventricle) have higher pressure than
pulmonary(right side/ventricle)\Why the systemic(peripheral) pressure is higher
than pumonary pressure?:
**The Peripheral resistance(resistance in the systemic circulation) is higher
than pulmonary resistance
-The distance that sytemic circultion pushes is longer(larger area) than that the
pulmonary circulation(small area) will push
-In the left side(systemic circulation) the pressure is 120/80(*in the left ventricle)
but in the right side(pulmonary) the pressure is about 25-26 mmHg
min 27.00
*Right atrium receive blood from peripheral\systemic circulation then it flows to
right ventricle through tricuspid valve and left atrium from pulmonary then it
flows to left ventricle through mitral valve,we call these valves A-V
valves(Atria-ventricular)
*then the ventricles push blood through semilunar valves(atrial & pulmonary) to
large arteries
summary:
atriumVentricle=A-V valves(Mitral & tricuspid)
Ventriclegreat arteries(Aorta & pulmonary artery)=semilunar valves
-----------------------------------------------------------------------MAIN FUNCTIONS OF THE CIRCULATORY SYSTEM
-Transport and distribute essential substances to the tissues.(pumping)
-Remove metabolic byproducts.
-Adjustment of oxygen and nutrient supply in different physiologic -states.
-Regulation of body temperature.
-Humoral communication.
----------------------------------------------------------------------------Distribution of Blood in the Circulatory System
67% IN THE SYST. VEINS/VENULES (Largest store)
5% IN THE SYSTEMIC CAPILLARIES
11% IN THE SYSTEMIC ARTERIES
5% IN PULMONARY VEINS
3% IN PULMONARY ARTERIES
4% IN PULMONARY CAPILLARIES
5% IN HEART ATRIA/VENTRICLES
total Blood in adult body is 4-5.5 L
---------------------------------------------------------------------------------
min 32
As we said The heart have left & right atrium and the blood flows only in one
direction from atria to ventricles by pressure,why?
because of A-V valves (which are closed by chordae tendanea) which prevent
blood to go back to atria
-A-V valves anchored against high pressure by the Chordae tendineae and
papilary muscles
*At some point the pressure in Aorta becomes greater than in left ventricle for a
short period of time,why the blood doesn’t go back?
-because of semilunar valve in this case Aortic valve closes
*the other semilunar valve called pulmonary valve and its between right ventricle
and pulmonary artery
This graph shows the pressure gradient or pressure change from large arteries
until veins
MIN 37
why the pressure in arteries is more than in veins?
because veins have thin wall and very elastic which means they can be
extended(stretched )easily but arteries have thick wall and hardly extended
and more resistant and because of that most of the blood is stored in veins
-to understand it better imagine a balloon which is thin,a child can blow it but a
football which is sick needs more pressure to be blown.The same is concidered
about arteries and veins
Q:which is more dangerous losing large amount of blood(around 1 L) from veins
or small amount but from arteries?
Min 41
-Small amount from arteries because the change in pressure will decrease a lot
but from veins the pressure slightly changes
*person who have pressure 80 instead of 120 is mostly diying
Summary:
*Arterial side have low amount(about 10%) of blood but High pressure and thick
wall
*Venous side have high amount(65-75%) of blood but Low pressure and thin
wall
------------------------------------------------------------------------------------------------Doctor started fragments from the next lecture
min 45
*there must be a signal that stimulates the heart, a mechanism that generates the
beat,and when the heart is stimulated it will begin to pump blood .
The heart can be devided into to 2 ways:
1-Anatomical description/structure: devides the heart into 4 chambers (2 atriums
& 2 ventricles) and 4 Valves and two great arteries
2-Physiological description\structure:devides into two sides (left(systemic) &
right(pulmonary))
The heart is composed of 3 units:
1-functional
2-systemic(left side)
3-polmunary (right side)
Heart is composed of 3 types of fibers
1-Atrial(muscle fibersthin/weak contraction/low pressure)
2-Ventricular(muscle fibersthick/greater contraction/higher pressure)
3-Conductive fibers(nor muscle-nor nerve fibers\they are specialized fibers)
Conductive system:
min 52
*it causes the beating
*It is composed of
1- S-A node(Sino-Atrial node) which is located in interance of superior vena
cava\top of right atrium)
2-A-V node (Atrio-ventricular node) \bundle of HIS
3-Fibers in between S-A node & A-V node which are called internodal fibers
4-A-V bundle which is devided in two branches left and right
5-Purkinje fiber
*all of these are conductive tissue
*They are neither muscles or nerves,why?! important
54.00
-They are not muscles because they don’t contract(not contractile)
-They are not nerves because of conduction velocity in them is not fast as nerves
(velocity of transmission is low)
**They can generate the impulse and conduct(transmit) it,the first step in heart
beating starts from the S-A node
Impulse movement:S-A nodeinternodal fibersA-V nodeA-V bundleleft
and right branchespurkinje fibers
***what cardiac syncytium means?
since myocardiac muscles are seperated by intercalated disks they act according
to the law of all-or-none so the both atrias will contract(atrial syncytium) or the
both ventricules will contract(ventricular syncytium) or none of them will
questions:
*main purpose of valves?
-prevent backflow of blood\keep blood flow in one direction
*Why veins have more blood?
-because it is thin and can be extended
*why systemic\peripheral pressure is higher than pulmonary?
-because perephiral resistance is higher than pulmonary