complete venous circulation Flashcards
بسم الله وكفي به وكيلا
Where is the refence point ?
In midpoint of the Right atrium and is located at the level of the costosternal junction
which pressure equals Zero
What happens in case of increased vr to the refence point ?
the pressue increases above the 0 so heart increase its contraction and pumping to eject the added amount to retain the 0 pressure at mid point of the right atrium
what happens in case of decreased VRto the Refernce point ?
the pressure is below the 0 and this decrased the blood to the left ventricle decreasing its activity and contractility and pumping and this leads to retain the 0 pressure at mid point of right atrium
Mechanism of action
• Diuresis →↓ plasma volume → ↓ venous return (VR) → ↓ preload → ↓pulmonary congestion & peripheral edema
• ↓ signs & symptoms of venous congestion such as orthopnea & nocturnal dyspnea
لما يرمي الحجم الزائد في الشارع ايه هيحصل؟
هيقلل اعراض الاحتقان كمان هيقلل الحمل علي القلب فهيقلل الحمل علي الرئة
لان القلب الان شايف شغله علي الكمية الباقية
Hydrostatic indifferent point explain /
it is a subdiapharagamtic point lies 2-3 inches below the opening of the inderior vena cava opeining in the diapharagm and the pressue at this point is not changed according to the position either supine or erect
all the point below it show increase in pressure in erect than supine
all the points above it show decrease in pressure #####
all humans have antigravity mechanisms to reduce effect of gravity on our circuation>
this point repersnts balance between gravit and anti gravity mechanisms
if anti gravit mechanisms are strong they cause its upward shift
if anti gravity are weaker it causes it downward shift
Mention antigravity mechanisms and theri role .
They are trying to decrease capcatiance to increasr VR 1- venomotor tone 2- incrasing blood vloume 3-skeletal muscle contraction 4-water immersion VISWA they cause upward shift of HIP
The Factors causing downward shift of the HIP .
AlHOr
1-alpa blockers DERESING VR
2-hypovlemia due to hemorrhage DECRASING VR
3-orthostatic hypotension postural hypotension DECRASING VR
Decrasing the activity of anitgravity m mechanisms
ليا دعوة باللي ظاهر ! ! ! ! ! !
اعمل اسكيمات براحتك طالما هتراجعها كتير
What is VR ?
It is the amount of venous blood entering the right atrium per minute and it is always equal to cardiac output and it is
VR=Change of pressure / resistance of veins
resistance of veins is ngelected
so (VR= Change of pressure )
VR = PVP-CVP
Factors affecting venous return mention .
Forces from the front visa foronto and forces fron the behind visa tergo
1- forces from the front
affect by decreasing the CVP to increase the gardient
a-thoracic pump
b-cardiac suction
2-forces from behind
affect by increaing the pvp
PMA VB
pressure gradient muscles pump arterial pulsaiton venomotor tone blood volume V MAP
Describe cardiac suction as vis A fornto .
During rapid ejection phase the ventricle contract casuing dilation of the right atria by the pulled cusps rings and the connecting CVENIS causing their VD and decrasing the CVP so the gradient increase and the VR increase !
in case of heart failure what happen to cardiac suction
the ventricle cannot contract cannot dilate the ra and the veins and the vr decreasses
لا حل مع الآلام والعقبات إلا بمواصلة العمل التشكي والتأوه لا يصنعان شيئا بل يزيدان الآلام والعقبات
ومن للأمة الغرقي إن كنا نحن الغريقينا ؟!
ان تدرس تعمل تدرس تتعلم تدرس ترضي ربك تدرس تزاد علما وفقها تدرس ترتقي منازل الصالحين تدرس تعلم الناس تدرس تنشر العلم
the effect of inspiration on the VR?
it increases negativity of the intrathoracic pressure thus decreases compression on the veins and casuing its dilatitation and decrasing pressure the veins central so the CVP decreases increaing the pressure graident and the Venous Return >.
expiration and VR ?
This incrasing the intrathoracic pressure and the central veins so the Central venous pressure increases decresing the pressure gradient so the VR is decreased
Factor incrasing the pressure graident by increasing the peripheral pressure :?
1-Arteriolar dilatation !
2-precapillay sphincters constrictions !
arteriolar dilatation increases the pvp ?
this is due to more blood flowing to the capillary and to venous side
describe the muscle pump ?
the skeletal muscles contract causing decraing capactance of veins and MCP increasing casues increased VR HELEPED BY VENOUS valve allowing unidierctional flow of blood towards the heart
Venous valves cannot be considered a counter
gravity force, but they are essential for the counter
gravity force of skeletal muscle contraction. Also,
venous valves divide the blood column in the vein
into short columns , thus minimizing venous
pressure increase in the dependent part of the
body
mention mecahnsisms of minimization of the venous pressure .
1-The valves in the veins divinding the blood clumns into small separate columns
2- the skeleteal muscle contraction casuing constircton of the artery decraseing flow of blood into the capillary and the vein
ربنا أصلح لنا ديننا الذي هو عصمة أمرنا وأصلح لنا دنيانا التي فيها معاشنا وأصلح لنا لآخرتنا التي فيها معادنا وأجعل الحياة زيادة لنا في كل خير و اجعل الموت راحة لنا من كل شر
What is the role of the arterial pulsation in the vr?>
it is Vis A tergo mechanism
Causing a milking effect on the vein like the skeletal muscles causing increased pressure and gradient and VR
Blood volume increases the VR why?
it is Vis A tergo mechanism causing increased MCP thus the PVP and then the Pressuure gradient thus the VR
Venoconstriction affects the VR? GR?
This is becacuse it is a Vis A tergo mechanism causing increased MCP and PVP and pressure gradient so the VR
Increasing pressure imaprted from cardiac contraction to blood ?
إن الله لا يضيع أجر ( المحسنيــــــــــــــــــن)
increasue pvp and pressure gradient and vr
tergo!
arteriolar vasodilation and capillary constriction ?!
What happens on standing?
The gravit affect blood making it flow down increasing the blood to lower part of body in the arterirs
arteries is tight system cannot accommodate large amount of blood casuing flowing of blood from the aretres to veins of high capacitance
congestion of the capillaries will lead capillaty shift fluid into ISF
The displacement of the blood causes increased capacitance of the veins decreasing the MCP ………………………..
And the increased Venous pressure increases shift of fluid from capillaries to the tissue
Counter gravity mechanisms and capacitance of veins
they attempt to decrease the capacitance causing the siffness of wall and increased MCP and VR by muscles contraction and sympathatic alpha receptor mediated contraction
atretiolar VD and capillary shift fluid?
the blood go to the veins but they are of high comliance and this make less effect on the blood pressure and make blood stasis in the capillary increasing its pressue and capillary shift into tissues
STANDING Withouts touching the ground this leads to ?
No anti gravity mechanisms Standing without touching the ground the HIP is shifted downward and this leads to reduced cardiac filling VR قليل بسبب الجائبية
the cardiac activity of the heart and the VR RELATIONSHIP?
- increased cardiac activity decreases the pressure on the refernce pressue and the big veins and the pressure gradient increases and the VR increases
- decreased cardiac activity increases the pressre on the refencce point of the right atrium and big veins decreasing the pressure gradient and thus the VR
STOP OF CARDIAC ACTIVITY AND VR?
stop of cardiac activity abolishes the Pressure gradient and leading to no VR
تم بحمد الله له الشكر والفضل والمنة له الحمد في الأولي والاخرة وهو الحكيم الخبير
ا
