Venous circulation Flashcards
بسم الله الرحمن الرحيم
اللهم عليك توكلنا فانصرنا وأنت نعم المولي ونعم النصـير
Arterirs contains more elastic than collagen circular shape steep p/v
veins contains more collagen than elastic varible shape flat p/v relationship
II- Past medical history
for asthma
-Patients with asthma may have past history of: • Recurrent upper and lower respiratory-tract infections (particularly children). • Allergy, such as eczema and hay fever. • Sinusitis • GERD • Co-morbidity: -HTN: B-blockers, ACE
describe forward function of the veins ?
they are the capacitance vessels wide have 2/3 blood of circulation
and they control the EDV so the the preload of the heart and the Cardiac output
so they are determinants of the COP
Describe backward function of the veins ?
they recive the capilary blood without a marked loss in the pressure
becasue they are low resistance vessels
veins are compliant structure as it fills with little increase in pressure
they have reserve in theri shape
ربنا نعوذ بك من الهم والحزن والعجز والكسل والجبن والبخل وغلبة الدين وقهر الرجال وشماتة الأعداء والمرض والحسد والسحر والحياء و إلف النعمة
Why veins are imp blood resevoir ?
because they can accommodat a large amount of blood without a marked increase in the pressure and as you know the gradient of flow of blood from high to low
the veins are still low pressure with high amount of blood because of theri complicance
Mention The role of vasomotor tone on the vein .
It decrases its capacitance making them reach the point of stiffness and stretching earlier than usaul and smaller amount of blood increases the pressure in them as this is the function os sympaththic> increase venous return ? ok?
Veins has high radius/wall tension ratio high raidus and low walltension
Show the variable confugration of the veins during differnt encapacitated states,
First it is flat and collapsed 0-6 mm Hg
incrasing the amount of blood becomes ellipitical
incrasing … becomes oval
incrasing beomes cirular now the smooth muscles are stretched and any incrase in the volume will lead to increase the pressure inside the vein due to increase wall tension and decrease in capacitance
Mention the effects of the sympathtic on the venous capactiance .
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it contracts the smoooth muscles of the vessel casuing its stifness and loss of capacitance and this will lead to increase of venous pressure at any given amount of blood in it
tip change in the voulme of blood from ellipitical to cirular shape of veins has no stretch or incrase in wall tension but when it becomes circular the wall tension increases with any added volume leading to incrase the pressure
Mention the effects of the sympathtic on the venous capactiance .
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it contracts the smoooth muscles of the vessel casuing its stifness and loss of capacitance and this will lead to increase of venous pressure at any given amount of blood in it
tip change in the voulme of blood from ellipitical to cirular shape of veins has no stretch or incrase in wall tension but when it becomes circular the wall tension increases with any added volume leading to incrase the pressure
لما تيجي تاخذ دم من عيان ويخاف الوريد بيختفي ليه ؟ عشان تاثير السمبثاوي عليه ونقص الاتساعية بتاعته بسبب انقباض العضلات الملساء ده هيسبب انه ينكمش في الحجم و الدم يعدي منه
Mention the direction of the venous blood ? and factor preserving it ?>
It is always unidirectiontal towards the heart due to
1- venous valves
2-skeletal muscle pumping
describe change in the venous blood flow velocity? and why ?
As we approximate to heart i mean when the venules are collecting together finally forming the big veins the TOTAL cross sectional area decrease so the velocit increases dt the inverse relationship to reach (25cm/s ) in vena cava
blood is faster in which of them the vena cava or aorta ?
definitely aorta as it has less total cross sectional area ^_^
GR/The rapid ejection phase casue increasing in VR?
This is due to pulling down of the AV rings during venricular contraction casuing strtch of the artium and decreasing their pressure also the deep veins connectin to it so the flow of VR increased as the gradient between the peripheral and central veins increase
GR/ the rapid filling phase increase the VR?
AV Valves are open allowing blood to move from the atria to the ventrciles decrasing the pressure in the atria and so the central veins increaing the flow gradient and the VR
Near the heart the Veins show pulsation ?
The show pulsation reflected from the heart as the Waves in increasing in VR
due to
Rapid ejection phase x descent
Rapid filling phase y descent
increasing in VR
due to ?
Rapid ejection phase x descent
Rapid filling phase y descent
Rapid ejection phase x descent
Rapid filling phase y descent
MCP mean ciculatory prssuere
can be determined in case of stop of heart
NORMAL 7mm Hg
is the pressure in all vessels around the the circulation
depends on the
blood volume
capacitance of the cirulation determined by the veins
MCP mean ciculatory prssuere determinants Metion .
depends on the
blood volume DIERCT PROPOTIONAL
capacitance of the cirulation determined by the veins INVERSE RELATIONSHIP
1giving vasodilator affect mcp ?
giving alpha blocker affect mcp ?
1
2giving alpah agonist affect?
1Venodilation will increase capacitance decrasing the mcp
Vasoconstriction decrasing the capacitance inreaing the mcp
مهم
لما الدم يبدا يشتغل تاني يبدا بالنبضة الاولي والتي تليها والتي تليها في تعلية الضغط البطيني عن الضعط الاذيني حتي يستطيع بعد محاولات عديدة ضخ الدم في الدورة الدموية في الشرايين كفاية لتتعدي الشريينات الضيقة المقاومة فتصل بضغط ايضا لل الاوردة الصغيرة فيكون بينها وبين الاوردة المركزية فرق ضغط يسمح بمرور الدم ورجوعه للقلب وهكذا حصل استعادة لعافية الدورة الدموية !
CVP
PVP
CVP 0 mm Hg at artia and usually the central veins a PVP is variable in venules 10-15 mm Hg veins 4-8 mmHg SVC IVC ? 0-2 mm Hg
PVP=MCP + Pressure arriving from the arterial side due to heart pumping !
Gravitation pressure mean?
it is hydrostatic pressue resulted from the weight of of column of blood
It can be measured when your feet not touching the ground so that there is not reflexex from the body abolishing it
When a person standing the Right atrial pressure is still 0 ?>
This is because heart acts as a feed back regulator of the pressure at this point 1
in adults standing still the pressure in the veins of the foot is +9o mm Hg
in adults standing still the pressure in the veins of the foot is +9o mm Hg why ?
due to hydrostatic pressue of gravity resulted from the weight of the 120 cm column of blood ! .77 x 120 = +90 mm Hg
tip the hand has veins of +35 mm Hg pressure
the top rib is +6 mm Hg
Why the intathoracic vein are not collapsed despite their negative pressure?
This is becasue they are surrounded by The negativre intrathoracic pressure which is more negative than them so no collapse occur
Describe veins of skull
The veins inside the skull are in a non-collapsible chamber,
so they can not collapse and the pressure in the sagittal
sinus is about -10 mmHg, thus if the sagittal sinus was
opened in surgery air embolism and death may occur
neck veins
The neck veins of a person standing upright are collapsed
almost completely all the way to the skull. This collapse
causes the pressure in these veins to remain at zero along
their entire length. This is because any tendency of the
pressure in these veins to rise, opens the vein and allows
pressure to fall to zero because of flow of blood. Conversely ,
any tendency for the pressure to fall below zero, the vein
collapses more with further increase in its resistance with
decrease in blood flow and elevation of pressure.
