Microcirculation
DR. Arwa Rawashdeh
Presented By :
Dr. Tareq Abu-Libdeh
Types of Arteries :
• Elastic ( Conducting ) arteries “ eg. : Aorta “
• Muscular ( Distributing ) arteries “ eg. : Radial “
• Arterioles
• Metarterioles ( Pre-capillary sphincter )
Types of Veins :
Large veins
Medium & Small veins
Venules
Capillary unit
• Here is the crux of all our information today
so this is a capillary unit in a tissue,
and this will be found anywhere in the body
its ubiquitous and this is going to supply our tissues
with all nutrient and oxygen and all that other nutrient needs to function
• What we are going to discus these arteriole, precapillary sphincters and the metarteriole
and you can see these banded with smooth muscle
and these precapillary sphincter are smooth muscle
Capillary unit
• and the function of these are a little bit different;
the metarteriole is basically a vascular shunt
for when these capillary sphincters are open or closed ,
serve either as
thoroughfare channels to the venules,
which bypass the capillary bed,
or as conduits to supply the capillary bed.
There are often cross-connections
between the arterioles and venules
as well as in the capillary network.
• arterioles are terminal endpoint of systemic circulation
with regard tissue perfusion
Anastomosis
• An anastomosis refers to any join between two vessels.
• Definition :
Alternative/Collateral channels for blood flow through
• Circulatory anastomoses are named based on the vessels they join:
•
• two arteries (arterio-arterial anastomosis / arterial anastomosis),
two veins ( veno-venous anastomosis / venous anastomosis),
or between an artery and a vein (arterio-venous anastomosis).
Anastomosis
Arterial anastomosis
Circle of Willis
Anastomosis
Venous anastomosis
basilic vein & cephalic vein
median cubital vein
Anastomosis
Arteriovenous anastomosis
metarteriole , thoroughfare channel
Blood Flow to specific areas in the body
1 - Skeletal muscles
2 - Brain
3 - Lung
4 - GIT and skin
Blood Flow to specific areas in the body
1 - Skeletal muscles:
Active hyperemia:
The increase in blood flow at the active tissues
by vasodilation
produced by accumulation of metabolites.
Or
the increase in organ blood flow (hyperemia)
that is associated with increased metabolic activity of an organ or tissue.
An example of active hyperemia is
the increase in blood flow that accompanies muscle contraction,
which is also called exercise hyperemia in skeletal muscle
Blood Flow to specific areas in the body
2 - Brain:
Autoregulation of cerebral blood flow .
The myogenic behavior of the cerebral smooth muscle
that constrict in response to elevated pressure
“ to protect the smaller cerebral vessels from rupturing “
When Dilate the
arterioles
Increases the amount of
the blood flow to the
capillaries
When constrict the
arterioles
Decreases the amount of
the blood flow to the
capillaries
and dilate in response to decreased pressure
High MAP
vasoconstriction
Low MAP
vasodilation
Myogenic Mechanism
Blood Flow to specific areas in the body
3 - Lung:
When PO2 decrease in one alveoli
blood shunt to the other alveoli
that has High PO2
Blood Flow to specific areas in the body
4 - GIT and skin :
Vasoconstriction in sympathetic stimulation
Leads to Shunt the blood into more vital organs
The Lymphatic System
Main Channels of Lymphatics
• Originate as lymph capillaries
• Capillaries unite to form larger vessels
• Resemble veins in structure
• Connect to lymph nodes at various intervals
• Lymphatics ultimately deliver lymph into 2 main channels
• Right lymphatic duct
• Drains right side of head & neck, right arm, right thorax
• Empties into the right subclavian vein
• Thoracic duct
• Drains the rest of the body
• Empties into the left subclavian vein
Lymph System is Open system ( Not Closed ) ;
Because it is started in the interstitial fluid
and ended up in veins
- the starting point is not the same as the termination point
that's why lymphatic system is an open system
• We can see lymph node swelling in patients with
bacterial or viral infections ( Tender )
and carcinoma ( Non-tender )
Lymph node
Immune system ;
Cortex
Paracortex
Medulla
Medullary sinus
B cells,
T cells,
plasma cells,
macrophages
Thank You ☺