Vessels Flashcards
Blood Volume Distribution
Systemic Veins 64% Systemic Arteries 13% Pulmonary vessels 9% Heart 7% Systemic Capillaries 7%
What is the Adventitia of the arterial wall composed of?
Strong fibrous tissue
What is the Media of the arterial wall composed of?
smooth muscles
elastic tissue
fibrous tissue
What is the Intima of the arterial wall composed of?
single layer of endothelial tissue
Describe the anatomy of the artery wall
- Thick and firm
- Dilate with systole to a small degree
- Low capacitance
In ASCVD initially, within the endothelial cells there is an inflammatory response with accumulation of what type of cells?
WBCs
Macrophages
In ASCVD, after WBCs and macrophages accumulate what happens next?
- Accumulation of cholesterol and triglycerides into a fatty deposit called and atheroma
- Accumulation of Ca2+
- Mass reduces elasticity of the artery (stiff) and narrow the lumen (hardening)
What is the progression of endothelial dysfunction?
- Initial lesion
- Fatty streak
- Intermediate lesion
- Atheroma
- Fibroatheroma
- Complicated lesion
What is a granuloma?
Accumulation of inflammatory cells 2/2 to an inflammatory process
(seen in Arteritis)
In Takayasu’s Arteritis what main vessel in involved?
Carotid artery (will see thickening of the wall on imaging)
There is one place you can actually see the arteries and veins..where is it?
The fundus of the eye
arteries appear redder sat. = 90-95%
Arteriole function
- Control amount of resistance through vasoconstriction and vasodilation
- Greatest drop in pressure occurs
Distal arterioles have only what 2 layers?
- media (smooth muscle)
- intima
What are the intrinsic mechanisms (autoregulation) for arterioles?
-Metabolic or myogenic controls
Distribute blood flow to individual organs and tissues as needed
What are the extrinsic mechanisms for arterioles?
- Neuronal or hormonal controls
- Maintain MAP
- Redistribute blood during exercise and thermoregulation
What metabolic factors will cause vasodilation of the arterioles?
Dec O2 Inc CO2, H+, K+ Prostaglandins Adenosine Nitric oxide
What neuronal and hormonal factors will cause vasodilation of the arterioles?
- Dec sympathetic tone
- Atrial natriuretic peptide (ANP - maintains fluid level and BP)
What neuronal and hormonal factors cause vasoconstriction of arterioles?
- Inc sympathetic tone
- Angiotensin II
- Antidiuretic hormone
- Epi and NE
Capillary anatomy
- single layer of endothelium (continuous with intima)
- small, short 5-10 micrometers in diameter
- 1 mm long
(est. 62,000 miles long)
Capillaries have the ____ total area and cross sectional diameter of any component of vascular bed
largest
The single cell layer of endothelium in capillaries facilitates the passage of?
- water
- electrolytes
- O2
- CO2
- waste & nutrients (glucose)
T/F: There are no large fluctuation in blood pressure in the veins or capillaries?
True
Venule walls have what two layers?
Intima and media
Veins have what layers?
Adventitia
Media
Intima
T/F: The adventicia and media are much thinner than in the arteries
True
Veins have much thinner walls and are collapsible (increased capacitance and lower BP)
Veins have ____ diameter lumens which offer little resistance to flow
large
Valves of the veins help to?
direct flow to the heart
Are veins usually pulsatile?
No - not unless transmitted by cardiac pulsations
Increased venous return to the heart is one of the primary mechanisms by which cardiac output is?
Increased rapidly
This can be done by increased sympathetic tone (smooth muscle in veins contract)
What factors increase Venous Return to the Heart?
- Sympathetic nerve stimulation (constriction)
- Skeletal muscle pump (calves)
- Breathing (neg intrathoracic pressure)
- Inc Blood volume (urine and tissue fluid volume)
There is a ____ and an ____ component to influencing venous return to the heart.
respiratory and abdominal
What does the Valsalva Maneuver do?
Increases intra-thoracic and intra-abdominal pressures
What does the increased pressured created by the Valsalva Maneuver cause?
It prevents blood from flowing into the vena cavae with resultant decreased venous return to the heart and decreased CO.
There is also a ____ component to venous return.
positional
lying down will increase venous return to the heart
What is phasicity?
The ebb and flow in the veins in response to respiration and cardiac right atrial contraction
With standing respiration what happens to the pressure in the thorax and what does this cause?
The pressure decreases and venous blood flows into the chest vena cavae. The intra abdominal pressure increases, increasing abdominal vein pressure.
Due to the veins having about 60-70% of the blood in your circulatory system, what are they responsive to?
Gravity
What is the primary factor in determining intravascular pressure?
Hydrostatic pressure
What is the pressure in the legs while supine vs while standing?
Supine = to RA pressure 10 mmHG Standing = 90+ mmHg and negative pressure in the head
(250mL of blood pools into LE)
When enough blood pools in the lower extremity veins, you have a decreased amount of blood flow to the heart and this results in?
Syncope “Coldstream Guard Down”
When blood pools in the lower extremity veins the increased hydrostatic pressure causes?
Leakage of fluid from the capillaries causing peripheral edema
What is Virchow’s Triad?
Stasis
Hyper-coagulability
Endothelial Injury
Healthy valves in the veins of the muscles should open when muscles contract and ___ when they relax
close
When blood clots, the RBCs tend to organize themselves into layers and this requires?
More energy to break the clot up than if the RBCs were just randomly clumped together
What occurs when there is decreased protein in the blood (albumin)
Edema
An average of how many liters of plasma remain in the interstitial fluid?
3 L
20 L out - 17 L reabsorbed
