Circulation 2 Flashcards
Do Arteries have a low or high resistance? Why?
Low resistance
Elastin and Smooth muscle cushions systole
Which blood vessel has the highest resistance? What does this equal?
Arterioles
Total Arteriolar resistance= Total Peripheral resistance
What determines the radius of a blood vessel? What happens to resistance, flow and BP when blood vessels constrict?
Smooth Muscle
Constriction= Decreased radius
Increased resistance
Decreased flow
Increased Blood pressure
What determines rate of flow in capillaries? (2)
Arteriolar resistance and Pre-capillary sphincter
Describe the area and flow in capillaries
Large area and slow flow
Do veins have a low or high resistance? What is the pressure in veins?
Very low resistance
~10mmHg
What 3 factors aids the Veins in returning blood to the heart?
Skeletal muscle
Valves (prevent Backflow)
Respiratory pump
What type of Innervation do blood vessels lack?
Parasympathetic
Name three Circulating hormonal Vasoconstrictors
Epinephrine
Angiotensin II
Vasopressin
Name two circluating Hormonal Vasodilators
Epinephrine
ANP
Name two Local Humoral vasoconstrictor.
Endothelin 1
Internal Blood pressure autoregulation
Where and how is Endothelin-1 produced? What 5 factors stimulate it?
Big Endothelin 1 converted to Endothelin 1 by Endothelin by Endothelin converting enzyme in endothelium
Factors stimulating:
-Vasopressin
-Angiotensin II
-Cytokines
-Thrombin
-Oxidative reactive species
What does Endothelin-1 act upon? What does this result in?
G coupled proteins stimulating IP3 to release Ca2+ to contract smooth muscle
What eight humoral factors result in Vasodilation?
-Hypoxia
-Prostacyclin
-Adenosine
-Nitric oxide
- CO2
-K+
-H+
-Tissue breakdown products
Where and How is Nitric oxide produced?
Endothelium
Ach and Insulin stimulate Ca2+ release
L-arginine (Amino acid)–> Nitric oxide via NO synthase
What are three blood volume regulators?
RAAS
ADH
Adrenal and kidneys
What is blood pressure autoregualtion?
Smooth muscle is stretched when BP increases
Results in it contracting
What two locations are Peripheral Chemoreceptors and arterial Baroreceptors located in? (both found here)
Carotid sinus
Aortic arch
What is the afferent and efferent nerve for baroreceptors respectively? Where does it travel to?
Glossopharyngeal (CNIX)
and Vagus (X)
Medulla
What type of regulation do Arterial baroreceptors provide? What happens if there is a continuous increase in BP?
Short term (Min-Min)
Baseline for arterial baroreceptors will change to that BP
What is the other type of baroreceptor (not arterial) called? where are they found (2)?
Cardiopulmonary baroreceptors
Atria and ventricles
What do cardiopulmonary baroreceptors result in the secretion of?
Atrial Natriuretic peptide (ANP)
Where are central chemoreceptors found? What are they most sensitive to? What does this result in?
Medulla
High PaCO2
Vasoconstriction
What affects Blood pressure in the long term? What influences this?(4)
Volume of blood
Na+, H2o, RAAS and ADH
What are Peripheral chemoreceptors most sensitive to (2)? What does this factor cause to happen?
PO2 and pH
Decreased parasympathetic to heart increased pulse and increased CO
