Circulation, Hemodynamics And Pressure Regulation Flashcards
What kind of valve is the circulatory system
One way, closed circuit
How does blood leave heart
Arteries
All vessels are lined with
Endothelium
Cargo is exchanged in the
Caps
Where do caps branch from
Arterioles
Blood is returned to the heart via
Veins
What vessel has a single layer of endothelium
Caps
Blood leaves the LV via
Aorta
Thick walled vessels
Arteries
High pressure, low volume. Resistance (what type of vessel)
Arteries
What vessel controls blood pressure and blood flow
Arterioles
Musculature of the arterioles
Very muscular
What is lacking in arterioles and what does it have more of
Less elastic, more smooth muscle
What kind of receptors in arterioles
a1 (SNS innervation)
B2 receptors
Elasticicity of aorta
Hugely elastic with out high pressure. Recoils and push blood out during diastole
Epinephrine on the arterioles
B2 receptors. Causes vasodilation (skeletal muscle)
Elastic, smooth, fibrous
Arteries
Thin walled vessels
Caps
Single layer of endothelium
Caps
Opened or closed by pre cap sphincter
Caps
What bridges the arteries and venous systems
Caps
Where does cargo exchange occur
Caps
____ join together to form progressively larger vessels
Venues
Thin walled vessels that are very compliant and elastic with a small amount of smooth muscle
Veins
Low pressure, high volume. Compliance (vessels)
Veins
How much smooth muscle in veins
Not much
Innervation of veins
SNS innervation (a1, B2) A1-gets less stretchy, lowers venous compliance, force more blood over to arteriole side
Flow in veins
One way flow due to valves
What drains into RA
Vena cava
Where does most of the blood sit
Veins
How does blood flow
High pressure to low pressure
As resistance increases, what happens to flow
Slows
As pressure difference drops, what happens to flow
Slows
What is velocity of blood flow dependent on
Size of total area of the vessels
Where does blood flow the fastest?
Through the single, large vessels (aorta)
Where does blood slowest?
Through many, small vessels (large cross section Bc so many of them)
Why does aorta have small cross section
Because there is only one aorta
Why do we want the caps to have slow blood flow
For nutrient exchange
Is blood dispersed evenly throughout the circulatory system?
No
What holds most of the blood
Veins
What is the blood volume reservoir of the body
Veins
Pressure in veins
Lots of volume, little pressure
What controls flow back to heart
Veins
Pressure in arteries
High pressure, low volume
What controls the flow to the caps
Arteries
At which level of the vasculature us blood pressure most controlled
Arterioles
At which level of the vasculature is venous return most controlled
Veins
Administration of an alpha 1 agonist would decrease blood flow to which kind of vessel
Capillaries
SNS has greatest effect on arterioles, it makes it harder to pass into caps, pressure builds in the arteries
Why is the venous system such a low pressure system, despite containing the most volume
High compliance vessels
What is resistance most dependent on?
Radius of blood vessels because its s raised to the 4th power
What is resistance determined by (equation)
Poiseuille equation
As diameter of vessels goes down what happens to resistance
Goes up
How is the circulatory system arranged
In both parallel and series
_____ arrangement occurs within an organ
Series
______ arrangement occurs when you look at multiple organs
Parallel
What are the two way in which blood flows
Laminar and turbulent
Straight line flows
Laminar
Not straight line flows, calculated by Reynolds number
Turbulent
What kind of flow prevents clot formation by keeping shear forces high at vessel walls
Laminar
What kind of flow happens when there is a kink in the vessel
Turbulent
- vessel no longer straight
- narrows
- blood velocity slows
- murmurs
What kind of flow will you hear murmurs
Turbulent
A carotid bruit (systolic murmur heard in the carotid artery) is most likely the result of
Carotid artery plaques
Where is the biggest drop in systemic pressure
Arterioles
Where is the most pressure in systemic
Aorta
Where is the pressure the lowest in systemic circulation
Caps 35-15
Which side of the heart has more pressure
Left
Which side of the heart ejects most blood
They eject the same amount of blood
Which side of the heart has a greater cardiac output
They are equal
Difference between systolic and diastolic pressures
Pulse pressure
SBP-DMP=PP
Average pressure during a complete cylce
Mean arterial pressure
DP+ 1/3PP=MAP
What is the normal MAP
About 100
What is the driving force for blood flow to organs and caps
MAP
What does your. Body regulate when regulating blood pressure
MAP
How can you alter MAP
Alternating CO (HR or SV) altering TPR (afterload)
Why do we have to be careful about altering TPR to regulate MAP?
Changing TPR can change CO
What is the easiest thing to change in order to alter MAP
HR
What does altering TPR do
Ultimately changing afterload
- constrict or dilate arterioles
- directly increases or decreases MAP
- also decreases or increases CO by changing SV
How do you change stroke volume
Increase SV, increase CO, increase MAP
- increase EDP or venous retune (preload)
- increase contractility (inotrope)
What are the two things that MAP is controlled by
- baroreceptors reflex
- renin-angiotensin-aldosterone system (RAAS)
What is the neural control of MAP
-baroreceptor reflex (TPR, HR, contractility an venous return)
What control of MAP is renal control
RAAS
-blood volume and TPR (Mostly blood volume)
Which control of MAP is the most powerful
RAAS
Which control of the MAP is the fastest
Baroreceptors (neural)
What does baroreceptors sense
MAP
How do baroreceptors sense MAP
- two mechanosenstive group of cells
- carries info to medulla via CN 9 and 10
- stretch activated
Carotid sinus bifurcation
- bifurcation of carotid artery
- info carried on CN 9
Aortic arch baroreceptor
- arch of aorta
- info carried on CN 10
What does HTN do to MAP
Rises
- decreased vasoconstrictors
- stretch stimulates decrease constrictions
- slow SA, decreased CO and TPR
What happens to MAP during hemorrhage
Drops
- decelerate inhibited, PNS turned down
- accelerator and constrictor increase
- increase MAP CO
What organ is very concerned about blood pressure
Kidney
Why does kidney need blood pressure
To filter blood to make urine
What kind of MAP control can cause a volume overload
RAAS
Reduced renal profusion (blood flow) causes kidney to release
Renin
What does renin do
Converts angiotensinogen to angiotensinogen I
What does angiotensinogen I do
Converted to angiotensin II by ACE (angiotensin converting enzyme)
What is an example of a reason for Renin secretion
Bleeding out
What does AngII do
Vasoconstriction and releases aldosterone
What does aldosterone do
Increases Na reabsorption, which then causes water reabsorption , which increases blood volume
Which system of blood pressure regulation would alter pressure the fastest
Neural (baroreceptor)
Given sufficient time, which system of blood pressure regulation would be Abel to create the largest change in blood pressure
Renal (RAAS)
What are other mechanisms of regulating MAP other than the neural and RAAS?
- antidiuretic hormone
- cardiopulmonary receptors
What is another name for antidiuretic hormone
Vasopressin
What does antidiuretic hormone do
-released from pos pituitary in high serum similarity and low BP
What do vasopressin 1 receptors do
Arteriolar constriction-raise BP
What do vasopressin 2 receptors do
Kidney reabsorbs more water, raises BP
What are the two basic things that the antidiuretic hormone does
Stops peeing, increase BP
Where are the cardiopulmonary receptor located
In veins, atria, and pulmonary arteries
What are the cardiopulmonary receptors
Volume receptors on venous side (low pressure)
-sense fullness
What do the cardiopulmonary receptors respond to
High volume
What do the cardiopulmonary receptor do
- Releases Atrial natriuretic peptide to produce more urine
- decreases ADH secretion (more urine)
- renal vasodilation (more urine)
- increased HR (indirectly more urine)
Assume point E is normal, hyperaldosteronism without cardiac compensation would result in a shift where
Moves up
Increase blood volume, move up on chart. It would compensate by lower contractility
If you have a massive MI, what kind of shift would there be
Decreased force, decreased contractility
Moves down on chart for contractility
