Organization of the Cardiovascular System: Dr. Wilson Flashcards
What system is the primary limiting factor whether young or old?
muscular system
What are the functions of the cardiovascular system?
1) gas exchange
2) nutrients
3) removal of wastes
d) protective cells and proteins
e) regulatory proteins
f) heat
Is heat a waste product?
YES, it is an important waste product that needs to be rid of if it is excess in the body.
CV diseases often affect all systems. Explain.
- because the CV system comes into contact and interacts with most of the cells of the body, CV diseases often affect all systems
- if you have disease of other organ systems it will also affect the CV system
At day 25 of embryo development, what is the first system to function?
Cardiovascular system
the heart begins to beat
The heart, vessels, and blood develop from what embryological origin?
mesoderm
Define ischemia, hypoxia, and anoxia.
Ischemia = mechanical obstruction of blood supply (deprive tissue of O2, nutrients and allow waste products to build up)
hypoxia = decreased levels of oxygen
anoxia: no oxygen
Hypoxia and anoxia are a consequence of ischemia
Define infarct.
an area of necrosis resulting from inadequate blood flow
The CV system is organized into what two closed loops?
- pulmonary loop (to lungs, gas exchange)
- systemic loop (to tissues, organs, and glands: exchange of nutrients and waste)
The pulmonary system supplies what tissues in the lungs?
alveoli (capillaries)
It is estimated that the body has 60,000 miles of blood vessels. Most of the body’s vessels are found in what system, pulmonary or systemic?
Most found in the systemic system
systemic: 59,000 vessels
pulmonary: 1,000 vessels
Which system presents the greatest resistance to blood flow? Has the highest blood pressure?
systemic system has the greatest blood flow and the highest pressure
-takes a lot of force and energy to pump blood to the whole body (this system supplies the heart, brain, muscles, skin, kidneys, and other orgas, glands, and tissues of the body) as opposed to one pulmonary organ (lungs)
Which side of the heart pumps blood through the pulmonary loop?
right side of heart
Which side of the heart pumps blood through the systemic loop?
left side of heart
Why is the left heart thicker than the right? Explain in terms of load.
Muscles hypertrophy when given load.
The load for pumping blood through the systemic system is higher due to higher resistance, therefor the left ventricle has to pump harder to get enough blood through the aorta to supply the body = thicker walls
Which side of the heart has higher cardiac output?
both the right and left heart must be EQUAL in cardiac output
What are other mechanisms for pumping blood besides the heart?
respiratory pump
muscle pump
How does the respiratory pump work to pump blood?
contraction of the diaphragm pumps blood into the right atrium by:
1) decreasing thoracic pressure
2) increasing abdominal pressure
3) opening up the IVC
How does the muscle pump work to pump blood?
contraction of the calf muscles helps to bring blood back to the heart with the help of one way valves ensuring unidirectional flow of the blood
Most veins have valves. What is the function of valves?
valves allow for unidirectional flow of blood towards to the heart
How does pressure affect blood flow?
the more pressure the heart produces the greater the blood flow
REMEMBER: the anatomical factor that affects flow is pressure)
Pressure =/~ flow
How does resistance affect blood flow?
blood flow is inversely proportional to resistance; the greater the resistance the lower the blood flow
Flow = 1/ Resistance
What causes resistance in the blood vessels?
Friction between blood and the walls of blood vessel
- resistance is irreversely proportion to (radius)4
- the greater the radius the lower the resistance
- when arteries get clogged up your resistance to blood flow goes up
Resistance = 1/r4
How does atherosclerosis affect resistance and flow turbulence?
- it increases resistance and flow turbulence
- it is going to take more pressure to deliver the same amount of blood to the tissues distal to the plaque
What are the 9 common sites to take pulse?
- superficial temporal
- facial
- common carotid
- brachial -radial
- femoral
- popliteal
- posterior tibial
- dorsalis pedis
If the pulse is not symmetrical on both sides what does this mean?
this could be a sign of vascular disease
To offset a 16 fold increase in resistance, pressure must be increased by 16 times. What does this mean?
- the heart has to work harder
- muscles hypertrophy when you put more load on them
Hypertrophy of the left ventricle occurs due to hypertension. How much can the left heart increase in size?
- the heart will hypertrophy until it fails
- if you cannot compress the lumen, the blood will not be able to go out and thus tissues will not receive oxygen
Increased vascular resistance due to emphysema affects what side of the heart?
right side of heart as this is a problem with pulmonary circulation
On a chest xray how do we classify a hypertrophied heart?
when the heart has taken 1/2 the diameter of the diaphragm
How does an aneurysm result?
- when the pressure in a vessel exceeds the elastic components of the tunics
- pressure causes the walls of blood vessels to weaken (bulging of the artey)
- can be caused by high BP
When an aneurysm ruptures, what does it produce?
hemorrhaging stroke
What are the functions of capillaries?
1) connect arteries and veins
2) site where gases, nutrients, and wastes are exchanged between blood and tissues
Arteries take blood _______ the heart. Veins take blood _________the heart.
arteries = away from
vein = to
Arteries carry blood of which oxygenation status? Veins?
Arteries: oxygen rich blood
Veins: oxygen deficient blood
Moving distally from the heart, how does the size of arteries and veins change?
arteries get progressively smaller veins get progressively larger
Approximate the size of capillaries.
diameter of a single RBC
Where would a thrombus forming in the venous of the lower limb most likely end up?
- it will most likely end up in the pulmonary circuit
- although the veins get progressively larger as you move towards the heart, they get smaller again in the pulmonary circuit towards the lungs
How does the cross-sectional area, resistance, and thinness of the wall change as the arteries move distally from the heart coursing to their targets?
- cross-sectional area decreases
- resistance increases
- walls get thinner
What three coats do blood vessels carry?
- tunica intima (endothelial cells, loose connective tissue)
- tunica media (smooth muscle, elastic and connective tissue fibers)
- tunica externa/adventitia (loose connective tissue (like epineureum)
What portion of the tunica media controls lumen diameter and blood flow during its contraction?
smooth muscles
- so when the smooth muscle contracts the lumen changes in size
Why do the arteries get thinner as they course from the heart to their targets?
As the arteries move more distally there is not a lot of load on them and thus the smooth muscles are not being stimulated; therefore the walls get thinner
What is the tunica media mostly made up of in large conducting arteries like the aorta?
elastic fiber
What is the tunica media mostly made up of in large distribution arteries?
smooth muscle
-contraction of the muscles in distribution arteries controls blood flow to a particular muscle, gland, organ, etc.
What occurs to the elasticity of the conducting arteries during systole and diastole?
- elastic arteries expand during systole, dampening the pulse surge
- elastic arteries recoil during diastole, propelling the pulse forward and conserving energy
What occurs to the blood pressure as blood flows from the heart?
blood pressure decreases, with the largest drop in the arterioles
Most peripheral resistance occurs in which blood vessels?
arterioles (due to its thick muscular wall)
-the resistance of a maximally constricted arteriole is 80 times that of a fully dilated arteriole (remember resistance is proportional to 1/(r^4))
Perivascular nerves innervate smooth muscles under what autonomic nervous system? and to do what?
- sympathetic nervous system
- vasoconstriction (of tunica media)
What is Raynaud’s disease?
excessive sympathetic tone in arteries supplying the limbs. The digits become cyanotic and cold.
Why does Raynaud’s disease result in cyanotic and cold digits?
-sympathetic system is over active which results in chronic vasoconstriction of arteries in the periphery thus reduced blood flow that goes through the arteries to the digits (hypoxic tissue)
Hands and feet are always cold
Fluid exchanges occur mostly at capillaries where there is a net flow of serum goes where?
interstitial fluid
What provides for control of perfusion through local capillary beds?
precapillary sphincters
They are located after arterioles. If the tissue has enough supply the sphincters will constrict a redirect blood supply else where. Blood flow is based on metabolic needs.
Approximately 25% of the capillary beds are _______ during rest?
opened
What occurs with closing of precapillary sphincters?
You create a shunt
non-nutritional flow, shunt, or arteriovenous anastomoses shunt= blood does not go through the capillary system resulting a mixture of arterial blood with venous blood since it did not perfuse through the capillary bed
Arteries and veins run in pairs in the body except where?
the skin
saphenous vein and cephalic vein run alone
Do veins or arteries have the same diameter?
No!
veins have larger diameters
Which has a thinner walls, arteries or veins?
veins
-smooth muscles are thinner in veins because they don’t have a lot of pressure like arteries
Which is blood vessels are more compliant, arteries or veins?
veins are more compliant (less resilient)
can change their shape more than arteries
What is the directional flow of blood in arteries compared to veins?
Blood in arteries and veins run in opposite directions. Arteries away from the heart. Veins towards the heart.
Describe the role of the blood and arteries running in opposite direction?
- this allows for counter current heat exchange
- heat from arteries can go into the veins particularly when you’re in a cold environment
- warms blood from the trunk can go to a distal capillary. Cool blood then returns to the trunk.
How does the wall thickness of a vessel reflects its load?
Arteries have a thicker wall because they have a load on them. Veins do not experience that same amount of load so this is why their walls are thinner.
CLinical correlation: Individuals with hypertension suffer from thickning of the walls due to the increase load of blood needed to be pumped through the heart (high blood vessel pressure)
How does compliance change with thickness of the blood vessels?
compliance (flexibility) reduces with thicker walled vessels.
Individuals with with hypertension develop thicker walls. Decrease in compliance only exasperate the problems of hypertension
Approximately 64% of blood is found in which blood vessels?
veins
“veins have more volume”
(arteries only contain about 1/3)
How does blood flow to muscles and brain change with exercises from rest?
- blood flow to muscles increases 10X
- blood flow to the brain remains the CONSTANT regardless of activity
What is the state of precapillary sphincters during rest?
they are closed
“they open up due to muscle ischemia”
What fluid is produced as blood goes through the capillaries?
interstitial fluid
-plasma leaks out of the capillaries to form interstitial fluid
Clinical Correlation: If you have a increase in blood pressure this will cause more fluid to leak leading to an incease in intersitial fluid -> edema
What vessel returns the interstitial fluid back to the cardiovascular system?
lymphatic capillaries
What results when there is mismatch between systemic output (capillary) and lymphatic uptake (lymphatic system) is overwhelmed?
Capillaryout > Lymphaticuptake
accumulation of interstitial fluid in lungs called pulmonary edema eventually leading to congestive heart failure
- will have ascites (acumulation of fluid in the abdominal cavity) and tissue edema (in legs primarily)
- can also develop papilledema
- skin can rip and fluid leaks into skin
Compare the cardiovascular and lymphatic system.
-cardiovascular system is a closed system whereas lymphatic system is an open system
How does pulmonary edema occur?
Efficiency of pulmonary cappillary system is not effecient
- interstitial fluid leaks into the alveoli producing hypoxia (on a normal day the pulmonary system typically quickly picks up any excess fluid to prevent this
- the person is literally drowning in their own interstitial fluid
- pulmonary edema final pathway is congestive heart failure/death
How many capillary beds does a blood cell pass through in the systemic, pulmonary, and portal system?
- in systemic and pulmonary circuit blood cell passes through a single capillary bed
- in a portal system, blood cell passes through TWO capillary beds in series before returning to the heart (exaples are hepatic portal system, hypophseal portal syste,, and remal portal system)
Why does blood need to go through the liver through the hepatic portal system before returning to the rest of the body?
liver filters the blood; detoxifies chemicals and metabolizes drugs in the blood
What are the two capillary beds in the hepatic portal system?
1) stomach and intestine
2) liver
What are the two capillary beds in the hypophyseal portal system?
1) hypothalamus
2) pituitary gland
What are the two capillary beds in the renal portal system?
1) glomerulus (in cortex)
2) medullary plexus (around loop of Henle)
The abdominal aorta becomes the common iliac. These are known as what type of arteries?
Conduction arteries
As arteries course to their targets & branch they become?
- More numerous
- smaller in diameter and cross sectional area
- higher in resistance
- thinner walled
T/F
Veins run in pairs
True
Unlike blood capillaries, lymph vapillaries begin as what?
cul-de-sec
(not connected in a loop, instead have a blind ending)
also 1 cell thick
What is the net flow of fluid out of the capillaries? what is important about this?
blood capillaries -> interstitial fluid -> lymph campillaries
Net flow of fluid out of the blood capillaries need to be the same amount of fluid that is returned to the heart from the lymphatic system.
What percent of cardiac output go to the alveoli?
50%
(they are surround by an abudance of capillaries)
