BIOL 208 Lecture Notes - Lecture 10: Heart Failure, Pulmonary Alveolus, Coronary Artery Disease
Congestive heart failure (CHF)
***when the heart becomes weakened, irrespective of the cause of that weakness, a similar
procession of signs and symptoms occur and are grouped together under the term CHF***
***CHF is the state that occurs when the heart is not capable of supplying enough O2 to the body
tissues***
Congestive heart failure
● whenever heart fails, and blood isn’t being delivered sufficiently to tissues in right amount of
time then you will have lack of O2 to tissues and might be some congestion (build up of fluids
where usually shouldn't be - in lungs or tissues)
● congestive heart failure caused by basically 3 principle causes
● 1) CAD (coronary artery disease) - general term given to when have blockage in coronary
arteries diminishing blood flow, partial blockage or complete blockage is possible. depending
where along the vascular tree this occurs, some cardiac cells may die whereas all others are
still healthy so heart is still beating but it isn't beating as efficiently. CAD over time brings
about a weakened myocardium and due to either a full blown heart attack, multiple
eschemias over period of time
● 2) valve failure - regurgitation. if every time ventricle contracts, some of the blood is going
back into the atrium instead of going out into the aorta (the AV valve doesn’t close tightly
enough). regurgitation. slowly but surely build up of fluid and this fluid will build up pressure,
and as the blood is trying to come into the left atrium it gets a little push back which
ultimately increases hydrostatic blood pressure in the pulmonary capillaries. if this happens
enough some plasma in the capillaries will exude into alveoli and cause lung congestion
● 3) persistent high blood pressure - if systolic pressure is high it means when blood leaves
ventricle it has high pressure against it, so not all blood can push out easily due to high
pressure. that high pressure pushing against blood trying to leave will slowly be translated
backwards to ventricle, then to the atrium, then to the pulmonary veins, and finally to
capillaries of lungs and finally have, bring about pulmonary edema. this is over a long
sustained period of time
● congestive heart failure can bring about 2 things;
● 1 - poor circulation. if you have poor circulation, then you have poor perfusion, and if you
have poor perfusion, then you have poor oxygenation of the tissues. so the tissues aren't
receiving enough o2
● 2 - either pulmonary edema OR systemic edema
● when talking about pulmonary edema, usually the left side of heart is weakened. if the left
heart is weakened, its not pushing out blood well. blood still returning from the lungs is
coming in and it cant come in so theres a build up build up in back pressure and finally an
extravasation of fluids into pulmonary alveoli and therefore congestion
● the diffusion barrier is the barrier that the molecule of oxygen must traverse from the alveolus
to the capillary when the oxygen goes into the pulmonary capillary
● the barrier is 2 cells thick
● either squamous cell of the alveolus or the squamous cell of the capillary
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● capillary wall, the alveoli wall is the diffusion barrier
● it is very very thin
● once you have pulmonary edema, the diffusion barrier expands, making it more difficult for
oxygen to come in
● if there is a right heart deficiency, right atrium or right ventricle, is weakened, so it cant pump
very strongly. right heart pumps the blood to the pulmonary trunk, pulmonary artery. if the
heart is weakened, so the blood can not be pumped to the lungs, theres a back pressure,
meaning any blood coming from the inferior and superior vena cava is having difficulty
getting to right atrium and moving down to right ventricle, and the right ventricle is weak so
you have a back pressure coming from right atrium going back to inferior and superior vena
cava. over a period of time this back pressure is felt throughout the body, so you've got the
condition known as systemic edema
● have right heart weakness, right ventricle can’t pump blood to lungs effectively so theres a
back pressure that continues and the major veins are congested and pressure goes down to
capillary level
● systemic edema is usually manifested in legs and arms
● another name for this is dropsy
Blood vessels
Basic circulatory pathway (general)
● heart gives rise to major vessels; the brachiocephalic and several large arteries
● they are referred to as conduction arteries
● or elastic conduction arteries
● aorta has large elastic element
● initial vessels from heart have a lot of elastic components
● as you proceed down have medium size vessels/arteries. known as muscular or distributing
arteries. these continue to get smaller and smaller as they are distributed to rest of the body,
the muscular distributing arteries
● these medium sized represent first level, especially more distant ones, of blood vessels that
exhibit what can be referred to as vasomotor activity
● they aren’t really the ones that bring about vasoconstriction and vasodilation, they can do
that but more under extreme circumstances
● these represent first level for potential for vasomotor activity
● whenever the term vasomotor activity is used, always relates to ability to vasoconstrict and
vasodilate
● arterioles are very muscular, walls of arterioles are very muscular. endothelial layer is mostly
all muscle and a very thin outside layer
● its arterioles that really contribute to most vasodilation and vasoconstriction that goes on
● what they do is that they are the vessels that lead to what we call the microcirculation
● microcirculation refers to small aspects of arteries and capillaries
● arterioles take you to that microcirculation
● microcirculation consists of beds of capillaries (capillary beds)
● ** no such thing as a drop of blood leaving aorta and going all the way down to different
vessels and entering just one capillary. doesn't happen capillary beds consist of an
aggregation of interconnecting either 10-100 capillaries (per capillary beds)
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● only place where exchange of materials is across the capillaries because capillaries are one
cell thick. squamous cell, very thin. capillaries are the key functional part of circulatory
system
● capillaries represent the functional unit of the circulatory system
● from the capillaries the smallest vein the capillaries empty into on its way back to the heart is
known as venules
● in many ways, they may be compared to arterioles. whatever subdivision of arteriole feeds
capillary, its the venule that takes that blood away from capillary. arterioles on one end,
venule on the other end, capillary in the middle doing all the work
● venules drian into smaller veins and these drain into larger veins, and 2 great veins that
return all systemic blood back to the heart, and those greta veins are superior and inferior
vena cava
● all blood leaves by aorta, comes in by superior and inferior vena cava (and coronary sinus)
● theres another supply of blood into right atrium called coronary sinus
Composition of arterial walls
● usually 3 layers referred to as tunics
● these layers exist both in arterial walls and venous walls (but those veins have quite different
arrangement in terms of thickness and what not)
● 1) inner layer, a single cell layer. this is called the tunica intima. its the endothelium, but in
terms of the view of different layers is called the tunica intimata. basically endothelial cells, 1
cell thick with scattered elastic fibers
● 2) middle layer. the thickest layer of them all, known as the tunica media. this is mostly
smooth muscle and elastic fibers
● 3) outer layer. this is moderate, not as thin as inner layer. known as tunica externa (can also
be called adventitia). mostly connective tissue and the outside layer has more collagenous
fibers than elastic
● what happens is you've got these 3 layers, and outside by being more CT, more collagenous
fibers, gives strength to the walls, doesn't allow them to bulge out. pressure gets higher or
lower, remains fairly firm aneurisms is an example of a malfunction of vessels, this is where
that wall weakens and it bubbles out, and then the bubble breaks. this is when someone dies
of aneurism. vessel bubble breaks and bleed out
● the middle coat allows for the vessels to be able to contract but they're also elastic, so
they've got contractility and the ability or characteristic of elasticity and between the 2,
especially when you are young, vessels work nicely
● special type of blood vessel called vasa vasorum - means vessels of vessels. they are
thicker vessels. walls are thick. walls are so thick that even though the blood has O2 in it,
they're too thick for O2 to diffuse through the thickness of the wall to get to all cells in the
wall, so as result theres these little vessels within the walls of large wall vessels that pick up
the blood through little openings and pores of the surface of the vessel, travels through wall
and comes out again, this is how muscles and other wall structures remain ok, they're
supplied O2 directly from the blood flow
● the tunica media is innervated by the sympathetic NS
● in medulla, theres a larger center known as the cardiovascular center. this suggests that in
the medulla, theres a center there that controls the heart and vessels. sympathetic fibers
going to heart and the vessels
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Document Summary
***when the heart becomes weakened, irrespective of the cause of that weakness, a similar procession of signs and symptoms occur and are grouped together under the term chf*** ***chf is the state that occurs when the heart is not capable of supplying enough o2 to the body tissues*** Congestive heart failure caused by basically 3 principle causes. Cad over time brings about a weakened myocardium and due to either a full blown heart attack, multiple eschemias over period of time. Congestive heart failure can bring about 2 things; 1 - poor circulation. if you have poor circulation, then you have poor perfusion, and if you have poor perfusion, then you have poor oxygenation of the tissues. so the tissues aren"t receiving enough o2. 2 - either pulmonary edema or systemic edema. Either squamous cell of the alveolus or the squamous cell of the capillary. Capillary wall, the alveoli wall is the diffusion barrier.
