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59 Cards in this Set

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Circulatory system consists of:
-Cardiovascular system
-Lymphatic system
Functions of the Cardiovascular system:
-Transportation of oxygen, nutrients, wastes, etc..
-Facilitation of body heat homeostasis
3 layers of blood vessel walls:
1. Tunica intima
2. Endothelium
3. Subendothelial Connective tissue
Components of the Tunica Intima:
Endothelium (simple squamous)
Subendothelial Connective Tissue
What separates the Tunica Intima from Tunica Media in arteries?
Internal Elastic Lamina
Components of the Tunica Media:
Smooth muscle
Fenestrated Elastic Laminae
What does Fenestra mean?
Window
What vessels have an External Elastic Lamina?
Large arteries
What does the External Elastic Lamina separate?
Tunica adventitia from Tunica media
So 3 types of laminae:
-External elastic lamina
-Fenestrated elastic lamina
-Internal elastic lamina
What are fenestrated elastic laminae?
Sheets of elastic fibers within the Tunica Media that have windows opening into the lumen.
What is their functional significance in Elastic Arteries?
Stretching during Systole
Recoiling during Diastole
To what cells do nuclei in the tunica media belong?
Smooth muscle cells
What is the function of Vasa Vasorum?
To provide oxygen and nutrients to the cells within the Tunica Media (of this muscular artery).
What procedure are cardiac specialists opting to do instead of coronary artery bypass now?
Angioplasty
What are ways to promote endothelialilzation?
-Local administration of VEGEF
-Put in stents to attract circulating endothelial cells
What structures can be seen in the uterine tube slide?
-Arterioles
-Veins
What is the diameter of an arteriole?
<100 um
How many RBCs can fit through an arteriole?
15
How does the wall:lumen thickness compare?
About equal
What do arterioles NOT have? Why?
An external elastic lamina - because their tunica adventitia is so small.
What type of muscle is the cremaster muscle?
Skeletal
How do you tell apart a muscular artery from an arteriole?
Artery >> arteriole in size
Less advential layer on the smaller arteriole.
How big is the diameter of a capillary?
7um
How many RBCs can fit through a capillary?
1 (7.5u)
What do the walls of capillaries consist of?
Only endothelial cells held together by tight junctions.
What do capillaries look like in cross section?
Basophilic nuclei that are moon-shaped, curving toward a thin rim of eosinophilic cytoplasm.
What type of capillaries are in skeletal muscle?
Continuous
What do tumor cells secrete to signal the need for vascular growth? What is that growth called?
Secrete VEGF for angiogenesis.
What does VEGF do?
Promotes vascular hyperpermeability so plasma proteins come in and build new blood vessels.
What changes occur in circulation when you stop the heart and take out nervous input?
1. MAP falls gradually all the way to 7 (Psf)
2. Venous pressure increases to about 4
Why is the decrease in MAP so much more dramatic than the increase in venous pressure?
Because of the ratio of compliance - about 25-30; look at the ratio of change in pressure of arterial side vs veinous (100-7)/(0-4).
Why does it take time for MAP to fall when you put the heart in asystole?
Because it has to move through total peripheral resistance to get to the veins.
What happens when you restart the heart (nerves still unhooked)?
a VERY strONG heartbeat
Why is the first heartbeat so strong?
Because 1. venous volume and hence return have increased dramatically - increasing preload; 2. Afterload is also mrkdly decreased due to decreased MAP.
Does heartrate increase when you restart the heart in this case?
No; there is no sympathetic input to do that. just starling contractility.
How does sympathetic input increase cardiac output?
By increasing contractility - increasing the stroke volume AT A GIVEN (unchanged) PRELOAD.
So does the frank starling mechanism really increase contractility?
No; it increases cardiac output by increasing preload and that is NOT the definition of contractility.
Main difference stopping/restarting the heart with nerves intact vs not?
Heartrate - sympathetics increase contractility, and MAP rises to higher levels due to venous constriction.
Psf is determined by 2 things:
1. Blood volume
2. Systemic compliance (RVR)
What happens when you hemorrhage 1 L and remove all reflexes?
Markedly decreases:
-CO
-MAP
-Psf
What happens if you hemorrhage 1 L but keep nerves intact?
SNS input increases, PNS input decreases, and MAP is maintained fairly well, though CO falls about 10%.
Why did CO fall but not MAP?
Because baroreceptors sense changes in PRESSURE not flow. They responded in order to increase TPR, and as a result CO decreased a little.
If not the baroreceptors, what does detect changes in bloodFLOW (cardiac output)?
Autoregulation - local changes determine what their resistance is and what it should be.
How is it that Psf is retained after a 1L hemorrhage with intact CNS nerves?
They cause veinous vasoconstriction and maintain Psf which maintains VR.
Can you recover from bleeding 1.5 L?
Yes
Can you recover from bleeding 2 L?
No
Why is 2L hemorrhage too much?
SNS activity overcompensates - the heartrate climbs very high, but since you've lost so much blood veinous return is low.
What is the result of lack of preload?
The heart becomes very ineffective; the blood it does pump out increases afterload.
What is the vicious cycle that occurs when 2 L hemorrhage happens?
Decreased VR + Increased Afterload
What are net effects of this on
-MAP
-Afterload
-Preload
-CO
-HR
Map = decreased
Afterload = increased
Preload = decreased
CO = decreased
HR = increased (SNS)
Does the end systolic volume increase much when you infuse a volume of blood into circulation? Why?
No; because the heart pumps out what returns to it - stroke volume just increases.
-Assuming contractility is normal.
What happens if you infuse volume and contractility is decreased?
The heart is incapable of pumping out the extra volume, and it accumulates in the left ventricle.
What does this look like on a pressure volume curve?
Completely shifted to the right.
How does increased blood volume in a decreased heart contractility situation affect:
-Stroke volume?
-End systolic volume?
SV = might increase, but not as much as in a normal situation.
ESV = increased
What type of shock would this situation be seen in, and how does it help you know how to treat these patients?
Cardiogenic shock - don't give them VOLUME b/c it won't help. Giving volume will just increase ESV.
Cardiogenic shock patients have Impaired ___ and are very sensitive to _____ and insensitive to _____?
-Impaired contractility
-Sensitive to afterload
-Insensitive to preload
What happens to the pressure volume curve of an individual that has had an MI? Why?
Severe shift to the right - due to dilation of the heart caused by accumulation of blood in the left ventricle (increased ESV).
Knowing that increasing volume is NOT the way to treat MI or cardiogenic shock victims, what is the way to go?
-Digitalis to increase contractility
-Diuretics to decrease volume.