Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
59 Cards in this Set
- Front
- Back
|
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. |
