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51 Cards in this Set
- Front
- Back
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What is the Law of Bulk Flow equation?
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Q=DeltaP/R
Q is the flow of blood DeltaP is the pressure drop R is the resistance |
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What is Poiseuille's equation?
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Q=DeltaP*pi*r^4/8Ln
8Ln/pi*r^4 is Resistance Bulk flow is Q=DeltaP/R so Poiseuille is the two equations put together. |
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What is vasocontriction?
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Causes a higher Resistance and a lower bulk flow by
DeltaP*pi*r^4 |
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What is vasodilation?
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Lower Resistance & Higher Q by 8Ln
n is viscosity of the fluid |
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Is ARTERIAL pressure lower or higher than the expected amount in the brain?
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LOWER because in some animals like giraffes, the animals head is much higher than its heart (which is about halfway up its 15-18 foot body), and the flow goes up AGAINST gravity.
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What is the equation for blood velocity?
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Q/A
Q is volume of fluid transferred per unit time A is cross section area of the channels |
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What is the relationship between velocity of flow and the cross section?
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They are inversely proportional. EXAMPLE: the total cross sectional area of the capillaries is very large, so the velocity is slow and there is a long time for diffusion.
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What is transmural pressure?
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A pressure exerts a force across vessel walls. SOO its the difference between internal and external pressure.
r is he vessel radius, if you hav a higher/larger radius the tension is increased. |
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What is the Law of LaPlace?
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T=aPr
T is the tension in the vessel walls a is the constant P is transmural pressure |
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What if the vessel wall is thick, is there a separate equation?
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Thick Wall
o=Pr/w w is the wall thickness o is stress |
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What are the two phases dealing with the pumping action of the heart?
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Systole & Diastole
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What is systole?
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Contraction where blood is pumped OUT into the circulation
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What is diastole?
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Relaxation where blood ENTERS the heart
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What occurs in an anthropod heart?
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Heart pumps HEMOLYMPH out via arteries
Blood returns via ostia (holes) during diastole (relaxation) Valves within the ostia open and close to regulate blood flow Heart is suspended with a series of ligaments |
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What does it mean when the heart is neurogenic?
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Contraction occurs in response to signals from the nervous system
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What are the 4 main parts of a vertebrate heart?
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Pericardium
Epicardium Myocardium Endocardium |
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What is the pericardium?
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Sac of connective tissue that surrounds the heart. It has an outer (parietal) and inner (visceral) layers
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What is the epicardium?
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Outer layer of the heart in continuation with the visceral pericardium. This part of the heart contains nerves that regulate heart and coronary arteries.
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What is the myocardium?
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Layer of heart muscle cells aka cardiomyocytes
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What is the endocardium?
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Innermost layer of connective tissue covered by epithelial cells
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How are the 4 main parts of the vertebrate heart arranged?
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pericardium-> epicardium -> myocardium->endocardium
*endocaridum is the OUTER most layer |
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When asked about atrial systole and ventricular diastole?
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REMEMBER that systole is contraction and it pushes blood out to the ventricles & DIASTOLE is relaxation and bloods comes back and enters the atria.
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Is pressure higher or lower in the ventricles?
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HIGHER especially in the left
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What is the difference between myogenic and neurogenic?
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Vertebrate hearts are myogenic where muscle cells in the heart produce spontaneous rythyms and THEY DO NOT REQUIRE A NERVE SIGNAL! & Anthropods are neurogenic where there is a contraction because of a signal from the nervous system.
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How does a pacemaker control contraction?
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Contraction of the heart is initiated by chemical impulses. The rate at which these impulses fire controls the heart rate.
The cells that create these rhythmical impulses are called pacemaker cells, and they directly control the heart rate |
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Where is the pacemaker located in fish?
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In the sinus venosus
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Where is the pacemaker located in other vertebrates?
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In the right atrium aka Sinoatrial node (SA)
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What makes pacemaker cells different?
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They are derived from cardiomyocytes (muscle cells in the heart) but they DO NOT CONTRACT.
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Instead of contracting what do pacemaker cells do?
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Contain unstable resting potential that drifts upwards until it reaches threshold and initiates an action potential.
Pacemakers resting potential is called pacemaker potential, and its action potential is called funny potential. |
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What does the funny potential/action potential do?
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Lets in Na+ and Ca2+
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How is heart rate increased?
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BASICALLY SNS (sympathetic neuron system) increases HEART RATE
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How is heart rate decreased?
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BASICALLY PNS decreases HEART RATE
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How do action potentials in cardiomyoctes differ from those in skeletel muscle?
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Plateau phase, where there is an extended depolarization period
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What is the equation for Cardiac Output?
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CO=HR*SV
This demonstrates the rate of contraction (beats per min) SV is stoke volume-- vol of blood pumped with each beat. |
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Can cardiac output be modified?
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YES! by regulating heart rate and/or stroke volume
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How is heart rate controlled?
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Modulated by autonomic nerves and adrenal medulla
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What is decreased HR?
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Bradycardia
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What is increased HR?
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Tachycardia
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What can control the stroke volume?
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Modulated by various nervous, hormonal, and physical factors.
* the nervous and endocrine systems can cause the heart to CONTRACT MORE forcefully and pump more blood with each beat. |
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How does the nervous and endocrine system cause the heart to contract more forcefully?
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Norepinepherine and epinepherine cause more Ca2+ to be released to create a stronger contraction and faster uptake.
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What is the Frank- Starline Law of the Heart?
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More blood there is entering the heart via diastole, the more forceful contraction there is and an increase in SV.
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What is autoregulation?
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When the heart automatically compensates for the increase in blood volume returning to the heart.
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What causes vasoconstriction?
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Norepinephrine from SNS, so decrease SNS tone causes vasodilation.
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What two hormones affect vasocontriction?
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Vasopressin (ADH) and Angiotensin II
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What hormone affects vasodilation?
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Atrial Natriuretic peptide (ANP)
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Which hormone is produced in response to decreased blood pressure causing vasoconstriction?
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Angtiotension II
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Which hormone is produced in response to increased blood pressure causing vasodilation?
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ANP
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What is the primary driving force for blood flow throgh organs??
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PRESSURE!
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How is blood pressure regulated?
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Blood pressure=CO*TPR
TPR is total peripheral resistance so Co and TPR vary in every body to maintain a healthy blood pressure. |
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IMPT:
What is the reflex that maintains blood pressure? |
BARORECEPTOR REFLEX
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What do baroreceptors do?
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In the carotid arteries and aorta there are stretch-sensitive receptors, the baroreceptors send nerve signals to medulla oblongata (control center) that end up regulating how blood pressure effects different regions.
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