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Phys2 Special Circ

QuestionAnswer
What are the 3 mechanisms involved in organ BF regulation to maintain a consistant perfusion pressure:vascular resistance relationship? 1.Metabolic control. 2.Myogenic control (strech induced relaxation and vicaversa). 3.NO
Can the heart cells increase their O2 extraction during exercise? NO. there is always MAX extraction (almost 100%) at rest and at exercise.
How does the Heart increase O2 to meet demands during increased exercise/activity/HR? INCREASES BF (this is the ONLY way). It can increase it 4-5X during exercise (from 250ml/min to 1200ml/min).
Why is Atherosclerosis such a problem in the coronary arteries? Since the ONLY way to increase O2 to heart is via BF, the arteries must be able to dilation and accomadate. **Compliance is lost with atherosclerosis so the heart cells may not get the needed O2 due to decreased BF.
What layer of heart muscle has the poorest autoregulation? Subendocardium. It is subjected to the highest pressure during systole, causing more compression of the capillaries)
What allows the Diastolic pressure run off seen in MAP (100 down to 80mmHg)? The elastic energy stored during peak systolic pressure.
Which Main Coronary artery has a higher BF? LEFT!! nearly 3X the BF due to the amount of heart tissue it supplies (LV>>>RV)
When is BF in the Left main coronary artery at a minimum (almost 0)? During Isovolumetric contraction. **Raises to an intermediate BF during ejection phase 3.
When is BF in the Left main coronary artery at a maximum? During Isovolumetric relaxation it doubles from what it was during isovolumetric contraction.
Does the perfusion rate in the Right main coronary artery decrease during isovolumetric contraction? Yes, but not as much as the Left due to a much lower pressure system during systole (25/10mmHg).
How does HTN affect cerebral BF? it causes a rightward shift on a MAP vs BF graph. **the curve shape stays the same b/c the vasculature just autoregulates at a different rate.
Can the heart cells increase their O2 extraction during exercise?
INCREASES BF (this is the ONLY way). It can increase it 4-5X during exercise (from 250ml/min to 1200ml/min).
Why is Atherosclerosis such a problem in the coronary arteries?
What allows the Diastolic pressure run off seen in MAP (100 down to 80mmHg)? The elastic energy stored during peak systolic pressure.
Which Main Coronary artery has a higher BF? LEFT!! nearly 3X the BF due to the amount of heart tissue it supplies (LV>>>RV)
During Isovolumetric contraction. **Raises to an intermediate BF during ejection phase 3.
Does the perfusion rate in the Right main coronary artery decrease during isovolumetric contraction? Yes, but not as much as the Left due to a much lower pressure system during systole (25/10mmHg).
What is 1st degree autoregulation in the brain? Myogenic arteries and arterioles that inc relaxation with inc stretch.
What is 2nd degree autoregulation in the brain? The brain maintains a uniform input/output of metabolic products. **Uses the same amount of O2 when sleeping as when exercising or taking an exam.
Is the Brain's BF sensitive to neurotransmitters? NO!!!!
What is one way cerebral BF could become impaired? Edema. Capillaries are extremely sensitive to external pressure.
How does Hypoxia effect Pulmonary BF? it would cause vasoconstriction/dec BF to that area. **Shunting BL away from poorly ventilated areas allows for the max amt of O2 to diffuse and enter the BL.
What is a major determinant of TPR (total peripheral resistance)? Degree of vasoconstriction in skeletal muscle vasculature (due to total muscle mass and symp tone).
What skeletal muscle vasculature sympathetic receptors are activated at REST? Alpha1 (vasoconstriction)
What skeletal muscle vasculature sympathetic receptors are activated during EXERCISE? Beta2 (vasodilation)
What is the primary regulator of skeletal muscle BF during exercise? Local metabolic control
What is Hyperemia? What is the difference b/w Active and Reactive? it is the BF spike that occurs immediately after a constricted arteriole relaxes(almost 2X Inc). Active: hyperemia occurs due to lactate, adenosine, dec O2, Inc CO2 & H+, K+. REactive: hyperemia occurs due to contraction of muscle.
What is the body's primary temperature control? Cutaneous circulation.
What happens to cutaneous circulation during exercise or hyperthermia? with hypothermia? Increased body temp: Symp tone decreases, causes vasodilation of arterioles and inc BF (Erythema) to release heat. Decreased body temp: Increased symp tone causing vasoconstriction and dec BF (maintaining body temp) **Negative feedback.
What is the difference b/w Active and Passive heat loss? Passive: Vasodilation of cutaneous circulation. Active: Sweat
How does trauma effect cutaneous circulation? causes the release of histamine and VASODILATION: 1.Line (initial red line). 2.Flare (flare out from line). 3.Wheal (Edema).
Created by: WeeG