click below
click below
Normal Size Small Size show me how
Phys2 Special Circ
| Question | Answer |
|---|---|
| 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). |