regulation of organ blood flow- ppt-2
TRANSCRIPT
![Page 1: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/1.jpg)
Regulation of Organ Blood Flow
Mark T Ziolo, PhD, FAHAAssociate Professor, Physiology & Cell Biology019 Hamilton [email protected]
![Page 2: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/2.jpg)
Objectives
• Describe the regulation of organ blood flow by myogenic regulation and autoregulation (intrinsic tone, neuronal influence, local or metabolic influence, hormonal influence)
• Describe active and reactive hyperemia
![Page 3: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/3.jpg)
Detailed Objectives
Understand the myogenic regulation and the autoregulation of blood flow
Know the mechanism of myogenic regulation Know how the different factors (intrinsic tone, neuronal
influence, local (metabolic) influence, and hormonal influence) responsible for autoregulation regulate blood flow
Understand the role of active and reactive hyperemia Understand how control of flow is different between
organs with strong local (metabolic) control of arterial tone and organs with strong neuronal control of arterial tone
![Page 4: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/4.jpg)
References
• Mohrman DE, Heller LJ. Cardiovascular Physiology Seventh Edition. Lange Medical Books/McGraw-Hill Publishers, 2010.
• Berne RM, Levy MN. Cardiovascular Physiology Sixth Edition. Mosby-Year Book, Inc., 2010.
• MediaPhys 3.0. An Introduction to Human Physiology. The McGraw-Hill Publishers, 2010.
![Page 5: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/5.jpg)
Myogenic Regulation
![Page 6: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/6.jpg)
Vital Organ
Myogenic Regulation
![Page 7: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/7.jpg)
Vital OrganPressure
Myogenic Regulation
![Page 8: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/8.jpg)
Vital OrganPressure
Myogenic Regulation
![Page 9: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/9.jpg)
Myogenic Regulation
![Page 10: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/10.jpg)
Autoregulation
![Page 11: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/11.jpg)
Myogenic Regulation
Smooth muscle contracts in response to an increase in transmural pressure
Smooth muscle relaxes in response to a decrease in transmural pressure
![Page 12: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/12.jpg)
Muscle
Autoregulation- with ↑ metabolic demand
![Page 13: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/13.jpg)
Muscle Working
Autoregulation- with ↑ metabolic demand
![Page 14: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/14.jpg)
Muscle Working
Autoregulation- with ↑ metabolic demand
![Page 15: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/15.jpg)
Autoregulation
Factors Responsible: Intrinsic tone Neuronal Influences Local Influences Hormonal Influences
![Page 16: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/16.jpg)
Intrinsic Tone
Arterioles remain partially constricted even when all external influences are removed
This baseline is what external influences adjust
![Page 17: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/17.jpg)
Neuronal Influences
Fibers innervate arterioles in ALL systemic organs
These fibers release NE proportionally to their electrical activity Acts via a-adrenergic receptors
Increases vascular tone Via decrease membrane potential & increase in AP
frequency Parasympathetic may act on the external
genitalia for vasodilation
![Page 18: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/18.jpg)
Local (metabolic) Influences
Smooth muscle is exposed to the chemical composition of the interstitial fluid of the organ
These substances reflect the balance of the organ’s metabolic activity and blood supply to that organ O2*, CO2, H+, K+, lactic acid, phosphate adenosine
* Pulmonary circulation
![Page 19: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/19.jpg)
TissueCells
Blood Flow
Release proportional totissue metabolism
Vasodilator factorsRemoval rate proportional
to blood flow
Local (metabolic) Influences
![Page 20: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/20.jpg)
Other Local Influences
Influences from Endothelial cells Nitric oxide, endothelin
Other influences Prostaglandins (COX pathway)
Some vasodilate, others vasoconstrict Histamine
Vasodilation and increases permeability (swelling) Bradykinin
Vasodilation via nitric oxide
![Page 21: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/21.jpg)
Hyperemia
![Page 22: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/22.jpg)
• Increased blood flow caused by enhanced tissue activity• Metabolic (local) influence
Active Hyperemia
![Page 23: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/23.jpg)
• Increased blood flow after removal of occlusion• Metabolic (local) influence AND myogenic regulation
• Reduced intravascular pressure• Decreased stretch
Reactive Hyperemia
![Page 24: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/24.jpg)
Reactive Hyperemia
![Page 25: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/25.jpg)
Metabolic vs Neuronal Control
![Page 26: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/26.jpg)
Hormonal Influences
Under normal circumstances play a minor role in regulating blood flow
Following hormones are vasoconstrictors NE and E (hemorrhagic shock) ADH (hemorrhage) Angiotensin II (hypertension?)
![Page 27: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/27.jpg)
Summary
Myogenic regulation maintains a constant organ blood flow (at constant levels of tissue metabolism) with changes in perfusion pressure.
Changes in transmural pressure will change smooth muscle contraction Autoregulation is maintaining constant organ blood flow which occurs via
myogenic regulation Intrinsic tone is the remaining constriction of the arterioles when all
external influences are removed. This is what the other influences adjust Neuronal tone is activation of the sympathetic fibers increasing vascular
tone (i.e., vasoconstriction) Local influence is the degree of smooth muscle contraction dependent
upon the chemical composition of the interstitial fluid of the organ Hormonal influence plays a minor role in regulating blood flow except
under various physiological (e.g., exercise) and/or pathological stresses
![Page 28: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/28.jpg)
Summary, cont
Active hyperemia is increased blood flow caused by enhanced tissue activity due to local (metabolic) influence
Reactive hyperemia is increased blood flow after removal of occlusion due to local (metabolic) influence and myogenic regulation
Blood flow to some organs such as heart and skeletal muscle has a higher responsiveness to metabolic than neuronal control. Blood flow to other organs such as GI tract, spleen, pancreas, and liver has a higher responsiveness to neuronal than metabolic control
![Page 29: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/29.jpg)
![Page 30: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/30.jpg)
![Page 32: Regulation of Organ Blood Flow- PPT-2](https://reader036.vdocuments.site/reader036/viewer/2022062519/55cf97f3550346d03394a3d4/html5/thumbnails/32.jpg)
Survey
We would appreciate your feedback on this module. Click on the button below to complete a brief survey. Your responses and comments will be shared with the module’s author, the LSI EdTech team, and LSI curriculum leaders. We will use your feedback to improve future versions of the module.
The survey is both optional and anonymous and should take less than 5 minutes to complete.
Survey