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Physiology Exam 3
| Term | Definition |
|---|---|
| Active Hyperemia | the increase in blood flow occurring in response to an increase in metabolic activity |
| Reactive Hyperemia | Increase in blood flow in response to a previous reduction in blood flow |
| Myogenic response | Change in vascular resistance in response to stretch of blood vessels in the absence of external factors |
| Compliance | Measure of how the pressure of a vessel will change with a change in volume |
| Calmodulin | Cytosolic calcium-binding protein; modulates the activity of intra-cellular proteins |
| MLCK (Myosin light chain kinase) | enzyme involved in excitation-contraction coupling in smooth muscle; phosphorylates myosin crossbridges |
| 5 events that provide excitatory input to smooth muscle | *Spontaneous excitation via pacemaker regions *Neurotransmitters (Ach) on Muscarinic receptors *Hormones *Changes in local chemicals (O2, CO2, ions, acids) *Mechanical stretch (gut after eating) |
| Types of smooth muscle | Single unit- Connected via gap junctions, innervated by very few autonomic neurons, mostly found in GI tract, Uterus Multi unit - not connected to adjacent smooth muscle cells, innervated by more neurons, found in Respiratory airways, large arteries |
| Latch Bridge Mechanism | When contraction is initiated, myosin cross bridge moves and locks into position without energy requirement, significantly reducing the energy requirement in tissues that utilize smooth muscle |
| Major difference between Systemic vessels and Pulmonary vessels | Systemic - High pressure (120/80mmHg), very low influence of surrounding tissues on blood flow except "secondary" muscle pump Pulmonary - Low pressure (25/15mmHg), High alveolar pressures my actually collapse capillaries |
| Common vasodilators of blood vessels | *Nitric oxide (NO) powerful vasodilator *Bradykinin stimulates NO release *Histamine released during inflammation and allergic reactions stimulates bradykinin, stimulating NO release *Heat *Cold |
| Capillary characteristics | *One cell thick *slow blood velocity, allows for optimal nutrient, gas, and waste exchange *ONLY site for exchange of these materials |
| Characteristics of Venules and veins | *Not as elastic as arterioles *low resistance conduit back to heart *2/3 of blood volume is here at any given time act as resovoir *Have 1 way valves back to heart *Increased venous return to heart- increase in sympathetic drive,& skeletal muscle pump |
| MAP (Mean Arterial Pressure) | Average aortic pressure occurring during cardiac cycle |
Created by:
claritamaria
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