Arterioles: Extrinsic Control and Regulation

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What is the primary mechanism of extrinsic control over arterioles?

Sympathetic nervous system (SANS) influence

What is the effect of increased sympathetic activity on arteriolar vasomotor tone?

Vasoconstriction

What is the function of the venous system in relation to blood volume?

Blood reservoir

How does the sympathetic nervous system influence arteriolar smooth muscle in the systemic circulation?

Through SANS fibers that supply arteriolar smooth muscle everywhere except the brain Signup and view all the answers

What is the result of decreased sympathetic activity on arteriolar vasomotor tone?

Vasodilation Signup and view all the answers

What is the primary function of arterioles in the regulation of blood flow?

To act as control valves, adjusting the radius of vessels to supply individual organs. Signup and view all the answers

What is the effect of vasoconstriction on blood flow and resistance?

Vasoconstriction increases resistance and decreases blood flow through the vessel. Signup and view all the answers

How do metabolic mechanisms regulate blood flow in response to changes in oxygen levels?

Buildup of local metabolic by-products, such as CO2, K+, H+, and lactic acid, can lead to vasodilation, increasing blood flow in response to decreased oxygen levels. Signup and view all the answers

What is the role of the endothelial mechanisms in regulating blood flow?

Substances secreted by vascular endothelium, such as nitric oxide, prostaglandins, and EDHF, can cause vasodilation and increase blood flow. Signup and view all the answers

How do changes in blood pressure affect arteriole diameter and blood flow?

Increased pressure leads to vasoconstriction, while decreased pressure leads to vasodilation, allowing for myogenic mechanisms to regulate blood flow. Signup and view all the answers

What is the primary mechanism by which more oxygen is delivered to the muscles during increased activity?

Vasodilation of arterioles, allowing for increased blood flow and oxygen delivery to the muscles. Signup and view all the answers

What is the role of desmosomes in cardiac muscle cells?

Mechanically link myocytes, allowing for stretch Signup and view all the answers

What is the purpose of gap junctions in cardiac muscle cells?

Electrically link cardiac myocytes, allowing for ion passage Signup and view all the answers

What triggers the release of calcium ions from the sarcoplasmic reticulum in cardiac muscle cells?

Calcium-induced calcium release (CICR) Signup and view all the answers

What is the unique property of autorhythmic cells in cardiac muscle tissue?

Initiate action potentials spontaneously Signup and view all the answers

What is the functional difference between atrial and ventricular cardiac muscle cells?

Atria beats slightly ahead of ventricles Signup and view all the answers

What is the term for the heart's ability to generate action potentials and contract rhythmically without external stimulation?

Autorhythmicity Signup and view all the answers