3120%20Cardio%209%20Jan%202012%20for%20WebCT

heart rate and contractility 5 sympathetic outflow

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Unformatted text preview: ic dilation increase blood decrease blood CV regulation during emotional stress 4.  $ activity of the vagal nerve and # activity of the sympathetic postganglionic fibers (Nor) to the heart ! # heart rate and contractility 5.  # sympathetic outflow to the capacitance vessels ! constriction (! # EDV) 6.  # sympathetic outflow to the renal and splanchnic (intestine) resistance vessels ! constriction norepinerphrine doesn't play direct role on blood vessel constriction, epinephrine can cuase constriction and dilation increase blood decrease blood Phys 312 - Lecture Outline Baroreceptor Reflex (A) Response to high BP ! (B) Response to a fall in BP ! CV regulation during emotional stress ! CV regulation during exercise $ Fight or Flight situations CV regulation during exercise 4 Mechanisms: 1.  2.  3.  4.  Local Mechanical muscle pump --> pump blood around Nervous System Humoral CV regulation during exercise 1. Local: CO2, lactic acid, H+, K+, inc metabolite Resistance vessels dilate in the active muscles due to vasodilator metabolites (A very powerful mech) These products also “disconnect”/block the sympathetic vasoconstrictor effects on the muscle vessels. (recall SNS is trying to vasoconstrict these blood vessels) we don't want to constrict, we want to dilate metablite block vasocontrictor CV regulation during exercise 2.  Mechanical: During dynamic exercise the “Muscle pump” returns blood from the lower limbs to the central circulation. ! # venous return ! # EDV ! # SV ! # CO ! # MAP CV regulation during exercise 3.  Nervous System: # sympathetic outflow to the heart and systemic blood vessels $ vagal outflow to the heart decreases (not s...
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