Chapter 26 Basics Flashcards
Vascular Peripheral Circulation - Disorders
Adequate blood flow
efficiency of heart as a pump
patency and responsiveness of blood vessels
adequate circulating blood volume
Rate and adequacy of blood flow
nervous system activity, blood viscosity, metabolic needs of tissues
Arteries
Resistance vessels, regulate
Arteriovenous anastomosis
blood passes directly from arterial to venous system; believed to regulate heat exchange between body and external environment
Veins
Capacitance vessels, allows large volume of blood to remain in BVs under low pressure
Sympathetic nervous system
innervates vein musculature and can stimulate vasoconstriction (red. venous vol. and inc. circulation vol.)
Contraction of skeletal muscles in extremities
creates PRIMARY pumping action to facilitate venous flow back to heart
Veins that transport against force of gravity: equipped with one-way bicuspid valves (endothelial leaflets)
preventing retrograde flow/ backflow as it is propelled back to heart
Right lymphatic duct
empties into the right subclavian vein
right side of head, neck, thorax, upper arms
Thoracic duct
empties into subclavian and internal jugular veins
remainder of body
Tissue ischemia
deficient blood supply when BVs fail to dilate in response to demand
Chronically elevated arterial resistance
myocardium hypertrophies (enlarges) to sustain great contractile force
Bruit
turbulent laminar blood flow
(inc. flow rate, viscosity, BV diameter, or narrowed/ constricted BV)
Hydrostatic Pressure
BP, push out
Osmotic Pressure
plasma proteins, pull in
How the body maintains fluid volume, removing tissue waste and debris:
process of filtration, reabsorption, lymph formation
Edema (Causes)
excess interstitial fluid accumulation, poor reabsorption
Edema (Effects)
damage to capillary walls and subsequent increase in permeability, lymphatic drainage obstruction, venous pressure elevation, dec. in osmotic force
PVR determined by:
vessel radius (diameter) and length, blood viscosity
Increased HCT means:
Men: 40 - 54%
Women: 36 - 48%
inc. blood viscosity (indic. dehydration, risk for HBP)
PVR Regulating Mechanisms
CNS sympathetic (adrenergic) activity med. by hypothalamus
Vasoactive substances (e.g. NE)
independent arterial wall activity
Epinephrine (adrenal medulla)
acts like NE, constrict peripheral blood vessels in most tissue beds; in low conc. causes vasodilation in skeletal muscle, heart and brain
Why is Angiotensin important in HF and hypovolemia?
Angiotensin I (renin from kidneys + angiotensinogen as precursor) + ACE (secreted by pulmonary vasculature) = Angiotensin II, potent vasoconstrictor of the arterioles
Potent Vasodilators
nitric oxide, prostacyclin, histamine, bradykinin, prostaglandin, some muscle metabolites
