Control of circulation Flashcards
Are valves uni or multi directional?
Unidirectional
What vessel has highest resistance?
Arterioles
Total arteriolar resistance=total peripheral resistance
What muscles do arteries contain?
Elastic, smooth muscle
What increases TPR?
Vasoconstriction- increased flow
What determines flow in capillaries? Function of flow?
Arteriolar resistance
Pre-capillay sphincter
Large area, slow flow- allow nutrient exchange
Veins have what muscle?
Skeletal muscle- contraction muscle squeeze back heart
How does respiratory pump lead to venous return?
Respiratory pump
Inhalation
Push down diaphragm
Increase abdominal pressure
Decrease thoracic pressure
Pressure difference enables venous return
What is sympathetic effect on veins?
Vasoconstriction
What is function of lymphatic system?
Excess fluid/proteins filtered from capillaries
Return fluid to CV system through thoracic duct- sc vain
Explain frank-starling mechanism?
Increased volume in diastole
LV systolic volume increases as ventricles stretched
Increased EDV= Increased stretch= Increased force of contraction
Increased venous return= increased EDV= increased SV= increased CO
CO= HR x SV
What does increased EDV lead to?
Increased EDV=Increased stretch=Increase force contraction
What does increased venous return lead to?
Increased venous return=Increased EDV=Increase SV=Increased CO
What occurs to ventricles as LV systolic volume increases?
Stretched due to increased volume in diastole
What happens to stroke volume as EDV increases?
Stroke volume increases as EDV increases
Name 3 circulating hormonal vasoconstrictors?
Epinephrine
Angiotensin 2
Vasopressin
Epinephrine acts alpha receptors- vasoconstriction
beta receptors- vasodilation
