IPHY 3430 10-13-11

1. IPHY 3430 10-13-11

2. BLOOD PRESSUREFlow rate = P x radius of vessel4 length x   = viscosity (function of number of red blood cells and concentration of plasma proteins)

8. Blood pressure = cardiac output x peripheral resistanceCardiac output = heart rate x stroke volume Peripheral resistance = degree of vasoconstriction or vasodilation of arterioles

9. Cardiac outputHeart rate  by SNS  by PNSStroke volume venous return  by SNS strength of contraction  by SNS

10. Peripheral resistance by SNS output by  SNS output

11. Regulation of blood pressureSensors: 1. baroreceptors in aorta and carotid 2. chemoreceptors in aorta and carotid 3. medulla itselfIntegrator: medulla vasomotor centerOutput: PNS and SNS

14.  BP --> sensors --> medulla -->  PNS-->  heart rate  SNS-->  heart rate  venous return -->stroke volume  peripheral resistance   BP

15.  BP --> sensors --> medulla -->  PNS-->  heart rate SNS-->  heart rate  venous return --> stroke volume  peripheral resistance   BP

18. And…. BP --> kidney (sensor and integrator)--> renin--> renin converts angiotensinogen to angiotensin I--which is converted to--> angiotensin II by lung converting enzyme->angiotensin II causes:1.vasoconstriction --  peripheral resistance2. reduces GFR --> kidney reduces urine production-> blood volume  -->  venous return -->  stroke volume3. Stimulates thirst-->  blood volume -->  venous return --->  stroke volumeand ….. 

19. Angiotensin II also causes: aldosterone release from adrenal gland --->  Na+ uptake from urine -->  water uptake from urine -->  blood volume -->  venous return --> stroke volume -->  cardiac outputnet effect of  angiotensin II -->  BP

20. Circulatory Shock1. Hypovolemic2. Cardiogenic3. Vasogenic4. Neurogenic

22. Shock Non-progressive--can recover with massive SNS output and renin-angiotensin Progressive--positive feedback BP -->  flow -->  BP --> flow …  flow leads to  BP because of lack of adequate oxygen to medulla, which loses control of SNS

23. Hypertension peripheral resistance due to athlerosclerosis  aldosterone secretion  renin secretion neurogenic“essential hypertension”

24. Local control over blood flow

26. ExerciseInput from higher centers causes Medulla/SNS to change distribution of blood and change in BP regulation