L9 Control of BP Flashcards
Does symp or para act on smooth and how
symp= constricts vascular smooth muscle
- vasa con= inc peripheral resistance
- venous con= inc venous return
what do most symp fibres in control of blood vessels release
release noradrenaline that acts on α-receptors
what two mechanisms prevent fall in CO (maintain MAP)
- inc venotone > inc ven return > inc SV > inc CO > maintains press (int)
- symp stim > inc cardiac contract > inc co (ext)
What are the two types of regulation for cardiac contraction
intrinsic = venous return
extrinsic = via inotrpoic agents
diff b/w chrono _ inotropic
chrono= HR ino= contract
4 methods of blood pressure control
HR chrono = CO
SV ino= CO
vent tone= SV= CO
vast tone= TPR = MAP
3 Reflexes BP is regulated by
- baro (cardiac + vasc)
- ADH
- Central ischia response
how does baro regulate bp
measures changes in MAP
in
mechanism for baro recep symp stim
fall pressure= baro detect = symp stimulation
CARDIAC (carotid) > chrono (HR) + ino (contract) = inc CO = inc MAP
VASC (peripher)=
> inc veno tone = inc VR = CO = inc MAP
>inc vaso = inc TPR = inc MAP
How does dec vol=dec press
o Blood volume decreases venous return > (frank stirling) > decrease SV + CO > decrease MAP
How does standing up increase venous pressure
o Veins expand > blood that flows in isn’t flowing out > VR falls > CO falls > new steady state
o Venous pressure 100mm Hg > capillary pressure inc > (starling law) > loses plasma to extracellular > reduces VR > MAP fall > baro recep increase symp activity
explain 2nd AHD reflex on MAP control
needs sig drop in BP
- = inc ADH =
1. vasoconstriction = inc TPR= inc BP
- dec water loss = inc blood vol = inc BP
explain 3ndcentral ischemic reflex on MAP control
blood supply to the brain produces the central ischemic response (CIR).
• Blood pressures bellow 60 mmHg will initiate CIR.
• CIR mimics the baroreceptor reflex
how is long term bp regulated
fluid control
- behavioural + urinary
