Blood pressure Flashcards
Mean arterial BP
MAP
Diastolic + (systolic-diastolic)/3
or
Cardiac output C0 x Peripheral resistance
what is Peripheral resistance (PR)?
Are factors that impede or oppose blood flow
eg.
Viscosity of blood (higher concentration of other components = higher PR)
Length - Longer blood vessels = higher PR
Diameter - vasoconstriction
What systems are involved in the regulation of BP
ANS
CNS
Endocrine
Renal
How is moment to moment (short term) BP controlled?
Automomic nervous system (ANS) using reflexes eg. Barroreceptors and chemoreceptor reflexes
What are to stimuli, receptor, pathways and control centre for short term BP regulation
Stimulus = BP rise or fall
Receptor = Barroreceptors stretch or contract
Afferent pathway
Control centre = Medulla cardiovascular control centre
Efferant pathway = increase Parasympathetic , Decrease sympathetic
Effectors = Arterioles contract or dilate
Peripheral resistance and cardiac output change
Long term regulation of BP is controlled by?
Renal and endocrine system
RAAS - Rennin - angiotensin - Aldrosterone system
+ antiduretic hormone
what stimulates the sympathetic nervous system to increase HR?
Neurotransmitter noradrenaline in the nerve endings.
There are 4 adrenoreceptors - 2 alpha and 2 Beta
What are the 4 adrenoreceptors and where and what are they?
Alpha 1 - Vasoconstriction of skin arterioles
Beta 1 - Present in myocardium cells and SAN (sinoatrial Node)
Alpha 2 -
Beta 2 - Vasodilation of the arterials in muscles
how does the parasympathetic nervous system to slow down HR?
Neurotransmitter acetylcholine
acts on the chloinergic receptors to act on the Vagus nerve slowing its signals.
(can react to emotions and fears)
What is bradycardia
over stimulation of the vagus nerve causing low BP, can lead to a vasovagal (fainting)
