Cardiovascular system V - Blood pressure & CVS disease continuum Flashcards
Blood pressure
Pressure exerted on the walls blood vessel (largely referred to Arterial pressure)
Pressure is essential to perfuse all the cells of the entire body (constant & consistent)
What is blood pressure measured in?
mmHg
What causes variation in blood pressure>
- Age
- Pathological conditions
Systolic and Diastolic BP
Systolic BP: MAP during heart contraction
Diastolic BP: MAP during heart relaxation
Systemic: 120/80 mmHg, Pulmonary: 25/8 mmHg, Venous: 6-8 mmHg
Normally BP is measured as the trend rather a single read
Equation for blood pressure
BP= Cardiac output x Peripheral Resistance
Cardiac output equation:
Cardiac output = Heart Rate x Stroke volume
= 70/min x 70 ml
= 4900 ml/min = 5L/min
Cardiac output equation:
Cardiac output = Heart Rate x Stroke volume
= 70/min x 70 ml
= 4900 ml/min = 5L/min
Blood viscosity can affect:
Recollect: Blood Lecture
Polycythaemia: Too much RBC
Regulation of Blood pressure control
1) Auto-regulation
2) Neural
3) Hormonal
Auto-regulation
Changes in blood flow detected by the local receptors during micro perfusion (recollect micro/capillary perfusion from lec. 2)
Neural
Short-term regulation of blood pressure, especially in responses to transient changes in arterial pressure, via baroreflex mechanisms
Hormonal - Long-term regulation of blood pressure
Renin-Angiotensin-Aldosterone
Anti-diuretic hormone (ADH; arginine vasopressin)
Atrial natriuretic hormone/peptide/factor
Erythropoietin
Adrenaline/Noradrenaline
Three types of regulation
Hypertension/ Normotension/ Hypotension
Brain Stem
Medulla & Pons
Cardiovascular control (sympathetic & vagal)
Vasomotor control (sympathetic)
Factors influence neural regulation of BP
Higher centre: High & Low
Low O2
Low CO2
Two types of nerves:
Vagus nerves
Glossopharyngeal nerves
What type of pressure sensors are located in aortic arch and carotid sinus?
Baroreceptors
What are the Baroreceptor pressure sensor role?
They are connected by nerve innovations to vasamotor centre
What is the role of the vasomotor centre?
Regulate sympathetic and vagus activation and the heart and other tissues
Glossopharyngeal nerves role
Connect carotid sinus to cardiovascular centre - regulate blood pressure short-term
What can cause rise in blood pressure?
Rise in stress levels
Heart > HIGH blood pressure > ventricle is pumping high amount of blood to aortic arch > what does aortic arch do?
Start firing Baroreceptors to the cardiovascular centre in brain stem
What is a high blood pressure?
120 - 180 mmHg
Increase in vagal activity will _______ heart rate (vagal innovation)
Suppress
What suppresses the sympathetic cardiac activity?
adrenaline and nonadrenaline will raise heart rate - AS VAGAL nerve suppresses heart rate these two will work and compliment each other so that contraction reduction and decrease heart rate.
Heart contraction and heart rate low; Heart output=
LOW - achieve normal homeostasis - low blood pressure
Suppression for sympathetic activity in the cardiac cells whereas there is a stimulus for the sympathetic activity which comes from…..
the vasomotor centre and the vaso-activation which causes vaso-DILATION .
Sympathetic activation at the vascular SMOOTH MUSCLE causes ______
Relaxation
the vessel of the smooth muscle tend to dilate which means….
The vessels expand (blood vessel becomes larger) more allowing more blood flow through
= blood pressure will DROP
Name for blood vessels dilating?
Vasodilitation
In LOW pressure in arteries> Barareceptors firing rates decrease > and cardiovascular centre in brain stem responds….
Increase in adrenaline - will increase the heart contraction and heart rate