Blood pressure Flashcards
what is blood pressure
blood pressure is the force exerted by the blood on the vessel walls
what is systolic blood pressure
systolic blood pressure is the force of the blood against artery walls when the heart pumps
what is systole
systole is when the heart muscle contracts, blood pressure increases
what is diastole
diastole is when the heart muscle relaxes, blood pressure decreases
what is diastolic blood pressure
diastolic blood pressure is the force of blood on artery walls when the heart is filling
What is mean arterial pressure
mean arterial pressure is the average pressure in a persons arteries during a single cardiac cycle
how can you calculate mean arterial pressure
MAP= systolic + (2x diastolic)/ 3
What are the three factors that affect blood pressure
Cardiac output, stroke volume and heart rate
What is cardiac output
Cardiac output is the amount of blood pumped per minute by each ventricle calculated by
CO= HR x stroke vol
What is stroke volume
Stroke volume is the volume of blood pumped by one ventricle with each heartbeat
What is heart rate
Heartrate is the number of heart beats per minute
What is peripheral resistance
Peripheral resistance is the total resistance to the flow of blood in the systemic circulation.
What is blood flow
Blood flow is the continuous movement of blood through the circulatory system, it can be affected by the thickness of blood and total vessel length
What factors cause vasoconstriction
Hormones, stress & anxiety, caffeine, salt, drugs, cholesterol
What factors cause vasodilation
Alcohol, exercise, temperature, inflammation
How does blood volume effect blood pressure
The more fluid a closed system holds, the greater the pressure
What are baroreceptors
Baroreceptors are receptors that detect changes in BP
What is the difference between the parasympathetic and sympathetic nervous systems
The parasympathetic is the rest and digest and the sympathetic is fight tor flight
How is blood pressure lowered
Either: Sympathetic input is lowered & parasympathetic input is raised which leads to an decrease in heart rate and stroke volume which lowers cardiac output and stroke volume
Or: Vasodilation decreases peripheral resistance which decreases BP
How is blood pressure raised
Either: There is an increase in sympathetic nerve activity which increases heart rate and stroke volume which increases cardiac output
Or: there is an increase in sympathetic input which leads to vasoconstriction and an increase in peripheral resistance
What is the baroreceptor reflex
The baroreceptor reflex is a homeostatic mechanism to maintain blood pressure
What is postural hypertension
Postural hypertension is where the baroreceptors are hindered due to prolonged high BP which leaves people dizzy when they stand
What are the cardiovascular changes in pregnancy
Cardiac output increases
Blood volume increases by 30-50%
BP decreases in 1st and 2nd trimester due to progesterone decreasing peripheral resistance
HR increases by 15 bpm
What is supine hypertensive syndrome
In the 2nd half of pregnancy due to the compression of the aorta and inferior vena cava cardiac output is decreased.
