Control of BP Flashcards
What does the systolic pressure represent
The force at which the heart pumps
What does the diastolic pressure represent
The resistance of blood vessels
Relaxing of the heart
What is the Normal BP range between
90/60 mm Hg and 120/80 mm Hg
What are the 2 receptors in the cardiovascular homeostasis system
Baro
Chemoreceptors
What is the control centre of the cardiovascular homeostasis system
Medulla oblongata
What is the cardiac output
The amount of blood pumped per ventricle per minute
What is the equation to find out the cardiac output
Heart rate x stroke volume = cardiac output
What are some positive chronotrophic factors which increase heart rate
Caffeine
Epinephrine
Thyroxin
Sympathetic stimuli
Exercise
What are some negative chronotrophic factors which decrease heart rate
Sedatives
Beta blockers
Parasympathetic stimuli
Ions
What does the parasympathetic system do to the heart rate
It decrease it primarily the vagus nerve
What does the sympathetic division of neural regulation do to the heart
Increases the heart rate and force of contraction
Cardiac muscle
Sinoatrial and atrioventricular nodes
Where are the 2 baroreceptors/peripheral chemoreceptors
Aortic arch
Carotid sinus
If there was a low blood pressure what would the baroreflex do
Increase cardiac output
Increase vasoconstriction
Increase blood pressure
Is quick
What stimulates a chemoreceptor reflex
A decrease in O2
An increase in CO2
A decrease in pH
What is the equation to find the stoke volume
End diastolic volume - end systolic volume = stroke volume
What is the preload
The amount ventricles are stretched by blood
What is the afterload
The force exerted on the ventricle wall during ejection
What is the contractility
The cardiac cell contractile force
What is the RAD system stand for and its key control
The renin angiotensin aldosterone system
Key for controlling blood volume
What are the stages of the blood volume control
Kidney - renin - liver - angiotensin I - lungs - angiotensin II - (vasoconstriction - increase BP) and adrenal glands - aldosterone - water re absorption - increase BP
List 3 things released from the pituitary in response to control of BP
Increased osmolarity of plasma
Reduced blood volume
Increase in angiotensin II levels
What are the 2 responses to BP control over longer time
ADH (antidiuretic hormone)
vasopressin
What happens during hypovolemic shock
Decrease of 20% blood volume
Dehydration
Body attempts to compensate by increasing the heart rate but lowering the preload then vasoconstriction, RAD system
What happens when lying down (supine position)
Blood evenly distributed in veins
Increased central venous pressure
Increased EDV (end of diastole)
Increased SV and pulse pressure
What happens during fainting (syncope)
Temporary reduction in blood flow to brain
A trigger vasovagal
Lower heart rate and BP
Lower BP when standing up can cause dehydration
What 2 factors will lower BP
Vasodilation
Reduced water retention
What do beta blockers do
The heart beats more slowly with less force
Blocks action of epinephrine
Used for angina, heart failure and high BP
What do diuretics do
Increase urine production (excretion of water)
Reduce oedema, blood volume and pressure
Inhibits sodium re absorption
Water follows sodium into the urine
