Control of Blood Pressure Flashcards
which vessels are muscular and elastic?
arteries
describe arterioles
thinner than main arteries but muscular
which vessels are thinned walled, burst under high pressure because they can not change diameter?
capillary
what do veins and venules act as?
conduits and reservoirs
where is approx 70% of blood volume within circulation?
in venous circulation - they act as drainage and have large diameter vessels and can enter active circulation whenever
what are conduits?
channel for conveying water/ fluid
define heart rate
number of times the heart beats in a minute
what is a normal heart rate?
60-100 bpm
define stroke volume
volume of blood ejected from the heart in one beat
what is the stroke volume at rest usually?
70ml per beat
what is cardiac output?
the volume of blood ejected from the heart per minute
what is usual cardiac output?
5l of blood pumped in a minute
what is classed as bradycardic?
less than 60bpm
what bpm starts to show signs of bradycardia?
50 or less
what is tachycardia?
heart rate greater than 100 bpm
what is the calculation to get Cardiac output?
SV x Hr
define mean arterial blood pressure
average pressure exerted by the blood on the walls of major arteries
what is an average MABP at rest?
107mmHg
why is peripheral resistance hard to measure?
invasive procedure - aortic catherization
what three factors affect arterial blood pressure?
- circulatory volume (stroke vol)
- force of ventricular contraction
- elasticity of arteries
can stroke volume be altered?
yes - endurance exercises
what happens to arterial elasticity with age?
arterial stretch declines with age. Gradual thickening and changes in wall content - less elastin, advanced glycation, more inflammation, build up of ROS
what is the pressure of MABP as it reaches RA?
0 - end of journey
what three factors affect resistance?
- viscosity of blood
- length of vessels
- radius of vessels
for every pound you put on, how much more vessels are made?
5 miles
which vessels have the largest role to play within vascular resistance?
arterioles, capillaries and venules
when does the blood have the fastest velocity?
through aorta and arteries but it fluctuates with each beat
which nerve slows the heart rate down?
vagus nerve
how does the vagus nerve slow heart rate?
cardioinhibitory works via parasympathetic systems. The activity of the vagus nerve results in Ach being released
which cranial nerve is the vagus nerve?
X