Physiology 4 and 5- Control of BP Flashcards
What is blood pressure?
The pressure exerted on the blood vessel walls by the blood
What is the systemic systolic blood pressure?
The pressure exerted on the walls of the aorta and systemic arteries when the heart contracts
What is the systemic diastolic blood pressure?
The pressure exerted on the walls of the aorta and systemic arteries when the heart relaxes
When will sound be heard when listening to the brachial artery?
When there is turbulent blood flow
When is the first Korotkoff sound heard?
Peak systolic pressure
When is the second Korotkoff sound heard?
Minimum diastolic pressure
What is mean arterial blood pressure?
The average arterial blood pressure during a full cardiac cycle including contraction and relaxation of the heart
How can MAP be worked out?
[(2 x diastolic pressure) + systolic pressure] / 3
OR
DBP + 1/3rd pulse pressure
What is pulse pressure?
Difference between systolic and diastolic pressure
What is the normal range and normal value of MABP?
Range- 70-105mmHg
Value- 90mmHg
A MAP of at least 60mmHg is needed for what?
To adequately perfuse essential organs e.g. coronary arteries, kidneys and brain
What can happen if MAP is too high?
Place extra strain on the heart and damage the blood vessels
What is the TPR?
The sum resistance of all peripheral vasculature in the systemic circulation
What are the major resistance vessels?
Arterioles
What does parasympathetic stimulation to control the BP act on and what does it do?
Acts on the heart to reduce HR, CO and hence MABP
What does sympathetic stimulation to control the BP act on?
Heart, veins and arterioles
How does sympathetic stimulation to the heart increase the BP?
Increases HR, CO and MAP
Increases FoC, SV, CO and MAP
How does sympathetic stimulation acting on the arterioles increase the BP?
Vasoconstriction, increased TPR and BP
How does sympathetic stimulation acting on the veins increase the BP?
Vasoconstriction, increased VR, SV, CO and MAP
Any change in BP will be sensed by the ? (pressure sensors) which will then inform the ? (control centre)
Baroreceptors
Medulla
What are the effectors involved in the baroreceptor reflex and what do they mediate?
Heart- HR and SV
Blood vessels- TPR
What type of feedback mechanism is the baroreceptor reflex?
Negative
Where are the baroreceptors?
Aortic arch and carotid sinus
The baroreceptors in the aortic arch send signal to the medulla via what cranial nerve?
X- vagus
The baroreceptors in the carotid sinus send signal to the medulla via what cranial nerve?
IX- glossopharyngeal
What happens to the rate of carotid sinus afferent nerve firing if BP increases or decreases?
BP increases- increases
BP decreases- decreases