Control Of Blood Pressure Short Term & Long Term Flashcards
Where are the baroreceptors found that control blood pressure short term ?
The carotid sinus and the aortic arch
What do baroreceptors react to ?
Stretch
What sets the ‘normal’ blood pressure for an individual ?
The number of action potentials per minute
The sympathetic system does what to blood pressure ?
Increases blood pressure
The parasympathetic nervous system does what to blood pressure?
Lowers blood pressure
What is driving blood through the systemic circulation?
Mean Arterial Pressure
Where are the cardiovascular centres in the brain found ?
The medulla
Via what nerve does the aortic arch communicate to the brain ?
The vagus nerve
Via what nerve does the carotid sinus communicate with the brain ?
Glossopharyngeal nerve
What effect does the sympathetic nervous system have on the strength of contractions ?
It will increase contractions via Beta 1 receptors.
Where are higher centres found & what is their purpose ?
They are found in the hypothalamus & they are a feed forward system that preempts actions
What is the Valsalva Manoeuvre ?
Forced expiration against a closed glottis
Explain what is occurring within the body during stage I of the valsalva manoeuvre
The pressure in the thoracic cavity increases & this pressure is transmitted across the aorta
Explain what is occurring within the body during stage II of the Valsalva manoeuvre
This increase in thoracic pressure causes the following to drop: Cardiac output Venous return Mean arterial pressure Stroke volume End diastolic volume
Explain what occurs within the body during stage III of the Valsalva manoeuvre
The baroreceptors in the aorta pick up the drop in MAP & increases cardiac output & total peripheral resistance
Explain what occurs within the body during stage IV of the Valsalva manoeuvre
The thoracic pressure decreases & this is transmitted through the aorta
Explain what occurs within the body during stage V of the Valsalva manoeuvre
Venous return is returned to normal therefore stroke volume increase but the reflex of increased CO & TPR has not worn off & then normality returns
What effect does standing have on blood pressure ?
Mean arterial pressure will drop when you stand due to the increase in hydro-static pressure which causes pooling of the blood in the lower extremities. The number of action potentials firing through the aortic baroreceptors decreases
What controls long term blood pressure ?
Long term blood pressure is not controlled by baroreceptors, its controlled by plasma volume & the kidneys & a hormone system
Na transport depends on what within the kidney/collecting tube ?
The osmotic gradient present on the outside of the collecting duct
If total plasma volume decreases what will happen to the blood pressure ?
Blood pressure will decrease
What is the RAAS system ?
Renin-Angiotensin-Aldosterone-System
What cells within the kidney release renin ?
Juxtaglomelular Cells
What is the name of the cells that sense Sodium concentration within the kidney ?
Maculadensa Cells
What are the three things that trigger the juxtaglomelular cells to release Renin ?
1: Sympathetic nerve cell input (fight or flight)
2: Low NaCl as noticed by the maculadensa cells
3: When blood pressure is low, detcted by afferent arteriole (lack of distension)
How do the maculadensa cells communicate with the juxtaglomelular cells ?
Prostaglandins
Where is Angiotensinogen made ?
The liver
What makes breaks Angiotensinogen into Angiotensin I ?
Renin
How is Angiotensin I converted to Angiotensin II ?
Angiotensin I travels through the blood vessels and the endothelial cells convert Angiotensin I to Angiotensin II
What are the four types of cell that Angiotensin II act on to increase blood pressure/regulate blood pressure ?
1: The adrenal Gland
2: The smooth muscle in blood vessels
3: The kidney cells
4: The pituitary Gland
What happens in the adrenal gland when acted upon by Angiotensin II ?
The adrenal gland releases Aldosterone.
Aldosterone acts upon the kidney cells, telling them to hold onto water/plasma volume which increases stroke volume.
An increase in SV increases BP.
What happens in the smooth muscle when acted upon by Angiotensin II ?
Angiotensin II makes the smooth muscle constrict which increases total peripheral resistance which increases blood pressure.
What happens to kidney cells when acted upon by Angiotensin II ?
The kidney cells hold onto their volume/water volume, which increases stroke volume which will increase blood pressure
What happens in the pituitary gland when acted upon by Angiotensin II ?
The pituitary gland releases ADH.
Anti-Diuretic Hormone acts on the smooth muscle within the blood vessels causing constriction & also acts on the kidney cells causing them to hold onto their volume.
Therefore increase in TPR & SV increases BP.
Where is atrial natriuretic peptide produced and released ?
ANP is produced and released by the myocardial cells within the atria
What does ANP do to the blood pressure and how does it do this ?
ANP reduces blood pressure by increasing diuresis & increasing the secretion of Na. Therefore decreasing blood volume & decreasing blood pressure.
What triggers the release of ANP ?
An increase in blood volume through the atria, increased distension.
Where is BNP released ?
The ventricles of the heart
What would a blood pressure be for an individual with stage 1 hypertension ?
140/90
What would a blood pressure be for an individual with stage 2 hypertension ?
160/100
What would be the first line anti-hypertensive drug prescribed to a young person ?
ACE Inhibitor
What would be the first line anti-hypertensive drug prescribed to an elderly person ?
Calcium Channel Blocker or Thiazide type diuretic
Explain the stepped approach to the treatment of hypertension
Drugs aimed at the treatment of hypertension should not be taken away or stopped. Drugs should continue to be added until the desired blood pressure is reached
What anti-hypertensive treatment should be given to women of child bearing age or pre-pregnancy ?
NOT ARB OR ACE
Nifedipine, Methyl Dopa or Atenolol
What anti-hypertensive treatment should be given to women during pregnancy ?
Nifedipin, Methyl Dopa or Atenolol with the addition of a thiazide type diuretic and/or amlodipine
