Lec 7 - Blood Pressure and the Kidney Flashcards
What two things can result to there being a low blood pressure?
- Sepsis
- –> This causes reduced systemic vascular resistance. - Vomiting
- –> This causes reduced intravascular volume.
What does a low blood pressure lead to in terms of preload?
- decreased preload
- decreased cardiac stretch (Starling’s law)
- Stroke volume.
What does a low blood pressure lead to in terms of activation of carotid sinus baroreceptors?
- activation of carotid sinus baroreceptors
- Increased sympathetic activity
- decreased sino atrial node threshold
- Increased heart rate
- increased contractility
- increased stroke volume
- renin release by the kidney
- constrict afferent arterioles
- increased systemic vascular resistance
- increased capillary refill time.
What else does a low blood pressure lead to?
Renin release by the kidney.
What is the equation to calculate blood pressure?
Blood pressure = cardiac output X Total peripheral resistance
What is cardiac output and how is it calculated?
- Cardiac output is the mechanism for oxygen delivery to the tissues of the body.
- CO = HR X SV
What is the normally measurement of capillary refill?
Normally < 2 seconds peripherally.
What is total peripheral resistance equal to?
Total peripheral resistance = systemic vascular resistance (SVR)
What are the actions of the sympathetic nervous system in terms of the heart?
- decreased beta-AR responsiveness
- Increased myocyte hypertrophy
- increased myocyte necrosis and apoptosis, fibrosis.
- decreased noradrenaline stores.
- decreased sympathetic innervation
- Increased arrhythmias
- There is impaired diastolic, systolic function.
What are the actions of the sympathetic nervous system in terms of the kidney?
- Increased renin release.
- Increased RAAS activation
- Increased sodium reabsorption
- decreased response to natriuretic factors.
What are the actions of the sympathetic nervous system in terms of the smooth muscle?
- Increased vasoconstriction.
2. Increased vascular hypertrophy.
How does kidneys cause dilation?
The kidney produces prostaglandins which causes dilation.
What are the mechanisms for renin release from the kidney?
- Dopamine is used as direct sympathetic stimulation of JGA.
- Due to low bp, there is reduced renal blood flow detected by baroreceptors in JGA.
- Reduced NaCl to JGA.
What is the pathway of the Renin - Angiotensin (RAAS) system?
- Angiotensinogen from the liver is converted into Angiotensin I by renin from the kidney.
- Angiotensin I goes to Angiotensin II by Angiotensin Converting enzyme from the lungs and kidney.
What are the actions of Angiotensin II in increasing blood pressure?
- Increase sympathetic activity.
- Tubular Na+ Cl- reabsorption and K+ excretion. H20 retention.
- Adrenal gland cortex resulting in aldosterone secretion.
- Arteriolar vasoconstriction leads to an increase in blood pressure.
- The posterior lobe of the pituitary gland does ADH secretion so there is water reabsorption in the collecting duct.