Lec 7 - Blood Pressure and the Kidney Flashcards
(21 cards)
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.
Where is Aldosterone made?
In the adrenal cortex
What are the structures In the adrenal cortex from outer to inner?
- zona glomerulosa
- zona fasciculata
- zona reticularis
What are the actions of aldosterone?
- up regulates Na/K pump in the basolateral membrane. of the DCT.
- up regulates Na channels in the collecting duct and colon.
- stimulates secretion of K into tubule.
- Stimulates Na and H20 in the gut, salivary and sweat glands.
- stimulates H+ secretion in the collecting duct.
- Upregulates Na/Cl cotransporter in the DCT.
what do the actions of aldosterone aim to do?
increase sodium reabsorption
increase water reabsorption
What do leaky capillaries in sepsis result in?
- decreased blood pressure
- increased salt and water retention, which will increase bp again.
- Increase ECF volume.
What does the pressure-natriuresis curve indicate?
- You need a higher blood pressure to excrete the same amount of sodium.
