Exam 2 – Cardio Ch 19 Flashcards
What percent of body weight is blood?
8%
What percent of blood is plasma? Cells?
60%
40%
What percent of total body water distribution is plasma?
5%
What percent of total body water distribution is interstitial fluid?
15%
What percent of total body water distribution is intracellular fluid?
40%
What percent of total body water distribution is extracellular fluid?
20-30%
What makes up extracellular fluid?
Plasma and interstitial fluid
What is the density/weight of blood?
1 kg/liter or 1 gram/ml
What percent of plasma is water? Protein?
92%
8%
What happens during the short term control of blood pressure?
Autonomic sympathetic increases peripheral resistance
Describe long term control of blood pressure
Renal control mechanisms
Sodium and extracellular fluid volume
What is sodium a major determinant of?
Extracellular fluid volume
What happens as sodium intake increases?
It stimulates thirst/drinking and ADH secretion
What does a change in the sodium intake lead to?
Changes in extracellular fluid volume (ECFV)
What is ECFV determined by?
The balance of sodium intake and output
Is there more sodium or potassium in the extracellular compartment?
Na
Is there more sodium or potassium in the intracellular compartment?
K
What do the kidneys have a dominant role in?
Long term pressure control by regulating ECFV
What happens as ECFV increases?
Arterial pressure increases
What does the increase in arterial pressure, which is caused by an increase in ECFV, cause?
The kidneys to lose Na and water which will return ECFV and blood pressure to normal
What does an increase in ECFV cause?
An increase in blood pressure which increases sodium excretion which increases ECFV (it’s a cycle)
What is the effect of pressure to increase water excretion?
Pressure diuresis
What is the effect of pressure to increase Na excretion?
Pressure natriuresis
What do pressure natriuresis and diuresis require?
Normal kidney function
What are determinants of long term blood pressure control?
Renal function and Na intake
What is the equilibrium point on the renal function curve and salt and water intake line?
Where intake and output curves intersect
What does the renal body fluid feedback system have in terms of gain?
Infinite gain: normal kidney can return high pressures to normal range
Do changes in TPR have an affect on long-term arterial pressure level?
No
What must be altered in order to have long-term changes in arterial pressure?
The renal function curve
What does changing renal vascular resistance lead to?
Long-term changes in arterial pressure
If you take a large piece of tissue from an animal, what have you taken?
A large amount of the extracellular fluid, which will change how the heart works because the fluid volume is different
Look at the effect of ECFV on arterial pressure
Look at the effect of ECFV on arterial pressure
What is the mean circulatory filling pressure?
The amount of blood coming back
What is the overall effect of ECFV?
Increased extracellular fluid volume
How does an increase in ECFV increase blood pressure?
Decreased kidney function
Increased NaCl intake
Where is renin synthesized and stored?
In modified smooth muscle cells in afferent arterioles of the kidney
What is renin released in response to?
A fall in pressure
What does renin act on?
A substance called angiotensin to form a peptide called angiotensin II
What is angiotensin I converted to angiotensin II by?
A converting enzyme located in the endothelial cells in the pulmonary circulation
What happens when there is decreased arteriole pressure?
It is noted very quickly by the glomerular apparatus. This releases renin
What happens when angiotensin II hits the lung?
We get angiotensinase
What is angiotensin II?
The most powerful vasoconstrictor that can affect the body globally
Look at renin-angiotensin system
Look at renin-angiotensin system
What does the renin-angiotensin system cause?
Vasoconstriction
Na retention by direct and indirect acts on the kidney
Shift in renal function curve to the right
What happens with direct acts on the kidney?
Decreased renal blood flow
More time for resorption
What happens with indirect acts on the kidney?
ADH secretion
What is the renin-angiotensis system important in?
Maintaining a normal AP during changes in Na intake
What happens to renin as Na intake increases?
Its levels fall to near 0
What happens to renin as Na intake decreases?
Its levels increase significantly
What does the renin-angiotensin system cause the Na loading renal function curve to be like?
Steep
What organs are important in the renin-angiotensin system?
Liver
Adrenal cortex
Lungs
What does angiotensin have a direct effect on?
Adrenal cortex
What will most of the angiotensin do?
Vasoconstriction of the arterioles
What are factors which decrease renal excretory function and increase blood pressure?
Angiotensin II
Aldosterone
Sympathetic nervous activity
Endothelin
What will total peripheral resistance do?
Raise the blood pressure
What are factors which increase renal excretory function and decrease blood pressure?
Atrial natriuretic peptide
Nitric oxide
Dopamine
What can dopamine cause?
Vasodilation globally
What is a normal blood pressure?
Less than 120/80 mmHg
What is a prehypertension blood pressure?
120-139/80-89 mmHg
What is a hypertension blood pressure?
Greater than 140/90 mmHg
What is the blood pressure for stage 1 hypertension?
140-159/90-99 mmHg
What is the blood pressure for stage 2 hypertension?
160 or greater/100 or greater mmHg
What percentage of hypertensive patients have primary/essential hypertension?
90%
What is the cause of primary/essential hypertension?
Unknown, but most likely related to weight gain. 2/3 of essential hypertensives are overweight
Linked to genetics
What does primary hypertension cause?
Loss of compliance of large arteries
What are some causes for secondary hypertension?
Renal artery stenosis Chronic renal disease Primary hyperaldosteronism Sleep apnea Pheochromocytoma Preeclampsia Aortic coarctation
How can you treat hypertension?
Drugs which affect renal blood flow
Drugs that inhibit Na reabsorption
What do drugs which affect renal blood flow do?
Inhibition of sympathetic nervous system
Angiotensin converting enzyme inhibitors
Vasodilators
What are drugs that inhibit Na reabsorption?
Diuretics
