Changes in heart rate via an increase or decrease of the SA node. Primarily influenced by rate of phase 4 in pacemaker cells (inward Na+ current); also rate of phase 0 in AV node of pacemaker cells (inward Ca2+ current).
Changes in conduction velocity primarily at the AV node and influences the PR interval on EKG. Negative dromotropic effect slows conduction from atrium thru the AV node, prolonging the PR interval. Primarily influenced rate of phase 0 in AV node of pacemaker cells (inward Ca2+ current).
Force of contraction. Influenced by preload or EDV, the free cytosolic Ca2+ concentrations, sarcomere length.
ALL muscles requires ___________ to induce the process of contraction.
Why do drugs we use to impact blood pressure not have a significant or noticeable effect on skeletal muscle?
Skeletal muscle predominantly utilizes pools of calcium stored in the SR rather than calcium moving thru VG calcium channels to induce contraction. SR is MUCH larger in skeletal muscle as compared to smooth muscle.
What is "preload"?
The EDV more specifically related to the right atrial pressure.
What happens to preload when venous return is increased?
Preload will increase which will stretch the sarcomere further and increasing the contractility (forward flow).
What happens when there is a sudden drop in preload?
Baroreceptor reflex is activated resulting in reflex tachycardia and angina.
What is "afterload"?
The reflected aortic pressures that must be overcome by the left ventricle or pulmonary artery pressures that must be overcome by the right ventricle. Afterload increases work load and can worsen angina (if ischemic heart disease is present).
What are the 2 functions of the arterial system?
Provide sufficient blood to body tissues
Convery a highly pulsatile flow into a more continuous flow at the level of smaller arteries
How and where is pulsatile blood flow dampened as to not destroy smaller arteries in the periphery?
It is dampened by elastin-containing central arteries (thoracic aorta and proximal branches).
1. Expansion during systole to store some of each stroke volume.
2. Recoil during diastole.
Define mathematically "pulse pressure".
PP = SBP-DBP; assumes a constant CO and HR
What does a wide pulse pressure indicate?
Decreased elasticity or increased arterial stiffness
Mean Arterial Pressure (MAP)
Average blood pressure over time; 100 mmHg
What are the 3 endogenous catecholamines?
What 2 factors potently stimulate adrenomedullary release of NE?
What type of receptors are found on postsynaptic cells in smooth muscle and the heart that regulate smooth muscle contraction and myocardial inotropy?
Alpha 1 adrenoreceptors
What type of receptor is found presynaptically, autoregulates NE release, and inhibits subsequent NE release when activated?
What type of receptors are found in the heart, kidney, and adipose tissue that increases the rate and force of cardiac contraction, stimulates lipolysis in fat cells, and stimulates renin release from the kidneys when activated?
What is the rate-limiting step in angiotensin II production?
What are 3 effects of the AT1 receptor in response to Angiotensin II?
1. Stimultes vascular smooth muscle contraction and aldosterone synthesis.
2. Stimulates formation of superoxide which deactivates NO (vasodilator).
3. Stimulates the activation, release, and synthesis of several growth factors.
What is the general effect expected when AT2 receptor is bound?
Antagonism of all the effects of binding to AT1. Major rationale for propsed superiority of ARBs.
What is the cardiovascular effect of Angiontensin II on smooth muscle in the vasculature?
What is the cardiovascular effect of Angiontensin II on endothelium of the vasculature?
Prostaglandin, NO, and endothelin production
What is the cardiovascular effect of Angiontensin II on connective tissue of the vasculature?
Extracellular matrix synthesis
What is the cardiovascular effect of Angiontensin II on the myocardium
Strength of contraction
What is the cardiovascular effect of Angiontensin II on platelets
Aggregation by catecholamines
What is the cardiovascular effect of Angiontensin II on monocytes?
Adhesion to vessel wall
What is the cardiovascular effect of Angiontensin II on the adrenal glomerulosa?
What is the cardiovascular effect of Angiontensin II on the adrenal medulla?
What is the cardiovascular effect of Angiontensin II on the adrenal fasciculata?
What is the cardiovascular effect of Angiontensin II on the posterior pituitary gland?
What is the cardiovascular effect of Angiontensin II on the juxtaglomerular cells of the kidney?
Inhibits renin release
What is the cardiovascular effect of Angiontensin II on the proximal tubule of the kidneys?
What is the cardiovascular effect of Angiontensin II on sympathetic neurons?
What is the cardiovascular effect of Angiontensin II on the brain?
Pressor center activation
What is the cardiovascular effect of Angiontensin II on the intestines?
Salt and water absorption
What is the cardiovascular effect of Angiontensin II on the liver?
What 4 factors is tissue angiotensin II a significant contributor?
1. blood pressure
2. local inflammation
Vasoregulation in the CNS continuously regulates constriction of [peripheral/central] veins and arterioles to control __________, __________, and ___________.
peripheral veins and arterioles;
HR, blood flow, and BP
How is the medulla of the CNS involved in vasoregulation?
Maintains SNS activity based on sensory information received from baroreceptors and chemoreceptors.
How is the hypothalamus involved in vasoregulation?
Coordinates BP thru alterations in neurohormonal release.
How are the cortical/subcortical areas of the CNS involved in vasoregulation?
Alter CV function based on emotion and stress. So basically, it wigs the hell out when the ex-wife calls.
Describe the baroreceptor reflex at carotid sinus in vasoregulation when there is a drop in arterial pressure?
Drop in arterial pressure --> drop in the stretch on walls of carotid sinus --> decrease in firing of the carotid sinus nerve to the nucleus regions in the medulla oblongata --> decreaced outflow of the PNS to the heart via efferent vagus nerve and increase in SNS outflow down descending tract of intermediolateral column of gray matter in spinal cord --> some preganglionic nerve fibers synapse eventually to heart and blood vessels where post-ganglionic sympathetic nerve fibers release NE and other preganglionic sympathetic nerves synapse on adrenal glands releasing both NE and Epi into circulation
Arterial barorelexes are known as [high/low] pressure baroreceptors.
Where are arterial baroreflexes found?
Aortic arch and carotid bifurcations
Cardiopulmonary baroreflexes are known as [high/low] pressure baroreceptors.
Where are cardiopulmonary baroreflexes found?
Cardiac atria and ventricles
Can you draw the "Effects of RAAS & SNS on MAP" diagram?
Hell no! Are you crazy?
Best get on that with the quickness.
What type of hypertension do adolescents and young adults predominantly suffer from? What are they sensitive to?
Isolated Systolic Hypertension (ISH)
These patients are salt sensitive.
List 3 lifestyle factors that affect the pathophysiology of hypertension.
3. Sleep Apnea
What type of hypertension is characterized in 20-50 years old? What is this type of HTN associated with?
Diastolic hypertension. Associated with increased vascular resistance and MAP.
What type of HTN is found in patients greater than 50 years of age? Why is this significant?
Resurgence of ISH due to central artery stiffness.
Significance: DBP is highly dependent on the stiffness of central arteries. Elasticity in these is lost as we age, manifesting as a rise in SBP, a decrease in DBP, and thus a rise in pulse pressure.
True or False: The majority of men and women with HTN are not overweight or obese.
False. 78% of men and 65% of women with HTN are overweight or obese. Get off the couch fatty and run a lap around the house!
What 6 potential effects on BP can obesity have?
1. Insulin resistance
2. Fluid volume
4. Leptin resistance/hyperleptinemia
Why is insulin important to BP when considering insulin resistance and obesity?
1. Insulin increases absorption of Na+ in the distal nephron resulting in water retention (increased volume).