Formula for BP
Formula for CO
What regulates CO?
1. Volume (Na)
2. HR (symp/para)
3. Force of contraction (symp)
What regulates Vascular Resistance?
1. Vasoconstriction (NE+, Angiotensin+, NO-)
2. Structural changes- remodeling/hypertrophy
What systems regulate BP? 2 Major+4 minor
1. Autonomic Nervous System
2. Renin-Angiotensin System
3. Chemoreceptors in Carotid/Aortic bodies
4. Centrally located chemoreceptors
5. Antidiuretic hormone
6. Low pressure baroreceptors: veins, atria, PA
How is the autonomic nervous system regulated?
Parasymp: decreases HR
Symp: increases CO & peripheral resistance via increase in HR and contractile force; increases renin from kidneys
Baroreceptors do feedback
What is the baroreceptor reflex?
Located in internal carotids, senses stretch
increase in BP --> increase in stretch --> decrease symp/ increase para
Bleeding, standing --> decrease in stretch --> decrease para, increase symp
What is the renin-angiotensin-aldosterone system?
Regulated by kidnes, leads to increased Na and H2O retention
What are the effects of Angiotensin II?
1. Adrenal cortex: stimulates synthesis & secretion of aldosterone (which acts on renal distal tubule collecting duct to increase Na reabsorption)
2. Vasoconstriction of arterioles
3. Directly stimulates Na/H exchange in kidneys
4. Hypothalamus: increases thirst, antidiuretic hormone (ADH)
5. Increases contractility and ventricular hypertrophy
What stimulates renin secretion?
Decreased renal perfusion (mechanoreceptors)
How is ADH stimulated? What are its effects?
Stimulated by angiotensin II & increase in serum osmolarity
Affects V1 receptors on vasc sm muscle--> vasoconstriction and V2 renal collecting ducts --> increased H2O reabsorption
How do the low pressure baroreceptors work?
Activated by increase in blood volume which increases venous/atrial pressure
Effect is to increase ANP which leads to relaxation of vascular smooth muscle & increasing blood flow to kidneys so water and salt can be excreted
Low pressure baroreceptors also increase HR (bc increased CO --> increased renal perfusion & Na/H2O excretion) and decrease antidiuretic hormone