Circle of Willis, skeletal blood flow, cutaneous circulation, renal circulation and control, tubuloglomerular feedback, angina pectoris, modern therapies, major discoveries

5 Pages
Unlock Document

Colorado State University
Biomedical Science
BMS 420
Charles Miller

15 October Circle of Willis Can provide continued circulation of blood flow if one of the main vessels is disrupted Interruption of blood flow in carotid arteries with preserved vertebral supply may result in severe coma, although not necessarily death Skeletal Blood Flow – Highlights Dependent upon contractile (metabolism) activity of muscle cells Low capillary recruitment at rest (25%); might be 100% in exercise High tone at rest related to sympathetic nervous vasoconstriction input Arterial baroreceptors influence sympathetic nervous input to vascular smooth muscle cells of skeletal muscle Huge muscle mass and vascularity has significant role in maintenance of arterial blood pressure levels At rest: sympathetic nervous system determines tone whereas in active contraction, local metabolic factors predominate Cutaneous Circulation Two types of resistance vessels: arterioles and arteriovenous anastomoses AV anastomoses: finger tips, toes, soles of feet, palms of hand, lips, ears and nose (muscular walls with richly supplied sympathetic nerves) – do not respond to metabolic vasodilators and with intense SNS, lumen may become obliterated Skin resistance vessels under dual control of SNS and local factors Blanching: stimulation of SNS by higher centers Blushing: inhibition of SNS by higher centers Exhibits autoregulation and reactive hyperemia Renal Circulation Renal artery → → afferent arteriole → glomerulus (capillaries, filtration, 180 L/day) → efferent arteriole (smaller than afferent, so creates higher pressure in glomerular capillary) Peritubular capillaries around proximal tubule brings liquid back to general circulation (these extend from efferent arteriole) Renal Blood Flow Control 90% of renal blood flow is to cortex (most of nephrons here) High glomerular blood pressure compared to other capillaries Peritubular capillary blood pressure is low favoring reabsorption Filtration fraction is about 20% Control Myogenic autoregulation Tubuloglomerular feedback Sympathetic adrenergic stimulation occurs under hemorrhagic or exercise conditions Body’s water balance in check Autoregulation maintains a nearly constant GFR when mean arterial blood pressure is between 80 and 180 mm Hg Tubuloglomerular feedback Concentration of fluid in filtrate sensed (in macula densa [in distal convoluted tu
More Less

Related notes for BMS 420

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.