Specialized Blood Flow + Circulation

Alpha-1, beta-2, splanchnic, coronary, dilation

Sympathetic control of vasculature

• __ Rs - Cause vasoconstriction to the arteries and veins

• __ Rs - Cause vasodilation to arteries and veins

• Vascular smooth muscle in __ arterioles have all alpha-1 Rs

• Vascular smooth muscle in __ arterioles have both alpha-1 and beta-2 Rs

  • Some __ at play along with vasoconstriction (larger vessel size)

Increases, arterial, decreases, increased

Sympathetic tone of vasculature

• Stimulation __ systemic vascular resistance

  • Increases central/systemic __ pressure by diverting flow from cutaneous and splanchnic circulations

• Stimulation__ flow beyond constricted arteries, despite increase in central pressure

• Flow thru other non-constricted arteries is __ due to increase in central pressure

Constriction, MAP, TPR, distal

Sympathetic __ can increase mean arterial pressure while reducing downstream flow

• __ is driving force for organ perfusion

• Increase sympathetic constriction → Increase __ (variable) → Thus increase MAP

• Constriction also reduces flow __ (proximal/distal) to the site of resistance (i.e. peripheral ischemia)

Constriction, I, RAAS

Angiotensin II hormonal control on vessels

• Direct vaso__ via action of ang II type _ receptors

• Indirect effects through many other elements of __ (cascade)

Constriction, I, kidneys, II

ADH hormonal control on vessels

• Direct vaso__ of vessels via action at vasopressin _ receptors

• Indirectly effects vessels by increasing water reabsorption in __ via action at vasopressin _ receptors

Relaxation, increasing, decreasing

ANP hormonal control on vessels

• Direct vein __ via ANP receptors

• Indirectly via __ heart rate and __ water reabsorption in kidneys

Alpha-1, Beta-2

Epinephrine hormonal control on vessels

• Vasoconstriction with __ Rs and vasodilation with __ Rs

Autoregulation, stretch, flow, metabolites, aterioles

Local control

• __ is the Intrinsic ability of organ to maintain constant blood flow despite changes in perfusion pressure and tissue oxygen demand

• Mechanisms involve vasodilation/vasoconstriction in response to vessel __, __ rates, vasoactive __

• Primarily influencing __ (vessel type)

Vasoconstriction, vasodilation

Myogenic and cerebral autoregulation to vessels

• Increase in arterial pressure = __ response

• Decrease in arterial pressure = __ response

Mechanically, MLCK, capillaries, increases

Myogenic autoregulation

• Vasoconstriction process

  • Stretch opens __-gated ion channels → __ (enzyme) activation → constriction

  • Protects downstream __ (vessels) from surges in pressure that could otherwise cause damage

• Vasodilation process

  • Decrease in arterial pressure

  • __ flow to downstream capillaries to maintain adequate blood and oxygen delivery

Baroreflex, RAAS, dilation, constriction, systemic

Homeostatic regulation of MAP

• Arterial __ (compensator) and __ (cascade)

• High pressure → Decrease sympathetic tone → __

• Low pressure → Increase sympathetic tone → __

• This is done at a __ level

Stimulus, TPR, perfusion

Systemic level of MAP regulation

• Requires system-wide__ (increased MAP)

• Changes __

• Preserve __ pressure

Constriction, dilation, local

Myogenic autoregulation of MAP

• High pressure → Vaso__

• Low pressure → Vaso__

• This is done at a __ level

stimulus, resistance, surges, tuning

Local control level of myogenic autoregulation

• Requires local __ (i.e. increased wall stretch)

• Changes local __

• Protects capillaries and tissues from __ in pressure or ensures a needed increase in flow

• Regional fine-__

Flow, oxygen, dilation

Metabolic autoregulation

• Tissue with increased metabolic demand relative to __

• __ delivery produces metabolic byproducts

• Result in vaso__

Hyperemia

Increased amount of blood is termed…

aerobic, lactic acid, adenosine, ATP, lactate, K+

Myogenic autoregulation

• CO2 and H+ (__ respiration)

• H+ (__ __ from anaerobic respiration)

• __ (released from hypoxic cells and ATP byproduct)

• __ (released from RBCs when offloading oxygen)

• __ (anaerobic respiration)

• __ (more action potentials → vasodilation)

Increases, metabolic

Active Hyperemia

• Blood flow __ as __ rate increases in response to higher metabolite production

Occlusion, influx

Reactive Hyperemia

• Blood flow __ → metabolites build up in downstream tissue

  • Remove occlusion → massive __ of blood flow

flow-mediated, stress, endothelial, nitric oxide, dilation

In __-__ dilation

• Increase in blood velocity → Increases shear __ on vessel wall of __ cells

  • Endothelial cells release __ __ → Vaso__

  • Dilation then normalizes shear stress

Histamine, bradykinin, vasodilation, leakiness, flow, slightly

• __ and __ (inflammatory markers - allergy)

  • Released during blunt trauma or inflammation

  • Cause arterial __ → inflammation signs - HPFRS

  • Capillary filtration - Increased permeability / “__” increases filtration

  • Flow to capillaries - Decreased resistance increases __

  • Effect on overall blood pressure - Decreased __ from small drop in systemic vascular resistance

Histamine, dilation, drop

In Anaphylaxis

• __ release resulting in systemic __ of all vessels and __ in perfusion pressure

• Blood no longer driven across "fixed" resistance of capillaries

Myogenic, metabolites, sympathetic, PCO2

Flow in Cerebral circulation

• Major site for __ autoregulation

• Variation of flow regulated by __

• Minimal regulation from __ system

• Arterial __ plays a huge role in circulation

  • Elevation in this increases cerebral bloodflow

Pressure, volume

The skull is relatively “closed box” and brain cannot tolerate a large increase in __ or __

Resistance, constriction

Why we pass out from hyperventilation?

• Increased cerebrovascular __ - think vaso__ of cerebral vasculature

50-150, constant

Within autoregulatory range (__-__ mmHg), cerebral blood flow remains __

Passive Collapse

Pressure insufficient to drive flow and keep vessel open - ischemia

(Cerebral autoregulation failure)

Passive Dilation

Ability to constrict maxed out and pressure overcomes constriction - rupturing

(Cerebral autoregulation failure)

Constriction, increases, decreases, arterioles, increase, decreases, increases, decrease

Other factors affecting cerebral flow

• Intracranial pressure increase = vaso__, __ R, __ F

• local constriction/dilation of cerebral __

• MAP at brain level = __ cerebral blood flow

• viscosity of blood = __ F, __ R

• mean venous pressure at brain level = __ F

Hypoxia, minimal, flow, dilators, left ventricle

Flow in Coronary circulation

• Primarily regulated by __ (abnormality in gas)

• __ regulation from sympathetic system

• Myocardial tissue extracts close to 60% of oxygen from blood and is very reliant on __

• Highly responsive to metabolic __

• During __ __ (heart region) contraction, pressure increases from compression of coronary blood vessels

compression, stops, diastole

Flow in coronary circulation

• During left ventricle contraction, pressure increases from __ of coronary blood vessels

  • __ blood flow to left ventricle

  • Left ventricle perfusion primarily occurs during LV __

Tachycardia, metabolic, systole, contractions

Left ventricle become ischemic during episodes of__ (sinus)

• Cardiac __ demand is elevated

• Greater percentage of cardiac cycle is spent in __ → blood flow is occluded during systole due to force of __ (contractions/relaxation) compressing microvasculature

Alpha-1, dilation, temperature, mechanical

Flow in skin/cutaneous circulation

• Primarily regulated by sympathetic system (__ Rs)

• During blunt trauma, histamine and other local metabolites cause significant vaso__

• Cutaneous blood flow is mainly modified for __ regulation

• __ pressure can cause different patterns of vasoconstriction and/or dilation (i.e. scratching skin)

Oxygen, minimal, arteries, veins, constriction

Flow in Pulmonary circulation

• Primarily regulated by __

• __ regulation from sympathetic system

• Pulmonary __ carry deoxygenated blood while pulmonary __ carry oxygenated blood

• Unlike most tissue, hypoxia causes vaso__ in pulmonary arteries

• Lower pressures than systemic circulation

Optimize, air

Why do pulmonary arteries constrict in response to hypoxia?

• __ blood flow to parts of lungs getting oxygen from __

• *Redistribute blood flow to well-ventilated areas to pick up O2

Sympathetic, RAAS, myogenic, total

Flow in Renal circulation

• Significantly regulated by __ NS and __

• Significantly auto-regulated by __ response and “tubuloglomerular feedback”

• Kidneys receive high percentage of __ blood flow

Alpha-1, exercise, SNS, strenuous

Flow in Skeletal muscle circulation

• Primarily regulated by sympathetic NS during rest via __ Rs

• Metabolic regulation predominates during __ and overcomes the __ (autonomic)

• During __ exercise, skeletal muscle can increase blood flow 50x and receive 80% of cardiac output

GI tract, before, catecholamines

Flow in Splanchnic circulation

• Veins draining in organs of __ __ empty into liver __ returning to heart

• Highly responsive to __ (neurot class) driving the sympathetic nervous responses

One-way, dead end, endothelial, vessels

Lymphatic circulation

• Facilitates __-__ movement of interstitial fluid back to cardiovascular system // Prevents backflow

• “__ __” lymph vessels intertwined with capillaries

• Large gaps between lymph __ cells

  • Allow lymph __ to absorb fluid, proteins, and bacteria from interstitial fluid

Subclavian, pump, force, smooth, contraction

Flow in lymphatic circulation

• Lymphatic thoracic duct drains into __ veins

• NO “__” in lymphatic system

• Flow is driven by:

  • External __ (i.e. skeletal muscle pump)

  • Waves of __ muscle __ (contraction/relaxation) in larger lymph vessels

Interstitial, resistance, extremities

How does lymph node excision increase risk of chronic edema?

• Increased __ pressure, and a __ to flow leads to fluid accumulation to the __