• venous blood
  • 1 ) the central (autonomic) command that accompanies active muscle contraction and 2 ) the displacement of large amounts of venous blood to the right atrium by the massive muscle action induced by active standing, eliciting a cardiopulmonary (CP) reflex effect on the systemic circulation. (physiology.org)
  • The venous blood is drained via superior and middle thyroid veins, which drain to the internal jugular vein, and via the inferior thyroid veins. (wikipedia.org)
  • reduction
  • 2. The term shallow water blackout has also been used in the scientific literature over many years to refer to loss of consciousness caused by cerebral hypoxia at the end of a deep breath-hold dive during the latter part of the ascent or immediately after surfacing due to lowered oxygen partial pressure caused by reduction in ambient pressure. (wikipedia.org)
  • pressure
  • Experiments were done in the isolated supported heart preparation to ascertain whether a change in coronary blood flow would induce a change in myocardial O 2 consumption if the activity of the heart (aortic pressure, heart rate and stroke volume) was controlled. (ahajournals.org)
  • The steady-state response to active standing and HUT is usually comparable, but there is a difference in the blood pressure (BP) and heart rate (HR) responses in the first 30 s ( Fig. 1 ). (physiology.org)
  • Blood pressure and heart rate responses to passive head-up tilt (HUT) and active standing. (physiology.org)
  • Bowie RA, O'Connor PJ, Hardman JG, Mahajan RP (2001) The effect of continuous positive airway pressure on cerebral blood flow velocity in awake volunteers. (springer.com)
  • Droste DW, Ludemann P, Anders F, Kemeny V, Thomas M, Krauss JK, Ringelstein EB (1999) Middle cerebral artery blood flow velocity, end-tidal pCO 2 and blood pressure in patients with obstructive sleep apnea and in healthy subjects during continuous positive airway pressure breathing. (springer.com)
  • {20} In refractory cases, the use of multiple drug therapy may be necessary for blood pressure support. (drugs.com)
  • {04} {28} It is also used in hypotensive states following sympathectomy, or following overdose with ganglionic blocking agents, antiadrenergic agents, or other medications that lower blood pressure in the treatment of hypertension. (drugs.com)
  • Methoxamine is indicated for supporting, restoring, or maintaining blood pressure during general anesthesia with agents that sensitize the myocardium to arrhythmias, such as halothane. (drugs.com)
  • Immersion of the human body in water has effects on the circulation, renal system and fluid balance, and breathing, which are caused by the external hydrostatic pressure of the water providing support against the internal hydrostatic pressure of the blood. (wikipedia.org)
  • Hydrostatic pressure on the body due to head out immersion causes negative pressure breathing which contributes to the blood shift. (wikipedia.org)
  • Common side effects include an irregular heart rate, low blood pressure, burning sensation at the site of injection, and the stopping of breathing. (wikipedia.org)
  • It relaxes the smooth muscles in the walls of arteries, which opens (dilates) the arteries, allows blood to flow more easily, and lowers blood pressure. (wikipedia.org)
  • Additionally, it lowers blood pressure by acting on the heart itself to reduce the rate, strength, and conduction speed of each beat. (wikipedia.org)
  • These effects also reduce blood pressure by causing less blood to be pumped out. (wikipedia.org)
  • A reflex sympathetic response, caused by the peripheral dilation of vessels and the resulting drop in blood pressure, works to counteract the negative inotropic, chronotropic and dromotropic effects of diltiazem. (wikipedia.org)
  • The mechanism of deep water blackout is hypoxia, arising from the rapid drop in the partial pressure of oxygen in the lungs on ascent as the ambient pressure drops and the gas in the lungs expands to surface volume. (wikipedia.org)
  • Latent hypoxia This describes the precursor to blackout on ascent where the partial pressure of oxygen remains sufficient to maintain consciousness, but only at depth, under pressure, and is already insufficient to maintain consciousness at the shallower depths that must be encountered on ascent. (wikipedia.org)
  • 3. Also used in diving but not in free diving, loss of consciousness while ascending on a rebreather due to sudden drop of oxygen partial pressure in the breathing loop, usually associated with manual CCR and SCR. (wikipedia.org)
  • In pooled data, from three comparative studies conducted in 200 patients with mild to moderate hypertension, 2.5 mg of levamlodipine was found to be equivalent in its blood pressure lowing efficacy to 5 mg of amlodipine. (wikipedia.org)
  • The quantification of cerebral autoregulation always involves variation seen in cerebral blood flow in relation to changes in blood pressure. (wikipedia.org)
  • This blood pressure variation can either be evoked or spontaneous. (wikipedia.org)
  • systemic
  • In a previous study we demonstrated that in lambs with an aortopulmonary left to right shunt, isoproterenol increased systemic blood flow more than dopamine did, because isoproterenol increased heart rate . (onlinejacc.org)
  • humans
  • Dawson EA, Secher NH, Dalsgaard MK, Ogoh S, Yoshiga CC, Gonzalez-Alonso J, Steensberg A, Raven PB (2004) Standing up to the challenge of standing: a siphon does not support cerebral blood flow in humans. (springer.com)
  • tissue
  • Using an epigastric pouching technique, it is possible to obtain a tissue-isolated preparation which makes direct studies of blood flow and oxygen supply in human tumors feasible. (aacrjournals.org)
  • Due to marked intra- and intertumor variabilities in blood flow, heterogeneities in the tissue oxygenation are characteristic features of human breast cancer xenografts. (aacrjournals.org)
  • From the results obtained it is concluded that human breast cancers growing as xenografts in rnu/rnu rats may be useful tools for cancer research, especially for investigations of blood flow, tissue oxygenation, and substrate turnover. (aacrjournals.org)
  • Blood flow values were significantly higher in the high-BAT group than in the low-BAT group for BAT (12.9 ± 4.1 vs. 5.9 ± 2.2 mL/100 g/min, P = 0.03) and white adipose tissue (7.2 ± 3.4 vs. 5.7 ± 2.3 mL/100 g/min, P = 0.03) but were similar for muscle (4.4 ± 1.9 vs. 3.9 ± 1.7 mL/100 g/min). (pubmedcentralcanada.ca)
  • The method of analysis was optimized by investigating potential reuse of myocardial blood flow (MBF), perfusable tissue fraction, and blood and lung spillover factors derived from separate O-15-water and (CO)-O-15 scans. (diva-portal.org)
  • The optimal accuracy and precision of OEF were obtained when fixing MBF, perfusable tissue fraction, and blood spillover to values derived from a O-15-water scan and estimating spillover from the pulmonary gas volume using an attenuation map. (diva-portal.org)
  • The first decade of research focused on physiologic profile of the penumbra tissue after stroke, mapping the cerebral blood flow, and quantifying oxygen and glucose consumption to define these areas. (wikipedia.org)
  • The third decade of penumbral research found a transitional leap as using positron emission tomography (PET) scanning can identify brain tissue with decreased blood flow and magnetic resonance imaging (MRI) has the ability to detect portions of the ischemic tissue that has not yet died. (wikipedia.org)
  • Circulation
  • a modeling approach to the study of the blood circulation and its response to postural changes can provide insight into the underlying physiology. (physiology.org)
  • velocity
  • To determine the body position least affecting indices of CBF and CBV, the middle cerebral artery mean blood velocity (MCA V mean ) and the near-infrared spectroscopy determined frontal cerebral hemoglobin content (cHbT) were evaluated in 11 healthy subjects during CPAP at different body positions (15° head-down tilt, supine, 15°, 30° and 45° upper body elevation). (springer.com)
  • Giller CA (1989) Transcranial Doppler monitoring of cerebral blood velocity during craniotomy. (springer.com)
  • heart rate
  • Diltiazem is a potent vasodilator, increasing blood flow and variably decreasing the heart rate via strong depression of A-V node conduction. (wikipedia.org)
  • blackout
  • Breath-hold duration is limited by oxygen reserves, and the risk of hypoxic blackout, which has a high associated risk of drowning. (wikipedia.org)
  • supply
  • Human breast cancer xenografts in T-cell-deficient rnu/rnu rats permit the detailed and systematic study of blood flow, oxygen supply, and characterization of the cellular microenvironment of human tumors in vivo . (aacrjournals.org)
  • Due to a restricted blood supply, the O 2 utilization of human breast cancer xenografts is high. (aacrjournals.org)
  • We conclude that the catecholamines isoproterenol and dopamine do not lead to a mismatch between myocardial oxygen supply and demand, nor do they change blood flow distribution unfavorably in 7-week old lambs with a left to right shunt. (onlinejacc.org)
  • Well trained cyclists through conditioning develop the ability to supply more blood to their lower body than most people can supply to their entire body so cyclists can reach their MHR cycling but other people generally can't. (sparkpeople.com)
  • muscles
  • However, the ability to perform useful work like staying afloat declines substantially after ten minutes as the body protectively cuts off blood flow to "non-essential" muscles. (wikipedia.org)
  • body
  • We sought to study the effects of catecholamines on myocardial oxygen consumption (V̇ o 2 ), regional blood flows and total body V̇ o 2 in lambs with circulatory congestion. (onlinejacc.org)
  • We infused isoproterenol (0.1 μg/kg body weight per min) and dopamine (10 μg/kg per min) and measured myocardial and total body V̇ o 2 and regional blood flows in chronically instrumented 7-week old lambs with and without a left to right shunt. (onlinejacc.org)
  • I was told by an exercise physiologist is that the problem most people have is since they are using mainly the lower body that the they never need all the blood the heart can pump. (sparkpeople.com)
  • the heart has to work harder to pump the same volume of blood throughout the body, and for people with heart disease, this additional workload can cause the heart to go into arrest. (wikipedia.org)
  • Prior to this, kidneys had been stored at normal body temperatures using blood or diluted blood perfusates, but no successful reimplantations had been made. (wikipedia.org)
  • values
  • He used diluted plasma or serum as the perfusate and pointed out the necessity for low perfusate pressures to prevent kidney swelling, but admitted that the optimum values for such variables as perfusate temperature, Po2, and flow, remained unknown. (wikipedia.org)
  • rate
  • At comparable tumor sizes, the average blood flow rate through human breast cancer xenografts is higher in medullary than in squamous cell carcinomas (0.17 versus 0.10 ml·g -1 ·min -1 ). (aacrjournals.org)
  • changes in blood
  • This resting brain activity is observed through changes in blood flow in the brain which creates what is referred to as a blood-oxygen-level dependent (BOLD) signal that can be measured using functional magnetic resonance imaging (fMRI). (wikipedia.org)
  • Functional magnetic resonance imaging (functional MRI or fMRI) is a specific magnetic resonance imaging (MRI) procedure that measures brain activity by detecting associated changes in blood flow. (wikipedia.org)
  • delivery
  • therefore, in the emergency department a major concern is to protect the penumbra by increasing oxygen transport and delivery to cells in the danger zone, thereby limiting cell death. (wikipedia.org)