Hemodynamics for Medical Students

Badeer, Henry S.

doi:10.1152/advances.2001.25.1.44

Cited by 61 publications

(41 citation statements)

References 3 publications

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“…However, a difference of 3 to 4 m in retinal vessel diameter corresponds to a difference in resistance of 13% to 17% according to the Poiseuille equation whereby resistance varies by the inverse of the fourth power of the diameter. 40 This change in resistance corresponds to an increase in pressure of 13% to 17%. We have also previously shown that changes of this magnitude predict the incidence of hypertension 18 and coronary heart disease, 23 and other researchers have found even smaller decreases in retinal arteriolar caliber are associated with significant increase in systolic blood pressure (eg, a 1.1-m reduction in arteriolar caliber is associated with a 10-mm Hg increase in systolic blood pressure).…”

Section: Discussionmentioning

confidence: 99%

Low Birthweight Is Associated With Narrower Arterioles in Adults

et al. 2008

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Abstract-Low birthweight is associated with increased risk of hypertension, but underlying mechanisms are obscure. We hypothesized structural microvascular alterations may be one such mechanism. We examined the association of birthweight and retinal arteriolar caliber in 3800 persons aged 51 to 72 years participating in a population-based study in 4 US communities (the Atherosclerosis Risk in Communities study). Participants reported full-term birth and their birthweight and had retinal photography. Retinal arteriolar and venular calibers were measured from digitized retinal photographs using a validated computer-assisted method. Lower birthweight was associated with narrower retinal arteriolar caliber, with each kg lower birthweight associated with 2.4 m (95% confidence intervals, 1.3 to 3.5, PϽ0.001) narrower retinal arteriolar caliber, after controlling for age, gender, race, education, smoking, alcohol consumption, adult body mass index, and height. Additional adjustment for blood pressure averaged over the past 6 years and fasting glucose did not alter these findings, with each kg lower birthweight associated with a 1.7 m (95% confidence intervals, 0.7 to 2.8, PϽ0.001) narrower retinal arteriolar caliber. This association was also present in persons without hypertension or diabetes. Lower birthweight was not associated with retinal venular caliber. These findings provide evidence that structural alterations in the arteriolar microcirculation may be a potential mechanism linking restricted fetal growth with subsequent risk of hypertension. (Hypertension. 2008;51:933-938.)

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Section: Discussionmentioning

confidence: 99%

Low Birthweight Is Associated With Narrower Arterioles in Adults

et al. 2008

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“…Although cardiac output and sympathetic activity may be elevated in the early stages of hypertension, increased peripheral resistance is the main driver for chronically elevated BP (Heagerty et al, 2010). Resistance to flow can be influenced by blood viscosity, vessel length and vessel diameter, with resistance being inversely proportional to the fourth power of the vessel's radius (Poiseuille's law) (Badeer, 2001;Sriram et al, 2014). Small arteries which provide the greatest percentage contribution to peripheral resistance have been termed resistance arteries, and are defined as pre-capillary vessels composed of a relatively thick media layer and having internal diameter of approximately 100-300 μm (Mulvany & Aalkjaer, 1990;Korsgaard et al, 1993;Christensen & Mulvany, 2001;Heagerty et al, 2010).…”

Section: Resistance Arteries and Essential Hypertensionmentioning

confidence: 99%

Plasma membrane calcium ATPases (PMCAs) as potential targets for the treatment of essential hypertension

Little

Cartwright

Neyses

et al. 2016

Pharmacology & Therapeutics

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The incidence of hypertension, the major modifiable risk factor for cardiovascular disease, is increasing. Thus, there is a pressing need for the development of new and more effective strategies to prevent and treat hypertension. Development of these relies on a continued evolution of our understanding of the mechanisms which control blood pressure (BP). Resistance arteries are important in the regulation of total peripheral resistance and BP; changes in their structure and function are strongly associated with hypertension. Anti-hypertensives which both reduce BP and reverse changes in resistance arterial structure reduce cardiovascular risk more than therapies which reduce BP alone. Hence, identification of novel potential vascular targets which modify BP is important. Hypertension is a multifactorial disorder which may include a genetic component. Genome wide association studies have identified ATP2B1, encoding the calcium pump plasma membrane calcium ATPase 1 (PMCA1), as having a strong association with BP and hypertension. Knockdown or reduced PMCA1 expression in mice has confirmed a physiological role for PMCA1 in BP and resistance arterial regulation. Altered expression or inhibition of PMCA4 has also been shown to modulate these parameters. The mechanisms whereby PMCA1 and 4 can modulate vascular function remain to be fully elucidated but may involve regulation of intracellular calcium homeostasis and/or comprise a structural role. However, clear physiological links between PMCA and BP, coupled with experimental studies directly linking PMCA1 and 4 to changes in BP and arterial function, suggest that they may be important targets for the development of new pharmacological modulators of BP.

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“…This formula has been used to determine the resistance of capillary beds. According to this formula, the total resistance is less than that of any individual resistance, and if the number of vessels in parallel increases, the total resistance should decrease [8]. However, with the increase in the vessels in parallel, the total cross-sectional area should be greater than that of the inlet and outlet.…”

Section: Parallel Network Resistancementioning

confidence: 99%

Flow Resistance of Vessels with an Enlarged Total Cross-Sectional Area in the Midsection

Song

2013

TOCVJ

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To understand the hemodynamics of the microcirculation, we compared the resistance of vessels that either had an enlarged cross-sectional area in the midsection (denoted vessel 1) or had a uniform diameter (denoted vessel 2). The length of the two vessels and the pressure difference between the ends were equal. The two vessels were filled with water, and the volume of water flowing through the two vessels per second was measured. The volume of water flowing through vessel 1 was 4.05 ml/sec, and the volume of water flowing through vessel 2 was 4.37 ml/sec. Vessel 1 had a higher resistance, and water drained more slowly than from vessel 2. These results demonstrate that vessels with a greater crosssectional area in the midsection have a lower flow than vessels with a constant cross-section, even though resistance in the midsection is lower when the cross-sectional area is greater.

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Hemodynamics for Medical Students

Cited by 61 publications

References 3 publications

Low Birthweight Is Associated With Narrower Arterioles in Adults

Low Birthweight Is Associated With Narrower Arterioles in Adults

Plasma membrane calcium ATPases (PMCAs) as potential targets for the treatment of essential hypertension

Flow Resistance of Vessels with an Enlarged Total Cross-Sectional Area in the Midsection

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