scholarly journals Effect of Pulsatile Flow Waveform and Womersley Number on the Flow in Stenosed Arterial Geometry

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Moloy Kumar Banerjee ◽  
Ranjan Ganguly ◽  
Amitava Datta
Keyword(s):  
Pulsatile Flow ◽  
Physiological State ◽  
Circulatory System ◽  
The Body ◽  
Arterial System ◽  
Hemodynamic Parameters ◽  
Flow Waveform ◽  
Womersley Number ◽  
Flow Features ◽  
Hemodynamic Flow

The salient hemodynamic flow features in a stenosed artery depend not only on the degree of stenosis, but also on its location in the circulatory system and the physiological condition of the body. The nature of pulsatile flow waveform and local Womersley number vary in different regions of the arterial system and at different physiological state, which affects the local hemodynamic wall parameters, for example, the wall shear stress (WSS) and oscillatory shear index (OSI). Herein, we have numerically investigated the effects of different waveforms and Womersley numbers on the flow pattern and hemodynamic parameters in an axisymmetric stenosed arterial geometry with 50% diametral occlusion. Temporal evolution of the streamlines and hemodynamic parameters are investigated, and the time-averaged hemodynamic wall parameters are compared. Presence of the stenosis is found to increase the OSI of the flow even at the far-downstream side of the artery. At larger Womersley numbers, the instantaneous flow field in the stenosed region is found to have a stronger influence on the flow profiles of the previous time levels. The study delineates how an approximation in the assumption of inlet pulsatility profile may lead to significantly different prediction of hemodynamic wall parameters.

The Cardiac System

2017 ◽  
Author(s):  
David C Mauchley
Keyword(s):  
Sinoatrial Node ◽  
Circulatory System ◽  
Atrioventricular Node ◽  
Atrial Septum ◽  
The Body ◽  
Arterial System ◽  
Pulmonic Valve ◽  
Anatomy And Physiology ◽  
Cardiac System ◽  
Cardiac Operations

The circulatory system, which consists of the heart, arterial system, venous system, and lymphatics, constitutes a complicated network of vessels and ducts that are responsible for the delivery of oxygenated blood to the body and return of deoxygenated blood to the heart and lungs. The heart is at the center of the circulatory system, and its pumping mechanism provides energy and nutrition to all organs in the body. This review focuses on the anatomy and physiology of the heart and describes anatomic details that are important to the planning of many common cardiac operations.    This review contains 28 figures, and 25 references. Key words: aortic root, aortic valve, atrial septum, atrioventricular node, coronary artery, fibrous skeleton of heart, mitral valve, myocardium, pericardium, pulmonic valve, sinoatrial node, tricuspid valve, ventricular septum 

II.—The Circulatory System of the Crustacean Euphausid, Meganyctiphanes norvegica (M. Sars)

1958 ◽  
Vol 67 (1) ◽  
pp. 32-41 ◽  
Author(s):  
John Mauchline
Keyword(s):  
Circulatory System ◽  
The Body ◽  
Arterial System ◽  
Ventral Region ◽  
Meganyctiphanes Norvegica

SynopsisIn Meganyctiphanes the blood is pumped from the heart to the various regions of the body by way of a well-developed arterial system. It passes out of the open ends of the final sub-branches of the arteries into the various sinuses, finally collecting in the posterior ventral region of the thorax. From there, by the action of the pericardium and the muscles associated with the afferent branchial channels, it enters the afferent branchial channels whence it circulates through the branchial veins in the branchiæ, to the efferent branchial channels. The beating of the heart draws the blood into the pericardium whence it reaches the heart cavity by way of two pairs of ostia.

Cardiac System

2017 ◽  
Author(s):  
David C Mauchley
Keyword(s):  
Sinoatrial Node ◽  
Circulatory System ◽  
Atrioventricular Node ◽  
Atrial Septum ◽  
The Body ◽  
Arterial System ◽  
Pulmonic Valve ◽  
Anatomy And Physiology ◽  
Cardiac System ◽  
Cardiac Operations

The circulatory system, which consists of the heart, arterial system, venous system, and lymphatics, constitutes a complicated network of vessels and ducts that are responsible for the delivery of oxygenated blood to the body and return of deoxygenated blood to the heart and lungs. The heart is at the center of the circulatory system, and its pumping mechanism provides energy and nutrition to all organs in the body. This review focuses on the anatomy and physiology of the heart and describes anatomic details that are important to the planning of many common cardiac operations.    This review contains 28 figures, and 25 references. Key words: aortic root, aortic valve, atrial septum, atrioventricular node, coronary artery, fibrous skeleton of heart, mitral valve, myocardium, pericardium, pulmonic valve, sinoatrial node, tricuspid valve, ventricular septum 

Analysis of Central Hemodynamic Parameters in Medical Students during the Pre-Examination Study Period

2021 ◽  
pp. 67-73
Author(s):  
VA Belyayeva
Keyword(s):  
Body Mass Index ◽  
Heart Rate ◽  
Medical Students ◽  
Cardiovascular System ◽  
Body Mass ◽  
Circulatory System ◽  
The Body ◽  
Hemodynamic Parameters ◽  
Adaptive Potential ◽  
Central Hemodynamic

Background: One of the main negative factors of the educational environment is the increased stress impact on the cardiovascular system of students preparing for examinations. The cumulative effect of a long-term, systematic exposure to stressors may be accompanied by impaired mental and somatic health of students. The extent of response to stress is individual; it is usually determined by cardiovascular health and a complex of psychophysiological characteristics of the body. Objective: To study the main parameters of central hemodynamics in medical students depending on the body mass index and adaptive potential in the pre-examination study period Materials and methods: In spring–summer 2019, 170 medical students (young men and women aged 20.4 ± 0.3 years) with different adaptive potential of the circulatory system were surveyed during a pre-exam study period to establish their anthropometric indicators, blood pressure and heart rate and to further estimate the body mass index and the main central hemodynamics parameters. Results: The average heart rate of students during the pre-exam study period was 85.4 ± 12.21 beats per minute. The level of metabolic and energy processes in the myocardium was characterized as moderate with a tendency to insufficient functional capacity of the cardiovascular system (CI = 90.4 ± 1.22). Significant differences were revealed in a number of parameters un-der study depending on gender, body mass index (F = 3.99; p = 0.00890) and the adaptive potential of the circulatory system (F = 23.08; p = 0.00000). Conclusions: In the pre-examination study period, both the heart rate and the Kerdo index among the students were elevated, which indicates the predominance of sympathetic autonomic stress. The students with tense adaptation mechanisms demonstrated higher values of certain hemodynamic parameters. The pulse pressure and the Robinson index were higher in overweight students compared to their peers with a normal body mass index. None of the students with class 1 obesity had a satisfactory level of adaptation of the circulatory system. The analysis of central hemodynamic parameters enables the assessment of tolerance of the cardiovascular system of students to the burden of learning.

Cardiac System

2017 ◽  
Author(s):  
David C Mauchley
Keyword(s):  
Sinoatrial Node ◽  
Circulatory System ◽  
Atrioventricular Node ◽  
Atrial Septum ◽  
The Body ◽  
Arterial System ◽  
Pulmonic Valve ◽  
Anatomy And Physiology ◽  
Cardiac System ◽  
Cardiac Operations

The circulatory system, which consists of the heart, arterial system, venous system, and lymphatics, constitutes a complicated network of vessels and ducts that are responsible for the delivery of oxygenated blood to the body and return of deoxygenated blood to the heart and lungs. The heart is at the center of the circulatory system, and its pumping mechanism provides energy and nutrition to all organs in the body. This review focuses on the anatomy and physiology of the heart and describes anatomic details that are important to the planning of many common cardiac operations.    This review contains 28 figures, and 25 references. Key words: aortic root, aortic valve, atrial septum, atrioventricular node, coronary artery, fibrous skeleton of heart, mitral valve, myocardium, pericardium, pulmonic valve, sinoatrial node, tricuspid valve, ventricular septum 

Cardiac System

2017 ◽  
Author(s):  
David C Mauchley
Keyword(s):  
Sinoatrial Node ◽  
Circulatory System ◽  
Atrioventricular Node ◽  
Atrial Septum ◽  
The Body ◽  
Arterial System ◽  
Pulmonic Valve ◽  
Anatomy And Physiology ◽  
Cardiac System ◽  
Cardiac Operations

The circulatory system, which consists of the heart, arterial system, venous system, and lymphatics, constitutes a complicated network of vessels and ducts that are responsible for the delivery of oxygenated blood to the body and return of deoxygenated blood to the heart and lungs. The heart is at the center of the circulatory system, and its pumping mechanism provides energy and nutrition to all organs in the body. This review focuses on the anatomy and physiology of the heart and describes anatomic details that are important to the planning of many common cardiac operations.    This review contains 28 figures, and 25 references. Key words: aortic root, aortic valve, atrial septum, atrioventricular node, coronary artery, fibrous skeleton of heart, mitral valve, myocardium, pericardium, pulmonic valve, sinoatrial node, tricuspid valve, ventricular septum 

Unsteady Entrance Flow Development in a Straight Tube

1994 ◽  
Vol 116 (3) ◽  
pp. 355-360 ◽  
Author(s):  
Xiaoyi He ◽  
David N. Ku
Keyword(s):  
Pulsatile Flow ◽  
Arterial System ◽  
Length Variation ◽  
Straight Tube ◽  
Phase Lag ◽  
Entrance Length ◽  
Flow Waveform ◽  
Mean Flow ◽  
Inlet Flow ◽  
Entrance Flow

The entrance conditions for pulsatile flow are important in the understanding blood flow out of the heart and in developing regions at branches. The pulsatile entrance flow was solved using a spectral element simulation of the full unsteady Navier- Stokes equations. A mean Reynolds number of 200 and a range of Womersley parameters from 1.8 to 12.5 was used for a sinusoidal inlet flow waveform 1+sin (ωt). Variations in the entrance length were observed during the pulsatile cycle. The amplitude of the entrance length variation decreased with an increase in the Womersley parameter. The phase lag between the entrance length and the inlet flow waveform increased for Womersley parameter α up to 5.0 and decreased for α larger than 5.0. For low α, the maximum entrance length during pulsatile flow was approximately the same as the steady entrance length for the peak flow. For high α, the pulsatile entrance length was more uniform during the cycle and tended to the entrance length for the mean flow. The wall shear rate reached its far downstream value after only about half of the entrance length and also exhibited a dependence on α. The results quantify the entrance conditions typically encountered in studies of the arterial system.

scholarly journals The Mechanism of Secretion and Metabolism of Gut-Derived 5-Hydroxytryptamine

2021 ◽  
Vol 22 (15) ◽  
pp. 7931
Author(s):  
Ning Liu ◽  
Shiqiang Sun ◽  
Pengjie Wang ◽  
Yanan Sun ◽  
Qingjuan Hu ◽  
...  
Keyword(s):  
Cell Metabolism ◽  
Circulatory System ◽  
Vital Role ◽  
The Body ◽  
Neuroendocrine Cells ◽  
Intestinal Lumen ◽  
Paracrine Signaling ◽  
Inflammatory Conditions ◽  
Epithelial Development ◽  
Ec Cells

Serotonin, also known as 5-hydroxytryptamine (5-HT), is a metabolite of tryptophan and is reported to modulate the development and neurogenesis of the enteric nervous system, gut motility, secretion, inflammation, sensation, and epithelial development. Approximately 95% of 5-HT in the body is synthesized and secreted by enterochromaffin (EC) cells, the most common type of neuroendocrine cells in the gastrointestinal (GI) tract, through sensing signals from the intestinal lumen and the circulatory system. Gut microbiota, nutrients, and hormones are the main factors that play a vital role in regulating 5-HT secretion by EC cells. Apart from being an important neurotransmitter and a paracrine signaling molecule in the gut, gut-derived 5-HT was also shown to exert other biological functions (in autism and depression) far beyond the gut. Moreover, studies conducted on the regulation of 5-HT in the immune system demonstrated that 5-HT exerts anti-inflammatory and proinflammatory effects on the gut by binding to different receptors under intestinal inflammatory conditions. Understanding the regulatory mechanisms through which 5-HT participates in cell metabolism and physiology can provide potential therapeutic strategies for treating intestinal diseases. Herein, we review recent evidence to recapitulate the mechanisms of synthesis, secretion, regulation, and biofunction of 5-HT to improve the nutrition and health of humans.

The internal anatomy of the woodlouse, Metoponorthus pruinosus (Brandt), (Porcellionidae, Peracarida)

1968 ◽  
Vol 46 (3) ◽  
pp. 321-327 ◽  
Author(s):  
M. A. Alikhan
Keyword(s):  
Nervous System ◽  
Digestive System ◽  
Circulatory System ◽  
Reproductive Organs ◽  
The Body ◽  
Internal Anatomy ◽  
Suboesophageal Ganglion ◽  
Digestive Tube ◽  
Thoracic Ganglia ◽  
Digestive Glands

Tbe circulatory system, lying in the mid-dorsal line of the body, consists of an oval heart, the opthalmic artery, and a dorsal abdominal artery.The digestive system comprises a wide, large alimentary tube and two pairs of digestive glands. An oesophagus, a proventriculus, midgut, and a short proctodacum or hindgut form the digestive tube. The digestive glands are very well developed and are beaded in form; each pair lies on either side of the alimentary canal.The reproductive organs are well developed in both sexes: in the male they consist of paired testes and their vas deferentia, and in the female paired bilobed ovaries and oviducts.A cerebral or supraoesophageal ganglion, a suboesophageal ganglion, and seven thoracic ganglia form the nervous system. The supraoesophageal ganglion is united with the suboesophageal ganglion by means of the circumoesophageal commissures, whereas the thoracic ganglia and suboesophageal ganglia are linked with each other by paired connectives.The gills and the tracheae are the organs of respiration. The gills are borne of the bases of the pleopods and are enclosed in the branchial chamber. The tracheae are located on the lateral lobes of the first two pleopods only.

Study of electrical conductivity of biologically active points on the skin before and after mental activity

Vestnik ◽  
2021 ◽  
pp. 190-195
Author(s):  
М.С. Кулбаева ◽  
А.Н. Курал ◽  
Л.Б. Умбетьярова ◽  
Н.Т. Аблайханова ◽  
Г.К. Атанбаева ◽  
...  
Keyword(s):  
Physiological State ◽  
Mental Activity ◽  
The Body ◽  
Biologically Active ◽  
Mental Work ◽  
Heart Meridian ◽  
Before And After ◽  
Specific Organ ◽  
The Brain ◽  
Biologically Active Points

Человека давно интересует вопрос о том, как умственная нагрузка влияет на организм. Известно, что при длительной умственной работе преобразуется сила процессов возбуждения и торможения, изменяется соотношение между ними. С возникновением утомления в головном мозгу нарушаются взаимосвязи между корой больших полушарий и подкорковыми образованиями. При этом наблюдается снижение регулирующего влияния больших полушарий на все функции организма и уменьшение активизирующих воздействий подкорковых отделов мозга. Кроме того, длительное сидячие положение, состояние низкой двигательной активности ведут к значительному уменьшению центростремительных импульсов с рецепторов мышц, сухожилий, суставов. В исследовании приняли участие 17 относительно здоровые, имеющие стабильное физиологическое состояние девушек-студенток в возрасте от 21 до 25 лет. Для исследования были взяты 16 биологически активных точек на стандартных меридианах, связаных с определенным органом. Для оценки физиологического состояния органов до и после умственной нагрузки были исследованы показатели ЭП БАТ на коже. Выявлено снижение показателей каждого органа после умственной нагрузки по сравнению с показателями до ее выполнения со статистической достоверностью во всех исследуемых органах (р<0,05). Особенно низкие значения показателей ЭП БАТ после умственной нагрузки были выявлены в биоактивных точках меридиана печени F.3 Тай-Чун, меридиана толстой кишки GI.5 Ян-Си и GI.4 Хэ-Гу, меридиана сердца С.7 Шэнь-Мэнь, меридиана тонкой кишки IG.1 Шао-Цзе и IG.2 Цянь-Гу, меридиана почек R.1 Юн-Цюань и Р.2 Жань-Гу. Humans has long been interested in the question of how mental activity affects the body It is known that with prolonged mental work, the strength of the processes of excitation and inhibition is transformed, the ratio between them changes. With the onset of fatigue in the brain, the relationship between the cerebral cortex and subcortical formations is disrupted. At the same time, there is a decrease in the regulatory influence of the large hemispheres on all body functions and a decrease in the activating effects of the subcortical parts of the brain. In addition, prolonged sitting, a state of low motor activity leads to a significant decrease in centripetal impulses from the receptors of muscles, tendons, and joints. The study involved 17 relatively healthy, stable physiological condition of female students aged 21 to 25 years. For the study, 16 biologically active points were taken from standard meridians associated with a specific organ. To assess the physiological state of the organs before and after the load of mental labor, the indicators of EC BAP on the skin. A decrease in the indicators of each organ after mental labor was revealed in comparison with the indicators before mental labor with statistical reliability in all the studied organs (p˂0.05). Especially low values of the EC BAP values after a load of mental labor were found in the bioactive points of the liver meridian F. 3 Tai-Chun, the colon meridian GI.5 Yang-Si and GI. 4 He-Gu, the heart meridian C. 7 Shen-Men, the small intestine meridian IG.1 Shao-tse and IG.2 Qian-Gu, the meridian of the kidneys R. 1 Yun-Chuan and R. 2 Zhan-Gu.

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