The Cardiovascular System

Smith, Frank M.; West, Nigel H.; Jones, David R.

doi:10.1016/b978-012747605-6/50010-9

Cited by 48 publications

(51 citation statements)

References 225 publications

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“…On average, the heart rate was 218 ± 13 beats per minute, the duration of Р wave was 29.7 ± 3.7 ms, the РQ interval was 59.3 ± 4.3 ms, the QRS complex was 29.3 ± 2.4 ms and the QT interval was 137.8 ± 7.4 ms. These parameters were in consistent agreement with normal values for chickens (Smith et al, 2000).…”

Section: Resultssupporting

confidence: 87%

“…The RV wall at the heart base is three times thinner than the LV wall (1.3 ± 0.2 vs 4.4 ± 0.7 mm, P b 0.05, n = 6). There is a similar ratio between the thickness of the right and left ventricular free walls in various avian species (Smith et al, 2000). Post-mortem measurements did not show the difference between the MV thickness, obtained in the region of the valve junction with the dorsal side of the interventricular septum (at the fibrous ring), and the RV free wall thickness estimated in the same region (1.6 ± 0.4 vs 1.8 ± 0.3 mm, P N 0.05, n = 6).…”

Section: Resultsmentioning

confidence: 82%

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Does the right muscular atrioventricular valve in the avian heart perform two functions?

Prosheva

Dernovoj

Kharin

et al. 2015

Comparative Biochemistry and Physiology Part A: Molecular &

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 82%

Does the right muscular atrioventricular valve in the avian heart perform two functions?

Prosheva

Dernovoj

Kharin

et al. 2015

Comparative Biochemistry and Physiology Part A: Molecular &

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“…As shown by the passerine data, it is possible that these birds decreased their haematocrit during the endurance flight, possibly by reducing erythropoiesis, to adapt oxygen delivery capacity to the decreasing total oxygen needs as body mass decreases during flight. A decrease in the haematocrit has the additional advantage that blood viscosity is decreased, thereby enabling an increased blood flow (Smith et al 2000); the reason for this being that avian erythrocytes are less deformable and tend to be larger than mammalian erythrocytes, and thus have more difficulties traversing the capillary bed (Smith et al 2000). Therefore, a decrease in the haematocrit would allow a concomitant reduction in heart size or heart beat frequency.…”

Section: Discussionmentioning

confidence: 97%

“…The blood has to transport oxygen, bound to the red blood cells, and metabolites (fuel) in the plasma that are soluble or bound to carrier proteins. Blood viscosity sets an upper limit on the proportion of erythrocytes in total blood (Smith et al 2000) and also on the concentration of metabolites and carrier proteins in the plasma, such as fatty acids bound to albumin (Jenni-Eiermann and Jenni 1992). Thus, the haematocrit, the percentage of packed red blood cells per blood volume, is probably a finely tuned blood parameter that may change at the onset of flight, but also during a migratory endurance flight as the requirements and conditions change.…”

Section: Introductionmentioning

confidence: 99%

Effect of endurance flight on haematocrit in migrating birds

et al. 2006

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The effects of an endurance flight on the haematocrit, the percentage of packed red blood cells per blood volume, were examined within the framework of six possible factors explaining possible changes in the haematocrit. Two approaches were adopted: (1) the haematocrit was studied in four species of passerine birds which landed on an Italian island after having crossed the Mediterranean Sea on their spring migration in a non-stop flight; (2) the haematocrit was evaluated in six individual red knots after a flight of 1, 2, 4 and 10 h in a wind tunnel and the data thus obtained compared with data on resting birds with or without food. In the four passerine species, the haematocrit decreased from 51% in fat birds to 48% in lean birds. In lean birds, the haematocrit dropped from 48% in birds with well-developed breast muscles to 36% in birds with emaciated breast muscles. In the red knots, the haematocrit was dependent on body mass in flying and resting birds. The haematocrit decreased from about 51% pre-flight to about 49% within 1 h of flight and remained at this level for up to 10 h of flight. Taking the results from the passerines and the red knots together, it seems that the haematocrit drops by a few percentage points within 1 h after the onset of flight, decreases very slowly with decreasing body mass and decreases more steeply in very lean birds having entered stage III of fasting. This indicates that dehydration is not an underlying factor in decreased haematocrit because if this were the case we would expect an increase with endurance flight. We found no effect of the presence of blood parasites on haematocrit. With the onset of flight, haemodilution may be adaptive, because it reduces blood viscosity and, thereby, energy expenditure by the heart, or it may be a sign of water conservation as an insurance against the risk of dehydration during long non-stop flights. During endurance flight, a reduction in the haematocrit may be adaptive, in that oxygen delivery capacity is adjusted to the decreased oxygen needs as body mass decreases. A decreasing haematocrit would also allow birds to reduce heart beat frequency and/or heart size, because blood viscosity decreases disproportionally with decreasing haematocrit. However, when energy stores are about to come to an end and birds increase protein breakdown, the haematocrit decreases even further, and birds probably become anaemic due to a reduced erythropoiesis.

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“…14 Normally, avian erythrocytes are less deformable and have a higher concentration of free cytoplasmic hemoglobin than do mammalian erythrocytes. 28 The presence of Heinz bodies causes the normally pliable membranes of red blood cells (RBCs) to become rigid, impeding passage through the microcirculation of the spleen. Such altered cells tend to swell because of alterations in osmotic gradients and membrane permeability and consequently undergo intravascular hemolysis or erythrophagocytosis by the reticuloendothelial system (extravascular hemolysis), primarily in the spleen.…”

Section: Discussionmentioning

confidence: 99%