The cardiovascular system
C. Simon Herrington in Muir's Textbook of Pathology, 2020
The heart is adapted as a pump, although, in each part of the circulation, tubes are structurally adapted to the pressure and flow of blood within them. Conductance arteries such as the aorta absorb the impulse of cardiac systole, and elastic recoil maintains blood flow in diastole. Hence, the wall of the aorta contains multiple layers of elastic tissue (Figure 7.1). On the arterial side of the circulation, the blood flow is at a high pressure of at least 100 mmHg, so the vessels have thick muscular walls. The more muscular, medium-sized arteries regulate distribution of blood to the various organs by vessel constriction and dilatation, so they have a thick medial wall with less elastic tissue (Figure 7.2). The veins contain blood at a low or even a negative pressure. They act as capacitance vessels and a reservoir of the circulation; thus, they have a large lumen and a thin wall (Figure 7.3). Excessive hypercontraction of the vessels causes hypertension. Hyperaemia is increased blood flow and is due to dilatation of the arteries and arterioles. It occurs in skeletal and heart muscle during exercise. There may also be excessive blood flow with blushing noticeable in the skin on exercise. Excessive dilatation is also associated with septic shock.
Control of blood vessels: intrinsic control
Neil Herring, David J. Paterson in Levick's Introduction to Cardiovascular Physiology, 2018
As the celebrated 18th century anatomist John Hunter pointed out, blood flow goes where it is needed. When the metabolic activity of the myocardium, skeletal muscle or cerebral neurons increases, the blood flow to the active region increases substantially, within seconds (Figures 13.1, 13.7 and 13.8). This metabolism-driven increase in blood flow is called functional hyperaemia or metabolic hyperaemia or metabolic vasodilatation. Metabolic hyperaemia is graded, so O2 delivery increases in proportion to O2 demand (Figure 15.4). The hyperaemia is caused by vasodilator substances released from the active cells, as indicated by experiments in which the fluid bathing stimulated cardiac myocytes acquires a vasodilator capacity, in proportion to stimulation intensity. The metabolic vasodilators act locally on the resistance vessels within the active tissue, with the more distal, smallest resistance vessels showing greater sensitivity than the more proximal, larger vessels (Figure 13.9). However, despite a century of research we still do not know for certain which agents account for metabolic hyperaemia. K+, H+ (acidosis), hypoxia, adenosine, adenosine triphosphate (ATP), phosphate ions, hyperosmolarity and hydrogen peroxide (H2O2) all increase in the interstitium with increased tissue activity, and each has a vasodilator effect. Their relative importance seems to depend on the time point and the tissue. K+ and CO2, for example, are particularly important regulators of cerebral vessels, while K+ and adenosine seem important in striated muscle.
Procedural skills
Jonathan M. Fishman, Vivian A. Elwell, Rajat Chowdhury in OSCEs for the MRCS Part B, 2017
Risks: Increased risk of ischaemic necrosis when operating on appendages supplied by end arteries (digits, penis etc.).Increased risk of cardiac dysrhythmias.It can precipitate critical ischaemia in poorly vascularised tissue.Reactive hyperaemia can occur in the post-operative period with increased risk of bleeding and haematoma.
Luteinised unruptured follicle syndrome: pathophysiological background and new target therapy in assisted reproductive treatments
Published in Journal of Obstetrics and Gynaecology, 2022
Andrea Etrusco, Giovanni Buzzaccarini, Gaspare Cucinella, Antonino Agrusa, Giuseppe Di Buono, Marco Noventa, Antonio Simone Laganà, Vito Chiantera, Giuseppe Gullo
On this regard, Espey proposed the hypothesis of ovulation as an inflammatory process (Espey 1994). This theory is based on the hyperaemia, due to the increased blood flow, and the tissue remodelling by the effect of proteolytic enzymes. The presence of TNF, IL-1, IL-6, GM-CSF, G-CSF and M-CSF in the follicular fluid and in the free fluid collected in the pouch of Douglas (Queenan 1980, Coetsier and Dhont 1996, Hock 1997, Revised American Society for Reproductive Medicine 1997, Qublan 2006) supported this hypothesis. However, if the cytokines participate in the mechanism, their concentration in the follicular fluid must be higher than serum concentration. Based on this, Nishimura et al., Salmassi et al. and Fujii et al. demonstrated that only IL-6, M-CSF and G-CSF showed significantly higher concentration in follicular fluid than in serum and, since granulocyte is the major leukocyte that plays a crucial role during inflammation process, the effects of its stimulating factor, G-CSF, in the mechanism of ovulation were investigated (Fujii 1999, Salmassi et al.2004).
Sonographic findings of immunoglobulin G4-related sialadenitis and differences from Sjögren’s syndrome
Published in Scandinavian Journal of Rheumatology, 2022
Y Liu, Z Wang, L Ren, Q Zeng, Z Wang, W Bian, Y Zhang, J Fu, D Chen, G Yu, S Zhang, Z Li
Colour Doppler sonography has also received a lot of interest in recent years and was analysed in our study. Among the submandibular glands, increased colour Doppler signalling was demonstrated more frequently in patients with IgG4-RS, whereas the colour Doppler sonography of parotid glands revealed no difference between IgG4-RS and SS. Shimizu et al (12) suggested that the nodal and reticular patterns of IgG4-RS show high vascularity, while SS exhibits small dot-like vascularity in the parotid glands, which can make differentiation between IgG4-DS and SS much easier. However, Carotti et al (22) implied that the hypervascular pattern had already been described in the course of autoimmune diseases with exocrine glandular involvement. This probably represents a common and unspecific finding, as hyperaemia is associated with inflammation in this class of diseases. Whether the colour Doppler sonography is helpful for the differentiation between IgG4-RS and SS still remains doubtful. Further studies with a larger sample size may be required.
Oxidative stress and histopathological changes in several organs of mice injected with biogenic silver nanoparticles
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2022
Shushanik Kazaryan, Lilit Farsiyan, Juleta Tumoyan, Gayane Kirakosyan, Naira Ayvazyan, Hrachik Gasparyan, Sona Buloyan, Lilit Arshakyan, Ara Kirakosyan, Ashkhen Hovhannisyan
There are noticeable pathological changes in the kidneys of animals treated with AgNPs, compared to the control group. In the glomeruli, there is glomerulosclerosis with the proliferation of mesangial cells. Also, in arteries of the kidneys was observed hyperplastic atherosclerosis with smooth muscle proliferation. Obstruction of the arteries in some areas of the tissue led to ischaemic processes, as a result, there was focal coagulative necrosis. As well, interstitial nephritis and acute tubular necrosis in some areas of the renal cortex were observed (Figure 1). Statistical comparison of different pathological parameters of the kidney showed that compare to control processes of inflammation and the presence of hyperaemia were significantly higher in this group (p < .05).
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