Pathology Chapter 11: Blood Vessels

What are the 4 Vascular anomalies?

Developmental or berry aneurysms occur in cerebral vessels; when ruptured, these can cause fatal intracerebral hemorrhage Arteriovenous fistulas are direct connections (usually small) between arteries and veins that bypass capillaries. Like berry aneurysms, arteriovenous fistulas can rupture. Large or multiple arteriovenous fistulas become clinically significant by shunting blood from the arterial to the venous circulations, forcing the heart to pump additional volume and leading to high-output cardiac failure. Fibromuscular dysplasia is a focal irregular thickening in medium and large muscular arteries including renal, carotid, splanchnic, and vertebral vessels, resulting in luminal stenosis. Anomalous coronary artery origin occurs from a developmental anomaly in which both coronary arteries arise over the same coronary cusp of the aortic valve

What's the difference between an embolism and a thrombosis?

Thrombosis occurs when a thrombus, or blood clot, develops in a blood vessel and reduces the flow of blood through the vessel. Embolism occurs when a piece of a blood clot, foreign object, or other bodily substance becomes stuck in a blood vessel and largely obstructs the flow of blood. A similar condition, thromboembolism, refers to a reduction in blood flow that's specifically caused by an embolism from a blood clot.

What type of tissues have the highest density of capillaries? For what reason?

Tissues with high metabolic rates such as myocardium and brain have the highest density of capillaries.

Collectively, _____ have a huge cross-sectional area and also have a relatively low flow rate. The combination of thin walls and slow flow makes _____ ideally suited for the exchange of diffusible substances between blood and tissues

capillaries (x2)

Blood pressure is a function of _____ and _____, both of which are influenced by multiple genetic and environmental factors. The integration of the various inputs ensures adequate systemic perfusion, despite regional demand differences.

cardiac output and peripheral vascular resistance

What two principles underly most vascular diseases?

1. Narrowing (stenosis) or complete obstruction of vessel lumens, either progressively (e.g., by atherosclerosis) or precipitously (e.g., by thrombosis or embolism) 2. Weakening of vessel walls, leading to dilation or rupture

_____ are the principal points of physiologic resistance to blood flow. Since the resistance to fluid flow is inversely proportional to the fourth power of the diameter (i.e., halving the diameter increases resistance 16-fold), small decreases in the lumen size of _____ caused by structural changes or vasoconstriction can have profound effects on blood pressure.

Arterioles (x2)

Arterial wall thickness gradually _____ as the vessels become smaller, but the ratio of wall thickness to lumen diameter _____, allowing these muscular vessels to exert control over blood flow and pressure.

diminishes ; increases

Purely muscular arteries have elastic fibers only at the intersection of the intima and media or media and adventitia. In comparison, the venous system has relatively poorly developed thinner medial layers that permit _____, and the capillary wall permits ready diffusion of oxygen and nutrients because it is comprised only of an endothelial cell and sparse encircling pericytes

greater capacitance

Factors released from the kidneys, adrenals, and myocardium interact to influence vascular tone and to regulate blood volume by adjusting _____

sodium balance

__x__ is a proteolytic enzyme produced by __y__, which are myoepithelial cells adjacent to the glomerular afferent arterioles.

x: Renin y: renal juxtaglomerular cells

Cardiac output is a function of __x__ and __y__. The most important determinant of __x__ is the filling pressure, which is regulated through sodium homeostasis and its effect on blood volume. __Y__ and myocardial contractility (a second factor affecting stroke volume) are both regulated by the α- and β-adrenergic systems, which also have important effects on vascular tone.

x: stroke volume y: heart rate

Peripheral resistance is regulated predominantly at the level of the arterioles by neural and hormonal inputs. Vascular tone reflects a balance between __x__ (including angiotensin II, catecholamines, and endothelin) and __y__ (including kinins, prostaglandins, and NO). Resistance vessels also exhibit autoregulation, whereby increased blood flow induces vasoconstriction to protect tissues against hyperperfusion. Finally, blood pressure is fine-tuned by tissue pH and hypoxia to accommodate local metabolic demands.

x: vasoconstrictors y: vasodilators

What is atelectasis?

Atelectasis is the collapse or closure of a lung resulting in reduced or absent gas exchange

Ectasia meaning

Ectasia, also called ectasis is dilation or distention of a tubular structure, either normal or pathophysiologic but usually the latter (except in atelectasis, where absence of ectasis is the problem).

Many disorders of the vasculature affect only particular types of vessels and thus have characteristic anatomic distributions. Thus _____ affects mainly elastic and muscular arteries, _____ affects small muscular arteries and arterioles, and different varieties of _____ characteristically involve only vessels of a certain caliber.

atherosclerosis ; hypertension ; vasculitis

Arterial walls are thicker than corresponding veins at the same level of branching to accommodate _____

pulsatile flow and higher blood pressures