elastic lamina

Examples of elastic lamina in the following topics:

• Muscular Arteries

  • Distributing arteries are medium-sized arteries that draw blood from an elastic artery and branch into resistance vessels.
  • Muscular or distributing arteries are medium-sized arteries that draw blood from an elastic artery and branch into resistance vessels, including small arteries and arterioles.
  • In contrast to the mechanism elastic arteries use to store and dissipate energy generated by the heart's contraction, muscular arteries contain layers of smooth muscle providing allowing for involuntary control of vessel caliber and thus control of blood flow.
  • Muscular arteries can be identified by the well-defined elastic lamina that lies between the tunicae intima and media.

• Coronary Artery Disease

  • Characteristics of atherosclerosis shown here include thickening of the tunica intima, fragmentation of the internal elastic lamina (a very thin black wavy layer) between the intima and media, partial duplication of the internal elastic lamina, smooth muscle infiltration of the intima (from the media, red staining of the intima), and luminal narrowing.

• Blood Vessel Structure

  • The tunica intima is surrounded by a thin membrane comprised of elastic fibers running parallel to the vessel.
  • Surrounding the tunica intima is the tunica media, comprised of smooth muscle cells and elastic and connective tissues arranged circularly around the vessel.
  • Fiber composition also differs; veins contain fewer elastic fibers and function to control caliber of the arteries, a key step in maintaining blood pressure.
  • The outermost layer is the tunica externa or tunica adventitia, composed entirely of connective fibers and surrounded by an external elastic lamina which functions to anchor vessels with surrounding tissues.
  • This diagram of the artery wall indicates the smooth muscle, external elastic membrane, endothelium, internal elastic membrane, tunica externa, tunica media, and tunica intima.

• Hemidesmosomes

  • Anchoring filaments traverse the lamina lucida space and appear to insert into the electron dense zone, the lamina densa.
  • Beneath the lamina densa, loop-structured, cross-banded anchoring fibrils extend more than 300 nm beneath the basement membrane within the papillary dermis.
  • The length of these loops may enable them to link or encircle dermal collagen fibers or other components such as those of the elastic microfibril network.
  • In a normal mouse (a) there are well-defined, organized hemidesmosomes with darkened areas in the lamina densa abutting the hemidesmosome (arrows).

• Basement Membranes and Diseases

  • The basement membrane is the fusion of two lamina: the basal lamina and the reticular lamina (or lamina reticularis).
  • The lamina reticularis is attached to the basal lamina with anchoring fibrils (type VII collagen fibers ) and microfibrils (fibrillin).
  • The basal lamina layer can further be divided into two layers: the clear layer closer to the epithelium is called the lamina lucida, and the dense layer closer to the connective tissue is called the lamina densa.
  • The electron-dense lamina densa membrane is about 30–70 nanometers in thickness, and consists of an underlying network of reticular collagen (type IV) fibrils (fibroblast precursors) which average 30 nanometers in diameter and 0.1–2 micrometers in thickness.
  • The most notable examples of basement membranes are in the glomerular filtration of the kidney, by the fusion of the basal lamina from the endothelium of glomerular capillaries and the basal lamina of the epithelium of the Bowman's capsule; and between lung alveoli and pulmonary capillaries, by the fusion of the basal lamina of the lung alveoli and of the basal lamina of the lung capillaries, which is where oxygen and CO2 diffusion happens.

• Definition of Price Elasticity of Supply

  • The state of these factors for a particular good will determine if the price elasticity of supply is elastic or inelastic in regards to a change in price.
  • Supply is "perfectly elastic."
  • An increase in price for an elastic good has a noticeable impact on consumption.
  • The elasticity of a good will be labelled as perfectly elastic, relatively elastic, unit elastic, relatively inelastic, or perfectly inelastic.
  • Differentiate between the price elasticity of demand for elastic and inelastic goods

• Types of Leaf Forms

  • Leaves may be categorized as simple or compound, depending on how their blade (or lamina) is divided.
  • There are two basic forms of leaves that can be described considering the way the blade (or lamina) is divided.
  • In simple leaves, the lamina is continuous.
  • In compound leaves, the lamina is separated into leaflets.

• Income Elasticity of Demand

  • A positive income elasticity is associated with normal goods.
  • A negative income elasticity is associated with inferior goods.
  • In all, there are five types of income elasticity of demand :
  • Zero income elasticity of demand (YED=0): A change in income has no effect on the quantity bought.
  • Income elasticity of demand measures the percentage change in quantity demanded as income changes.

• Tax Incidence and Elasticity

  • Tax incidence or tax burden does not depend on where the revenue is collected, but on the price elasticity of demand and price elasticity of supply.
  • The key concept is that the tax incidence or tax burden does not depend on where the revenue is collected, but on the price elasticity of demand and price elasticity of supply.
  • If the consumer is elastic, the consumer is very sensitive to price.
  • Because the consumer is elastic, the quantity change is significant.
  • Explain how elasticity influences the relative tax burden between suppliers and consumers (demand).

• Measuring the Price Elasticity of Supply

  • The price elasticity of supply is the measure of the responsiveness of the quantity supplied of a particular good to a change in price.
  • The price elasticity of supply is directly related to consumer demand.
  • The elasticity of a good provides a measure of how sensitive one variable is to changes in another variable.
  • When calculating the price elasticity of supply, economists determine whether the quantity supplied of a good is elastic or inelastic.
  • PES = infinity: Supply is perfectly elastic.