Answer:
One way in which complement activation destroys pathogens is by C3b binding to the surface of microbes, which then causes inflammation through histamine and heparin release.
Explanation:
C3b binds to the surface of microbes (opsonin), and functions as a component of C3 and C5 convertases while C3a stimulates inflammation.
The alternative pathway of complement activation is triggered by the deposition of C3b on the surface of a microbe. The microbe- bound C3b binds another protein called Factor B, which is then broken down by a plasma protease called Factor D to generate the Bb fragment.
This fragment remains attached to C3b, and the C3bBb complex functions as an enzyme, called C3 convertase, to break down more C3. The C3 convertase is stabilized by properdin, a positive regulator of the complement system.
As a result of this enzymatic activity, many more C3b and C3bBb molecules are produced and become attached to the microbe. Some of the C3bBb molecules bind an additional C3b molecule, and the resulting C3bBb3b complexes function as C5 convertases, to break down the complement protein C5 and initiate the late steps of complement activation.
The main effectors of the complement system are opsonization, cell lysis and inflammation. It also stimulates B cell responses and antibody production.
They use photosynthesis to turn sunlight, carbon dioxide, and water into carbohydrates.
<span>it comes and goes through the madreporite - a small valve like structure</span>
Answer:
(b) Voltage gated
Explanation:
The cell membrane acts as a barrier that separates two aqueous media of different composition, the extracellular and the intracellular, regulating its composition. Most of the liposoluble drugs and solutes, when not ionized, directly cross the cell membrane through a passive diffusion process, which facilitates the passage of the medium where it is more concentrated to the one that is more diluted. The difference in concentration between the two media is called the concentration gradient, and diffusion will continue until this gradient is eliminated. According to Fick's law, the speed of this process will be much faster the higher the concentration gradient and the liposolubility of the molecule and the smaller its size.
More hydrophilic molecules, such as ions, are immiscible in membrane lipids and pass through specific specific transport mechanisms. In some cases, ions pass through hydrophilic pores called ion channels, and in others a favor of their concentration gradient is transported by binding to the transporter or transporter proteins. Both transport systems are passive and therefore do not consume energy. The great advantage is that the ion channels allow the flow of ions through a much higher speed than that of any other biological system. The flow of ions through each channel can be measured as an electric current, which is capable of producing rapid changes in membrane potential.
