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Nata [24]
3 years ago
14

What systems work together to detect external stimuli

Biology
1 answer:
Liula [17]3 years ago
6 0
The nervous system and the integumentary system<span />
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Are viral infections curable? Why or why not?
Anna11 [10]

Answer:

no.

Explanation:

Viruses, on the other hand, are not cellular. We can't kill them simply by disrupting their cells. They are infective nucleic acids which cannot replicate outside of living cells. They must invade a human cell to reproduce, because they cannot produce energy or synthesize molecules on their own. Some viruses replicate inside human cells and then bud off from the human cell inside an "envelope" made from the human cell's own membrane, which helps them evade the immune system on their way to infecting another human cell. Many viruses are protected by protein capsids, which are extremely protective--unlike a bacterial cell wall or membrane, the virus doesn't have to be alive inside the capsid or exchange nutrients and waste with the environment across the capsid; the capsid is merely there to protect the nucleic acid of the virus.

Viruses need to match some sort of receptor in order to gain entry into human cells, and in some viruses, this receptor is one of the few good targets for drug therapy; however, unlike antibacterials, the drug will only work for that particular virus/receptor, because each virus uses a different receptor.

Viruses spend time inside human cells, which protects any outer antigens from some of the aspects of the immune system. There are times when viruses are especially vulnerable during replication, but there are reasons they are harder than bacteria to target with these antireplication drugs: 1) unlike for most bacteria, the drugs need to be small enough to enter the human cell where the virus is replicating, 2) unlike for most bacteria, the drugs can't simply target a protein shared by most viruses; furthermore, many viruses hijack human proteins which cannot be targeted. Overall, there are comparatively few antiviral drugs compared to antibiotics because of the huge difficulty in obtaining selective toxicity. And 3) most drugs available target a certain step of viral replication for a certain family of viruses; however, by the time the patient shows symptoms, the virus has already created countless copies of itself or become latent in human cells, and at that point it is too late for most of the antiviral drugs to be super helpful since they target the replication itself. Even when a good antiviral drug is developed, most of them work only against a single species (or at best, a family) of viruses, which is not the case for most antibiotics.

Many viruses don't spread in ways where they can easily targeted (Polio moves from the GI tract to lymph nodes and then to the blood stream on it's way to the spinal cord to cause paralysis; it is vulnerable to the immune system in vaccinated individuals while it is forced to travel in the blood. In contrast, some viruses like rabies, herpes, and varicella-zoster spread through neurons in order to evade the immune system. Other viruses form syncytia because they travel directly from cell to cell). Also remember that some viruses integrate themselves into human DNA and remain latent for long periods of time, which prevents them from being cleared by drugs or the immune system. The human immune system does have its ways of dealing with viruses, which I can get into in greater detail in another post. For certain viruses, the only way we have to treat them is to use interferons to ramp up the immune system (a very unpleasant therapy which must often be maintained for very long periods of time).

One of the reasons that vaccines for some viruses are not effective is that oftentimes, a live (attenuated) vaccine cannot be made for those certain viruses since the reversion mutation rate is too high to provide an acceptable risk; for many viruses, only killed strains can be used, if at all. Without a live attenuated virus strain multiplying inside cells, certain critical aspects of the immune system are not activated against these certain viruses. In cases where killed viruses are able to be used as vaccines, the protection is lesser (for instance, no type-switching to IgA antibodies which would be more effective than IgM) and shorter-lived.

7 0
3 years ago
Read 2 more answers
Given that our model finch population is capable of rapid evolution in response to a changing environment, explain why you think
SIZIF [17.4K]

Darwin's finches are a traditional illustration of an adaptive radiation. Their ancestor came on the Galapagos Island about two million years ago. With time Darwin's finches have developed into fifteen different species separated on the basis of beak shape, body size, and feeding and song behavior.  

The population of finches possesses the tendency of evolving rapidly in response to a changing environment. However, they can also get extinct in condition if the weather fluctuates too briskly between the dry and wet seasons. This would most likely take place due to the immigration of genes and mutations within the genes that are conducted on to the next generations.  


7 0
3 years ago
Study this image of space. A cloud of gas and dust. What object is shown in this image? a nebula a red giant a supernova a neutr
zubka84 [21]

Answer: The image to be studied is missing from the question,so I attached it to my answer,please click on the attachment provided to view the image being studied.

The correct answer to the question is option A.

NEBULA

The object shown in the image is known as a nebula.

Explanation: A nebula is found in interstellar space,it has a form of a giant cloud of dust. When some stars goes into dying process,they explode throwing out gas and dust which forms a nebula.(a supernova remnants nebulae).

Some nebulae(singular form of nebula) are also found where new stars are being formed.

Nebula are the basic building blocks of the universe,they are made up 90% hydrogen,10% helium and other heavier elements in trace amounts from which stars and other solar systems are made.

Nebula exist in 5 distinct types namely;

Emission nebulae, Reflection nebulae,Dark nebulae, Planetary Nebulae and supernova remnants Nebulae.

4 0
3 years ago
What happens when weathering and erosion work together?
egoroff_w [7]
Search Results
Featured snippet from the web
is dissolved, worn away or broken down into smaller and smaller pieces. Once the rock has been weakened and broken up by weathering it is ready for erosion. ... Erosion happens when rocks and sediments are picked up and moved to another place by ice, water, wind or gravity.
5 0
3 years ago
Some lifespan developmentalists use a(n) ____________ approach, drawing on several perspectives.
Zigmanuir [339]

Answer:

Decidable approach

Explanation:they need to make sure how to approach

5 0
3 years ago
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