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Evgen [1.6K]
3 years ago
12

Which of the following is a role of lymph nodes?

Biology
1 answer:
maxonik [38]3 years ago
4 0

Answer: They filter lymph.

Explanation: Lymph nodes filter lymph, a fluid that comes from the blood plasma and passes through the lymph nodes; small structures that consist of immune cells. Their function is to engulf foreign parcticles. They prevent these foreign matters from circulating in the blood stream, playing a very important role in the immune system.

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The bacteria have an initial concentration of 1000 cells/cm3 . Each cell divides once every 30 minutes. Calculate how long it wi
Levart [38]

It will take <u>120 minutes</u> for the concentration to become > 15000 cells/cm³

<u>Given data:</u>

Initial concentration ( density ) = 1000 cells / cm³

Target/final concentration = > 15,000 cells /cm³

<h3 /><h3>Calculating the concentration every 30 minutes </h3><h3 />

<em>note</em><em> : Given that each cell divides every 30 minutes </em>

  • <u>After the first 30 minutes </u>

Concentration = 2000 cells / cm³

  • <u>After 60 minutes </u>

concentration = 4000 cells / cm³

  • <u>After 90 minutes </u>

concentration = 8000 cells / cm³

  • <u>After 120 minutes </u>

concentration = 16000 cells / cm³

Therefore after 120 minutes the concentration of the cells will be greater than 15000 cells/cm³ ( i.e. 16000 cells/cm³ )

Learn more about concentration : brainly.com/question/17206790

4 0
2 years ago
Hey can someone help me with a question?
SIZIF [17.4K]

the answer you are looking for is option d

7 0
3 years ago
Which of the following accurately describes nutrient limitation?
Studentka2010 [4]
When an ecosystem has a scarce nutrient, that is when there is a nutrient limitation.

So the answer is C. <span>Nitrogen is typically the limiting nutrient in freshwater environments.

This is because Nitrogen is the "scarce" nutrient </span>
6 0
3 years ago
Autonomic dysreflexia is characterized by a. hypotension and shock. b. hypertension and bradycardia. c. pallor and vasoconstrict
omeli [17]

Answer:

B) hypertension and bradycardia.

Explanation:

Autonomic dysreflexia is a syndrome which is characterised by the sudden rise in the blood pressure of the human. The disease is common in the people with a higher level of spinal cord injuries above the T6 level.

The condition occurs when some external stimuli like pain or irritant activate the involuntary response in the body which cause the blood pressure to rise (hypertension). This leads to the slowdown of the heartbeat (bradycardia) to restore the blood pressure but the body cannot restore the blood pressure due to the damage in the spinal cord.

Thus, Option-B is the correct answer.

8 0
3 years ago
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
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