The human immunodeficiency virus (HIV) that causes the disease known as aids selectively infects helper T cells (CD4+).
This retrovirus also infects macrophages and dendritic cells. When CD4+ T cell numbers decrease below a critical level (due to the killing of this cells with different mechanisms), cell-mediated immunity is lost. As a result, the body becomes progressively more susceptible to infections, leading to the development of AIDS.
<span> HIV can be transmitted only via body fluids like blood, semen, pre-seminal fluid, rectal fluids, vaginal fluids, and breast milk, which means that people usually get or transmit HIV through sexual behaviours and use of the needle. For HIV infection, these fluids must come in direct contact with a mucous membrane or damaged tissue. Another way is to be directly injected into the bloodstream (from a needle for example).</span>
The answer is D as there are fluctuations which means that changes in the population of one affects the population of the other. as prey pop increases predator pop increases leading to a decease in prey pop which causes predator pop to decrease due to lack of food then prey increases and the cycle repeats
The correct answer is: prevent reception of a signal in a receiving neuron
Neurotransmitters are signal molecules or chemical messengers which transmit signals across a chemical synapse. Neurotransmitters send the signal, from one neuron (nerve cell) to another neuron, from neuron to muscle cell (motor plate), or from neuron to gland cell.
Drugs that bind to neurotransmitter’s receptor can have two effects on its action:
• Antagonists-they bind to receptor and thus prevent a neurotransmitter from binding to it
• Agonists-they bind to receptor and mimic the normal neurotransmitter (have the same effect as neurotransmitter).
Answer:
heterozygous A father and heterozygous B mother
Explanation:
