Answer:
Having considered how an appropriate primary immune response is mounted to pathogens in both the peripheral lymphoid system and the mucosa-associated lymphoid tissues, we now turn to immunological memory, which is a feature of both compartments. Perhaps the most important consequence of an adaptive immune response is the establishment of a state of immunological memory. Immunological memory is the ability of the immune system to respond more rapidly and effectively to pathogens that have been encountered previously, and reflects the preexistence of a clonally expanded population of antigen-specific lymphocytes. Memory responses, which are called secondary, tertiary, and so on, depending on the number of exposures to antigen, also differ qualitatively from primary responses. This is particularly clear in the case of the antibody response, where the characteristics of antibodies produced in secondary and subsequent responses are distinct from those produced in the primary response to the same antigen. Memory T-cell responses have been harder to study, but can also be distinguished from the responses of naive or effector T cells. The principal focus of this section will be the altered character of memory responses, although we will also discuss emerging explanations of how immunological memory persists after exposure to antigen. A long-standing debate about whether specific memory is maintained by distinct populations of long-lived memory cells that can persist without residual antigen, or by lymphocytes that are under perpetual stimulation by residual antigen, appears to have been settled in favor of the former hypothesis.
He ovary would not release the egg, i.e. ovulation would not happen.
the egg would not be released into the fallopian tube
A)Antibiotics can always be used to treat bacterial infections.
Answer:
The correct answer is: Electrical impulses in the heart cause the muscles to contract.
Explanation:
The heart contracts thanks to a series of electrical impulses that travel through the muscles of this organ. The electrical impulse begins in the SA (sinoatrial) node and is transmitted to the muscles that conform the left and the right atria to produce their contraction which will make the atria pump the blood to the ventricles. When the electrical impulse reaches the AV node and then the Bundle of His, this information will transmit to both ventricles and will produce their contraction as well.
The only muscle tissue capable of stimulating their own contractions is the muscle in the heart, the myocardium, thanks to the existence of "pacemaker cells" that are located in the SA node.
The waves in the ECG represent the depolarization of the atria, depolarization of the ventricles, and repolarization of the ventricles.
