Answer:
The correct answer will be option-C
Explanation:
The rhythm of the heartbeat is controlled by the pacemaker of the heart called the sino-atrial node.
The SA node generates action potentials which trigger the contraction and relaxation of the atrium and ventricles. The membrane potential generation initiates by the depolarization of the cell membrane when the L type of Ca⁺² ions opens up and calcium ions enter the cell.
This depolarizes the cell until the potential threshold is reached which lies between the -40 and -30 mV.
Thus, Option-C is the correct answer.
Cations are positive so they have less electrons than protons, while anions are negative so they have more electrons.
The correct answer of the given question above is option A. The line of defense that his immune system is exhibiting in this situation is the first line of defense. The first line of defense includes the physical or external line of defense of the body that are responsible for inhibiting of the entry of foreign microorganisms. Such include the skin, tears, cilia, mucus, urine flow and even stomach acid.
C. Movement of the human body
Skeletal muscles gives us the ability to move
Answer:
5%
Explanation:
The adrenal cortex in both males and females produce a small amount of weak androgens. One of the major weak androgen secreted by adrenal cortex is dehydroepiandrosterone (DHEA).
Levels of dehydroepiandrosterone secretion exhibit changes with age. The dehydroepiandrosterone secretion increases till the age of 20-24 years and falls off with increasing age after the age of 30 years in both males and females. The DHEA production at the age of 80 years is about 5% of its secretion at the age of 30 years.
