Answer:
The correct answer will be option-A
Explanation:
Electrocardiogram or ECG is the recording and representation of the electrical changes that are taking place during the cardiac cycle.
The QRS complex is preceded by the P wave or atrial systole or atrial depolarization after which the electrical signals are passed on to the AV node.
As soon as the AV node passes the electrical signals to bundle of His, it is observed in as the QRS interval which represents the atrial diastole and the onset of ventricular depolarization.
Thus, option-true is the correct answer.

I believe the answer is...
Taking medicine in a pill form.
Hopefully, this helps you!!

Answer:
The correct answer is option E. only water-soluble hormones use second messengers.
Explanation:
Water soluble hormones can not diffuse through cell membranes as only lipid soluble molecules can pass through the cell membranes and these hormons are not lipid soluble molecules,
These water hormones are usually glycoproteins, peptide and catecholamnies such as TSH, FSH, LH and insulin. these hormones need second messengers because there receptors are present on the plasma membrane.
Thus, the correct answer is option - e. only water-soluble hormones use second messengers.
Answer:
I am certain 2 of out 3 of these are part of it
Explanation:
I forgot if alveoli is part of it.