Human Endocrine System

The question asks for the INCORRECT statement. Option A states that insulin is a steroid compound, which is FALSE - insulin is actually a peptide hormone (protein) composed of amino acids, not a steroid. All other statements are correct: steroids are used to suppress immune responses after organ transplants, proteases are used in pharmaceutical manufacturing, and some yeasts can metabolize hydrocarbons.

Progesterone belongs to a group of steroid hormones called the progestogens, and is the major progestogen in the body. In mammals, progesterone, like all other steroid hormones, is synthesised from pregnenolone, which in turn is derived from cholesterol.

Neurotransmitters like noradrenaline are released from synaptic vesicles into the synaptic cleft through exocytosis: the vesicle membrane fuses with the presynaptic membrane and dumps contents. Endocytosis brings materials IN, pinocytosis is fluid uptake, and active transport moves individual molecules.

Antidiuretic hormone (ADH, vasopressin) is produced in the hypothalamus but stored in and released from the posterior pituitary into circulation. The anterior pituitary releases different hormones (FSH, LH, ACTH, etc.), and the adrenal cortex releases cortisol and aldosterone.

Enterochromaffin cells  release serotonin.

Relaxin is a hormone produced during pregnancy that specifically targets and relaxes the pelvic ligaments, particularly the pubic symphysis, to widen the birth canal. While it may have some effect on other tissues, its primary and most significant action is on ligament relaxation.

Norepinephrine is a neurotransmitter and hormone that acts as a vasoconstrictor, narrowing blood vessels and thereby increasing blood pressure. It is released by sympathetic nerve endings and the adrenal medulla as part of the fight-or-flight response. The other options are incorrect: urine formation occurs in kidneys, and norepinephrine does not directly stimulate adrenaline secretion.

Myosin is a principal contractile proteins found in muscle which forms thick filaments in myofibrils of muscle fibers.

Hormone adiponectin modulates glucose and lipid metabolism in muscle and liver.

Aldosterone is the mineralocorticoid hormone secreted by the adrenal cortex that specifically regulates sodium and water balance in the kidneys. Adrenalin (epinephrine) and nor-epinephrine are from the adrenal medulla and regulate stress responses, while Corticosterol is not a standard hormone name.

Juvenile hormones (JHs) are a group of acyclic sesquiterpenoids that regulate many aspects of insect physiology.

Adrenaline (epinephrine) is called the emergency hormone because it's rapidly released during stressful situations, triggering the fight-or-flight response. It increases heart rate, blood pressure, and energy availability while redirecting blood to essential organs.

 Gonadotropins are glycoprotein polypeptide hormones secreted by gonadotrope cells of the anterior pituitary of vertebrates.This family includes the mammalian hormones follicle-stimulating hormone (FSH), luteinizing hormone (LH), and placental/chorionic gonadotropins human chorionic gonadotropin (hCG) and equine chorionic gonadotropin (eCG).

Parathyroid hormone is secreted from the four parathyroid glands which are small glands in the neck, located behind the thyroid gland. Parathyroid hormone regulates calcium levels in the blood, largely by increasing the levels when they are too low. It does this through its actions on the kidneys, bones and intestine.

ADH is a hormone that is produced in a part of the brain called the hypothalamus. Absorption of H2O in DCT is controlled by ADH.