(d) Leydig cells produce androgens (mainly testosterone). Androgens play a major stimulatory role in spermatogenesis.
(c) Insulin stimulates conversion of glucose to glycogen (glycogenesis) in target cells, decreasing blood glucose.
(b) Thyroid gland secretes thyroxine. Lack of iodine results in goitre.
(b) Steroid hormones pass through the plasma membrane and bind to intracellular receptors, then bind to DNA triggering gene transcription.
(c) Insulin deficiency leads to diabetes mellitus.
Thyroxine hyper/hyposecretion causes goitre.
Deficiency of corticoids leads to Addison's disease.
Overproduction of growth hormone by pituitary causes acromegaly.
(d) Deficiency of iodine causes hypothyroidism during pregnancy, leading to stunted growth, mental retardation (cretinism) and abnormal skin.
(a) GnRH pulse frequency is controlled by feedback from progesterone and estrogens.
(d) Relaxin and Inhibin are not antagonistic; relaxin softens pelvic ligaments while inhibin inhibits FSH secretion.
(a) Epiphyseal plates close after adolescence, preventing further bone growth.
(a) Cortisol increases blood glucose level (anti-insulin effect) by converting proteins and fats into glucose.
