Which of the following situations could result in maternal antibodies attacking fetal blood cells during a second pregnancy?

a) Entering the nucleus of a cell and initiating or altering the expression of a gene: Steroid hormones (e.g., cortisol, estrogen) are lipid-soluble and can pass through the cell membrane to bind intracellular receptors, influencing gene transcription.

b) Finding an appropriate cell receptor and initiating cAMP activity: This describes non-steroid hormones (e.g., catecholamines, peptide hormones) using second messenger systems, not steroids.

c) Stimulating the synthesis of glycogen: This is an effect of some hormones (e.g., insulin), but it’s not how steroid hormones act.

d) Increasing blood pressure: While some steroid hormones (like aldosterone) may affect blood pressure, this is not their mechanism of action.

a) Lumen of follicle: Iodide is actively transported into follicular cells, then secreted into the follicular lumen, where it becomes oxidized and incorporated into thyroglobulin during the synthesis of thyroid hormones (T3 and T4).

b) Secretory vesicles inside follicular cells: These vesicles may contain thyroglobulin, but iodide is concentrated in the lumen for hormone synthesis.

c) Golgi apparatus of parafollicular cells: Parafollicular (C) cells produce calcitonin, not thyroid hormones.

d) Cytoplasm of follicular cells: While iodide is transported into the cytoplasm briefly, its major functional location is in the lumen.