5.) A target cell is the cell that a hormone acts on when you are referring to the endocrine system. For example, the target cells of human growth hormone, a chemical messenger, are bone cells. This results in the growth of the person's body as additional bone cells are produced. When referring to the immune system, target cells are cells in the body that are not recognized as "self" and are then the recipient of the immune response. In this case, cells such as bacteria, viruses or mutated cells will be targeted by white blood cells and antibodies to be destroyed. The expression "target cell" makes one think of a cell with a bullseye to be targeted for some reaction to occur inside the body in an attempt to maintain homeostasis.

Neurosecretory cells are specialized nerve cells that produce and secrete hormones. Well-known examples of neurosecretory cells are oxytocin- and vasopressin-secreting neurons in the hypothalamus and cells in the adrenal medulla. These cells are found in vertebrates and invertebrates.

6.) A traditional part of the definition of hormones described them as being secreted into blood and affecting cells at distant sites. However, many of the hormones known to act in that manner have been shown to also affect neighboring cells or even have effects on the same cells that secreted the hormone. Nonetheless, it is useful to be able to describe how the signal is distributed for a particular hormonal pathway, and three actions are defined: * Endocrine action: the hormone is distributed in blood and binds to distant target cells. * Paracrine action: the hormone acts locally by diffusing from its source to target cells in the neighborhood. * Autocrine action: the hormone acts on the same cell that produced it. if you have studied enzymes its a similar concept. Cells have proteins on the surface of their cell which hormones bind to (called receptors) The receptor must be a complimentary shape to the hormone for it to bind. Only target cells have the receptor with the complimentary shape so only these cells will be affected.

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10.) The hypothalamic–pituitary–thyroid axis (HPT axis for short, aka thyroid homeostasis or thyrotropic feedback control) is part of the endocrine system responsible for the regulation of metabolism.

As its name suggests, it depends upon the hypothalamus, the pituitary gland, and the thyroid gland.

The hypothalamus senses low circulating levels of thyroid hormone (T3 and T4) and responds by releasing thyrotropin-releasing hormone (TRH). The TRH stimulates the pituitary to produce thyroid-stimulating hormone (TSH). The TSH, in turn, stimulates the thyroid to produce thyroid hormone until levels in the blood return to normal. Thyroid hormone exerts negative feedback control over the hypothalamus as well as anterior pituitary, thus controlling the release of both TRH from hypothalamus and TSH from anterior pituitary gland.

firstly, for an hormone to be released, something must be a trigger. The trigger can be a change in the chemical or osmotic balance of the body. The hypothalamus first notices this. Then, it gives proper response by stimulating other organs that actually release the hormone. We know the pituitary gland as the master gland. It's anterior and posterior lobes release different hormones.
The hypothalamus sends the signal to the anterior lobe by releasing chemical secretions into the bloodstream called FACTORS. For example, the factor that stimulates the release of thyroxine is called thyroid releasing factor (T.R.F) which stimulates thyroid stimulating hormone production which further stimulates the thyroid gland to produce thyroxine. It is the hypothalamus that produces such factors.
The posterior lobe of the pituitary gland receives instruction from the hypothalamus to secrete an hormone by electrical impulses. This is because the hormones in the posterior lobe are actually produced by the hypothalamus itself. It only stores the hormone in the posterior lobe.
Furthermore, the hormones in the pituitary gland also stimulates the release of other hormones in the body. For instance, follicle stimulating hormone and luteinising hormone contribute to the release of progesterone and oestrogen.
Basically, the hypothalamus detects the change and sends the instruction to the pituitary gland and other hormone producing organs for appropriate response.
The hypothalamus is the link between the nervous system and the endocrine system.

You should think of each hormone, whether from the anterioir or posterior pituitary as unique, with it's own unique set of functions and regulatory mechanisms.

There are two hormones which come from the posterior pituitary: Vasopressin (also known as antidiuretic hormone) and Oxybutinin. Vasopressin main role is to make sure we have enough water flowing through our blood vessels, permitting normal blood pressures and delivery of the oxygen/nutrients to all our tissues. Oxybutinin is involved in the contraction of the uterus during delivery of a baby. Both of these hormones are actually made in the neurons of the hypothalamus (part of the brain), which is directly/physically connected to the posterior pituitary. They are made in the hypothalamus, but secreted by the posterior pituitary gland. (So the posterior pituitary can be thought of as an extension of the brain!)

The anterior pituitary makes many more hormones, including thyroid stimulating hormone (regulates/stimulates the thyroid gland), prolactin (stimulates breast milk production), growth hormone (stimulates cellular growth and metabolism), luteinizing and follicle stimulating hormones (both are involved in the female menstrual cycle and ovulation), and adrenocorticotrophic hormone (stimulates/regulates the adrenal gland). Each of these hormones have unique activaties and regulatory mechanisms...they just happen to be made close to each other within the body (the anterior pituitary).

The Hypothalamus is a bundle of specialized cells in the brain that is the link between the endocrine system and the nervous system. The pituitary gland is the master gland of the endocrine system that secretes hormones. The hypothalamus influences the pituitary gland by releasing special chemicals that stimulate or decrease the production of hormones released by the gland.

Some of the hormones synthesized and secreted by the special neurons of the hypothalamus are called hypothalamic releasing and inhibiting hormones or factors. They act directly on the tissues of the anterior pituitary gland. Some of the major hypothalamic factors are: thyroid-stimulating hormone releasing hormone (TRH), which activates the release of the thyroid-stimulating hormone (TSH) from the anterior lobe of the pituitary gland; corticotropin-releasing factor (CRF); growth hormone releasing factor (GHRF); gonadotropin releasing hormone (GnRH); and prolactin-inhibiting factor (PIF).
Oxytocin in a nine amino acid peptide that is synthesized in hypothalamic neurons and transported down axons of the posterior pituitary for secretion into blood.
Antidiuretic hormone, also known commonly as arginine vasopressin, is a nine amino acid peptide produced in the hypothalamus and secreted from the posterior pituitary.

Secretions of the anterior and posterior pituitary are usually controlled by the hypothalamus in the brain.

Under the guidance of the hypothalamus, the anterior pituitary produces and secretes several peptide hormones that regulate many physiological processes including stress, growth, and reproduction. Unlike the posterior pituitary (pars nervosa), which originates from neural ectoderm, the anterior pituitary arises from an invagination of the oral mucosa called Rathke's pouch (which is itself ectoderm derived).

This differentiation is exhibited by the fact that while the posterior pituitary merely secretes those hormones produced in the hypothalamus (ADH and oxytocin), the anterior pituitary actually produces its hormones, while being under control of the hypothalamus as to when they should be secreted.

Adrenocorticotropic hormone

Endorphins

Follicle-stimulating hormone

Luteinizing hormone (females), Interstitial Cell Stimulating Hormone (males)

Human growth hormone

Prolactin

Thyroid-stimulating hormone

**A useful acronym for the hormones secreted by the anterior pituitary is 'B-FLAT A-PEG' (Basophils release FSH, LH, ACTH, TSH, and Acidophils release Prolactin, Endorphins, GH).

Yes ADH antidiuretic hormone also called vasopressin and Owytocin

And all others by the anterior pituitary

And Gh is controlled by the hypothalamus but produced by the anterior pituitary

12.) In general antagonistic effects mean that two things have the opposite effect. In terms of hormones this means that two hormones have the opposite effect on what is being regulated. So insulin lowers blood glucose levels and glucagon raises blood glucose levels; calcitonin lowers serum calcium levels and parathyroid hormone raises it. This idea is often used to explain various types of homeostasis in the body - keeping some parameter at a constant level by raising or lowering it when needed.

Insulin and glucagon regulate the concentration of glucose in the blood. When the blood sugar is too high, insulin is released to trigger the absorption of glucose from the blood, to decrease the blood glucose concentration. When the blood glucose it too low, glucagon promotes the release of glucose into the blood. So, insulin and glucagon have an antagonistic relationship because although they are both responsible for returning the blood sugar to normal, insulin absorbs excess glucose while glucagon returns glucose to the blood when there is not enough.