Chemical Coordination and Integration Test 16

Thyroxine and Triiodothyronine are iodinated form of an amino acid called tyrosine

Glucagon increases blood sugar level. It is secreted by α-cells of islets of Langerhans of pancreas (heterocrine gland).

Thyroid gland stores its hormones in the colloid. Colloid is a homogenous material present in the thyroid follicles of thyroid gland.

Prolactin hormone secreted by the anterior lobe of pituitary stimulates the secretion of milk in females.

Thyroid hormones, thyroxine and tri-iodothyronine regulate the basal metabolism of our body.

Gonadotropic hormones (LH and FSH), secreted by anterior lobe of pituitary regulate growth and activity of gonads.

Luteinising hormone (LH) secreted by the anterior lobe of pituitary gland stimulates corpus luteum of the ovary to secrete progesterone.

Oxytocin, secreted by the posterior pituitary gland causes contraction of smooth muscles of the uterus during child birth.

Secretin hormone is secreted by the Brunner's glands present in the wall of the duodenum.

Middle lobe of pituitary secretes MSH (melanocyte stimulating hormone) that controls the synthesis of melanin granules in the chromatophores.

Adrenaline prepares the body for emergency reactions like fight and flight. Therefore, it directly affects the SA node to increase the rate of heart beat.

Sertoli cells are regulated by FSH secreted by the anterior pituitary.

Adrenaline (Epinephrine) hormone is secreted by adrenal medulla under the conditions of emergency. Therefore, it is also known as emergency hormone. During emergency, it is released and causes dilation of blood vessels, so that the blood flow is increased. It also increases heart beat so that more oxygen is consumed and it also increases blood glucose level.

Parathyroid glands located behind the thyroid gland, produce a hormone called parathormone. This hormone maintains calcium and phosphorus balance in the body. Thus, if a person is having problem with calcium and phosphorus metabolism in the body, this means, his parathyroid gland is not functioning properly.

Parathormone secreted by parathyroid gland regulates the level of calcium in the blood. It stimulates the release of calcium from the bones into the blood, increases calcium absorption from the intestine into the blood and it also increases calcium reabsorption from the nephrons into the blood. Therefore, its deficiency leads to low blood calcium level.

Vasopressin (antidiuretic hormone, ADH) released from posterior pituitary increases reabsorption of water from distal and collecting tubules of the kidney, thus, helping in producing concentrated urine. If there is hyposecretion of vasopressin, then water will not be reabsorbed from the tubules and the urine thus produced will be dilute. This disorder is called diabetes insipidus which is characterised by producing dilute urine several times a day.

The neurosecretory cells of the hypothalamus secrete releasing factors (neurohormones) that regulate the secretion of hormones from the anterior pituitary.

Insulin, glucagon and somatostatin, are secreted by islets of Langerhans of pancreas, Somatostatin suppresses the release of other hormones from pancreas.