Test: Human Endocrine System - NEET MCQ

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.

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.

• The hormone secreted by the inner part of adrenal gland is mainly responsible for controlling the blood pressure in emergency.
• Under emergency conditions, it initiates a quick reaction to control the blood pressure by increasing heart rate and force of heart contractions.

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.

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.

Cortisol affects muscle tissue balance by increasing protein breakdown and decreasing protein synthesis, thus it is a catabolic hormone.

Thymus is known as the training school of T-lymphocytes and is responsible for the proliferation and maturation of T-lymphocytes.

Adrenocorticotropic hormone is secreted by anterior pituitary. This hormone stimulates adrenal cortex to secrete its hormones.

Islets of Langerhans are found in pancreas. It consists of four types of cells - alpha cells that secrete glucagon, β-cells that secrete insulin, delta cells that secrete somatostatin and F cells that secrete pancreatic polypeptide.

Ovulation in females is under the control of luteinsing hormone (LH). Secreted by the anterior pituitary gland. It also stimulates development of corpus luteum.

Pineal body is a very small, reddish-grey, vascular, conical, solid body located in the brain. It secretes a hormone named melatonin. Melatonin makes the skin colour lighter in certain animals and also regulates the functioning of gonads, thus, controls sexual behaviour and regulates the period of puberty.

Insulin hormone produced by beta cells of pancreas, is central to regulating carbohydrate metabolism in the body. It causes cells in the skeletal muscles, and fat tissue to absorb glucose from the blood.

Glucagon secretion increases with low blood glucose to raise the concentration of glucose in the bloodstream. Exercise also stimulates secretion of glucagon.

Calcitonin is a hormone secreted by the thyroid gland. It lowers the calcium level in the blood by suppressing the release of calcium ions from the bones.

Adrenal gland is called the emergency gland of the body. Adrenaline is secreted by adrenal medulla on stimulation by sympathetic nervous system for meeting an emergency of stress condition, like injury, pain fear, Accident, grief, fall in blood pressure etc. Hence adrenal gland is called emergency hormone.

Thyroid stimulating hormone (TSH) is produced by the anterior lobe of the pituitary and it stimulates production and secretion of thyroid hormones.

Calcium plays an important role in blood clotting. Parathormone, a hormone released by parathyroid glands, increases calcium level in the blood. Therefore, deficiency of this hormone will decrease Ca²⁺ level in blood, thus leading to delay in blood clotting and increase in bleeding time.

Estrogen, secreted by ovaries in females, stimulates the development of secondary sexual characters during puberty and maintains them through the reproductive years of adult life in females Testosterone is produced by testes in males, it stimulates the development of male secondary sexual characters like beard, moustache, etc.