Test: Endocrine System- 1 - MCAT MCQ

Key Points

• The pituitary gland, sometimes referred to as the hypophysis, is a tiny, pea-sized gland that is situated beneath the hypothalamus at the base of the brain.
• The sella turcica, a little chamber under your brain, is where it is located. It is a component of your endocrine system and is responsible for producing a number of critical hormones.
• The pituitary gland is known as the "master gland" because by the hormones it generates, it controls and regulates a variety of body processes, including: Growth and sexual/reproductive development and function. 
• Luteinizing hormone is produced by the gonadotropic cells of the anterior pituitary gland. The hypothalamus's gonadotropin-releasing hormone regulates the production of LH. 

Additional Information

• The lymphatic system contains a tiny gland known as the thymus that produces and develops T-cells, specialised white blood cells. T-cells assist your immune system in fighting disease and infection. Before birth, your thymus gland produces the majority of your T-cells.
• A butterfly-shaped gland called the thyroid is located in your neck, slightly above the collarbone. It is one among the hormone-producing endocrine glands in your body. Numerous bodily processes are regulated in terms of speed by thyroid hormones. These include your heart rate and how quickly you burn calories.
• To digest food, the pancreas produces pancreatic enzymes, which are natural fluids. Ducts carry these liquids throughout your pancreas. They discharge into the duodenum, which is the upper portion of your small intestine.

Concept:

• Hormones are non-nutrient chemicals that act as intercellular messengers and are produced in trace amounts.
• The endocrine glands and hormone-producing diffused tissues/cells located in different parts of our body constitute
• the endocrine system.
• The food we consume is mainly comprised of proteins, polysaccharides (carbohydrates), and fats.
• These are first broken down into smaller units: proteins into amino acids, polysaccharides into sugars, and fats into fatty acids and glycerol.

​Explanation:

• The endocrine pancreas secretes glucagon and insulin.
• Glucagon stimulates glycogenolysis and gluconeogenesis
• resulting in hyperglycemia.
• Insulin stimulates cellular glucose uptake and utilization, and glycogenesis resulting in hypoglycemia.
• Insulin deficiency and/or insulin resistance result in a disease called diabetes mellitus.

Thus, High blood sugar level is controlled by insulin.

Additional Information

Key Points

• Liver
  • It is in the upper right section of the abdomen and sits below the diaphragm.
  • It is the largest solid organ and the largest gland in the human body.
  • It carries out over 500 essential tasks.
  • The roles of the liver include detoxification, protein synthesis, and the production of chemicals that help digest food.
  • It is part of the digestive system.
  • Liver is the largest gland.

Additional Information

• Pancreas
  • It is an organ and a gland.
  • he pancreas performs two main functions-
    • Exocrine function: Produces substances (enzymes) that help with digestion.
    • Endocrine function: Sends out hormones that control the amount of sugar in your bloodstream.
• Lungs
  • These are a pair of spongy, air-filled organs located on either side of the chest (thorax).
  • The main function of the lungs is respiration (or breathing).
  • In respiration, oxygen from incoming air enters the blood, and carbon dioxide, a waste gas from the metabolism, leaves the blood.
• Kidney
  • It is made up of about a million filtering units called nephrons. Each nephron includes a filter, called the glomerulus, and a tubule.
  • Kidney remove wastes and extra fluid from human body.

Only three endocrine glands are located in the region of the brain are the hypothalamus, pituitary, and pineal gland.
Key Points

• The hypothalamus is the basal part of the diencephalon of the forebrain.
• It contains a hormone of stimulating and inhibiting the pituitary.
• The pituitary gland is also located at the base part of the brain region just below the hypothalamus and joined together whereas the pineal gland is present in the very deep region where two halves of the brain join together.
• This area is present in the middle of the brain known as the epithalamus.
• It secretes melatonin which functions during the darkness and sends information of night.

Key Points

• The adrenal glands are small glands located on top of each kidney.
• The adrenal cortex produces several hormones.
• The most important are aldosterone (a mineralocorticoid), cortisol (a glucocorticoid), and androgens and estrogen (sex hormones).
• These hormones help regulate metabolism, immune system, blood pressure, response to stress, and other essential functions.

Additional Information
Thyroid gland:

• It produces hormones that regulate the body's metabolic rate-controlling like heart, muscle, and digestive function, brain development and bone maintenance.
• Its good functioning depends on a good supply of iodine from the diet. 

Thymus gland:

• The thymus is a lobed organ situated near the heart and, beneath the breastbone.
• It is quite large at the time of birth but it gradually gets reduced with age.
• The thymus provides the micro-environment needed for the maturation & development of T-lymphocytes.
• The T-lymphocyte cells originate in the bone marrow but migrate or move to the thymus for maturation & development, hence if the thymus gland is removed from the newborn baby T-lymphocyte cells will not form.

Corpus luteum:

• ​The follicular cell is known as the corpus luteum.
• The Corpus luteum is a follicular cell and gets filled with a yellow pigment called lutein.

Concept:

• Growth hormone is released into the bloodstream from the anterior pituitary gland.
• The pituitary gland also produces other hormones that have different functions from growth hormone.
• Growth hormone is produced by the pituitary gland.
  • It has many functions including maintaining normal body structure and metabolism.
  • It is a small pea-sized gland that plays a major role in regulating vital body functions.
  • It is also referred to as the 'master gland' of the human body as it controls the activity of most of the other hormone-secreting glands.

Important Points
Pineal gland:

• The Pineal gland is situated in the middle of the human brain and it is the major site of the body's Melatonin production which is usually secreted in the darkness and thus is sometimes referred to as the “Dracula of hormones”.
• Melatonin is a hormone that regulates the sleep-wake cycle. It is sometimes consumed from external sources by mouth to adjust the body's internal clock, as well as its external supplements, are commonly used for insomnia and improving sleep in different conditions.

Hypothalamus:

• To maintain homeostasis, the hypothalamus is responsible for creating or controlling many hormones in the body. The hypothalamus works with the pituitary gland, which makes and sends other important hormones around the body.

Adrenal gland:

• Adrenaline hormone is secreted by the adrenal glands in the centre of the medulla.
• The main function of adrenaline is to produce contraction of the spleen so as to store the blood, increase heartbeat and sweating, reducing the blood clotting period, and pupillary dilation.

• The Pituitary gland, also known as ‘master gland’, is an endocrine gland.
• A gland is called endocrine gland when it secretes hormones directly into the bloodstream.
• The pituitary gland is called master gland as most of its hormones control the activity of other endocrine glands.
• It produces growth hormones, prolactin, TSH (Thyroid-stimulating hormone), etc.

Key Points

• Growth hormone is released into the bloodstream from the anterior pituitary gland.
• This is controlled by two other hormones that are released from the hypothalamus (a part of the brain): growth hormone-releasing hormone, which stimulates the pituitary to release growth hormone, and somatostatin, which inhibits that release.

Important Points

• The pituitary gland is also called the master gland, controls the function of most other endocrine glands.
• The pituitary, a pea-sized gland at the base of the brain, produces a number of hormones.
• Each of these hormones affects a specific part of the body (a target organ or tissue).

Additional Information

• Adrenaline is produced both by the adrenal glands and by a small number of neurons in the medulla oblongata.
• Its major action, together with noradrenaline, is to prepare the body for 'fight or flight'.
• Insulin is a peptide hormone produced by beta cells of the pancreatic islets.
• Insulin regulates the blood glucose level in the body.
• Thyroxin hormone is produced by the thyroid gland.
• This hormone increases the metabolic rate and so regulates growth and development.

Key Points

• Located in the middle of the brain, the pineal gland is a small gland that is responsible for setting the body's biological clock.
• Circadian rhythms are the rhythms or signals in the body which make an individual wake up, sleep, feel alert or tired around the same time every day.
• The pineal gland secretes melatonin which is a hormone that regulates the circadian rhythm.

Additional Information

• The thymus gland is responsible for the development of the T-lymphocytes and is therefore associated with the immune system of the body.
• The adrenal glands are located on the top of each kidney.
• It secretes adrenaline to help your body respond to stress.
• The hormones secreted by the thyroid gland regulate many vital body functions like body weight, menstrual cycle, heart rate, breathing, etc.

Concept:

• The thyroid gland secretes tetraiodothyronine or thyroxine (T4 ), triiodothyronine (T3 ) and thyrocalcitonin (TCT).
• Thyroid hormones play important role in the regulation of the basal metabolic rate, control metabolism of carbohydrate, proteins and fats.
• The hormones support the formation process of RBCs.

Important Points

• Iodine is essential for the normal rate of hormone synthesis in thyroid gland.
• Iodine plays significant role in the synthesis of thyroxine hormone.
• Deficiency of iodine in our diet results in hyperthyroidism and enlargement of the thyroid gland.

Hence, the correct option is (3) thyroxine.
Additional Information
Adrenaline

• This hormone is secreted by adrenal medulla.
• Adrenaline is associated with maintenance of homeostasis of the body.
• It is secreted in response to any kind of stress or emergency in the body, thus it is called emergency hormone or hormone of Fight or Flight. 

Insulin

• Insulin is secreted by the β- cells of the Islets of Langerhans of pancreas.
• Insulin is a peptide hormone, which plays a major role in the regulation of glucose homeostasis.

Testosterone

• Testosterone is the primary sex hormone in males, secreted by the Leydig cells of the testis.
• It regulates maturation, development and functions of male accessory sex organs.

Key Points

• Pineal gland is the smallest gland in the human body with a length of about 5-8 mm.
• It is located in the epithalamus, near the center of the brain.
• The gland produces melatonin and serotonin and is, therefore, responsible for modulating sleep patterns.

Additional Information

• Largest gland of the human body - Liver
• The smallest exocrine gland - Goblet cell 
• The pancreas has both an endocrine and an exocrine function.
• Apocrine sweat glands are usually associated with hair follicles, continuously secrete a fatty sweat into the gland tubule.
• The parotid gland is a bilateral salivary gland located in the face.
• Ebner glands, also known as serous glands, are minor salivary glands located on both sides of your oral cavity toward the back of your tongue.

• Pituitary Gland is an Endocrine gland in the human body.
  • It is also known as the master gland.

Key Points

• A Gland is called the endocrine gland when it secretes hormones directly into the bloodstream.
• Endocrine: End means no duct required and the hormones go directly into the blood.
• Examples: Thyroid Gland, Parathyroid Gland, Adrenal Gland, etc. 

Additional Information

• The glands which have ducts through which enzymes pass are known as the Exocrine Glands.
• Exocrine: Exo means external help is needed, that is the hormones go through the duct.
• Examples: Digestive Gland, Salivary Gland, Sweat gland, etc.

• The hormone released from testes is Testosterone.
• Testosterone is the male sex hormone.
• It plays a key role in the development of male reproductive tissues such as the testis and prostate.
• It also increases the growth of body hair.

Key Points

• The pancreas is an organ of the digestive system located in the abdomen behind the stomach and functions as a gland.
• The pancreas performs both an endocrine as well as exocrine function. 
• As an endocrine gland, it helps to regulate blood sugar levels and aids the secretion of hormones such as insulin and glucagon.
• It also functions as an exocrine gland secreting pancreatic juice into the duodenum through the pancreatic duct.
• Insulin is a peptide hormone produced by beta cells of the pancreatic islets.
• It is responsible for allowing glucose in the blood to enter cells, providing them with the energy to function.

Additional Information

• Melatonin hormone plays an important role in the regulation of 24-hour rhythms of the sleep-wake cycle.
• It is also involved in the pigmentation of the skin, menstrual cycle, and metabolism.
• It also controls the cardiac rhythms of our body.
• Its increased secretion promotes healthy sleeping.
• This hormone delays puberty and affects the menstrual cycle.

Key Points

• Prolactin is the hormone of the anterior pituitary which stimulates the production of milk and also develops the mammary gland.
• Progesterone maintains the pregnancy and is involved in female sexual characteristics development and cortisol response against stress and also stimulates the formation of RBC.
• Cortisol is called the "stress hormone" because of its connection to the stress response. Cortisol is one of the steroid hormones and is made in the adrenal glands.