CBSE Questions for Class 11 Medical Biology Chemical Coordination And Integration Quiz 10 - MCQExams.com

• The hormones which generally have opposite actions on our body are called antagonistic hormone or hormones. 
• Insulin and glucagon are considered to be one such pair of the antagonistic hormone. The action of insulin in our body is opposite to that of glucagon.
• Insulin works to decrease blood sugar levels by converting extra glucose into glycogen that will be stored in the liver and muscles while glucagon works to increase the blood sugar level by promoting glycogenolysis. 
• Similarly, calcitonin and parathormone also have antagonistic functions
• When calcium level falls below normal then parathormone maintains it by promoting its absorption, reabsorption, and also by demineralization of bones. When blood calcium level exceeds above normal then calcitonin hormone increases the excretion of calcium in the urine.
  

A.Pituitary gland - The pituitary gland is a tiny organ, the size of a pea, found at the base of the brain. As the “master gland” of the body, it produces many hormones that travel throughout the body, directing certain processes or stimulating other glands to produce other hormones.

C.Thyroid gland - The thyroid gland is an endocrine gland in your neck. It makes two hormones that are secreted into the blood: thyroxine (T4) and triiodothyronine (T3). These hormones are necessary for all the cells in your body to work normally.

D.Ovary - The ovary is a ductless reproductive gland in which the female reproductive cells are produced. Females have a pair of ovaries, held by a membrane besides the uterus on each side of the lower abdomen. The ovary is needed in reproduction since it is responsible for producing the female reproductive cells, or ova.

A. Glucagon - The pancreas releases glucagon when the concentration of insulin (and indirectly glucose) in the bloodstream falls too low. Glucagon causes the liver to convert stored glycogen into glucose, which is released into the bloodstream. High blood glucose levels, on the other hand, stimulate the release of insulin.

B. Thyroxine - It plays vital roles in digestion, heart and muscle function, brain development and maintenance of bones.

C.Insulin - It plays vital roles in digestion, heart and muscle function, brain development and maintenance of bones.

D.Adrenaline - hormone increasing the heart rate, increasing blood pressure, expanding the air passages of the lungs, enlarging the pupil in the eye (see photo), redistributing blood to the muscles and altering the body's metabolism, so as to maximize blood glucose levels (primarily for the brain).

In the human body, every receptor is specific for a hormone and every hormone is specific for a receptor.

• • The pituitary gland is a tiny organ, the size of a pea, located at the base of the brain below the hypothalamus(located below the thalamus part of the brain). The pituitary gland is divided into three parts, also called lobes:
    
  • Anterior pituitary, Intermediate pituitary (Absent in adult human beings)and Posterior pituitary.
  • Melanocyte-stimulating hormone (MSH) is secreted from the intermediate lobe of the pituitary gland. It Stimulates the production of melanin by skin and hair.
  • Posterior lobe pituitary gland secretes Oxytocin. Oxytocin Controls certain aspects of pregnancy and childbirth such as uterine contraction and production of milk.
  • Somtotropic hormone secretes from the anterior lobe of the pituitary gland.
  • So, the correct answer is (I),(II),(III).

$$\textbf{Correct option:A}$$ 

$$\textbf{Solution:}$$

$$\textbf{Option (A)}$$

$$\bullet$$ When the calcium level rises due to excessive amounts of parathormone that withdraws more calcium from bones causing demineralisation and softening of bones which can easily be fractured etc.This disease due to hypersecretion of parathormone is called osteoporosis/osteitis fibrosa cystica. Excess of parathormone also causes deposition of calcium in the kidneys.

$$\bullet$$ Estrogen deficiency can lead to excessive bone resorption accompanied by inadequate bone formation. Estrogen deficiency can therefore lead to osteoporosis.

$$\textbf{Option (B)}$$

$$\bullet$$ Deficiency of adrenal hormone aldosterone leads to Addison's disease which is characterized by low blood sugar,low plasma sodium,high potassium ,nausea ,vomiting and skin pigmentation.

$$\textbf{Option (C)}$$

$$\bullet$$ Prolactin hormone activates the growth of the mammary gland during pregnancy and secretion of the mammary gland after child birth.Excess prolactin can cause the production of milk secretion in men and in women who are not pregnant or breastfeeding.

$$\textbf{Option (D)}$$

$$\bullet$$ Progesterone secretion is increases so that the endometrium lining is maintained and it checks the implantation in case there is fertilisation, due to sudden drop of progesterone results in menstruation.

$$\textbf{Hence, the correct option is (A)}$$

$$\textbf{Correct option:D}$$ 

$$\textbf{Solution:}$$

$$\textbf{Option (A)}$$

$$\bullet$$ Thyrocalcitonin(calcitonin) is a 32 amino acid chain peptide hormone which is secreted from the thyroid gland when calcium level in blood is higher .It is antagonist to parathormone and inhibits the release of calcium from bones into the bloodstream.

$$\textbf{Option (B)}$$

$$\bullet$$ Parathyroid glands secrete parathormone from the chief cells. Parathormone regulates the metabolism of phosphate and calcium in the body, it increases the release of calcium from bones to blood, reabsorption of calcium from intestines and nephrons, inhibits collagen synthesis by osteoblasts and increases the excretion of phosphate.

$$\textbf{Option (C)}$$

$$\bullet$$ Adrenal gland is divided into parts; adrenal cortex secretes aldosterone which regulates sodium metabolism, cortisol which regulates sugar metabolism and sex corticoids, adrenal medulla secretes epinephrine and norepinephrine which is secreted at the time of emergency.

$$\textbf{Option (D)}$$

$$\bullet$$ Both (a) and (b) are correct, they work together to regulate calcium and phosphate metabolism in body.

$$\textbf{Hence, the correct option is (D)}$$