Tag: pineal gland and thymus

Questions Related to pineal gland and thymus

Mammals born without a thymus gland fail to manufacture 

zoology control and coordination in living organisms thymus thymus gland pineal gland and thymus

  1. B - Lymphocytes

  2. T - Lymphocytes

  3. Plasma cells

  4. Basophils

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Correct Option: B
Explanation:

Removal of the thymus gland in the adult has little effect, but when the thymus is removed in the newborn, T cells in the blood and lymphoid tissue are depleted and failure of the immune system causes a gradual, fatal wasting disease. 

The animal whose thymus has been removed at birth is less able to reject foreign tissue grafts or to make antibodies to certain antigens. Moreover, certain parts of the white pulp of the spleen and lymph nodes are much reduced in size. Hence, the T cells produced in the thymus and transported to the lymphoid tissues are crucial elements in the development of immunity.

T-cells mature in the

zoology control and coordination in living organisms thymus thymus gland pineal gland and thymus

  1. Peyer's patch

  2. Lymph node

  3. Thymus

  4. Bursa of fabricius

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Correct Option: C
Explanation:

T cells or T lymphocytes are a type of lymphocyte, that plays a central role in cell-mediated immunity. They are called as T-cells because they mature in the thymus gland.

Damage to thymus in a child may lead to

zoology control and coordination in living organisms thymus thymus gland pineal gland and thymus

  1. Loss of cell mediated immunity

  2. A reduction in the haemoglobin content in blood

  3. A reduction in the amount of plasma proteins

  4. Loss of antibody mediated immunity

Show answer
Correct Option: A
Explanation:

The thymus gland is an organ in the upper chest cavity, that processes lymphocytes, a type of white blood cell, that fights infections in the body. 

The thymus is most important in children and young adults, when it programs lymphocytes to attack antigens, like viruses. 
People who do not have this gland, or in whom it does not function correctly, usually have compromised immune systems and difficulty fighting disease.

Which gland decreases in size with increasing age?

zoology control and coordination in living organisms thymus thymus gland pineal gland and thymus

  1. Thyroid

  2. Adrenal

  3. Thymus

  4. Pituitary

Show answer
Correct Option: C
Explanation:

The thymus is a specialized organ of the immune system. Within the thymus, T cells or T lymphocytes mature. At birth, it is about 5 cm in length, 4 cm in breadth, and about 6 mm in thickness. The organ enlarges during childhood and atrophies at puberty. The thymus is at its largest in children. The thymus reaches maximum weight (20 to 37 grams) by the time of puberty. As one ages, the thymus slowly shrinks, eventually degenerating into tiny islands of fatty tissue. By the age of 75 years, the thymus weighs only 6 grams.

Hassall's corpuscles are found in 

zoology control and coordination in living organisms thymus thymus gland pineal gland and thymus

  1. Pineal body

  2. Thymus gland

  3. Thyroid gland

  4. Adrenal gland

Show answer
Correct Option: B
Explanation:

Hassall's corpuscles (or thymic corpuscles) are structures found in the medulla of the human thymus, formed from eosinophilic type VI epithelial reticular cells arranged concentrically. 

The cytoplasm in Hassalls corpuscles contains keratohyalin granules and intermediate fibres and may be keratinised. 

Thymus gland develops from embryonic 

zoology control and coordination in living organisms thymus thymus gland pineal gland and thymus

  1. Mesoderm

  2. Endoderm

  3. Ectoderm

  4. All of the above

Show answer
Correct Option: B
Explanation:

The triploblastic animals have three prominent germ layers known as ectoderm, endoderm and mesoderm. Thymus gland develops from two hollow elongations (third and fourth pharyngeal pouches) of endoderm which descends to the embryonic thorax by the end of eight weeks of gestation. The lymphoid cells of the gland originate from mesoderm. Thus, the correct answer is option B.

Which endocrine gland is not an ectodermal origin?

zoology control and coordination in living organisms thymus thymus gland pineal gland and thymus

  1. Pineal body

  2. Anterior pituitary

  3. Adrenal medulla

  4. Thymus

Show answer
Correct Option: D
Explanation:

Endoderm, the innermost of the three germ layers, or masses of cells (lying within ectoderm and mesoderm), which appears early in the development of an animal embryo. The endoderm subsequently gives rise to the epithelium (tissue that covers, or lines, a structure) of the pharynx, including the eustachian tube, the tonsils, the thyroid gland, parathyroid glands, and thymus gland; the larynx, trachea, and lungs; the gastrointestinal tract (except mouth and anus), the urinary bladder, the vagina (in females), and the urethra. 

If thymectomy is done during adulthood then what is the probable result of it?

zoology control and coordination in living organisms thymus thymus gland pineal gland and thymus

  1. Immunosuppressant

  2. Die immediately

  3. No adverse reaction

  4. Myasthenia gravis

Show answer
Correct Option: C
Explanation:

Thymectomy is the process in which the thymus gland is removed. Thymus gland is located in the chest area. Thymus gland is responsible for T-cell differentiation. The gland is recommended to be removed in cases of people suffering from Myasthenia gravis. The gland is removed in childhood, which generally have no adverse effects. However, when the gland is removed in adulthood, certain immune functions get affected. T-cells differentiation may be affected leading to improper production of T-cells.

So, the correct answer is option C. 

Given are four statements(A-D) each with one or two blanks. Select the option which correctly fills up the blank in any two statements.
(A) Thymus secretes _____(i) which help in differentiation of _(ii).
(B) The adrenal medulla secretes _(i) which stimulates the breakdown of _(ii) to increase the blood glucose concentration during emergency situations.
(C) The Leydig's cells or __(i) present in the intertubular spaces in testis, produce a group of hormone called __(ii).
(D) Thyroid gland secretes ___(i) and triiodothyronine which contain ______(ii)

zoology endocrine system and chemical co-ordination thymus thymus gland pineal gland and thymus

  1. (A)-(i) melatonin, (ii) T-lymphocytes, (B)- (i) adrenaline, (ii) fat

  2. (B)- (i) catecholamine, (ii) glycogen, (C)-(i) interstitial cells, (ii) glycogen

  3. (B)-(i) catecholamine, (ii) glycogen, (D)- (i) thyroxine, (ii) iodine

  4. (D)- (i) parathyroid hormone, (ii) calcium, (A)-(i) thymosin, (ii) B- lymphocytes

Show answer
Correct Option: C
Explanation:
The adrenal medulla secretes catecholamine  which stimulates the breakdown of glycogen to increase the blood glucose concentration during emergency situations.
Thyroid gland secretes thyroxine and triiodothyronine which contain iodine.
So, the correct option is '(B)-(i) catecholamine, (ii) glycogen, (D)-(i) thyroxine, (ii) iodine'

Which of the following statements is/are INCORRECT regarding the immune system of an adult human being when compared to a child?

zoology endocrine system and chemical co-ordination thymus thymus gland pineal gland and thymus

  1. Thymus degenerates in old individuals
    resulting in a decreased production of thymosins

  2. The immune responses of old persons become weak

  3. The immunity of old person becomes weak

  4. Vaccination is mostly given in childhood as an immune response is weaker in children

Show answer
Correct Option: A,B
Explanation:

The thymus gland is a lobular structure located between the lungs behind sternum on the ventral side of the aorta. The thymus plays a major role in the development of the immune system.
 Thymosins play a major role in the differentiation of T-lymphocytes, which provide cell-mediated immunity. In addition, thymosins also promote the production of antibodies to provide humoral immunity. 
 the immune responses of old persons become weak because Thymus is degenerated in old individuals resulting in a decreased production of thymosins.
So, the correct option is 'Both A and B'.