Thymus - class-XII
Mammals born without a thymus gland fail to manufacture
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B - Lymphocytes
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T - Lymphocytes
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Plasma cells
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Basophils
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.
T-cells mature in the
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Peyer's patch
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Lymph node
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Thymus
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Bursa of fabricius
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
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Loss of cell mediated immunity
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A reduction in the haemoglobin content in blood
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A reduction in the amount of plasma proteins
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Loss of antibody mediated immunity
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.
Which gland decreases in size with increasing age?
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Thyroid
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Adrenal
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Thymus
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Pituitary
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
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Pineal body
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Thymus gland
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Thyroid gland
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Adrenal gland
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.
Thymus gland develops from embryonic
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Mesoderm
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Endoderm
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Ectoderm
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All of the above
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?
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Pineal body
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Anterior pituitary
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Adrenal medulla
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Thymus
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?
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Immunosuppressant
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Die immediately
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No adverse reaction
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Myasthenia gravis
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.
The gland which is related to the maturation of lymphocytes is
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Thymus
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Thyroid
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Adrenal
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Pituitary
Thymus is small lymphoid structure present in lower art of neck in front of trachea, below the thyroid gland. It is the primary source of lymphocytes before birth and is the site of maturation or development of T-lymphocytes which circulates in lymphoid tissues.
Which endocrine gland becomes inactive after puberty?
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Thyroid
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Parathyroid
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Thymus
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Gonads
Thymus becomes inactive after puberty and shrinks. Most of the glands is replaced by adipose tissue. It produces thymosin which stimulates the development of disease-fighting T cells. The immune system produces most of its T cells during childhood and requires very few new T cells after puberty so the gland degenerates.
Ageing is caused by disappearance of
Or
Which one of the following is gradually reduced and degenerated in ageing according to immunity theory
Or
Which is called "Clock of ageing"
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Thyroid
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Parathyroids
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Thymus
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Pitutary
According to one of the theories of ageing, the decline and disappearance of which gland by late middle age is the primary cause of ageing?
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Thyroid
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Parathyroid
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Thymus
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Posterior lobe of pituitary
Which of these is related to the maturation of lymphocytes?
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Thymus
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Thyroid
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Adrenal
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Pituitary
Which of the following glands grows to the maximum size at puberty and then diminishes gradually?
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Thymus
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Pituitary
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Thyroid
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Adrenal
Endocrine gland responsible for immunity is
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Pineal
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Thymus
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Pituitary
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Adrenal
Removal or absence of thymus in early life shall bring about
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Lack of lymphocytes
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Lack of antibodies
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Decreased immune response
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All of the above
Which endocrine gland becomes inactive after puberty?
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Adrenal
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Pineal
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Thymus
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Pituitary
Hassall's corpuscles are found in
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Thyroid
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Thymus
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Adrenal
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Pineal
An endocrine gland that atrophies at the age of 14 - 16 years is
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Thyroid
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Thymus
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Pancreas
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Spleen
Which of these is correctly matched with the accompanying description?
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Pancreas - Delta cells of islets of Langerhans secrete a hormone which stimulates glycolysis in liver
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Thyroid - Hyperactivity in young children causes cretinism
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Thymus - Starts undergoing atrophy after puberty
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Parathyroid - Secretes parathormone that promotes movement of $Ca^{2+}$ ions from blood into bones during calcification
Which of these has a role in immunity?
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Pineal gland
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Thymus
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Adrenal gland
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Parathyroid gland
Thymosin hormone is secreted by
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Thyreid
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Thymus
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Parathyroid
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Hypothalamus
Thymus gland has a role in
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$Na^+$ $K^+$ balance
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Immune system
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Maintaining glucose level
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Maintaining $Ca^{2+}$ level
Which of these is the correct combination for gland, hormone and its function?
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Anterior pituitary - oxytocin - contraction of uterine muscles
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Anterior pituitary - vasopressin - induces reabsorption of water in nephron
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Thymus - thymosin - proliferation of T-lymphocytes
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$\alpha$-cells - glucagon - uptake of glucose by cells
Which is not the function of endocrine gland, located in upper dorsal side of heart and aorta?
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Plays important role in development of immune system
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Induces differentiation of T-lymphocytes
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Induces formation of RBCs
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Induces development of T-lymphocytes
Which of the following helps in differentiation of cells of immune system?
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Cortisol
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Thyroxine
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Thymosin
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Steroid
The letter T in T-lymphocyte refers to :
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Thymus
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Thyroid
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Thalamus
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Tonsil
Which of the following glands is lost as the age advances?
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Thyroid
-
Thymus
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Pancreas
-
Adrenal
Thymus glands is a specialised lymphoid organ of the immune system. It helps in the maturation of the T cells. it plays an important role during the puberty at the adolescence stage. After puberty, it degenerates and it is replaced by fat. This shrinkage of thymus mainly takes place due to a high level of sex hormones.
The name of endocrine gland in the human brain is
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Thyroid
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Adrenal
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Thymus
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Pituitary
Which of the following do not play any role in calcium balance in the human body?
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Vitamin D
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Parathyroid hormone
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Thyrocalcitonin
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Thymosin
Which gland atrophies in adults?
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Pancreas gland
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Thymus gland
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Adrenal gland
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Thyroid gland
Thymus gland is a prominent gland at birth but gradually atrophies in the adult. It is a soft, pinkish, bilobed mass of lymphoid tissue. It secretes a hormone thymosin which is involved in producing immunity.
Which one of the following is termed temporary gland?
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Pineal
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Thymus
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Pancreas
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Kidney
Thymus is called temporary gland as it degenerates in old individuals resulting in a decreased production of thymosin.
The regression in size of which organ is associated with reduction in the power of defence against invasion by pathogens with ageing?
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Bone marrow
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Thymus
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Spleen
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Peyer's patches
The thymus gland, located behind our sternum and between our lungs, is only active until puberty.
Central tolerance takes place in
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Lymph nodes
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Thymus
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Spleen
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Liver
Central tolerance is the tolerance established by deleting autoreactive lymphocyte clones before they develop into fully grown immunocompetent cells. It occurs primarily in the thymus.
Which one of these does not pertain to B-cells?
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Have passed through the thymus
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Synthesize and liberate antibodies
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Have antibody-mediated immunity
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Have specific receptors
B cells develop in the bone marrow but achieve maturity in peripheral lymphoid organs. Developmental stages are defined by the successful expression of heavy-chain and light-chain immunoglobulin genes. B cells provide humoral immunity against extracellular pathogens through antibody production. Antibodies neutralize pathogens and toxins, facilitate opsonization, and activate complement. The B-cell receptor or BCR is composed of immunoglobulin molecules that form a type 1 transmembrane receptor protein usually located on the outer surface of a lymphocyte type known as B cells.