31 Years NEET Previous Year Questions: Chemical Coordination & Regulation

Electroencephalogram is the recording of  electric potentials originating from different parts of the brain in the form of waves. Fractionation is the technique of  rupturing cells and separating  their components especially cell organelles for studying their chemistry and functions. Electrophoresis is the technique of separation of charged solutes on the basis of their differential migration in an applied electric field.

Progesterone is a steroid hormone secreted by corpus luteum and causes routine temporary changes in the endometrial lining of uterus. Follicle stimulating hormone secreted by anterior pituitary lobe stimulates spermatogenesis in testes of males. Luteinizing hormone  activates Leydig’s cells of testes to secrete  testosterones.

Insulin is released from the pancreas it helps in conversion of glucose to fatty acids. It increases fat synthesis in adipose tissues.

Thymus gland is present in children with maximum development at puberty and thereafter it begins to shrink and  atrophies with the development of sex glands. 

Melatonin is secreted by pineal gland present between the cerebral hemispheres. Melatonin concentration in blood follows a diurnal cycle, it rises in the evening and drops at noon. Melatonin lightens skin colour in certain animals and regulates working of gonads.

Parathyroid gland secretes parathormone which regulates Ca2⁺ level in blood. Anterior lobe of pituitary secretes the following hormones growth hormone, ACTH, TSH, FSH, LH. Posterior pituitary secretes vasopressin and oxytocin.
The intermediate lobe (pars intermedium) of the pitutary gland secretes MSH which causes dispersal of pigment granules in the pigment cells which give colour to the skin

Contraceptive pills have estrogen and progesterone. Progesterone suppresses ovulation and production of LH while estrogen suppresses the production of FSH. 

Melanin is secreted from the intermediate lobe of pituitary. Melanin mainly protects the skin from harmful effects of UV-rays. People living in tropics tend to disperse more melanin in their skin – an adaptive feature.

Estrogens are steroid hormones secreted by growing ovarian follicles. During menstrual cycle a negative feedback prevents the over secretion of estrogen. FSH stimulates maturation of Graafian follicles. LH stimulates ovulation and development of corpus luteum.

Estrogen is released from the ovarian follicles. Oxytocin is secreted by posterior pituitary and prolactin is released by anterior pituitary. Gonadotropin releasing factor is produced by hypothalamus.

Adrenaline is a neurotransmitter that directly acts on the S A node.
The hormone adrenaline (epinephrine) is secreted by adrenal medulla. This was first hormone to be isolated in crystalline form. This hormone is primarily responsible for the alarming  reactions. It increases the heart rate, breathing blood glucose level.

Deficiency of thyroxin causes cretinism in infants and myxoedema in adults. Excess of adrenalin does not cause any disorder. Acromegaly is caused by over secretion of STH or somatotrophic hormone (Growth hormone). 

Microbial transformation is a biological process in which organic compounds are modified into reversible products. These biotransformation reactions are catalysed by purified enzymes present in microbial  cells or pure cullures of microorganisms. Cholesterol forms a major component  of animal cell membranes liposomes (artificially created spheres surrounded by a phospholipid bilayer like a membrane). Cholesterol is used for microbial transformation (transgenics).

Deficiency of parathyroid hormone causes tetany. The disease causes sustained contraction of muscles of larynx, face, hands and feet.

Hormones are chemical messengers formed by endocrine cells. Chemically hormones are of the following types: Amines–composed of amino group e.g.,
Melatonin.
Amino acids            – eg. thyroxine
Peptides                   – eg. insulin
Steroids                    – eg. aldosterone

 Luteinizing hormone (LH) stimulates  ovulation. Deficiency of insulin causes diabetes mellitus. Deficiency of ADH or  vasopressin causes diabetes insipidus. Deficiency of parathormone causes tetany. Deficiency of thyroxine causes cretinism in infants and myxoedema in adults.

Human chorionic gonadotropin is released by Anophoblast cells of the placenta. Estrogen and progesterone are also released by placental cells to maintain pregnancy. Prolactin is secreted from anterior lobe of pituitary. Placenta secretes Human Placental Lactogenic Factor which prepare mammary glands to secrete milk. 

Epinephrine is synthesized from amino acid tyrosine. While estrogen and progesterone are modified steroids and prostaglandins are basically fat.

Parkinson’s disease (Paralysis agitans) (i) It develops due to deficiency of neuro transmitter, dopamine. The dopamine is not produced due to gradual destruction of neurons in the substantia nigra. (ii) It produces muscle tremors so called shaking palsy. (iii) There is lack of control and coordination of movements resulting in expression less face and stooping posture which gradually produces physical disability.

During spermatogenetic developments spermatids get nourished by nurse or sertoli cells. The function of sertoli cells and hence the spermatogenesis is under the direct influence of folliclestimulating hormone (FSH) secreted by adenohypophyses of pituitary gland.

Cortisole is the steroid hormone secreted by adrenal cortex and plays an important role in carbohydrate metabolism. It retards the glucose consumption & hence level of glucose in blood increases & blood pressure increases.

In heart cells AMP acts as secondary messenger which is made in the response of adrenaline and it stimulates Ca²⁺ ions to come out from the sarcoplasmic reticulum of muscle fibres which causes muscle contraction. cGMP (Cyclic Guanosine Monophosphate) which acts as secondary messenger works on the action of acetylcholine, increase in flow of Ca²⁺ into muscle fibres & hence causes muscle relaxation. There is no role of sodium in hormonal action.

Epinephrine or adrenaline, norepinephrine or noradrenaline and acetylchloline are the neurotransmitters. These are released by the nerve fibres to transmit the impulse to the next neurone. Cortisone is not the neurotransmitter.

Neurohormones are actually secreted by the neurosecretory cells of the hypothalamus. They are circulated to the posterior part of the pituitary gland through the blood & stored there and released when required.

 Adrenaline (called Frieght-Flight-Fight hormone) in responsible for the dilation of blood vessels, increased oxygen consumption by tissues & glucogenesis to prepare the body for emergency reactions under the threatening conditions.