Tag: mechanism of hormone action

• Thymosin hormones are typically produced by the thymus gland and trigger the creation of T-cells, which are used by the immune system to fight disease. 
• Once puberty occurs in a human, a normal thymus has created the T-cells needed by the body and begins to shrink, eventually being replaced by fatty tissue. Hence, Thymosin helps in the differentiation of lymphocytes.

• The LH surge causes the initiation of the process of ovulation. 
• After ovulation, the follicle is transformed into the corpus luteum, which is stimulated by LH.
•  It occurs roughly 36 hours before ovulation which indicates egg has matured and is ready for fertilisation. Hence, The LH surge is essentially a signal sent from the brain to the ovary, which indicates An egg is mature.

• Parathyroid hormone (PTH) is essential for the physiologic maintenance of mineral homeostasis. 
• PTH regulates the mineral transport in bone and kidney and through its secondary actions on mineral transport in the intestine. 
• Calcitonin, in many ways, acts as a physiologic antagonist to PTH. Hence,  Parathyroid hormone is antagonistic to calcitonin

• Erythropoietin is produced by interstitial fibroblasts in the kidney in close association with the peritubular capillary and proximal convoluted tubulin the cell named juxtaglomerular cells. 
•  It is also produced in perisinusoidal cells in the liver. Hence, The cells which produce erythropoietin Juxtaglomerular cells.
So, the correct answer is 'Juxtaglomerular cells'.

Hormones are the chemical substance, released from endocrine glands. They are directly released into the blood and affect the targeted organ. They may be the peptide such as insulin or steroid such as cortisol. Thus, the correct answer is option B.

A pheromone is a chemical released by one animal to affect the behaviour of another animal and thus it is used to trap the beetle to reduce their population.

Hormonal actions are regulated by two mechanisms: feedback and antagonistic effects of two hormones. A feedback mechanism can work as a negative or positive mechanism. The negative feedback mechanism is activated by surplus and proceeds to correct the process that caused the surplus. Therefore, increased the blood level of a certain hormone or its effect on target organ act to prevent its further release. For example, increased blood glucose level stimulates insulin secretion. The positive feedback mechanism of hormone regulation includes stimulation of release of the same hormone caused by its increased blood level. For example, the release of oxytocin is stimulated by uterine contraction during labor pain. 

Gonadotropin is a hormone which stimulates production of sex hormones and development of secondary sexual characters.
Females : Ovaries : Oestrogen and Progesterone
Males : Testes (testicle) : Testosterone.

When the secretion of hormone is controlled by the factors or other hormones it is called feedback control. For example, homeostasis means keeping the internal environment of the body constant. Hormones help in maintaining internal environment of the body. Thus, the correct answer is option B.

An increased amount of thyroxine in the blood exerts an inhibitory effect on the hypothalamus. in such a way that less of thyroid releasing hormone (TRH) and thyroid stimulating hormone (TSH) is produced respectively. This eventually results in a decrease in thyroxine. This is called negative feedback control.