• Tuesday , 21 August 2018

What is hormone ?

Hormone

  • Chemical substance secreted by endocrine gland
  • Mixed with the blood for transport to a local distant target.
  • Target cells have specific receptors
  • Regulates cell reactions by affecting gene expression (often gene transcription factors)

Function of hormone

Controlling the metabolism

Regulating growth, development and reproduction

Name of endrocrine glands

Hypothalamus

Pituitary (master)gland

  1. Anterior pituitary gland
  2. Posterior pituitary gland

Thyroid gland

Parathyroid gland

Adrenal gland

Pancreas

Testes and ovary

Placenta during pregnancy

Female reproductive system

Layers of the uterus

Perimetrium- outer layer

Myometrium –middle muscular layer

Endrometrium- inner lining

Ovaries are female reproductive glands. They begin to function at puberty the functions of ovary are controlled by hormones from anterior pituitary, these hormones are called gonadotropins( follicle-stimulating hormone & leutinizing hormone)

The menstrual cycle, under the control of the endocrine system, is necessary for reproduction it is commonly divided into three phases, the follicular phase, ovulations, and luteal phase.

Follicular phase

This phase is also called the proliferative phase. Through the influence of a rise in follicle stimulating hormone(fsh) during the first days of the cycle, a few ovarian follicles are stimulated

As they mature, the follicles increased amount of estrogen, the estrogen initiates the formulation of new layer of endometrium in the uterus, histologically identified as the proliferative endometrium the estrogen also stimulates cervix to produce fertile cervical mucus.

Ovulation

Ovulation is the phase of a female’s menstrual cycle in which a mature egg is released from the ovarian follicle into oviduct. After ovulation, during the luteal phase, the egg will be available to be fertilized by sperm, concomitantly, the lining of the uterus ( the endrometrium) is thickened to be able to receive a fertilized) egg. If no conception occurs, the uterine lining as well as blood will be shaded off during menstruation.

During the follicular phase, estrogen suppresses production of luteinizing hormone ( lh) from the anterior pituitary gland. When the egg has nearly matured, levels of estradiol reach a threshold above which this effect is reversed and estrogen actually stimulates the production of a large amount of LH. This process, known as the LH surge, starts around day 12 of the average cycle and many last 48 hours.

The release of LH matures the egg and weakens the wall of the follicle in the ovary, causing the fully developed follicle to release its secondary oocyte. The secondary oocyte promptly matures into and ootid and then becomes a mature ovum.

Which of the two ovaries –left or right-ovulates appears essentially random, no known left and right co-ordinations exists. Occasionally, both ovaries will release and egg, if both eggs are fertilized, the result is fraternal twins.

After being released from the ovary, the egg is swept into the fallopian tube after about a day, an unfertilized egg will be disintegrate of dissolve in the fallopian tube.

Luteal phase

The luteal phase is also called the secretory phase. An important role is played by the corpus luteum, the solid body formed in an ovary after the egg has been released from the ovary into the fallopian tube. This body continues to grow for some time after ovulation and produces significant amount of hormones, particularly progesterone, progesterone plays as a vital role.

In making the endometrium receptive to implantation of the blastocyst.

Supportive of the early pregnancy, by increasing blood flow and uterine secretions

Reducing the contractility of the smooth muscle in the uterus

 

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