Category Science

Which part of a girl’s body produces and releases eggs at the mid-point of each menstrual cycle?

The ovaries form part of the female reproductive system. Each woman has two ovaries. They are oval in shape, about four centimetres long and lie on either side of the womb (uterus) against the wall of the pelvis in a region known as the ovarian fossa. They are held in place by ligaments attached to the womb but are not directly attached to the rest of the female reproductive tract, e.g. the fallopian tubes.  

The major hormones secreted by the ovaries are oestrogen and progesterone, both important hormones in the menstrual cycle. Oestrogen production dominates in the first half of the menstrual cycle before ovulation, and progesterone production dominates during the second half of the menstrual cycle when the corpus luteum has formed. Both hormones are important in preparing the lining of the womb for pregnancy and the implantation of a fertilised egg, or embryo.

If conception occurs during any one menstrual cycle, the corpus luteum does not lose its ability to function and continues to secrete oestrogen and progesterone, allowing the embryo to implant in the lining of the womb and form a placenta. At this point, development of the foetus begins. 

 

Picture Credit : Google

Which are group hormones that primarily influence the growth and development of the male reproductive system?

Androgen, any of a group of hormones that primarily influence the growth and development of the male reproductive system. The predominant and most active androgen is testosterone, which is produced by the male testes.

In males the interstitial cells of Leydig, located in the connective tissue surrounding the sperm-producing tubules of the testes, are responsible for the production and secretion of testosterone. In male animals that breed only seasonally, such as migratory birds and sheep, Leydig cells are prevalent in the testes during the breeding season but diminish considerably in number during the nonbreeding season. The actual secretion of androgens by these cells is controlled by luteinizing hormone (LH) from the pituitary gland.

The adrenal production of androgens is of importance to several physiological processes. Certain adrenal androgens—androstenedione, dehydroepiandrosterone (DHEA), and dehydroepiandrosterone sulfate (DHEA sulfate)—can be converted to testosterone in other tissues.

 

Picture Cedit : Google

Which gland in the hypothalamus of your brain is responsible for releasing special hormones that trigger the onset of puberty?

The hypothalamus is a small but important area in the center of the brain. It plays an important role in hormone production and helps to stimulate many important processes in the body and is located in the brain, between the pituitary gland and thalamus.

The hypothalamus is responsible for the regulation of certain metabolic processes and other activities of the autonomic nervous system. It synthesizes and secretes certain neurohormones, called releasing hormones or hypothalamic hormones, and these in turn stimulate or inhibit the secretion of hormones from the pituitary gland. The hypothalamus controls body temperature, hunger, important aspects of parenting and attachment behaviours, thirst, fatigue, sleep, and circadian rhythms.

The hypothalamus is a divided into 3 regions (supraoptic, tuberal, mammillary) in a parasagittal plane, indicating location anterior-posterior; and 3 areas (periventricular, medial, lateral) in the coronal plane, indicating location medial-lateral. Hypothalamic nuclei are located within these specific regions and areas. It is found in all vertebrate nervous systems. In mammals, magnocellular neurosecretory cells in the paraventricular nucleus and the supraoptic nucleus of the hypothalamus produce neurohypophysial hormones, oxytocin and vasopressin. These hormones are released into the blood in the posterior pituitary. Much smaller parvocellular neurosecretory cells, neurons of the paraventricular nucleus, release corticotropin-releasing hormone and other hormones into the hypophyseal portal system, where these hormones diffuse to the anterior pituitary.

 

Picture Credit : Google

Who is Govind Swarup, and how is he connected to radio telescopes?

Govind Swarup was a radio astronomer and one of the pioneers of radio astronomy, known not only for his many important research contributions in several areas of astronomy and astrophysics, but also for his outstanding achievements in building ingenious, innovative and powerful observational facilities for front-line research in radio astronomy. He was the key scientist behind concept, design and installation of the Ooty Radio Telescope (India) and the Giant Metrewave Radio Telescope (GMRT) near Pune. Under his leadership, a strong group in radio astrophysics has been built at Tata Institute of Fundamental Research that is comparable to the best in the world.

Prof Swarup was born in Thakurdwara, now in the state of Uttar Pradesh, on March 23, 1929. He obtained his undergraduate education at Allahabad University and then joined the National Physical Laboratory in Delhi. After a stint in Australia building telescopes at Pott’s Hill near Sydney, Prof Swarup moved to the US, where he obtained a PhD from Stanford University. At the back of his mind, always, was the thought to return to India to establish the newly emerging field of radio astronomy.

Initially he joined National Physical laboratory for two years. Returning from Stanford to India in March 1963, he joined TIFR as a Reader at the request of Dr. Homi Bhabha. In 1965, he became Associate Professor, Professor in 1970, and Professor of Eminence in 1989. He became Project Director of the GMRT in 1987, Centre Director of the National Centre for Radio Astrophysics (NCRA) of TIFR in 1993 and retired from TIFR in 1994.

 

Picture Credit : Google

Who is Jocelyn Bell, and how is she linked to Radio Astronomy?

Dame Susan Jocelyn Bell Burnell is an astrophysicist from Northern Ireland who, as a postgraduate student, discovered the first radio pulsars in 1967.[9] She was credited with “one of the most significant scientific achievements of the 20th century”.

Burnell was a PhD student at Cambridge at the time and was working with her supervisor Hewish to make radio observations of the universe. She ended up discovering a pulsar using a vast radio telescope occupying an area of 4.5 acres that was designed by Hewish and joined him and the team of five when the construction of the telescope was about to begin. The telescope was built to measure the random brightness flickers of a different category of celestial objects called quasars.

The telescope took over two years to build and the team started operating it in July 1967. As per Burnell, she had the sole responsibility of operating the telescope and analysing its data output, which amounted to 96-feet of chart paper everyday, which she analysed by hand.

In the 1977 article, titled, “Little Green Men, White Dwarfs or Pulsars?”, Burnell wrote that the story of the discovery of pulsars began in the middle of 1960s when the technique of interplanetary scintillation (IPS) was discovered. This technique involved the fluctuation in the emission of radio signals from a compact radio source such as a quasar and was chosen by Hewish to pick out quasars. While analysing the telescope’s output, Burnell saw that there were unexpected markings on the chart that were recorded approximately every 1.33 seconds.

 

Picture Credit : Google

Who is considered to be the founder of the field called Radio Astronomy?

Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The first detection of radio waves from an astronomical object was in 1932, when Karl Jansky at Bell Telephone Laboratories observed radiation coming from the Milky Way. Subsequent observations have identified a number of different sources of radio emission. These include stars and galaxies, as well as entirely new classes of objects, such as radio galaxies, quasars, pulsars, and masers. The discovery of the cosmic microwave background radiation, regarded as evidence for the Big Bang theory, was made through radio astronomy.

Radio astronomers use different techniques to observe objects in the radio spectrum. Instruments may simply be pointed at an energetic radio source to analyze its emission. To “image” a region of the sky in more detail, multiple overlapping scans can be recorded and pieced together in a mosaic image. The type of instrument used depends on the strength of the signal and the amount of detail needed.

Observations from the Earth’s surface are limited to wavelengths that can pass through the atmosphere. At low frequencies, or long wavelengths, transmission is limited by the ionosphere, which reflects waves with frequencies less than its characteristic plasma frequency. Water vapor interferes with radio astronomy at higher frequencies, which has led to building radio observatories that conduct observations at millimeter wavelengths at very high and dry sites, in order to minimize the water vapor content in the line of sight. Finally, transmitting devices on earth may cause radio-frequency interference. Because of this, many radio observatories are built at remote places.

 

Picture Credit: Google