Glands and
hormones
Glands are
those cells which produce secretion called hormones that are released in the
blood stream to reach their target sites
Hormones are
the chemical messenger that travel inside our body through blood stream and
control our body to function and perform its day to day activity.
Glands are
divided in two types: endocrine glands and exocrine glands
Endocrine
glands: these glands are ductless glands that mean that they pour their
secretion directly in the blood stream. The secretion reaches its target site
travelling through blood. Eg; pineal, pituitary, parathyroid, thyroid, thymus,
adrenal, ovaries(female), testes(male).
Exocrine
glands: these glands release their secretion with the help of duct at the
specific sites. Eg; tear gland(lachrymal), salivary, mammary(female), live,r
intestinal, urethral(male).
Heterocrine
glands: these are the exceptional gland which poses both kinds of
characteristics. Some secretions are released through duct while some
secretions are released directly in the blood stream. Eg; pancreas and gonads.
What is the
role of hormone is initiating reproductive system?
When the pituitary
gland also called as master gland secrete follicle stimulating hormone (FSH),
it stimulates the gonads (testes and ovary) to release testosterone and
estrogen respectively. These hormones cause the physical change in human body
to take place. Along with this testosterone and estrogen activates the testes
and ovary to release their respective gametes, sperm and ova.
Reproductive
phase in life of humans:
Reproductive
phase in the life of a female: in female the reproductive phase starts at
puberty with the time when the ovary releases it first ova and it lasts till
the age of 45-50 years. With the onset of puberty ova start to mature. During
the reproductive period the two ovaries start to release ova after each 28
days. Each ovary release an ovum alternately at the difference of 28 days. When
the ovum is released it passes through the fallopian tube, during this period
the uterus prepares itself for the situation in which egg gets fertilized and
zygote is formed. In the presence of estrogen and progesterone the wall of
uterus gets thick and gets enriched with lots of capillaries. This happens
because the foetus settles in the uterus and the foetus gets nutirition from
the mothers blood through the umbical cord. If there is no fertilization the
uterus wall slowly breaks down and blood and mucous is released from the
vagina. This process is called menstruation and it repeats at every 28 days in
the form of a cycle.
Sex
determination of boy or a girl
The genetic
information of a person is carried in the nucleus of its cell. In the nucleus
the information is present in the chromosomes in the form of genes. Genes carry
the information from parents to offsprings. Sex chromosome of a female is XX
while that of a male is XY. When the gamete are formed the mother gamete
contain X chromosome gamete while the gametes of father will be of two type,
one having X chromosome and another one having Y chromosome.
When X
chromosome of female fuses with X chromosome of male a girl child is born while
When X chromosome of female fuses with Y chromosome of male a boy child is
born.
