Menstrual Cycle


 
 
Concept Explanation
 

Menstrual Cycle

The reproductive cycle in female primates, e.g., Monkeys, apes and human beings is called menstrual cycle.

The first menstruation begins at puberty and is called menarche. In human females, menstruation is repeated at an average interval of about 28/29 days. The menstrual cycle stops around 50 years of age, in humans and this stage is termed as menopause.

The cyclic menstruation is an indicator of normal reproductive phase and extends between menarche and menopause. The cycle of events starting from one menstruation till the next one is called menstrual cycle.The menstrual cycle consists of following four phases

Menstrual Phase

  • The cycle starts with menstrual phase. It lasts for about 3-5 days and involves the following events
  • If fertilisation does not occur, the unfertilised egg undergoes autolysis.
  • Reduction of LH level causes regression of corpus luteum by autolysis and a consequent fall in the progesterone level in the blood.
  • The uterine lining dies due to he deficiency of progesterone and is sloughed off. Blood rupture, causing bleeding the process is called menstruation or menstrual flow.
  • Follicular (Proliferating) Phase

    It lasts for about 14 days and involves the following events

  • The primary follicles in the ovary grow to become a fully mature Graafian follicle.
  • Simultaneously the endometrium of uterus regenerates through proliferation.
  • The changes in the ovary and the uterus are induced by changes in the levels of pituitary and ovarian hormones.
  • The secretion of gonadotropins (LH and FSH) increases gradually Fertility during the follicular phase and stimulates follicular development as well as secretion of estrogens by the growing follicles.
  • Luteal Phase:

    This phase lasts for about 10 days and involves the following events

  • The remaining part of Graafian follicle transform as the corpus luteum.
  • The peak of LH, together with prolactin hormone from anterior pituitary stimulates the follicular cells of the empty Graafian follicle to form corpus luteum.
  • The corpus luteum secretes large amount of progesterone essential to maintain endometrium.
  • The endometrium is necessary for implantation of the fertilised ovum and other events of pregnancy. During pregnancy, all events of the menstrual cycle stop and there is no menstruation. In the absence of fertilisation, the corpus luteum degenerate.

  • This causes disintegration of endometrium leading to menstruation and a new cycle starts.
  •                              

    Chapters
    Pre-Historic Period
    Indus Valley Civilization
    Vedic Civilization
    Religious Reform Movement
    The Early Kingdoms
    The Mauryan Empire
    Post Mauryan Period
    The Age Of The Guptas
    Post Gupta Era
    Age of Rajput
    Khilji Dynasty
    Slave Dynasty
    Tughlaq and Sayyid Dynasty
    Vijaynagar Empire And Bahamani Kingdom
    Mughal Empire And Beyond
    Lodhi Dynasty
    Cholas, Chalukyas and Pallavas
    Arab Invasions
    Bhakti and Sufi Movement
    Rise of Sikhs, Jats and Marathas
    Administrative Structure of Delhi Sultanate
    Architecture During Medivial India
    Advent Of The Europeans
    Post Mughal Period
    Rise of New States in 18th Century
    Growth of British Paramountacy
    Socio Religious Reforms
    Constitutional Development of India
    Indian Struggle Against British Rule
    The Revolt Of 1857
    Education Under British Rule
    Role of Press in Freedom Struggle
    First Phase of National Movement
    Second Phase of National Movement
    Third Phase of National Movement
    Constitutional Development in India
    Constituent Assembly
    Union And Its Territory
    Structure of Indian Constitution
    Fundamental Rights and Duties
    The Union Executive
    The Union Legislature
    Constitutional Amendments and Provisions
    Judiciary In India
    Emergency Provisions
    Center - State Relations
    The State Executive
    The State Legislature
    Election Commission Of India
    Constitutional Organisation
    Non-Constitutional Organisation
    Local Self Goverment
    India - Size And Location
    Geological History Of India
    The Physical Features Of India
    Climate Of India
    Soils In India
    Natural Vegetation
    Windlife Conservation In India
    Drainage System of India
    Irrigation System Of India
    Agriculture In India
    Livestock And Fisheries In India
    Minerals And Energy Resources In India
    Means Of Transport In India
    Major Industries In India
    Tribes of India
    Census of India 2011
    Music
    Dance
    Theatre
    Pantings
    Art, Architecture & Culture of India
    Bio-Diversity
    Earth And Its Structure
    Land Rock And Soil
    Atmosphere, Climate And Weather
    Oceanography
    Human And Regional Geography
    Economic Growth And Development
    Sectors Of Indian Economy
    Economic Planning Of India
    Fiscal And Monetary Policy In India
    Infrastructure In India
    Effects Of British Rule On Indian Economy
    National Income
    Banking System In India
    Poverty And Unemployment
    Inflation And Trade Cycles
    Major Institutions
    Environmental Studies
    Tissues In Organism
    Cytology
    Classifucation Of Plants
    Structural Composition Of Plants
    Nutrition In Plants, Harmones And Plant Disease
    Ecosystem
    Classification In Animals
    Nutrition In Animals
    Human Digestive System
    Human Respiratory System
    Human Skeleton System
    Human Excretory System
    Human Nervous System
    Human Circulatory System
    Human Endocrine System
    Human Reproductive System
    Genetics
    Human Diseases
    States Of Matter
    Metals And Non Metals
    Acid Bases And Salts
    Periodic Classification
    Fuel, Combustion And Flame
    Environmental Chemistry
    Rest And Motion
    Work Power And Energy
    Gravitation
    Pressure And Its Effects
    Simple Harmonic Motion
    Sound and Waves
    Heat And Temperature
    Light - Reflection
    Electricity And Magnetism
    Modern Physics
    Force And The Laws Of Motion
    Light - Refraction
    Dispersion And Human Eye
    Magnetic Effect Of Electric Current
    Atom And Molecule
    Chemistry In Everyday Life
    Units And Dimensions
    Content / Category
    Class / Course
     
     
    Related Videos
    Language - Hindi/English
    Language - Hindi/English


    Students / Parents Reviews [10]