Menstrual Cycle Overview

Menstrual Cycle

• The menstrual cycle is the series of physiological changes from the start of one period to the next.
• Menstruation is the regular discharge of blood, uterine tissue, and unfertilized egg cells.
• Menarche is the first menstrual period.

Dysmenorrhea

• Dysmenorrhea is also known as menstrual cramps.
• Characterized by throbbing or cramping pains in the lower abdomen.
• Can occur before or during menstrual periods.
• 1-7 days of menstruation

Menstrual Cycle Phases

• The average menstrual cycle is 28 days.
• Menstrual Phase: (days 1-7)
  • The uterine lining sheds, causing menstruation.
• Follicular Phase: (days 1-13)
  • FSH stimulates the growth of ovarian follicles and egg cells.
  • Follicles mature and one becomes dominant.
• Ovulation Phase: (day 14)
  • The dominant follicle releases an egg.
  • LH triggers the release.
• Luteal Phase: (days 15-28)
  • If fertilization doesn't occur, the corpus luteum disintegrates.
  • Estrogen and progesterone levels drop.
  • The uterine lining sheds during menstruation.

Significance of the Menstrual Cycle

• Reproduction: The cycle prepares the body for potential pregnancy by regulating ovulation.
• Hormonal Regulation: Maintains hormone balance (estrogen and progesterone) critical for bodily functions.
• Health Indicator: A regular cycle is a sign of good health; irregularities may indicate conditions like hormonal imbalances or stress.
• Endometrial Renewal: The shedding of the uterine lining ensures a healthy environment for embryo implantation.

DNA vs. RNA

• Chromosome: A structured package of chromatin (DNA and protein) found within the cell's nucleus.
• DNA: Deoxyribonucleic acid; stores and transmits genetic information.
• RNA: Ribonucleic acid; plays a role in protein synthesis.

DNA Structure and Function

• Watson-Crick Model of DNA: A double helix structure with sugar-phosphate backbones and nitrogenous bases (Adenine, Thymine, Guanine, Cytosine).
• Chargaff's Rule: The amount of adenine equals thymine, and the amount of guanine equals cytosine.
• Genes: Segments of DNA that carry genetic information.

Central Dogma of Molecular Genetics

• Replication: Copying of DNA to produce identical copies.
• Transcription: Copying of DNA into messenger RNA (mRNA).
• Translation: mRNA decoding by ribosomes to create proteins.
• Codons: Three-nucleotide sequences on mRNA that specify amino acids.
• Nucleotides: Building blocks of DNA and RNA consisting of a sugar, phosphate group, and a nitrogenous base.
• Amino Acids: Building blocks of proteins.
• Proteins: Complex molecules that perform various functions in the body.

DNA Mutations

• Mutations: Changes in an organism's genetic material.
• Types of Mutations: Gene mutations (gene alteration) and chromosomal mutations (chromosomal abnormality).
• Point Mutations: Changes to a single nucleotide in DNA.
• Insertions: Adding extra base pairs.
• Deletions: Removing base pairs.
• Duplications: Extra copies of a sequence.
• Inversions: Reversal of gene order.
• Translocations: Transfer of a chromosome segment to another.
• Causes of Mutations: Radiation, chemicals, and infectious agents

Examples of Genetic Disorders

• Tay-Sachs Disease: Recessive disorder affecting the nervous system.
• Sickle Cell Anemia: Single-gene disorder affecting hemoglobin.
• Phenylketonuria (PKU): A metabolic disorder affecting neurodevelopment.
• Hemophilia: Blood clotting disorders.
• Cri-du-chat Syndrome: Missing chromosome segment.
• Down Syndrome: Trisomy 21
• Edward's Syndrome: Trisomy 18