Female Reproductiv

Urine Storage and Micturition Reflex
  • Urine Storage Capacity: The bladder can store approximately 3 liters of urine, with around 100 mL present at the time of reflex.
  • Storage Reflex:
    • This reflex allows the bladder to store urine without voiding.
    • The detrusor muscle—composed of smooth muscle layers—relaxes during urine storage.
    • The internal sphincter is contracted to prevent urine from exiting.
    • The external sphincter, which is voluntary, remains contracted to maintain urine storage.
Detrusor Muscle and Urination Control
  • Detrusor Muscle:
    • Comprises layers of smooth muscle around the bladder, oriented in different directions.
    • Responsible for bladder contraction during urination.
  • Sphincters:
    • Internal Sphincter: Involuntary control.
    • External Sphincter: Voluntary control, affected by conscious brain decisions through the central nervous system.
Signals and Potty Training
  • As the bladder fills, pressure receptors signal fullness.
  • Signals are sent to the cerebral cortex, necessary for voluntary control over micturition.
  • The pons also plays a role in involuntary responses, which can take precedence if the bladder fills too much, triggering involuntary urination to prevent damage.
Overview of Reproduction and Cell Division
  • Mitosis:
    • Defined as a cell division process that replicates cells, leading to two identical cells (genetic clones).
  • Meiosis:
    • A specialized form of cell division that reduces the chromosome number by half to produce gametes.
    • Involves two divisions: Meiosis I and Meiosis II.
Chromosome Number and Gamete Formation
  • Chromosome Basics:
    • Humans have 46 chromosomes (23 pairs) in somatic cells.
    • Gametes (sperm and eggs) each have 23 chromosomes.
    • This reduction is due to meiosis, maintaining genetic consistency in offspring (46 chromosomes as diploids).
Process of Meiosis
  • Meiosis I: Separates homologous chromosomes; reduces chromosome number by half (23).
  • Meiosis II: Similar to mitosis, separates sister chromatids.
  • Random assortment and crossing over during meiosis generate genetic diversity, crucial for evolution.
Gametogenesis
  • Spermatogenesis:
    • Male gamete formation; each spermatocyte produces four sperm cells through meiosis.
  • Oogenesis:
    • Female gamete formation; results in one egg and polar bodies (degenerate and reabsorbed).
    • Oocytes undergo meiosis, phylogenetically conserving cytoplasmic resources for the egg, crucial for embryonic development.
    • The ovum is larger than sperm due to the need for reserves during early development.
Ovarian Follicle Development
  • Ovarian follicles evolve through stages—primordial, primary, secondary, to Graafian (mature).
    • Primordial Follicle: Contains a primary oocyte and squamous follicular cells; present at birth.
    • Primary Follicle: Follicle cells become cuboidal, starting hormone production.
    • Secondary Follicle: Fluid-filled spaces form as follicle matures, leading to the Graafian follicle stage.
    • Graafian Follicle: Expands significantly; prepares for ovulation.
    • Ovulation: Upon rupture, the oocyte with surrounding cumulus cells is released into the fallopian tube.
Post-Ovulation and Hormonal Function
  • The remaining cells form the corpus luteum, secreting hormones (progesterone and estrogen) for uterine preparation for potential implantation.
  • Corpus luteum: Plays a crucial role in the menstrual cycle, degenerating if implantation does not occur, marking the onset of menstruation.