Questions and Answers
What is the primary function of the primitive testes at 8 weeks into pregnancy?
Which duct is associated with male development?
What is the term for the condition where genotypic sex does not match phenotypic sex?
At what point in pregnancy do the external genitalia start to develop?
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Which chromosomes determine the genotypic sex in humans?
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What is the approximate length of the cervix in non-pregnant form?
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What is the primary function of the mucus secreting glands in the cervix?
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During labor, what is considered a measurement of 1 inch in dilation of the cervical area?
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Which portion of the uterus is described as the shortest and connects the body to the cervix?
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What is the primary function of the internal and external OS of the cervix?
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Study Notes
Uterus Anatomy and Function
- The uterus, or womb, weighs 40 to 70 grams and is pear-shaped, measuring approximately the size of a fist.
- Its length is around 6 to 8 cm and is divided into three regions: cervix, isthmus, and corpus (endometrial cavity).
Cervix
- The cervix is the lowest portion, approximately 2.5 cm in length, connecting the uterus to the vagina.
- Contains two openings: internal os (junction with isthmus) and external os (opens during menstruation and active labor).
- Functions include effacement (thinning) and dilatation (enlargement) during labor.
- Dilation measurement is significant, with 1 inch indicating active labor and a 10 cm diameter signaling imminent delivery.
- Comprises one-third of uterine size and maintains an alkaline environment for sperm survival.
- Houses mucus-secreting glands that provide lubrication and have bacteriostatic properties.
Isthmus
- The isthmus connects the cervix to the corpus, measures about 6 mm, and is a site for low segment cesarean sections during pregnancy.
Homologous Reproductive Organs
- Male and female reproductive systems share similar structures, functions, and embryonic origins.
- Development of reproductive organs is the last among body systems and occurs without fertilization until sexual maturity.
Intrauterine Development
- Genotypic sex is established (XX for females, XY for males) and leads to phenotypic sex differentiation.
- Physical characteristics develop between 5 to 24 weeks into pregnancy, including the formation of undifferentiated ducts: wolffian (male) and mullerian (female).
- Hormonal influences dictate the presence or regression of these ducts; testosterone promotes male traits, while its absence allows female traits to emerge.
Endometrium
- The endometrium is the mucosal layer lining the uterus, undergoing monthly regeneration controlled by hormones.
- Prepares the uterine environment for fertilization and sustains the embryo before implantation, referred to as decidua during pregnancy.
Uterine Support Structures
- Multiple ligaments support uterine position including:
- Broad ligament: Stabilizes the uterus and maintains its central position within the pelvic cavity.
- Round ligament: Maintains the position of the uterus, especially during labor.
- Additional ligaments in the middle and lower segments include cardinal, uterosacral, and pubocervical ligaments, which prevent uterine prolapse and provide structural integrity.
Follicular Development
- The primordial follicle matures into a graafian follicle around the 14th day of the menstrual cycle, releasing the mature egg during ovulation influenced by hormonal peaks.
- The corpus luteum forms post-ovulation, producing progesterone and degenerating into corpus albicans if fertilization does not occur.
Uterine Cycle Phases
- Comprised of pre-ovulatory (menses, proliferative) and post-ovulatory (secretory) stages.
- The ischemic phase occurs on days 26 to 28, characterized by constricted arteries and subsequent shedding of the endometrial lining, restarting the menstrual cycle.
Ovulation
- Occurs approximately 14 days before the next menstrual period; peak fertility corresponds to this timing.
- The lifespan of an egg is 24 to 48 hours, while sperm remains viable for 48 to 72 hours.
- Female libido peaks around ovulation, enhancing sexual responsiveness.
Detection of Ovulation
- Fern test: Observing cervical mucus under a microscope reveals a fern-like pattern due to high estrogen levels, indicating optimal time for conception.
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Description
Explore the anatomy and functions of the uterus, focusing on its structure, including the cervix, isthmus, and corpus. Learn about its significance in fetal growth and its characteristics in non-pregnant form.
