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What is the primary function of the infundibulum in the female reproductive system?
What occurs if the ovaries are removed before puberty?
Which hormones are produced by the ovaries that help in the menstrual cycle regulation?
What is the approximate length of the infundibulum?
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What is the physical description of the uterus?
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What is the size of the non-pregnant uterus approximately?
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Which hormone influences the glandular layer of the uterus?
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What happens to the glandular layer if pregnancy does not occur?
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What is the primary function of the myometrium during pregnancy?
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Which of the following statements is true about the perimetrium?
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After pregnancy, what is the size of the uterus?
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Where is the isthmus located in relation to the uterus?
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What is the function of the fundus in the uterus?
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What is the primary role of progesterone during pregnancy?
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Which of the following changes in electrolytes is indicated to decrease uterine contraction potential?
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What hormone is primarily aimed at supporting the corpus luteum during early pregnancy?
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By which week of pregnancy does the placenta start producing progesterone?
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Which membrane is the innermost fetal membrane?
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What happens to HCG levels in the mother's serum after the placenta takes over progesterone production?
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What structure is responsible for giving the placenta its shiny appearance?
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How many layers does the amniotic membrane consist of?
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What role does FSH play in the menstrual cycle?
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What occurs if fertilization does not take place?
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How do estrogen and progesterone influence LH and FSH secretion after ovulation?
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What marks the day of ovulation?
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Where are sperm produced in the male reproductive system?
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What happens to the fertilized egg after fertilization?
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What is the composition of sperm in terms of chromosomes?
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What is the primary function of LH during the menstrual cycle?
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What occurs during the positive feedback mechanism in the menstrual cycle?
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What happens to the uterine lining if there is no fertilization or implantation?
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What is the role of amniotic fluid during pregnancy?
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How is the umbilical cord structured?
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During which week of gestation is organogenesis completely finished?
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What happens by the end of the 20th gestational week?
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What is the normal range of amniotic fluid volume during pregnancy?
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What is the primary purpose of Wharton's jelly in the umbilical cord?
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During which gestational week does the fetus begin to demonstrate spontaneous movements?
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What is a significant milestone observed by the end of the 24th gestational week?
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What physiological change occurs by the end of the 28th gestational week?
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What is the weight of a fetus around the end of the 36th gestational week?
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When can sex be visibly distinguished in the fetus?
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What occurs in the fetal body during the end of the 32nd gestational week?
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What is the characteristic feature of polyhydramnios?
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Study Notes
Infundibulum
- Distal part of the fallopian tube, trumpet-shaped, swollen at ovulation.
- Approximately 2 cm long, covered by fimbria, which guide the ovum into the fallopian tube.
- Functions to produce, mature, and discharge ova (egg cells).
- Ovaries secrete estrogen and progesterone, initiating and regulating the menstrual cycle.
- Removal of ovaries before puberty affects maturation and maintenance of secondary sex characteristics, leading to a male-pattern pubic hair distribution.
Uterus
- Hollow, thick-walled muscular organ with variable size, shape, and weight.
- Typical size: approximately 5 to 7 cm long and 5 cm wide when non-pregnant; weighs 60g.
- Shape varies: pear-shaped when non-pregnant and ovoid when pregnant; olive shape during childhood.
- After pregnancy, uterus size changes to about 9 cm long, 6 cm wide, 3 cm thick, and weighs approximately 80g.
- Consists of two layers:
- Basal Layer: unaffected by hormones.
- Glandular Layer: influenced by estrogen and progesterone, supports pregnancy, sheds during menstruation if no pregnancy occurs.
- Myometrium: middle muscle layer constricts the fallopian tubes to prevent menstrual retrograde flow and maintains internal cervical closure during pregnancy.
- Perimetrium: outermost layer providing strength and support.
Uterine Divisions
- Body of Uterus (Corpus): expands to accommodate the growing fetus.
- Fundus: palpated to assess uterine growth and contraction strength.
- Isthmus: short segment connecting body to cervix, site for cesarean section incision.
Menstrual Cycle and Fertilization
- Decreased progesterone leads to menstrual flow; FSH initiates follicle development.
- Estrogen produced by follicles stimulates GnRH, FSH, and LH secretion, enhancing estrogen production in a positive feedback loop.
- LH triggers ovulation and formation of the corpus luteum.
- If fertilization does not occur, progesterone secretion declines, resulting in menstruation.
- Mittelschmerz: mild abdominal pain marking ovulation day.
Fertilization Process
- Pregnancy begins when sperm meets the egg.
- Sperm produced in testes, eggs reside in ovaries.
- Hormones regulate the menstrual cycle and egg maturation.
- Ovulation occurs when a mature egg is released from the ovary.
- Sperm can swim to locate and fertilize the egg post-ejaculation.
- Fertilized egg moves to the uterus for implantation.
- Without fertilization, the uterine lining is shed during menstruation.
Sperm Characteristics
- Male reproductive cell measuring about 0.05 mm with a head, middle piece, and tail.
- Contains 23 chromosomes: 22 autosomes and 1 sex chromosome, determining offspring sex when fused with X chromosome.
Progesterone Functions
- Maintains endometrial lining during pregnancy.
- Reduces uterine muscle contractility to prevent premature labor by altering electrolyte balance.
Fetal Membranes
- Surround the fetus, contributing to the shiny appearance of the placenta.
- Chorionic Membrane: outermost fetal membrane.
- Amniotic Membrane: consists of two layers (chorion and amnion), fuses over pregnancy, and no nerve supply.
- Provides support for amniotic fluid, essential for fetal development.
Placental Hormones
- Human Chorionic Gonadotrophin (HCG): detectable in urine and blood shortly after implantation; stimulates corpus luteum to maintain endometrium, serving as a pregnancy test marker.
- Around the 8th week of pregnancy, placenta begins progesterone production; decline in HCG levels occurs post-placental formation, with HCG undetectable 1-2 weeks after delivery.### Hormones and Functions
- Human Chorionic Somatomammotropin, also known as Human Placental Lactogen, is produced starting at the 6th week of pregnancy, peaking at term.
- Prostaglandins, initiated by phospholipids, may trigger the onset of labor.
Amniotic Fluid
- Forms within the amniotic cavity, surrounding the embryo.
- Typical volume ranges from 800ml to 1200ml, contains fetal urine, lanugo, epithelial cells, and subaqueous materials.
- Maintains a pH of 7.2 and specific gravity of 1.005 - 1.025.
- Oligohydramnios is defined as less than 300ml, whereas polyhydramnios exceeds 2000ml.
- Fluid is not stagnant; the fetus swallows amniotic fluid, which is absorbed into the fetal bloodstream and exchanged with the mother.
- Adequate fluid levels ensure proper kidney function of the fetus.
Umbilical Cord Structure
- Formed from the amnion and chorion, establishing circulatory communication between mother and fetus.
- Transports oxygen and nutrients from the placenta to the fetus and returns waste products.
- Composed of 1 vein (carrying blood to the fetus) and 2 arteries (returning blood to the placenta), associated with potential congenital disorders.
- Average length is about 53cm (21in.) and thickness is around 2 cm.
- Blood flow rate through the umbilical cord reaches 350ml/min at term.
- Wharton’s jelly provides cushioning to protect the vein and arteries.
Fetal Development Milestones
End of 4th Gestational Week
- Length ranges from 0.75 to 1 cm and weight is approximately 400 mg.
- Formation of spinal cord and notable head size relative to the body.
- Development of rudimentary heart and budlike structures for arms and legs.
End of 8th Gestational Week
- Length reaches about 2.5 cm (1 inch) and weight is 20 gm.
- Organogenesis is completed with a rhythmically beating heart and developing facial features.
- External genitalia are present but not distinguishable by simple observation.
End of 12th Gestational Week
- Length measures 7 to 8 cm, weighing around 45 gms.
- Formation of nail beds and possible spontaneous fetal movements, though subtle.
- Bone ossification centers begin forming, and sex is discernible.
End of 16th Gestational Week
- Length varies from 10 to 17 cm with a weight between 55 to 120 gms.
- Fetal heart sounds audible with a stethoscope, exhibiting well-formed lanugo.
End of 20th Gestational Week
- Length at approximately 25 cm, weight is around 223 gms.
- Visible spontaneous fetal movements and antibody production capacity.
End of 24th Gestational Week
- Length ranges from 28 to 36 cm, weight about 550 gms.
- Presence of meconium in the intestine and antibody transfer from mother to fetus begins.
End of 28th Gestational Week
- Length between 35 to 38 cm and weight 1200 gms.
- Lung development progresses with maturity of alveoli, and descent of testes begins.
End of 32nd Gestational Week
- Length measures 38 to 43 cm, weight around 1600 gms.
- Fetus demonstrates responsive movements to external sounds and may assume birth position.
End of 36th Gestational Week
- Length ranges from 42 to 48 cm and weight between 1800 to 2700 gms.
- Development of subcutaneous fat and distinctive sleeping/activity patterns.
End of 40th Gestational Week
- Length of 48 to 52 cm with a birth weight of approximately 3000gms (7 to 7.5 lbs).
- Notable fetal movements and reactions to light and sound; increased availability of vernix caseosa.
Measurement Units
- Pregnancy duration may be tracked in lunar months (4 weeks) or by trimester (3 months).
- Total pregnancy is typically 10 lunar months (40 weeks), with fetal development occurring over 9.5 lunar months or 3 full trimesters (38 weeks or 266 days).
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Description
Explore the infundibulum, the distal part of the fallopian tube, shaped like a funnel and crucial during ovulation. This quiz covers its functions, structure, and significance in ovum production and transport. Test your knowledge of this essential anatomy!
