Reproductive physiology Flashcards
What is the main function of the Pineal gland?
The main function of the Pineal gland is the regulation of diurnal cycles (sleep and wake cycles) by producing melatonin.
What are the components of the Diencephalon?
The Diencephalon consists of the Thalamus, Hypothalamus, and Epithalamus, including the Pineal gland and Habenula (habenular commissure).
Why is the Pineal gland sometimes referred to as the third eye?
The Pineal gland is sometimes called the third eye due to its association with regulating diurnal cycles and producing melatonin in response to light and darkness.
Which nucleus is known as the biological clock?
The Suprachiasmatic Nucleus (SCN) is known as the biological clock.
How does the Retinohypothalamic Tract (RHT) contribute to the regulation of sleep-wake cycles?
The RHT carries action potentials from light receptors in the retina to the SCN, contributing to the regulation of sleeping and waking.
What chemicals are released by the SCN to stimulate different organs?
The SCN releases specific chemicals, usually glutamate, to stimulate different organs in the body.
What is the role of the Paraventricular Nucleus (PVN) in the regulation of the sleep-wake cycle?
The PVN is stimulated and sends signals down the spinal cord to the Superior Cervical Ganglion (SCG), contributing to the regulation of the sleep-wake cycle.
Which neurotransmitter is secreted by postganglionic motor neurons to signal the Pineal gland?
Postganglionic motor neurons secrete norepinephrine (NE) to signal the Pineal gland.
What type of receptors do Pinealocytes have for NE?
Pinealocytes have specific adrenergic receptors for NE.
Describe the intracellular pathway stimulated by adrenergic receptors in Pinealocytes.
Adrenergic receptors in Pinealocytes stimulate the intracellular pathway: Tryptophan → 5-hydroxytryptamine → Serotonin → Melatonin.
How does light influence the SCN and Pineal gland activity?
Light inhibits the SCN, leading to Pineal gland inhibition and decreased melatonin secretion, promoting staying awake.
What happens in response to darkness regarding the SCN and Pineal gland activity?
Darkness stimulates the SCN, leading to Pineal gland stimulation and increased melatonin secretion, promoting sleep.
Where are the receptors for melatonin located, and what effect does increased melatonin have on the SCN?
Receptors for melatonin are located in the SCN, and increased melatonin levels rest the biological clock of the SCN.
What is the general timeframe for a normal menstrual cycle?
A normal menstrual cycle typically lasts around 28 days, with a normal timeframe ranging from 21 to 39 days.
Define ovulation in the context of the menstrual cycle.
Ovulation is the process where a mature female sex cell (ovum) is released by a Graafian Follicle, traveling to the fallopian tube in preparation for fertilization.
What are the two special nuclei in the hypothalamus responsible for releasing Gonadotropin-Releasing Hormone (GnRH)?
The two special nuclei in the hypothalamus responsible for releasing GnRH are the Arcuate Nucleus and the Pre-Optic Nucleus.
What hormones are synthesized and released by the anterior pituitary in the context of the menstrual cycle?
The anterior pituitary controls the synthesis and release of gonadotrophins, specifically Follicular Stimulating Hormone (FSH) and Luteinizing Hormone (LH).
In the ovary, what do gonadotropins (FSH and LH) work on?
Gonadotropins (FSH and LH) work in the ovary.
What hormones are released by the ovary, and what are they converted into?
The ovary releases androgens, which are converted to estrogen, followed by the later release of progesterone.
What is the role of primordial follicles in the context of ovarian follicle growth?
Primordial follicles, which arise from oogoniums, are diploid cells that become necessary stem cells during a female’s reproductive years.
How many chromosomes do oogoniums have, and what do they develop into before puberty?
Oogoniums have 46 chromosomes (diploid), and before puberty, they develop into primordial cells.
What is the status of the first oocyte in a primordial cell, and in which phase is it stationary?
The first oocyte in a primordial cell continues to be diploid and is stationary in Prophase I.
What are the potential variations in menstruation, and what conditions do they indicate?
Menstruation can vary, with conditions like amenorrhea (non-existent menstruation) or menorrhagia (longer and heavier bleeding events) indicating variations in the menstrual cycle.
What stimulates primordial follicles to develop into a primary follicle in females after reaching puberty?
Local androgens stimulate primordial follicles into developing into a primary follicle.
What is the composition of a primary follicle, and what is the status of the primary oocyte within it?
A primary follicle is composed of a single layer of cuboidal or columnar-like epithelial cells, surrounded by thecal cells. The primary oocyte within is still frozen in prophase I and has not undergone meiosis I.
How does FSH and LH contribute to estrogen production in the follicular phase?
FSH causes the development of additional layers of granulosa cells surrounded by thecal cells, while LH stimulates thecal cells to convert cholesterol to androgens. Androgens pass from the thecal cells to the neighboring granulosa cells, contributing to estrogen production.
What is the glycoprotein layer produced by the early secondary follicle, and what stimulates its formation?
The early secondary follicle produces a glycoprotein layer called the zona pellucida, and its formation is stimulated by FSH.
Describe the composition and characteristics of the early secondary follicle.
The early secondary follicle is composed of multiple layers of cuboidal or columnar-like epithelial cells, a zona pellucida, and is surrounded by thecal cells. It is still in prophase I and produces estrogen.
How does the late secondary follicle differ from the early secondary follicle in terms of granulosa cell proliferation and fluid production?
The late secondary follicle undergoes further proliferation of granulosa cells and produces follicular fluid pockets rich in hyaluronic acid. It has an almost similar composition to the early secondary follicle but with increased granulosa cell proliferation and fluid pockets.
What is the final stage in the follicular phase, and how is it initiated?
The Graafian Follicle, also called the vesicular or tertiary follicle, is the final stage in the follicular phase. It is produced from the stimulation of the late secondary follicle by FSH.
What significant events occur in the Graafian Follicle, and what does it undergo in terms of meiosis?
The Graafian Follicle undergoes further proliferation of epithelial cells and continuous production of follicular fluid pockets, forming a large fluid-filled cavity called the antrum. It undergoes meiosis I, resulting in the haploid cell splitting into two daughter cells, one becoming a polar body. Subsequent splits produce a daughter cell and three polar bodies. The daughter cell has a corona radiata.
What is the duration of the follicular phase, and what are the key products produced during this phase?
The follicular phase typically occurs from day 1 to 14 and produces multiple layers of granulosa cells, estrogen, zona pellucida, corona radiata, and follicular fluid antrum. It also involves the conversion of a primary oocyte to a secondary oocyte.
What characterizes the Mid-Follicular Phase, and when does it occur in the menstrual cycle?
The Mid-Follicular Phase is marked by the rise in estrogen levels entering the bloodstream, starting around the middle of the follicular phase (around day 7-10). The increased estrogen exerts negative feedback on the hypothalamus and anterior pituitary, inhibiting GnRH release and subsequently FSH and LH release.
What initiates the Late Follicular Phase, and how does the feedback loop change during this phase?
The Late Follicular Phase is initiated by a change in feedback loop from negative to positive due to increased estrogen levels in the blood. The hypothalamus produces GnRH, and the anterior pituitary releases gonadotropins, leading to an LH surge. This surge stimulates angiogenesis, increasing blood supply to the Graafian follicle, and results in ovulation.
Describe the process of ovulation and its timing in the menstrual cycle.
Ovulation usually occurs around mid-cycle, approximately day 14-15, triggered by the LH surge. The fimbriae of the fallopian tubes become stiff, creating fluid-filled currents that pull the secondary oocyte into the fallopian tube’s ampulla for potential fertilization.
When does the Luteal Phase occur, and what transformations happen to the Graafian follicle during this phase?
The Luteal Phase occurs in the second half of the cycle, approximately day 15-28. The Graafian follicle, now called corpus hemorrhagicum, is stimulated by LH to accumulate cholesterol, lipids, and fats, turning it into the corpus luteum. The corpus luteum produces progesterone.
What stimulates the corpus luteum to accumulate cholesterol, lipids, and fats during the Luteal Phase?
LH stimulates the corpus luteum, which was the Graafian follicle that expelled the oocyte, to accumulate cholesterol, lipids, and fats during the Luteal Phase.
What is the role of the corpus luteum during the Luteal Phase, and what hormone does it produce?
The corpus luteum produces progesterone during the Luteal Phase. It is formed from the Graafian follicle expelled during ovulation and is further stimulated by LH.
What happens during the follicular phase from day 1-14?
Conversion of the primary follicle to a secondary follicle, producing multiple layers of granulosa cells, zona pellucida, corona radiata, follicular fluid antrum, and estrogen.
What triggers the events of the ovulatory phase, and when does it occur in the menstrual cycle?
The ovulatory phase is triggered by the LH surge and typically occurs on day 14-15. It involves the release of the secondary oocyte to the fallopian tube for transport to the area of fertilization.
What transformations occur during the luteal phase, and when does it take place?
The luteal phase occurs from day 15-28 and involves the formation of the corpus luteum from the Graafian follicle, which produces progesterone.
In the follicular phase, what structures and substances are produced from day 1-14?
Multiple layers of granulosa cells, zona pellucida, corona radiata, follicular fluid antrum, and estrogen are produced during the follicular phase from day 1-14.
What are the different cells involved in the follicular phase, and what are their characteristics?
- Primordial Cell: Continues to be a diploid cell.
What hormones are involved in the production of estrogen in the follicular phase?
d) FSH and LH
What produces progesterone during the luteal phase?
c) Corpus Luteum
What timeframe does the luteal phase encompass?
a) Day 15-28
What timeframes of the menstrual cycle are considered pathological?
c) Less than 20 and more than 40 days
In mid-follicular phase, do the levels of estrogen in the blood cause a positive feedback loop on the hypothalamus and anterior pituitary gland?
b) False
What is the inner lining of the uterus called?
Endometrium
How many sublayers or strata compose the endometrium, and what are they called?
Two sublayers or strata compose the endometrium: Stratum functionalis (green layer) and Stratum basalis (blue layer).
During menstruation, which sublayer of the endometrium is shed from the uterus?
The stratum functionalis is shed during menstruation.
What is the time frame for the menstrual period, and what factors can influence its duration?
The menstrual period typically occurs from days 1 to 5, but it can vary from person to person, depending on whether they have a regular menstrual period or experience heavy menstruation (menorrhagia).
What structures are lost during the shedding of the stratum functionalis in the uterus?
Spiral and coiled arteries are lost during the shedding of the stratum functionalis.
Differentiate between the types of arteries found in the stratum basalis and stratum functionalis.
In the stratum basalis, straight arteries are present, while in the stratum functionalis, spiral and coiled arteries are found. These arteries are branches of uterine arteries, which come off the internal iliac artery.
