Reproductive Physiology Flashcards
1
Q
As the Vas deferens descends downwards below the urinary bladder it penetrates a gland called the ______ gland
A
As the Vas deferens descends downwards below the urinary bladder it penetrates a gland called the prostate gland
2
Q
What is contained in the spermatic cord?
A
- Vas deferens
- Vasculature
- Innervation
3
Q
Male gonads are the ______ and are housed in the _____
A
Male gonads are the Testes and are housed in the scrotal sac
- Outside the body
- Contains testis, blood vessels, nerves
4
Q
Blood vessels within the testes allow for:
A
Countercurrent bloodflow = temperature regulation
5
Q
The spermatic cord is a cord-like structure that passes through a slit in the ______ of the _______ down into the ________
Composed of: (3)
A
The spermatic cord is a cord-like structure that passes through a slit in the inguinal canal of the abdomen down into the scrotal sac
Composed of: (3)
- Vas deferens
- Blood vessels
- Nerves
6
Q
What is the purpose of counter-current bloodflow?
A
- To regulate temperature
- Testis is housed outside the body
- temp is lower than core temp = Necessary for optimal spermatogenesis
- Testis is housed outside the body
- Countercurrent exchange works to cool the blood before it enters the testis
- Blood flows in opposite directions in very close proximity
7
Q
During development:
- Testis are first found in the _______ before descending to their final position in the ______
A
During development:
- Testis are first found in the abdominal cavity before descending to their final position in the scrotum
8
Q
During the gestation period:
- At 8 weeks where are the testes located?
- 1st phase: when and what?
- 2nd phase when and what?
- At time of birth:
A
During the gestation period:
- At 8 weeks where are the testes located?
- high up in the abdomen (near level of kidneys)
- 1st phase: when and what?
- Between 8-12 weeks
- Testes move closer to the inguinal canal
- 2nd phase when and what?
- Between 7th-9th month intrauterine life
- Testes pass through inguinal canal
- come to rest in the scrotum
- At time of birth:
- Testes should have descended into scrotal space
- In some cases baby could be born w/ undescended testes = corrected with surgery
9
Q
The testes (male gonads) are filled with highly twisted/convoluted tubules known as the ________
A
The testes (male gonads) are filled with highly twisted/convoluted tubules known as the seminiferous tubules
10
Q
What is the site of sperm production?
A
Seminiferous tubules (within the testes)
11
Q
Seminiferous tubules (within the ____) lead into a network-like structure called the ______
A
Seminiferous tubules (within the testes) lead into a network-like structure called the Rete Testis
12
Q
The Rete Testis (leading from the seminiferous tubules in the testes) leads onto highly porous structures known as the _________
A
The Rete Testis (leading from the seminiferous tubules in the testes) leads onto highly porous structures known as the epididymis
13
Q
The efferent ductules lead into the ________
A
The efferent ductules lead into the epidiymis
14
Q
What is the pathway of tubes within the testes?
A
Seminiferous tubules -> Rete Testis -> Efferent ductules -> Epididymis
15
Q
The Seminiferous Tubules are the site of _________.
They sit on the __________ and contain a _______ and many cells called the ________
A
The Seminiferous Tubules are the site of sperm production.
They sit on the basement membrane and contain a lumen and many cells called the spermatogenic cells
16
Q
When does spermatogenesis begin?
A
At puberty
17
Q
How can mumps affect spermatogenesis?
A
Mumps can cause seminiferous tubules to become much smaller
- lumen becomes much bigger and the spermatogenic cells look very small
18
Q
What are the three types of cells within the testis?
A
- Leydig cells (interstitial cells)
- secrete testosterone
- Sertoli cells (epithelial cells)
- support sperm development
- Smooth muscle (myoid cells)
- Peristalsis
- propel sperm
- Peristalsis
19
Q
What cell type in the testis secretes testosterone?
A
Leydig cells (interstitial cells)
20
Q
What are the 7 function of Sertoli cells?
A
- Support sperm development: “trophic role”
- Secrete luminal fluid for sperm housing
- Secrete androgen-binding protein (under influence of FSH)
- Androgen buffer
- Helps maintain steady [Androgens] in lumen
- Secrete inhibin
- Hormone of negative feedback loop for FSH
- Act as target cells for testosterone and follicle stimulating hormone (FSH)
- Phagocytosis of old and damaged sperm
- Site of immunosuppression (blood testis barrier)
- tight junction
21
Q
Leydig cells are found in the ________ surrounding the ________ where they function to:
A
Leydig cells are found in the connective tissues surrounding the seminiferous tubules where they function to: produce and secrete testosterone
22
Q
What cells of the testis are laid out side by side and sit on a basement membrane?
A
Sertoli cells
23
Q
Sertoli (epithelial) cells are joined by _______ thus creating the _________
A
Sertoli (epithelial) cells are joined by tight junctions thus creating the blood testis barrier
24
Q
Why are tight junctions in the testis important?
A
Form the blood-testis barrier
- prevent infections or other substances that might harm growing sperm
- Create an invisible ring-like structure through which nothing can permeate from outside to inside
25
What are the two compartments created by the blood testis barrier?
* Luminal compartment
* Tight junction to lumen
* Basal compartment
* Basement membrane to tight junction
26
Myoid cells (smooth muscle cells)
Where are they located?
Function?
Myoid cells (smooth muscle cells)
* Where are they located?
* Just outside the basement membrane
* Function?
* Have **contractile properties**
* Help with *peristalsis* to move the sperm forward
27
Testosterone is produced by _____ cells and is a ______ hormone
Testosterone is produced by _Leydig_ cells and is a _steroid_ hormone
28
What is the significance of testosterone being lipophilic?
* Testosterone can permeate through the basement membrane of the **seminiferous tubules** and enter into the *luminal compartment* of the *seminiferous tubules* where it binds to the **androgen binding protein** which works like a buffer = maintains high luminal [testosterone]
29
Testosterone and FSH act on sertoli cells to cause \_\_\_\_\_\_\_
Testosterone and FSH act on sertoli cells to cause _secretion of paracrine factors_
30
\_\_\_\_\_\_\_\_\_ and ____ use sertoli cells as their target and help in sperm development
_testosterone_ and _FSH_ use sertoli cells as their target and help in sperm development
31
Seminiferous tubules contain developing ________ situated very close to ______ which produce testosterone
Seminiferous tubules contain developing _germ cells_ situated very close to _Leydig cells_ which produce testosterone
32
Seminiferous tubules contain developing germ cells situated very close to Leydig cells.
The Leydig cells produce _______ which quickly permeates through the basement membrane and acts on the _______ contained in the seminiferous tubules
Seminiferous tubules contain developing germ cells situated very close to Leydig cells.
The Leydig cells produce _testosterone_ which quickly permeates through the basement membrane and acts on the _germ cells_ contained in the seminiferous tubules
33
What two hormones can regulate the development of spermatogenesis?
FSH and Testosterone
34
Testosterone is a _____ hormone synthesized from \_\_\_\_\_
Testosterone is a _steroid_ hormone synthesized from _Cholesterol_
35
Steroid hormones are primarily produced by the ______ and the \_\_\_\_\_\_\_
Steroid hormones are primarily produced by the _adrenal cortex_ (zona reticularis) and the _gonads_
36
In Male Gonads:
Progesterone is produced from ______ and the predominate enzymes channel the production towards \_\_\_\_\_\_\_
- formation of ______ and ________ is bypassed in the male gonads and more testosterone is produced
In Male Gonads:
Progesterone is produced from _cholesterol_ and the predominate enzymes channel the production towards _testosterone_
- formation of _mineralocorticoids_ and _glucocorticoids_ is bypassed in the male gonads and more testosterone is produced
37
Depending on enzymes present, what three molecules can Progesterone be converted to?
Mineralocorticoids
Glucocorticoids
Androgens
38
In the Leydig cells:
* Cholesterol -\> _______ -\> \_\_\_\_\_\_\_
In the Leydig cells:
* Cholesterol -\> _Pregnenolone_ -\> _progesterone_
* Both Pregnenolone and progesterone produce testosterone
39
In the bloodstream testosterone is converted to ________ by the enzyme \_\_\_\_\_\_\_
In the bloodstream testosterone is converted to _dihydrotestosterone (DHT)_ by the enzyme _5-alpha Reductase_
40
What is the function of Dihydrotestosterone (DHT)?
DHT
* maintains other tissues/sexual characteristics
* maintenance of the prostate
* secondary male sex characteristics
41
Testosterone may be converted to estrogen by _______ which occurs in \_\_\_\_\_\_, \_\_\_\_\_\_, ______ and \_\_\_\_\_
Testosterone may be converted to estrogen by _aromatase_ which occurs in _liver, adipose, brain_ and _testes_
42
What is the pattern of Plasma testosterone concentration over life span?
* Before birth:
* High peak of testosterone which then decreases until birth (parturition)
* Neonatal
* High peak for a short duration
* levels decrease for duration of childhood years
* Puberty until Adulthood:
* Plasma testosterone levels slowly increase through stages of puberty and remain high during adulthood
* Around 40
* testosterone starts to decline = "adropause"
43
Sperm production pattern parallels testosterone:
Sperm production begins at the onset of puberty with a sharp rise until adulthood
* maintained until 40-45 and then decreases (andropause)
44
What is the activity of the Hypothalamic-Pituitary-Leydig Cell Axis at the onset of puberty?
* Cues/signals acting on hypothalamus through higher brain centres act to initiate firing of the cells that produce the hormone **gonadotropin releasing hormone** (GnRH) (from hypothalamus)
* At onset of puberty in males there is a **pulsitile secretion** of **GnRH**
* acts on the **gonadotropic cells** of the anterior pituitary
* Causes the pulsatile secretion of hormones
45
Why must GnRH be released via pulsatile secretion?
Because receptors won't respond to constant high levels
46
What are 6 effects of androgens?
1. Stimulate **spermatogenesis**
2. Promote development of secondary sex characteristics during puberty and maintenance of these characteristics in adult life (via testosterone and DHT)
3. Increase sex drive
4. Promote protein synthesis in skeletal muscle (**anabolic effect**)
5. Stimulate growth hormone secretion, which permits bone growth during adolescence
6. Promote development of male reproductive structures during embryonic life
47
Before genetic sex is determined, the structure from which the _______ tract develops has bipotential.
The presence of the ___ chromosome determines male sex
Before genetic sex is determined, the structure from which the _urogenital_ tract develops has bipotential.
The presence of the _Y_ chromosome determines male sex
48
The formation of male gamete (sperm) is called:
Spermatogenesis
49
What are the three phases of Spermatogenesis?
1. Mitosis
* Spermatogonium divides via mitosis
* One cell remains a spermatogonium, the other, the **committed cell** is called the **Primary spermatocyte**
* Occurs in the Basal compartment in between two Sertoli cells
* ensures continuous supply of spermatogonia
2. Meiosis I
* Primary spermatocyte moves forward to the luminal compartment
* Meiotic division starts
* Produces 2 secondary spermatocytes from one primary spermatocyte
3. Meiosis II
* Each secondary spermatocyte gives rise to 2 spermatids
50
What is the last stage of Spermatogenesis?
Spermiogenesis
51
What happens in spermiogenesis?
* Remodelling of the cytoplasm
* Neck piece with mitochondria
* Head holds genetic material
* Takes approx 24 days
* Head has acrosome containing enzymes
52
Early spermatids are embedded in the space between adjacent sertoli cells where they become \_\_\_\_\_
Early spermatids are embedded in the space between adjacent sertoli cells where they become _Spermatozoa (sperm)_
53
In the seminiferous tubule, the spermatozoa are released into the ____ in their ______ form where they remain immotile for about ____ days
In the seminiferous tubule, the spermatozoa are released into the _lumen_ in their _immature_ form where they remain immotile for about _20_ days
54
As sperm are essentially immotile following spermiogenesis, what propels them toward the epididymis?
Fluid pressure generated by the sertoli cells pushes the sperm forward towards the epididymis
55
What happens to sperm in the epididymis and how long are they housed there?
Sperm reside in the epididymis for 6-12 days where they undergo a process of maturation before they are capable of progressive motility and fertilization
* Acquire motility
* Wave-like tail movement initially
56
Sperm move to the _____ by the process of peristalsis where they are stored until ejaculation
Sperm move to the _vas deferens_ by the process of peristalsis where they are stored until ejaculation
57
The ________ acts as the "pulse-generator" of GnRH
The _hypothalamus_ acts as the "pulse-generator" of GnRH
58
The hypothalamus generates pulsatile secretion of ______ which acts on the anterior pituitary to release _____ which acts on sertoli cells
The hypothalamus generates pulsatile secretion of _GnRH_ which acts on the anterior pituitary to release _FSH_ which acts on sertoli cells
59
What is the effect of FSH on Sertoli cells?
FSH stimulates sertoli cells to secrete **androgen binding protein** and **inhibin**
60
How does the pulse-generator work and how is it regulated?
Hypothalamus (pulse-generator) -\> GnRH -\> Anterior pituitary -\> gonadotropins (FSH and LH)
* FSH acts on Sertoli cells
* stimulates spermatogenesis
* Release Androgen-binding protein (ABP) and inhibin
* LH
* Acts on leydig cells
* stimulates androgen secretion (testosterone)
* Inhibin regulates the axis at the level of the anterior pituitary to decrease secretion of FSH
61
Inhibin regulates the axis at the level of the ______ to decrease secretion of \_\_\_\_
Inhibin regulates the axis at the level of the _anterior pituitary_ to decrease secretion of _FSH_
62
* LH acts on the _____ cells to secrete testosterone.
* This testosterone inhibits the secretion of ____ at the level of the anterior pituitary and hypothalamus
* FSH acts on the ______ cells
* Release of FSH from the anterior pituitary is inhibited by _____ released from _____ cells
* LH acts on the _leydig_ cells to secrete testosterone.
* This testosterone inhibits the secretion of _LH_ at the level of the anterior pituitary and hypothalamus
* FSH acts on the _Sertoli_ cells
* Release of FSH from the anterior pituitary is inhibited by _inhibin_ released from _sertoli_ cells
63
3 functions of seminal fluid
1. Dilution of sperm
2. Provision of energy (fructose)
3. Formation of semen "clot"
* fibrin like protein or clotting protein that helps in the formation of the semen plug
64
Where does seminal fluid come from?
* Seminal vesicles
* provide bulk of volume
* Prostate gland
* maintaining health of the sperm
* Bulbourethral gland
65
How do each of the following contribute to seminal fluid?
* Seminal vesicles
* Prostate gland
* Bulbourethral glands
How do each of the following contribute to seminal fluid?
* Seminal vesicles
* bulk
* alkaline fluid with fructose, enzymes and prostaglandins (contraction of female)
* Prostate gland
* Secrete citrate and enzymes (prostate specific enzyme PSA -\> increase fluidity)
* increase in the concentration of PSA may indicate cancer
* Bulbourethral glands
* secrete viscous fluid with mucus
66
What does "semen" refer to?
Sperm + Seminal fluid
67
The male sexual response is controlled by the \_\_\_\_\_\_
* Erection: _______ nervous system
* Emission: ______ nervous system
* Ejaculation: ________ control
The male sexual response is controlled by the _ANS_
* Erection: _Parasympathetic_ nervous system
* Emission: _Sympathetic_ nervous system
* sympathetic (thoracolumbar) stimulation to the smooth muscles of the ducts
* movement of sperm from vas deferens with mixing of seminal fluid into the common urogenital tract
* Ejaculation: _Somatic_ control
* Rapid contraction of skeletal muscle for semen expulsion
68
How is erection maintained?
During erection
* Activity of sympathetic neurons decreases
* Activity of parasympathetic neurons to penile structures increases
* causes relaxation of smooth muscle which increases blood flow
69
Parasympathetic control of Erection:
* Activation of Parasympathetic nerve causes the release of \_\_\_\_\_\_\_
* Activates enzyme _______ = converts GTP into cGMP
* increased cGMP causes \_\_\_\_\_\_\_\_
* cGMP is broken down by \_\_\_\_\_\_\_
Parasympathetic control of Erection:
* Activation of Parasympathetic nerve causes the release of _Nitric Oxid from nerves to the erectile tissue_
* Activates enzyme _guanylate cyclase_ = converts GTP into cGMP
* increased cGMP causes _vasodilation (acts on smooth muscle of blood vessels)_
* cGMP is broken down by _phosphodiesterase_
* __stops erection
70
What ends erection?
cGMP is broken down by enzyme phosphodiesterase
(cGMP causes vasodilation)
71
What is the mechanism of action of viagra?
viagra acts as an inhibitor of phosphodiesterase = cGMP is not broken down
72
What two processes are involved in the final maturation of sperm and where does it occur?
* Occurs in the female tract
1. Capacitation
* receptors made available through the removal of **glycoprotein layer**
* alters acrosomal cap
* tail movement changes = whiplike
2. Acrosomal reaction
* triggered by binding of sperm with zona pellucida
* involves progressive fusion of acrosomal membrane with plasma membrane of the sperm creating many pores through which acrosomal enzymes can be released
* digest through zona pellucida
73
What are three important differences between the female repro tract and the male repro tract?
1. Females have cyclic changes in activity associated with the menstrual cycle
2. Restricted periods of fertility
* Ovulation
* Sperm are always fertile
3. Limited gamete production
* males have unlimited
74
Three "M"s of female reproductive activity over the human life span
* Menarche
* onset of puberty
* Menstruation
* Reproductive system cycles
* Menopause
* loss of reproductive ability (45-50)
75
What are the female gonads?
Ovaries
76
The ovaries are the site of \_\_\_\_\_
The ovaries are the site of _ova maturation_ (Ovarian Cycle)
77
What is the structure of ovaries?
Connective tissue with follicles suspended by ligamentous tissue in the peritoneal cavity
78
What are Fimbra (Fimbriae)
Finger-like projections that stick out and sit very close to the ovary
* contain small hair-like cells (ciliated cells) which can move
* catch released ovum and sweeps it into the infundibulum
79
How does the ovum move through the uterine tube?
Initially - peristaltic contractions
Mostly ciliary actions
Takes 4 days to reach the uterus
80
Where does fertilization occur?
Ampulla of the Uterine tube
81
What are the three layers of the wall of the uterus?
1. Perimetrium - outer
* epithelial cells and connective tissue
2. Myometrium - middle
* smooth muscle
* thickest
3. Endometrium - inner
* Layer of epithelial cells
* Layer of connective tissue
* Numberous glands
82
What does the birth canal include?
Cervix and Vagina
83
What are the three follicular stages of the ovarian cycle?
* Primordial follicles
* Primary follicles
* Mature follicles - releases egg
84
What is the corpus luteum?
Mature follicle following release of the egg
- becomes and endocrine gland and releases LH
85
What is the corpus albicans?
Forms after the corpus luteum degenerates
86
What are the 3 cycles of the female body?
1. Hormonal cycle
* cyclic changes in the secretion of FSH and LH secreted from the anterior pituitary causing ovarian changes
2. Ovarian cycle
* development of an ovarian follicle, rupture of the follicle and release of the ovum and formation/regression of a corpus luteum
3. Uterine cycle (menstrual cycle)
* cyclic operation of the uterus
* prepare the lining of the uterus called the endometrium to receive an embryo
87
What are the 2 phases of the ovarian cycle?
1. Follicular phase
* first 14 days
* Development of follicles
* Ovulation
* Release of egg
* 14th day
2. Luteal phase
* corpus luteum - secretory gland
88
What are the three phases of the Uterine cycle?
1. Menstrual phase
* Day 1 - first day of menstrual bleeding
* 4-5 days
2. Proliferative phase
* development/growth of endometrium
* layers become thicker
* angiogenesis
3. secretory phase
* Further vascularization and development of uterine glands
89
Which phases of the ovarian cycle and the uterine cycle are happening simultaneously?
* Menstrual phase and Proliferative phase of the Uterine cycle coincide in time with the **follicular** phase of the ovarian cycle
* Secretory phase of the uterine cycle coincides with the luteal phase of the ovarian cycle
90
What is oogenesis?
Development of female gamete (oocyte = female gamete)
91
When and where does oogenesis occur?
In follicles within the ovary
92
Each follicle contains 1 oocyte in the ________ stage
* This is the Primordial follicle and consists of:
* \_\_\_\_\_\_
* \_\_\_\_\_\_\_\_\_
Each follicle contains 1 oocyte in the _primary oocyte_ stage
* This is the Primordial follicle and consists of:
* _oocyte_
* _single layer of specialized epithelial cells (granulosa cells)_
* __divides to produce more layers
93
As the follicle grows by mitosis of granulosa cells, connective tissue cells surrounding the granulosa cells differentiate and form two layers:
Theca interna (inner)
Theca externa (outer)
94
What is folliculogenesis?
Describes the progression of a number of small primordial follicles into large preovulatory follicles that occurs in part during the menstrual cycle
95
What happens during the primary follicle phase?
* Primary follicle is larger than the primordial follicle
* Involves:
* proliferation/growth
* Granulosa cells secrete proteins and glycoproteins which form a thick layer of material around the oocyte - **zona pellucida**
96
What is the Preantral follicle? How is it formed?
* Formed from
* mitosis of granulosa cells results in many layers of granulosa cells around the oocyte
* Connective tissue around the granulosa cells differentiate and become the early theca cells
* two regions:
* internal and external
* NO ANTRUM (fluid filled space)
97
What is the early antral follicle? How is it formed?
* A fluid filled space known as the antrum begins to form
98
What is the mature follicle and how is it formed?
* Major growth due to growth of antral space
* Granulosa cells just outside oocyte become suspended in a bridge like fashion = become the **cumulus oophorus**
99
How does the growing oocyte within the zona pellucida receive nutrients?
* Granulosa cells send out cytoplasmic processes through the zona pellucida and form gap junctions with the oocyte
* Nutrients and paracrine factors are sent through these junctions to help the growth of the oocyte
100
What are the two phases of the hormonal cycle?
1. Estrogenic phase
* first 14 days of the hormonal cycle
* Predominant hormone effect is from **estrogen**
2. Progestational phase
* after ovulation
* predominant hormone effect is from progesterone
101
Multiplication, growth, and mitosis of the granulosa cells happen due to the effect of \_\_\_\_\_\_\_\_
Multiplication, growth, and mitosis of the granulosa cells happen due to the effect of _the anterior pituitary hormone **FSH**_
102
Which stages of the 3 female cycles are occurring simultaneously?
* First:
* Follicular phase (ovarian)
* Estrogenic phase (hormonal)
* Menstrual/proliferative (uterine)
* Second
* Luteal (ovarian)
* Progestational (hormonal)
* Secretory (uterine)
103
The first phase of the Ovarian cycle is the _________ and it coincides with the ______ phase of the hormonal cycle
The first phase of the Ovarian cycle is the _follicular phase_ and it coincides with the _estrogenic_ phase of the hormonal cycle
104
In general, what happens during the follicular phase of the ovarian cycle and which hormone is dominant during this phase?
What happens on the 14th day?
* This is the phase where the dominant follicle is selected
* as the follicles are growing, they produce **estrogen**
* Ovulation occurs on the 14th day - follicle ruptures and expels the ovum
* empty follicle becomes the corpus luteum
105
Cells of the follicle include:
layers of granulosa cells and the theca cells outside the granulosa cells
106
Which cells of the follicle make estrogen?
Granulosa cells - make estrogen from **androgens** (androgens come from the theca cells) - but can't make estrogen from cholesterol
* FSH upregulates enzyme **aromatase** that converts androgens to estrogen in the granulosa cells
* Theca cells make androgens by converting cholesterol to progesterone to androgens
107
During the early/mid follicular phase, the ________ releases FSH.
What effect does this have?
During the early/mid follicular phase, the _anterior pituitary_ releases FSH.
What effect does this have?
* initially:
* FSH causes granulosa cells to increase in number by mitosis
* Granulosa cells have FSH receptors
* Theca cells have receptors for LH
* FSH causes an upregulation in the number of receptors for LH on theca cells
108
What is the effect of LH during early/mid follicular phase? Which cells does this hormone target?
Theca cells have LH receptors
* LH stimulates thecal cells to secrete androgens
* Androgens permeate to granulosa cells and where they are converted to estrogen
109
Which follicle becomes the dominant follicle?
The one secreting the most estrogen
110
What days are the late follicular phase?
Day 7 to day 14
111
What effect does the rise in estrogen cause on the granulosa cells during the late follicular phase?
Rise in estrogen causes the granulosa cells to start developing LH receptor
112
What happens once granulosa cells develop LH receptors (late follicular phase)
Under the influence of LH, the granulosa cells can now convert cholesterol to progesterone
= small rise in progesterone occurs toward late follicular phase
113
Why is there a large amount of produced progesterone as the corpus luteum phase begins?
Large amount of progesterone is made due to the granulosa cells expressing LH receptors and converting cholesterol to progesterone
114
One of the functions of LH receptors is to increase the concentration of \_\_\_\_\_\_\_
What effect does this have on LH receptors?
One of the functions of LH receptors is to increase the concentration of _estrogen_
Estrogen upregulates LH receptors
115
The luteal phase of the ovarian cycle coincides with the ______ of the hormonal cycle. Where does this hormone come from?
The luteal phase of the ovarian cycle coincides with the _progestational_ of the hormonal cycle. Where does this hormone come from?
Progesterone is produced by the corpus luteum
116
What effect does progesterone have on the uterine endometrial cells?
Progesterone, with the help of estrogen, builds up progesterone receptors on the uterine endometrial cells to prepare for a possible pregnancy
117
The granulosa cells of the follicle are similar to which cells in the testis?
How?
Sertoli cells.
* control the environment of the developing gamete
* Secrete antral fluid
* provide nutrients for developing oocyte
* secrete paracrines that support follicle development
* secrete inhibin
* secrete estrogens
* secrete substance that forms zona pellucida
118
How often do the frequency and amplitude of the hypothalamic pulse generator change during the menstrual cycle?
How does it differ from males?
Hypothalamic produces gonadotropin releasing hormone (GnRH) in a pulsatile manner
The frequency and amplitude of these pulses change every 24 hours over the course of the menstrual cycle
= males pulsatile secretion occurred every 90 minutes
119
What is the hypothalamic-pituitary-ovarian axis?
* Hypothalamus:
* secretes GnRH in a pulsatile manner
* GnRH acts on the:
* Anterior pituitary
* Secretes:
* LH
* FSH
* LH and FSH act on the ovary and estrogen and progesterone (depending on phase) are produced by the granulosa cells
120
How does estrogen regulate the Hypothalamic-pituitary-ovarian axis?
Estrogen has a negative feedback effect at the level of both the **anterior pituitar****y**and the**hypothalamus**
* stops release of GnRH from hypothalamus and release of LH and FSH from Ant Pit
Estrogen can either dampen the amplitude of the pulse generator or reduce the responsiveness of the pituitary to GnRH
* Estrogen can also have *positive feedback* on the axis - act on hypothalamus to Increase the amplitude and responsiveness of the pituitary to GnRH
121
How does progesterone regulate the Hypothalamic-pituitary-ovarian axis?
Depending on the phase of the cycle, progesterone has a negative feedback effect at the level of the pituitary and the hypothalamus (in the presence of estrogen, progesterone has (-) feedback)
\*No Positive feedback\*
122
What is oogenesis?
Process by which the female gametes, or ova, are created
- begins with oogonium and then converts it into the ovum
123
Mitotic divisions of oogonia produce _______ which are diploid (2n)
Mitotic divisions of oogonia produce _primary oocytes_ which are diploid (2n)
124
When do oogonia develop into primary oocytes?
During early fetal development (via mitotic division)
* then begin the first meiotic division (meiosis I)
* Do not complete this division in the fetus = meiotic arrest
125
At birth, all eggs are ________ and contain ____ chromosomes
At birth, all eggs are _primary oocytes_ and contain _46_ chromosomes
126
What happens every month from puberty to menopause (oogenesis)
the oocyte is released from meiotic release and completes meiotic I division producing two daughter cells:
1. Secondary oocyte
2. First polar body
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When does the second meiotic division of oogenesis occur?
After ovulation and only if the secondary oocyte is fertilized by a male gamete
- produces the ovum and the second polar body
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Net result of oogenesis is the production of ______ with ___ number of chromosomes
Net result of spermatogenesis is the production of ______ with ___ number of chromosomes
Net result of oogenesis is the production of _1 primary oocytes_ with _1_ number of chromosomes
Net result of spermatogenesis is the production of _4 spermatozoa_ with _n_ number of chromosomes
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Feedback of the following hormones:
Estrogen
Progesterone
Inhibin
Feedback of the following hormones:
* Estrogen
* negative and positive feedback depending on phase
* Progesterone
* mainly negative feedback
* Inhibin
* peptide hormone
* Neg feedback on FSH
130
The uterine changes during a menstrual cycle are caused by changes in \_\_\_\_\_\_\_
The uterine changes during a menstrual cycle are caused by changes in _plasma concentrations of estrogen and progesterone_
131
Phases of the Uterine cycle:
* Menstrual phase:
* Days:
* Proliferative phase
* Days
* Hormone?
* Secretory phase
Phases of the Uterine cycle:
* Menstrual phase:
* Days: 1-5
* epithelial lining degenerates = menstrual flow
* Proliferative phase
* Days: 5-14
* Hormone?
* under influence of estrogen
* Endometrial lining grows out and blood vessels become enlarged
* After ovulation (day 14) glands (containing glycogen) begin to secrete and become larger
* Secretory phase
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The Menstrual Phase of Uterine Cycle:
* Estrogen levels?
* effect on GnRH
* What is happening in the ovaries?
The Menstrual Phase of Uterine Cycle:
* Estrogen levels?
* Estrogen levels are still low from the previous cycle
* low [estrogen] (early/mid follicular phase) has a neg feedback effect on Gonadotropin release
* What is happening in the ovaries?
* FSH increases due to decreased progesterone, estrogen and inhibin
* slight increase in FSH causes rapid mitosis of granulosa cells
* growth of follicles
* follicles grow and produce estrogen
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Pre-antral follicles include:
Antral follicles include:
Pre-antral follicles include: Primary, primordial, or secondary follicles
Antral follicles include: Tertiary or ovulatory follicles
134
Androgen production and release during folliculogenesis is dependent on the stimulation of the \_\_\_\_\_\_
Androgen production and release during folliculogenesis is dependent on the stimulation of the _theca cells by LH_
* LH surge causes ovulation
135
Why do the gonadotropins, LH and FSH remain low all throughout the luteal phase?
High concentration of progesterone released from the corpus luteum keeps the levels of LH and FSH low (we don't want another LH surge/ovulation event during pregnancy)
136
Key points of hormone cycle:
* What causes growth of the follicles
* Estrogen pattern?
* Inhibin?
Key points of hormone cycle:
* What causes growth of the follicles
* initial rise in FSH (follicular phase) because of low concentration of plasma estrogen
* Estrogen pattern?
* Low levels of estrogen have a negative FB effect on gonadotropins, in particular FSH
* FSH levels decrease
* Estrogen levels increase as dominant follicle produces estrogen (late follicular)
* High levels of estrogen have positive feedback effect = surge of LH 18 hours before ovulation
* LH surge =\> ovulation =\> ovum released
* Corpus luteum acts as temporary endocrine gland
* secrete estrogen and progesterone
* High Progesterone inhibits FSH and LH during luteal phase
* Inhibin
* mainly affects FSH
* Decline in FSH during follicular phase due in part to inhibition by low levels of estrogen and inhibin
* causes atresia of all other follicles
137
What triggers menstruation?
Decrease in estrogen and progesterone (corpus luteum degeneration)
138
What do cervical glands secrete?
Thin mucus
139
What do glands secrete during the secretory phase?
Glycogen rich fluid
Cervical secretions more sticky - form plug
140
What is necessary for sperm to be capable of fertilization?
Capacitation
- acted on by enzymes in female tract
141
What is capacitation?
The process by which the previously regular wave-like action of the sperm's tail is replaced by more whiplike action that propels the sperm forward in stronger surges and the sperm's plasma membrane becomes altered so that is capable of fusing with the surface membrane of the egg
142
What four events block polyspermy?
1. Change in membrane potential
2. Release of contents from cortical granules
3. Enzymes enter and harden zona pellucida
4. Enzymes inactivate sperm binding receptor = cannot bind
143
what does fertilization trigger within the ovum?
Activation of egg enzymes required for cell divisions and embryogenesis
Zygote starts going through a number of mitotic divisions and a **morula** is formed
144
What is the morula?
Zona pellucida around many cells (due to cell cleavage (increase in number of cells but not in size of structure))
145
Cells at the morula are **totipotent**, what does this mean?
have capacity to develop into a complete individual - can differentiate into any structure from this point on
Totipoten up to the 16-32 cell stage
146
The morula develops into the \_\_\_\_\_\_
The morula develops into the _blastocyst_
147
How do we get identical twins?
Division of totipotent morula cells
148
How do we get fraternal twins?
Fertilization of two oocytes released during the same cycle
149
What is the blastocyst? When is it formed?
Formed 4-5 days after fertilization
* Cells lose their totipotentiality and begin to differential
* No zona pellucida
* Outer cell mass = trophoblast
* becomes the fetal placenta
* Inner cell mass
* will become the embryo
* Fluid filled cavity = bastocoele
150
Cell divisions and formation of the morula coincides with what phase of the uterine cycle?
Secretory phase
- glands of the uterus secrete glycogen-rich fluid
151
When does implantation occur?
6-7 days after fertilization
152
How does implantation occur?
Blastocyst anchors itself to the wall of the endometrial lining w/ the side containing the inner cell mass positioned against the endometrium
* sticky trophoblast cells stick onto the walls of the endometrium
* Stimulates proliferation of the trophoblast - divides into two parts
153
What happens to the trophoblast after implantation?
Implantation stimulates proliferation of the trophoblast into two parts:
1. Syncytiotrophoblast (fused layer)
* some of the outer trophoblast cells enter deep into the endometrial layer and start dividing and become fused
* form the **syncytium** - multiple nuclei but no membrane
2. Cytotrophoblast
* Closest to the inner cell mass
* secretes early hormones for growing embryo
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What is the syncytiotrophoblast?
Implantation stimulates proliferation of the trophoblast into two parts:
* Syncytiotrophoblast: (fused layer)
* some of the outer trophoblast cells enter deep into the endometrial layer and start dividing and become fused
* form the syncytium - multiple nuclei but no membrane
Cytotrophoblast
Closest to the inner cell mass
secretes early hormones for growing embryo
155
What is the cytotrophoblast?
Implantation triggers division of the trophoblast into two parts, Syncytiotrophoblast and cytotrophoblast.
* Cytotrophoblast:
* Closest to the inner cell mass
* secretes early hormones for growing embryo
156
What is the decidua?
Endometrium during pregnancy
157
What is the decidual response?
response of the endometrial tissue where there is the appearance of blood vessels and glycogen-secreting glands for the newly anchored or implanted embryo/blastocyst
158
What are the two components of the placenta?
1. Fetal placenta
2. Maternal placenta
159
What does the placenta contain?
* Amniotic fluid inside amniotic space
* **Amnion** (innermost membrane that encloses the embryo) fused with **chorion** (outer layer)
160
What is the chorion?
embryonic derived portion of the placenta (outer layer)
* made of trophoblasts
* invades the maternal endometrium and develops finger-like projections called chorionic villi
* allow transfer of materials between maternal blood and embryonic blood
161
What are the blood vessels of the umbilical cord?
Umbilical cord contains
* two umbilical arteries (carry deoxygenated bloodvfrom fetus to the placenta)
* 1 umbilical vein (carries oxygenated blood from placenta to the fetus)
162
Three functions of the placenta?
1. Endocrine function
* Temporary endocrine gland
2. Exchange
* respiratory gases, nutrients and waste products
3. Filter/immunological protection
163
Where is Human Chorionic Gonadotropin (hCG) released from and where does it act?
hCG is released from the chorionic layer of the placenta
* stimulates female gonads to secrete hormones
* helps maintain the corpus luteum in early stages of pregnancy while placenta is being formed (formed placenta takes over secretion of estrogen and progesterone)
164
What is human placental lactogen hPL (human chorionic somatomammotropic hCS)?
GH-like and anti-insulin like actions in the mother
Helps the fetus get more glucose
165
Effect of progesterone from the placenta?
* Decrease uterine contraction
* inhibit LH and FSH
* Growth of mammary alveolar glands
* secrete sperm unfriendly mucus
166
Effect of estrogen from placenta?
* growth of uterus (myometrium)
* growth of mammary ducts
* Inhibition of LH and FSH at level of ANT Pit
167
How does estrogen increase responsiveness of uterus to oxytocin?
Increases number of receptors to which oxytocin binds
= increases contratile of smooth mm
168
What causes the posterior pituitary to release oxytocin?
Pressure of fetus against the cervix
169
Myometrial contractions are **increased** by: (4)
* Estrogen
* Prostaglandins
* Oxytocin
* Stretch from fetus' head against cervix
170
What is cervical ripening?
Caused by?
Process that prepares the tissue in such a way that the cervix becomes soft = easier expansion
* due to Prostaglandins and relaxin (from Corpus luteum and then from placenta)
Inhibited by progesterone
171
What is the role of prolactin and where is it released from?
Released from the anterior pituitary
Promotes lactation (Lactogenesis)
172
What is galactopoiesis?
Process of maintenance of lactation while the mother is breastfeeding
Requires prolactin
173
Which cells of the mammary gland produce milk?
174
Which cells of the mammary gland are required to expel milk?
Myoepithelial cells
Muscle like
have contractile properties
Receptors for oxytocin
175
Suckling activates ______ in the mothers breast tissue which activates \_\_\_\_\_
Suckling activates _tactile receptors (mechanoreceptors)_ in the mothers breast tissue which activates _hypothalamus_
* stimulates the neurosecretory cells of the post pit to secrete oxytocin
* oxytocin causes contraction of the **myoepithelial** cells and milk is ejected
176
How does dopamine regulate milk release?
Dopamine inhibits prolactin secretion by the ant pit cells
- activation of the hypothalamus by suckling decreases dopamine secretion thus removing the inhibition of prolactin secretion
177
Which hormones stimulate the development of male sex characteristics?
Testosterone and Anti-mullerian hormone (AMH)
178
What is klinefelters syndrome?
XXY
* infertile
* no spermatogenesis
* Taller than average
* reduced facial/body hair
* feminine fat distribution
* small testes
* breast development (gynecomastia)
179
What is Turners syndrome?
Lack of X
XO = streak ovaries (do not look round = flattened)
* short stature
* Characteristic facial fetaures
* cardiovascular defects
* poor breast development
* no menstruation
180
What region of the Y chromosome determines sex?
SRY (sex determining region of Y)
181
Both male and female gonads develop from the same site:
Urogenital ridge or Gonadal ridge
182
Before the functioning of the fetal gonads, the undifferentiated repro tract includes a double-genital duct system
These ducts are:
1. Mullerian ducts (persist in female)
2. Wolffian ducts (persist in male)
183
What is MIH?
* Mullerian inhibiting hormone
* secreted from Sertoli cell sin the testes
* causes regression of the mullerian duct
* regression of female internal genitalia
184
How do testosterone and MIH cause sexual differentiation in males?
* MIH from sertoli cells causes regression of the mullerian duct
* Testosterone from leydig cells causes development of **male internal genitalia**
* epididymis, vas deferens, seminal vesicles, ejaculatory ducts
* Testosterone is converted to dihydrotestosterone (DHT)
* causes masculinization of male external genitalia
185
What causes sexual differentiation in females?
* Absence of MIH allows mullerian duct to grow into female internal genitalia
* Absence of Testosterone prevents development of Wolfian duct
* Default
186
What causes development of the wolffian duct?
Testosterone
- leads to development of internal genitalia
187
What is congenital adrenal hyperplasia?
Female genetically (XX) but outwardly male
* Problem with Adrenal steroid secretory pathway
* decrease cortisol -\> increase ACTH -\> adrenal androgens -\> vascularization of external genitalia
* Too much androgen production causes development of male external appearance
INFERTILE
188
What is androgen insensitivity syndrome?
* Male genetically (XY) outwardly Female
* tissues in body were unresponsive to the male hormone testosterone during development
* no internal duct system development
* Infertile
189
What alters GnRH secretion?
Genetic influences and environmental influences
190
Kisspeptin?
Neuropeptide which acts on the cells that release GnRH in the hypothalamus
Cues trigger changes in the cells that cause the production of kisspeptin at the time of puberty
191
What is a source of leptin and how does leptin contribute to puberty?
Adipose tissue is a source of leptin
* Leptin acts in hypothalamus on the cells which release kisspeptin
* important for regulating the pulse generator
192
Menopause;
Decreased follicle numbers and decreased responsiveness to gonadotrophs =
decreased estrogen and decreased inhibin
193
What causes menopausal "problems"
decreased estrogen
