Reproductive Flashcards
In the reproductive system, what system is a vascular arrangement in which blood flows from one capillary bed in the hypothalamus to another capillary bed in the anterior pituitary?
hypophyseal portal system
Give an example of another portal system in the digestive system
hepatic portal vein/system
What are the two neurosecretory peptide hormones?
oxytocin and antidiuretic hormone (ADH/Vasopressin)
Where are oxytocin and ADH synthesized? Where are they stored and released?
hypothalamus, posterior pituitary
How do the anterior and posterior pituitary gland differ?
posterior - does not directly produce hormones but stores hormones synthesized by the hypothalamus and releases them in response to neural signals
The gonadotrophs are located in the ___ pituitary
anterior
The two gonadotrophins produced are?
FSH follicle stimulating hormone and LH leuteinising hormone
Is the regulation of gonadotrophin secretion positive or negative from the hypothalamus to the gonadotrophs?
positive
Is the regulation of gonadotrophin secretion positive or negative from the gonads to the hypothalamus?
negative
What female endocrine gland is where gonadotrophins act?
ovaries
The male endocrine gland where gonadotrophins act is/are?
testes
What is the role of follicle stimulating hormone (FSH) in males and females?
males: acts on the testes to stimulate the production of gametes
females: acts on the ovaries to stimulate the growth and development of gametes
What is the role of leuteinising hormone (LH) in males and females?
males: acts on the testes to promote the synthesis of testosterone
females: acts on the ovaries to trigger ovulation and promote the synthesis and release of ovarian hormones
Describe the pathway of sexual differentiation
- bipotential gonad develops into ovary or testes
- OVARY - estrogens and progestogens - Mullarian duct development and Wolffian duct regression -internal female genitals
- TESTES - splits to sertoli and leydig cells
- SERTOLI CELLS: Anti-Mullarian hormone - Mullarian duct regression
- LEYDIG CELLS: testosterone - Wolffian duct development - Internal male genitals
What determines whether the bi-potential gonad develops into an ovary or testis?
The SRY gene
The criteria for staging development of secondary sexual characteristics is known as?
The Tanner stages
Describe the sequence of key events in puberty in females
- breast budding (10/11 by oestrogen secretion, ovulation causes full breast development)
- pubic hair development (within 6 months of budding, exposure of hair follicles to androgens)
- growth spurt (steroid hormones, 11/12)
- menarche (12/13)
Describe the sequence of key events in puberty in males
testes enlargement - pubic hair development (6 months after)- penile enlargement - growth spurt. Spermatogenesis also happens during this time (Spermache - motile sperm in urine 13)
What cells are responsible for testicular enlargement?
Leydig cells secrete testosterone
What cells are responsible for testicular enlargement?
Leydig cells secrete testosterone
How long after testicular enlargement does penile elongation begin?
within a year of testicular enlargement
When does ovulation in girls take place first? Why?
6-9 months after menarche. This delay is because the positive feedback mechanisms involving oestrogen have not yet developed
What is the response elicited when GnRH (Gonadotropin-stimulating hormone) is produced by the hypothalamus?
The two gonadotropin hormones, FSH and LH are secreted from the anterior pituitary gland
What is ovarian senescence?
when approximately one year after menopause the ovary has ceased producing hormones
By how much percent does eostrogen production reduce after menopause?
10%
After menopause, what form of oestrogen is produced? Where does it arise from?
oestrone
stromal cells in adipose tissue
Label the phases associated with the end of reproductive life in normal women
pre-menopause –> menopausal transition + peri-menopause –> post menopause –> ovarian senescence
What hormones in the reproductive system are lipid soluble?
androgens, estrogens, progestogens
Where are lipid soluble hormones secreted?
testes and ovary
What are the water soluble hormones in the reproductive system? Where are they secreted respectively?
GnRH - hypothalamus
FSH, LH - anterior pituitary
Oxytocin - posterior pituitary
What are the two androgens?
testosterone and 5𝛼 Dihydrotestosterone
What are some key properties of androgens?
- male sex development
- spermatogenesis
- sexual behaviour
- muscle development
What are the main estrogens? Describe their properties.
oestradiol - most potent
oestrone - produced by adipose tissue, menopause, main in men
oestriol - produced by the placenta, softens the cervix
Where is the main oestrogen production site?
granulosa cells of the growing follicle
What are some key properties of oestrogens?
- female sex development
- growth of the endometrium
- regulation of the menstrual cycle
- bone growth
What is progesterone and what is its function?
Progesterone is the major steroidal hormone of the corpus luteum and of the placenta.
Associated with the preparations for pregnancy and its maintenance
What does the SRY gene stand for?
Sex determining Region on the Y chromosome
Define sex differentiation
the phenotypic development of genital structures due to the action of hormones produced following gonadal development
What do the Wolffian ducts develop into?
the epididymis, vas deferens and seminal vescicles
What do the Mullarian ducts develop into?
fallopian tubes, uterus, cervix and upper vagina
Describe the development of the male external genitalia
- fusion of the urethral folds enclosing the urethral tube forming the shaft of the penis
- labioscrotal swellings fuse in the midline forming the scrotum
- the genital tubercle expands forming the glans penis
Describe the development of the female external genitalia
the urethral folds and labioscrotal swellings remain separate forming the labia minora and majora
the genital tubercle forms the clitoris
What are the first signs of puberty in terms of hormones?
an increase in plasma LH levels as a result of increased GnRH release
what can cause precocious puberty?
hypothalamic tumors
What can cause delayed puberty?
inadequate gonadotropin signals
What is the cause of menopause?
ovaries running out of follicles
Describe some symptoms of menopause
vasomotor (hot flushes and night sweats), genitourinary symptoms, osteoporosis, behavioural or psychological changes
Label the diagram of the uterus in LEC 15: Repro 02 CCA
Endometrium, myometrium, cervical canal
What part of the uterus is the thickest? What is its function?
myometrium, important for contractions during pregnancy
The ovary is comprised of three distinct regions, what are these regions?
Outer ovarian cortex
Central ovarian medulla
Inner hilius
Where is the entry and exit point of nerves and blood vessels in the ovary?
inner hilius
Where are the ovarian follicles found?
outer ovarian cortex
Where are the steroid producing cells and the ovarian stroma found?
ovarian medulla
Label the stages of the ovarian cycle/follicular development in the diagram of the ovary in LEC 15: Repro 02 CCA
Primordial follicle, primary follicle, secondary follicle, mature follicle, corpus haemmoragicum, corona radiata, ovulation, corpus luteum, corpus albicans
What hormones are most dominant in days 10-14 of the menstrual cycle?
estrogen and LH
List the main events of the female reproductive cycle
- Corpus luteum regresses, oestrogen and progesterone levels are low, see increased FSH
- FSH stimulation leads to increased follicular growth
- About day 6-7, see selection of dominant follicle, with increased oestrogen
- Oestradiol suppresses FSH (and LH) production in the pituitary
- Oestrogen levels rise, by day 12 a threshold concentration of oestradiol is exceeded. If this is maintained for 36 hours, there is a temporary switch from a negative feedback to positive feedback
- Oestrogen-mediated positive feedback triggers a rise in GnRH leading to an LH surge
- LH surge induces ovulation
- Corpus Luteum develops, see increased progesterone
- Elevated progesterone levels inhibit GnRG, lead to decreased FSH and LH
- Demise of the corpus luteum
What is the primordial follice?
The oocyte once surrounded by a single layer of flat follicular cells (which develop into granulosa cells), form the primordial follicle
What is the primary follicle?
As the follicle grows, they are called primary follicles or pre-antral follicles.
Immature primary follicles consist of only one layer of granulosa cells.
In response to FSH, some follicles get larger producing many layers of granulose cells surrounding the oocyte
These secrete glycoproteins which form the zona pellucida
What is the secondary follicle?
As granulosa cells proliferate they produce a viscous follicular fluid that coalesces to form a single follicular antrum. These are called secondary or antral cells.
The theca develops to become the inner glandular, highly vascular theca interna, and the surrounding fibrous capsule, the theca externa.
Innermost layer of granules cells becomes attached to the zona pellucid forming the corona radiata
What is the function of the theca interna?
interact with granulosa cells to produce oestrodiol
What is the function of the theca externa?
protect the growing follicle
What is the mature (Graafian or pre-ovulatory) follicle?
As the follicle antrum grows, the oocyte becomes suspended in fluid. It is connected to the rim of peripheral granulosa cells by a thin stalk of cells
What occurs during ovulation?
The increasing size of the follicle and its position in the cortex of the ovarian stroma causes it to bulge out from the ovarian surface.
The follicle ruptures, carrying with it the oocyte and its surrounding mass of cumulus cells.
The oocyte is collected by cilia on the fimbria, which sweep the cumulus mass into the uterine tube.
What is the corpus luteum?
The antrum breaks down, the basement membrane between the granulosa and thecal layers breaks down and blood vessels invade.
The granulosa cells form large lutein (yellow pigment) cells. This transformation is referred to as luteinisation and is associated with an increasing secretion of progestogens.
The whitish scar tissue remaining, the corpus albicans, is absorbed back into the stromal tissue of the ovary over weeks or months.
What happens during fertilization?
If the oocyte is fertilised and begins to divide, the corpus luteum persists past its normal two week life span. It is rescued from degeneration by hCG (human chronic gonadotropin) The hormone is produced by the chorion of the embryo beginning about 8 days after fertilisation.
Label the transverse section of part of the seminiferous tubule LEC 16 Repro CCA 03 or pg. 114
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Where does spermatogenesis occur?
seminiferous tubules
What is contained in the mid-piece of the sperm?
Mitochondria to provide ATP, a source of energy required for the sperm to move
List the number of chromosomes from the spermatogonium to the sperm/spermatozoon
Spermatogonium - 46
Primary spermatocyte - 46
Secondary spermatocyte - 23
Spermatid - 23
Sperm/spermatozoon - 23
Label a sperm cell
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What is the order of ejaculate in semen?
Prostatic secretions - 30%
sperm - 10%
Seminal fluid - 60%
What are the components of seminal fluid?
Clotting proteins
alkaline
contains fructose
60% ejaculate
prostaglandins which allow smooth muscle contractions of female reproductive tract to push sperm along
What are the components of sperm?
10% of ejaculate
contains DNA
What are the components of prostatic secretions?
acidic (neutralized by seminal fluid)
Contains citrate fro atp
Milky in color
30% of ejaculate
contains PSA (prostate specific antigen. –> breaks down clot)
What is oligospermia?
reduced sperm count
What is azoospermia ?
No sperm in ejaculate
Describe the conditions needed for IVF
50,000 sperm required
needs motile sperm
sperm fertilise oocyte in the petri dish
Describe the conditions needed for ICSI (Intracytoplasmic sperm injection)
requires a single sperm
motile sperm not required
sperm injected directly into the oocyte
Label the male organs of reproduction in the sagittal section pg 118. CCA 17
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In the normal adult male, sperm are produced in which structure?
Seminiferous tubules of the testes
The stem cells that sit on the basement membrane of the seminiferous tubules are called?
Spermatogonia
Leaving the testes, the next tubular structure that sperm enters is called the
rete testes
The tubules coalesce into a single tubule, where sperm mature, gain motility and the ability to fertilise an oocyte. This tube is known as the
Epididymus
The sperm that enter a muscular tube known as the
vas deferens
During ejaculation, the final tubular structure through which the sperm travels in the main body is called the
urethra
Draw out the pathway and label the different tubes through which the sperm travels.
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An erection is initiated and maintained by the activation of the ____ branch of the autonomic nervous system.
parasympathetic
In order to establish an erection, human males rely solely on the ______ _______ within the penis
hydronamic pressure
What are the chambers called in the penis, responsible for erection?
corpora cavernosa
Relaxation of the smooth muscles is dependent upon the intracellular second messenger ____ ?
cGMP
What does cGMP do?
reduces the intracellular calcium levels
What is the enzyme that breaks down cGMP?
phosphodiesterase type 5 / PDE5
The ____ is a circular structure which surrounds and prevents the occlusion of the penile urethra during an erection-
corpus spongiosum
Once erect, the penis contains approximately ____ times more blood that the flaccid penis
eight
During which decade of life will the incidence of Benign prostatic hyperplasia be approximately 35%
70-79
One potential treatment for BPH is the inhibition if the following enzyme which converts testosterone to 5 alpha dihydrotestosterone. What is the name of this enzyme?
5 alpha reductase
what are the three phases of spermatogenesis?
mitotic division
meiotic division
cytodifferentiation
When does sperm production begin?
After puberty has begun
Where can sperm be stored for long periods of time?
vas deferens
What two chemicals cause the corpora cavernosa to relax?
nitric oxide and prostaglandin E1
How does viagra work?
Relaxes the smooth muscle in the corpora cavernosa inhibits the enzyme phosphodiesterase - inhibiting breakdown of cGMP - results in relaxation and engorgement.
What is Benign Prostatic Hyperplasia?
prostatic overgrowth
What does BHP result in?
difficulty voiding the bladder as the prostate increases in size, narrowing urethral tube. This can lead to UTI and kidney infections
What are the treatment options for BPH?
surgery
drugs - finasteride or dutasteride –> stops prostate enlarging
How does finasteride and dutasteride work?
inhibit the enzyme 5𝛼 - reductase which stops production of dihydrotestosterone (relevant because BPH is androgen dependent)
Describe the incidence of BHP in ages 40 to 80
< 40 - rare
50-59 - 17%
60-69 - 27%
70-79 - 35%
What is a good indicator of prostate cancer?
PSA screening test (prostate specific antigen)
What are treatment options for prostate cancer?
androgen depletion (use finasteride)
removal of prostate gland
waiting
What is the function of 5 alpha reductase?
converts testosterone to dihydrotestosterone (DHT)
What is the function of phosphodiesterase?
breaks down cGMP resulting in higher calcium levels - erectile dysfunction
What is the function of oxytocin
effects on smooth muscle contraction, causing milk ejection, contraction of uterus during childbirth
Define puberty
physical, emotional and sexual transition from childhood to adulthood
What age does precocious puberty starts
7y girls
9y boys
What age is delayed puberty
13 girls
14 boys
What age does menopause begin
50-52
List three functions of the vagina
passageway for the elimination of menstrual fluids
receives the penis during sexual intercourse
holds spermatozoa before they pass into the uterus
What are the layers of the endometrium
inner functional zone - stratum functionalis, contains uterine glands
outer basilar zone - stratum basalis, attaches endometrium to the myometrium
Where does fertilization usually occur?
ampulla
What is the environment like in the fallopian tubes
rich, nutritive environment containing lipids and glycogen for the spermatozoa, oocyte and developing embryo
sertoli cells secrete ABP, why?
androgen binding hormone - supporting, traps testosterone in seminiferous tubule - necessary to make sperm
how does sperm move in the reproductive tract?
peristaltic contractions
Where does spermiogenesis occur?
epididymis
What is a mass of loosely associated granulosa cells called
Cumulus oophorus
Where does the spermatogonium go to once mitosis division is complete
Move between Sertoli cells to the adluminal compartment - called primary spermatocyte
What does the 1 spermatocyte undergo
Meiosis 1
How many chromatids does a 2 spermatocyte have and how many chromosomes
2, 23
What division do 2 spermatocyte undergo
Meiosis 2 to give 4 spermatids
What is the residual body
Structure lost by the spermatic that contained excess cytoplasm and is phagocytosis by Sertoli cells
What is the function of kisspeptin
Controls release of GnRH
How many days does it take spermatocyte to acquire the ability to swim
10-14 days
What structure reads orbs liquid around the sperm to make it more concentrated
Epididymis
Commitment of the gonad to a testis or an ovary is known as
sex determination
