Reproductive System Flashcards
Name the structures in the male reproductive system
Penis
Scrotum
Testes (2 testicles)
Epididymis
Vas deferens
Prostate gland
Urethra
Seminal vesicles
Name the external parts of the male reproductive system
Penis
Scrotum
Testes (which are contained inside the scrotum)
Name the internal parts of the male reproductive system
Prostate gland
Seminal vesicles
Vas deferens
Urethra
What arteries supply the testes ?
The testicular arteries which arise from the abdominal aorta.
Each testicular artery is separate from each other.
Where is venous drainage in the testes ?
Venous drainage on the :
Right - to the vena cava
Left - to the renal vein
What is the function of the scrotum ?
This is a loose bag of skin that suspends the testes outside the body.
Describe the surrounding material of the scrotum ?
The skin is wrinkled and contains smooth muscle.
It has a midline raphe and is divided by a septum.
What is the function of the penis ?
The organ used for urination and sexual intercourse.
Describe the internal structure of the penis
It has spongy tissue which can fill with blood to cause an erection. It contains the urethra, which carries both urine and semen.
What is the function of the testes ?
These are a pair of glands that sit in the scrotum, on the outside of the body.
They produce sperm and testosterone, which is the male sex hormone.
What are the testes covered by ?
Tunica albuginea which is a fibrous layer.
Describe the external structure of the testis
The testis is surrounded by the ‘TUNICA ALBUGINEA’, which sends fibrous projections called septa towards the center of the testis.
Function of septa
Partition each testis into around 20 lobules, each containing between 1-4 seminiferous tubules.
Describe the internal structure of the testis
The testis contains seminiferous tubules which is where sperm is synthesised.
The seminiferous tubules come together to form a series of straight tubules which enter a small network of tubules called the rete testis.
Once the sperm make it through the rete testes, they go through the efferent ducts to the epididymis.
What is the function of the epididymus ?
This is a highly coiled tube that lies at the back of the testes.
All sperm from the testes must pass through the epididymis, where they mature and start to ‘swim’.
What are gonads ?
The reproductive organs
What do the male gonads produce ?
Sperm - which is produced by spermatogenesis
What is outside the seminiferous tubules ?
Outside the tubule, there’s connective tissue with capillaries, as well as Leydig cells.
What are Leydig cells ?
Leydig cells produce testosterone
What are Sertoli cells ?
Large cells that extend from the margin all the way to the lumen of the tubule.
What is the function of Sertoli cells ?
Sertoli cells provide nutrients to developing sperm cells, and contribute to the blood-testis barrier by only allowing certain molecules, like testosterone, in the seminiferous tubule.
What is sperm production under the command of ?
The hypothalamus.
What is the function of the hypothalamus in male reproductive system ?
The hypothalamus is a part of the brain that secretes gonadotropin-releasing hormone, or GnRH.
Function of GnRH in Male reproductive system
That GnRH travels to the nearby pituitary, which secretes LH and FSH, which reaches the gonads.
What hormones does the pituitary gland release in the male reproductive system ?
Follicle stimulating hormone
Luteinising hormone
What is the function of LH in the male reproductive system ?
LH binds to Leydig cells, and stimulates the production of testosterone.
What is the function of FSH in the male reproductive system ?
FSH binds to Sertoli cells, making them produce androgen binding protein - or ABP, for short - which allows more testosterone to cross the blood-testis barrier and enter the seminiferous tubule.
Describe the process of spermatogenesis
Spermatogonia - diploid cells - have 46 chromosomes
Primary spermatocytes - 23 chromosomes
Secondary spermatocytes - 23 chromosomes, but only one chromatid (so right no of chromosomes and DNA)
Spermatids
Spermatozoa
What hormones are involved in regulation of spermatogenesis ?
FSH and Testosterone
Describe the main structure of sperm
Head
Midpiece
Tail
Describe the head of the sperm
At the head is the acrosome, which contains enzymes that will help penetrate the oocyte - the female gamete.
Also contains the nucleus which contains the genetic material.
Describe the midpiece of the sperm
The mid piece is loaded with mitochondria that provide the sperm with energy to move.
Describe the tail of the sperm
Specialised flagellum which propels the sperm forward
What happens during ejaculation ?
During ejaculation, the sperm that have matured exit through the tail of the epididymis, and enter the vas deferens.
What happens once the sperm are in the vas deferens ?
The left and right vas deferens go behind the bladder and descend along the posterior bladder wall.
Here, they dilate in a region called the ampulla, before narrowing again to continue as the ejaculatory ducts, which empty out into the first portion of the urethra.
What is the function of the vas deferens ?
This is a thick-walled tube joined to the epididymis. It carries sperm from the epididymis up to the prostate gland and urethra.
What is the function of the prostate gland ?
This is a walnut-sized gland that sits in the middle of the pelvis.
The urethra runs through the middle of it. It produces the fluid secretions that support and nourish the sperm.
What is the function of the urethra ?
This is a tube that extends from the bladder to the external opening at the end of the penis.
The urethra carries both urine and sperm.
What is the function of the seminal vesicles ?
These are 2 small glands above the prostate gland that make up the majority of the fluid in semen.
What is spermination ?
Release of mature spermatozoa into the seminiferous tubule lumen.
How is urination separated from ejaculation ?
Now, the urethra is also the way urine exits the body, but during ejaculation, the bladder sphincter right above the prostate contracts, and that prevents urine from mixing with semen.
Effect of testosterone on the bone
Increased growth of bone and connective tissue
Effect of testosterone on the muscle
Increased growth of muscle and connective tissue
Effect of testosterone on the reproductive organs
Increased growth and development of :
- testes
- prostate
- seminal vesicles
- penis
Increased growth of larynx
Effect of testosterone on the skin
Increased sebaceous gland size and secretions
What is Inhibin B ?
Produced by Sertoli cells, helps support spermatogenesis and inhibits the production of FSH, LH and GnRH
What happens when there is increased levels of testosterone ?
Increased levels of testosterone and inhibin have a negative feedback effect on the pituitary and hypothalamus.
This results in decreased production of LH and FSH.
As a result, the production of testosterone and inhibin is also decreased.
Name the structures in the female reproductive system
2 Ovaries
Fallopian tubes
Uterus
Cervix
Vagina
What is the function of the ovaries ?
Female hormones (oestrogen and progesterone) are produced in the ovaries, and eggs are stored here to mature and be released in ovulation.
Name the internal female reproductive organs
Vagina
Uterus
Uterine tubes (fallopian tubes)
Ovaries
What is the vagina ?
This is a muscular tube connecting the cervix to the outside of the body.
What is function of the vagina ?
Functionally, it facilitates menstruation, sexual intercourse and childbirth.
Where is the vagina located ?
The vagina is located posterior to the urinary bladder and urethra, and anterior to the rectum.
The upper end of the vagina is attached to the cervix of the uterus.
What supplies blood to the vagina ?
The vagina is supplied by branches of the internal iliac artery.
Where does venous drainage of the vagina occur ?
Venous drainage of the vagina is provided by the vaginal veins which flow into the internal iliac veins.
Where is lymph drainage from the vagina ?
Lymph is drained from the vagina into the iliac and superficial inguinal lymph nodes.
What is the uterus ?
The uterus (womb) is a hollow muscular organ located deep within the pelvic cavity.
Describe the position of the uterus
Anterior to the rectum and posterosuperiorly to the urinary bladder.
Anteflexed between the cervix and body
Anteverted at entry to vagina
What is the function of the uterus ?
Organ for implantation of the fertilised ovum and growth of foetus.
What are the 3 main parts of the uterus ?
Body
Isthmus
Cervix
Describe the body of the uterus
The main part of the uterus, connected to the fallopian tubes via the uterine horns.
The body has a base (fundus) and an internal chamber (uterine cavity).
Describe the isthmus of the uterus
The constricted part of the uterus, located between the body and the cervix.
Describe the cervix of the uterus
This is the lower part of the uterus that connects it to the vagina.
What supplies blood to the uterus ?
The uterus is supplied mainly by the uterine artery which arises from the internal iliac artery
What are the female gonads ?
The ovaries.
They produce and store your eggs (also called ovum) and make hormones that control your menstrual cycle and pregnancy.
During ovulation, one of your ovaries releases an egg.
How are the ovaries held in place ?
With the help of ligaments
Describe the blood supply to the ovaries
Ovaries receive arterial supply from the ovarian arteries, which arise from the abdominal aorta.
What are fallopian tubes ?
These are 2 thin tubes that connect the ovaries to the uterus, allowing the egg to be transported.
Name the parts of the fallopian tube
Infundibulum
Ampulla
Isthmus
Uterine part
Describe the function of the infundibulum
The infundibulum contains finger-like projections called fimbriae.
What do fimbriae do ?
Each month, your fimbriae catch the egg that one of your ovaries releases during ovulation.
Your fimbriae then sweep the egg (ovum) into the fallopian tube where the egg can be fertilized.
Describe the function of the ampulla
The longest and widest part of the uterine tube. It is the most common site of fertilisation.
What are oocytes ?
Eggs - female gametes
When does oogenesis begin ?
Begins in the foetus prior to birth
What happens in oogenesis ?
Primordial germ cells (oogina) increased in number
Many oogina mature into oocytes
Around 20 weeks, the oocytes reach max numbers
Oocyte numbers decline until exhausted.
Around 40,000 eggs at birth.
Where does the oocyte grow and develop ?
In a follicle
What are the 2 cell types involved in the follicle ?
Theca cells
Granulosa cells
Name the follicles at the different stages of development from early to late
Primordial
Primary
Secondary
Tertiary
Mature (Graafian)
Describe theca cells
Superficial layer of follicle
Have LH receptors
Convert cholesterol into pregnenolone
Then produce androgens and testosterone
Describe granulosa cells
Deep compared to theca
Layer increases in size markedly during 1° to 2° follicle development
Have LH and FSH receptors
Also convert cholesterol into pregnenolone + activate aromatase
Describe the female gondal axis
- The hypothalamus secretes GnRH.
- GnRH travels down to the anterior pituitary gland and binds to receptors on the gland.
- This promotes the release of LH (luteinizing hormone) and FSH (follicle-stimulating hormone).
- LH and FSH travel in the bloodstream to the ovaries.
- When LH and FSH bind to the ovaries they stimulate the production of oestrogen and inhibin:
Oestrogen helps to regulate the menstrual cycle and is an essential component in many other physiological processes
Inhibin causes inhibition of activin which is usually responsible for stimulating GnRH production
- Increasing levels of oestrogen and inhibin have a negative feedback effect on the pituitary and hypothalamus.
- This leads to the decreased production of GnRH, LH and FSH.
- This, in turn, results in decreased production of oestrogen and inhibin.
Function of GnRH in female reproductive system
Stimulates LH and FSH release from anterior pituitary gonadotrophin cells.
What are the 2 phases in the ovarian cycle ?
Follicular
Luteal
When does ovulation occur ?
Around day 14
Peak LH levels
What is the menstrual cycle ?
Ovarian + Endometrial cycles
What happens in the follicular phase ?
Development of mature Graafian oocyte and secondary oocyte.
What happens in the luteal phase ?
Dominated by the corpus lutem actions
What does the corpus lutem do ?
Synthesis and secretion of oestrogen and progesterone, which are need for implantation and maintenance of any fertilised oocytes.
The corpus lutem regresses and degenerates if no fertilisation.
What are the phases in the endometrial cycle ?
Menstrual
Proliferative
Secretory
Name the 3 main oestrogens
Oestradiol (most potent)
Oestrone
Oestriol (secreted in pregnancy)
Effect of oestrogen on bone
Increased growth via osteoblasts
Effect of oestrogen on endocrine
Increased progesterone responses
Effect of oestrogen on liver
Increased clotting factors
Increased HDL
Decrease Total and LDL
Increase in steroid binding proteins
Effect of oestrogen on reproductive organs
Increased growth of all reproductive organs
Increase LH receptors on granulosa cells
Effect of progesterone on breast
Increased lobular development
Decrease in milk production
Effect of progesterone on reproductive organs
Decreased endometrial growth
Increase in endometrial secretions
Mucosal secretions become thicker
Effect of progesterone on temperature
Increase in internal temperature
Prolactin
Milk production
Oxytocin
Milk let down - flow of milk
What is endometriosis ?
Growth of endometrial tissue outside the uterine cavity
The tissue responds to oestrogens of the menstrual cycle.
Treatment of endometriosis
Continuous administration of GnRH analogue inhibits gonadotropin secretion and reducing oestrogen levels, leading to reduced endometriotic tissue
Role of GnRH in IVF
GnRH analogues used before controlled IVF cycle commences
Function of birth control pill
Contraceptive steroids feedback on hypothalamic neurons and gonadotropin cells and suppress LH and FSH secretion
So no follicular development or LH surge (ovulation)
Progestin effect causes cervical mucous thickening and increase viscosity, reduces uterus and oviduct motility, endometrial changes
Inhibits sperm penetration
Reduces chances of implantation
