Reproductive System Flashcards
What is the vas deferens?
The duct which conveys spent from the testes to the urethra.
Describe the seminal gland
+ Holds the liquid that mixes with sperm to form semen
+ Also called the seminal vesicle
Describe the ejaculatory duct
+ Formed by the union of the vas deferens with the duct of the seminal vesicle
+ Pass through the prostate and open into the urethra at the Colliculus seminalis.
Describe the epididymis
+ A highly convoluted duct behind the testis
+ Sperm passes to the vas deferens via the duct
Describe the seminiferous tubules
+ Tubules made up of columnar Sertoli cells surrounded by spermatogenic cells
+ Produce sperm and house Sertoli cells
+ The site of the germination, maturation, and transportation of the sperm cells within the male testes
Describe the features of the scrotum
+ Skin is rugose
+ Contains dartos muscle
+ Has a midline raphe
+ Divided by a septum
Describe the uterus
\+ A central pelvic organ \+ Inner lining: endometrium \+ Middle muscular layer: myometrium \+ Outer later: perimetrium \+ Responsible for the implantation of the fertilised ovum and growth of the foetus \+ Pear shaped
Describe the uterine tube
+ a.k.a Fallopian tubes/Oviducts
+ Transport the ova from the ovary to the uterus
Describe the ovaries
+ Female reproductive organs in which ova are produced
+ Present as a pair
How is the ova/oocyte transported to the uterine tube?
It is “picked up” by the fimbriated end of the uterine (Fallopian) tube.
Describe fascial thickenings.
+ Supportive uterine ligaments
+ On the pelvic floor
+ Pass from the uterus and cervix to the sacrum, pubis and lateral pelvic walls
Describe the features of gonads
+ Produce gametes
+ Female gonads produce oocytes (eggs) by oogenesis
+ Male gonads produce sperm by spermatogenesis
What are the gonadal hormones involved in?
\+ Gamete production \+ Supporting conception \+ Pregnancy \+ Lactation \+ Affect bone \+ Affect muscle \+ Affect blood vessels
What is the hypothalamic signalling hormone involved?
Gonadotropin-releasing hormone (GnRH)
What are the pituitary hormones involved?
+ Luteinising hormone (LH)
+ Follicle stimulating hormone (FSH)
What do the ovaries secrete?
+ Oestrogens
+ Progestins
What are the main hypothalamic areas involved in ovarian control?
+ Preoptic nucleus
+ Supraoptic nucleus
What do the neurons of the preoptic and supraoptic nucleus secrete?
GnRH, a peptide hormone
What are the features of GnRH?
+ Produced as a prohormone
+ Modified to active form
+ Secreted into the hypophyseal portal system
+ Release is pulsatile
- requires less energy
- does not desensitise target tissue receptors
- stress and other inputs influence secretion
What is the relationship between GnRH and the pituitary gland?
GnRH is delivered via hypophyseal portal circulation to the anterior pituitary gonadotropes, where they then bind to receptors.
What hormones do gonadotropes secrete?
+ LH
+ FSH
+ They target the gonads
What is an oocyte?
+ An immature ovum
+ Contain follicles
What are the various stages of follicular development?
\+ Primordial \+ Primary \+ Secondary \+ Tertiary \+ Graafian
Endocrine ovaries primarily related to latter follicles.
Describe the features of theca cells
+ Superficial layer of follicle
+ LH receptors
+ Convert cholesterol into prenenolone
+ Then produce androstenedione and testosterone
Describe the features of granulosa cells
+ Deep compared to theca cells
+Layer increases in size markedly during 1° to 2° follicle development
+ Lh and FSH receptors
+ Also convert cholesterol into prenenolone and activate aromatase
+ Then produce testosterone and oestradiol
What do theca cells donate to granulosa cells, and why?
They donate androstenedione because granulosa cells cannot produce it due to a lack of key enzymes.
What does FSH activate?
It activates aromatase, which facilitates the formation of oestradiol.
What is oogenesis?
The process by which female gametes/ova are produced
+ Begins in foetal stage of females
- primordial germ cells (oogonia) increased in number
+ Some/many oogonia mature into oocytes
+ At ~20 weeks gestation, oocyte number reach max.
+ Oocyte numbers then decline until exhausted
What are the main 3 oestrogens?
+ Oestradiol
+ Oestrone
+ Oestriol
What are the effects of oestrogens on bone?
+ Increases growth via osteoblasts
What are the effects of oestrogen on the endocrine system?
+ Increases progesterone responses
What are the effects of oestrogens on the liver?
+ Increases clotting factors
+ Increases steroid-binding proteins
+ Decreases total and LDL
+ Increases HDL
What are the effects of oestrogen on the reproductive organs?
+ Increases uterine growth
+ Increases vaginal and fallopian tube growth
+ Increases breast growth
+ Increases cervical mucus secretion
+ Increases LH receptors in granulosa cells
What type of feedback do oestrogens (and progestins) provide?
+ Mainly negative feedback except in the mid-cycle, where it shifts to positive due to activins
- caused by upregulation of receptors ( e.g GnRh in anterior pituitary) when oestrogen levels are increased
- results in LH and FSH surge prior to ovulation
What type of progestins are there and where are they produced?
+ Progesterone (& 17α-hydroxyprogesterone)
+ Produced in theca and granulosa cells
+ Has short half life (5mins) in circulation
+ Secretion regulation intrinsically linked to oestrogen secretion
What are the effects of progestins on breast tissue?
+ Increases lobular development
+ Decreases milk production
What are the effects of progestins on reproductive organs?
+ Decreases endometrial growth
+ Increases endometrial secretions
- mucosal secretions become thicker
What is the effect of progestins on temperature?
+ Increases internal temperature
What two cycles are associated with the female reproductive system?
+ Ovarian cycle
+ Endometrial cycle
Describe the follicular phase of the ovarian cycle
- main result is the development of mature Graafian follicle and secondary oocyte
Describe the luteal phase of the ovarian cycle
+ Dominated by corpus luteum actions i.e synthesis/secretion of oestrogen and progesterone
- needed for implantation and maintenance of any fertilised oocytes
+ Corpus luteum regresses and degenerates in 10-12 days if no fertilisation
What are the phases of the ovarian cycle?
+ Follicular phase
+ Luteal phase
What are the phases of the endometrial cycle?
+ Proliferative phase
+ Secretory phase
+ Menstruation
Describe the proliferative phase of the endometrial cycle
+ Endometrial growth mediated by increased oestrogens
- from 1-2mm to 8-10mm thick
- blood vessels and gland growth occur
+ Ovulation marks the end of this phase
Describe the secretory phase in the endometrial cycle
+ Maturation (not growth) of the endometrium due to decreasing oestrogens
+ Mucus glands more fully develop
+ Glands and blood vessels increase surface area
Describe the menstruation phase in the endometrial cycle
+ If no conception, endometrial lining is replaced
- vasoconstriction of spiral arteries
- local ischaemic injury
- inflammatory cell infiltration
What is lactation?
Milk production and secretion
Breast tissue is prepared during puberty via female gonadal hormones. Via which hormones during pregnancy is there further development?
+ Oestrogens
+ Progestins
+ hCG from fetus
+ Prolactin
What is the role of prolactin?
It mediates milk production
What is the role of oxytocin?
Mediates milk “let down”/ejection
What are the hormones involved in lactation regulation?
+ Prolactin
+ Oxytocin
Describe the testis
+ Glands where sperm and testosterone are produced
+ Contained in the scrotum
Describe what the testis conatin
+ Leydig cells (produce testosterone)
+ Blood vessels
+ Seminiferous tubules (produce sperm ad house Sertoli cells)
Where do testicular endocrine functions occur?
Leydig and Sertoli cells (cf theca and granulosa cells)
What are the processes of testicular endocrine function?
+ LH stimulation increases testosterone
+ Testosterone enter the Sertoli cell
+ Estradiol helps to regulate protein synthesis int he nucleus of the Leydog cell
+ FSH stimulation activates aromatase, which forms more oestradiol
What are the various stages of spermatogenesis?
- Spermatogonia
- Primary spermatocyte
- Secondary spermatocyte
- Spermatids
- Spermatozoa
What is spermatogenesis regulated by?
Testosterone
What are the effects of testosterone on bone?
+ Increases growth of bone and connective tissue
What are the effects of testosterone on muscle?
+ Increases the growth of muscle and connective tissues
What are the effects of testosterone on reproductive organs?
+ Increases growth and development of testes, prostate, seminal vesicles and penis
+ Increases growth of facial, axillary, and pubic hair
+ Increases growth of the larynx
+ Increases spermatogenesis
What are the effects of testosterone on the skin?
+ Increases sebaceous gland size and secretions
What hormones provide negative feedback in the female reproductive system?
+ Oestrogens
+ Progestins
+ Inhibins
What hormones provide positive feedback in the (female?) reproductive system?
Activins
What hormones provide negative feedback in the male reproductive system?
+ Testosterone
+ Inhibin B
