Reproductive System Flashcards by Anna Dunlop

What is the vas deferens?

The duct which conveys spent from the testes to the urethra.

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Describe the seminal gland

+ Holds the liquid that mixes with sperm to form semen

+ Also called the seminal vesicle

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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.

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Describe the epididymis

+ A highly convoluted duct behind the testis

+ Sperm passes to the vas deferens via the duct

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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

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Describe the features of the scrotum

+ Skin is rugose

+ Contains dartos muscle

+ Has a midline raphe

+ Divided by a septum

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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

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Describe the uterine tube

+ a.k.a Fallopian tubes/Oviducts

+ Transport the ova from the ovary to the uterus

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Describe the ovaries

+ Female reproductive organs in which ova are produced

+ Present as a pair

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How is the ova/oocyte transported to the uterine tube?

It is “picked up” by the fimbriated end of the uterine (Fallopian) tube.

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Describe fascial thickenings.

+ Supportive uterine ligaments
+ On the pelvic floor
+ Pass from the uterus and cervix to the sacrum, pubis and lateral pelvic walls

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Describe the features of gonads

+ Produce gametes

+ Female gonads produce oocytes (eggs) by oogenesis

+ Male gonads produce sperm by spermatogenesis

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What are the gonadal hormones involved in?

\+ Gamete production
\+ Supporting conception
\+ Pregnancy
\+ Lactation
\+ Affect bone
\+ Affect muscle
\+ Affect blood vessels

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What is the hypothalamic signalling hormone involved?

Gonadotropin-releasing hormone (GnRH)

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What are the pituitary hormones involved?

+ Luteinising hormone (LH)

+ Follicle stimulating hormone (FSH)

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What do the ovaries secrete?

+ Oestrogens

+ Progestins

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What are the main hypothalamic areas involved in ovarian control?

+ Preoptic nucleus

+ Supraoptic nucleus

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What do the neurons of the preoptic and supraoptic nucleus secrete?

GnRH, a peptide hormone

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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

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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.

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What hormones do gonadotropes secrete?

+ LH
+ FSH
+ They target the gonads

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What is an oocyte?

+ An immature ovum

+ Contain follicles

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What are the various stages of follicular development?

\+ Primordial
\+ Primary
\+ Secondary
\+ Tertiary
\+ Graafian

Endocrine ovaries primarily related to latter follicles.

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Describe the features of theca cells

+ Superficial layer of follicle
+ LH receptors
+ Convert cholesterol into prenenolone
+ Then produce androstenedione and testosterone

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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?

1. Spermatogonia 2. Primary spermatocyte 3. Secondary spermatocyte 4. Spermatids 5. 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