Reproductive System Flashcards by Eilidh Miles

What are the testis surrounded by?

The tunica vaginalis and are suspended in the scrotum to keep cool

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Describe the skin and structure of the scrotum?

It is rugose ( wrinkled) and contains dartos (smooth) muscle. It has a midline raphe and is divided by a septum.

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What allows for the ovum to be taken up?

The frimbriated end of the uterine tube (fallopian tube)

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Describe the basic shape and function of the uterus

It is a pear-shaped, central pelvic organ that is the site for implantation of a fertilised ovum and growth of foetus

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Describe the structure and function of fascial thickenings on the pelvic floor.

They pass from the uterus and cervix to the sacrum, pubis and lateral pelvic walls. These are important, supportive uterine ligaments.

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What do the female and male gonads produce?

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, affects bones, muscle and blood vessels

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What are the hormones of the hypothalamic-pituitary gonadal axis?

Hypothalamic - Gonadotropin-releasing hormone (GnRH)

Pituitary - Luteinising hormone (LH) and Follicle stimulating hormone (FSH)

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What are the differences in the hypothalamic-pituitary gonadal axis in males and females?

The signalling molecules are exactly the same, the only difference is the target tissues.

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What do female gonads produce?

They secrete oestrogens and progestins

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What allows for the precise regulation of function of the ovaries?

Ovaries are subjected to multi-tiered endocrine axis feedback.

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What are the main hypothalamic areas involved in both ovarian and testis control?

The Preoptic nucleus (secrets GnRH that targets gonadotropes) and the Supraoptic nucleus (neurons secrete GnRH)

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Describe some of the features of GnRH

It stands for Gonadotropin-releasing hormone (GnRH)

It is a peptide hormones which is produced as a prohormone, it is then modified to active form and secreted into the hypophyseal portal system.

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Describe some of the features of GnRH release

The release is pulsatile (meaning pulsation), it requires less energy and does not desensitise target tissue receptors. Stress and other inputs can influence secretion.

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How and where is gonadotropin releasing hormone delivered?

It is delivered via the hpophyseal portal system to anterior pituitary gonadotrobes

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What do gonadotrobes secrete?

Luteinising hormone (LN) and the follicle stimulating hormone (FSH)

Describe the function of the ovary?

To house female germ cells (oocytes)

Name the different follicle development stages

Primordial, primary, secondary, tertiary, graafian and follicles.

What does the endocrine function of the ovaries involve?

It is related to follicles (i.e occurs when oocyte folicles are at the follicle stage of development)
It involves theca and granulosa cells working together to synthesis and secrete oestradiol

Describe some of the features about Theca cells

They found on the superficial layer of follicles, they have luteinising hormone (LH) receptors, concert cholesterol to pregnenolone and produce androstenediol and testosterone

Describe some of the features about granulosa cells

They are found in a layer deep to theca cells. Size of the layer increases during follicle development. Have both LH and FSH receptors and can convert cholesterol to pregnenolone and activate aromatase.

Where to and why do thecal cells donate androstenedione?

To granulosa cells and this is because they are unable to produce it due to a lack of enzymes

What is oogenesis and describe a bit about it in foetal life?

It is the production of oocytes. It begins in the foetus and continusly occurs until the feotus reaches 20weeks, this is when they have their max number of oocytes, the number then begins to decrease form there until later in life when the number are exhausted.

What are the three oestrogens?

Oestradiol,
Oestrone
Oestriol

name some of the effects oestrogen has on tissues

Bone - increased growth of osteoblasts Endocrine - Increased progesterone responses Liver- increased clotting factors, steroid hormones, and HDL levels and decrease total and LDL levels. Reproductive organs - uterine growth, vaginal and fallopian growth, breast growth, increased cervical mucus secretion and increased luteining hormone receptors on granulosa cells

Describe the mid-cycle shift from negative to positive feedback?

The feedback to they hypothalamus changes from negative to positive due to high oestrogen levels. This causes an upregulation of receptors and resulting in an LH and FSH surge prior to ovulation.

Describe some of the features of progetins

There are two types; progesterone and 17alpha-hydroxyprogesterone They are produced in the theca and granulosa cells, they have a short half life (5mins) and their secretion regulation is linked to oestrogen secretion

Describe some of the effects that progestins has on tissues

Breast - increases lobular development but decreases milk production. Reproductive organs - Decreases endometrial growth but increases endometrial secretions and the mucosal secretions become thicker Temperature - increased internal temperature

What are the two parts of the menstrual cycle?

Ovarian cycle and endometrial cycle

Describe the steps involved in the ovarian cycle (ovulation and menses)

Follicular phase - Development of mature Graafian follicle and secondary oocyte Luteal phase - Dominated by corpus luteum (syntheses and secretion of oestrogen and progesterone). The corpus luteum regresses and degenerates in 10-12 days if no fertilisation occurs

Describe the steps involved in the endometrial cycle

Proliferative Phase- Endometrial growth which is mediated by increased oestrogen (it increases in thickness and bllod vessels and glands grow) Ovulation marks the end of the proliferative phade Secretory Phase - Maturation of endometrium due to decreased oestrogens, mucus glands fully develop Menstruation - if no conception then the endometrial lining is replaced. There is vasoconstriction of spiral arteries which causes local ischaemic injury and inflammatory cells infiltrate.

What causes the further development of breasts during pregnancy?

Oestrogens, Progestins, hCG from feotus and prolactin

What is milk production and release regulated by?

Production - prolactin Release - oxytocin The suckling of the baby sends positive feedback to the hypothalamus which increases the levels of prolactin and oxytocin

Describe the cells and structural features of the testis

They contain leydig cells that produce testosterone. Blood vessels and seminiferous tubules (produce sperm and house sertoli cells)

Where are the testicular endocrine functions?

In the leydig and sertoli cells. The leydig cells contain receptors for LH and then the testerone produced by the leydig cells enters the sertoli cells which contain receptors for FSH

Describe the development stages in spermatogenesis

Spermatogonia to primary spermatocytes to secondary spermatocytes then spermatids and finally fully developed spermatozoa. The whole process is regulated by testosterone.

Describe the effects of testosterone on target tissues

Bone - increases growth of bone and connective tissue Muscle - Increases growth of muscle and connective tissue Reproductive organs - Increased growth and development of testes, prostate, seminal vesicles and penis. Increased growth of facial, axillary and pubic hair. Increased growth of larynx and increases spermatogenesis. Skin - increased sebaceous gland size and secretions

Describe the differences in secretion regulation between males and females

In males there is only 1 primary hormone (testosterone) and no role of actins has been established.