Female Reproductive System Flashcards
what are the ovaries?
- female gonads
- responsible for producing haploid gametes
- attached to wall of uterus
- suspended from side of uterus by ovarian ligament and mesovarium ligament to keep ovaries in correct position
what is the fallopian tube?
- oviduct is an open cavity that starts the fallopian tube
- finger-like projections called fimbriae form a cup over the ovary to collect the ova and project it down the fallopian tube
- infundibulum is the first section of the tube
- ampulla is the curving section of the tube
- isthmus connects fallopian tube to uterus
what is the uterus?
- thick-walled structure with cavity in centre
- fertilised ovum is implanted here to the embryo can develop
what are the functions of the female reproductive system?
- produce haploid gametes: ova
- facilitate fertilisation of ova by sperm
- provide a site of implantation of the fertilised egg
- provide physical and nutritional needs throughout gestation period
- nurture the neonate after birth by producing milk
what are the structures of the ovaries?
cortex: outer zone with germinal epithelial layer containing oocytes
inner medulla: blood vessels and lymph
- supporting tissue for developing oocytes
follicle: where oocytes are enclosed
- as follicle matures, it forms other structures in a continuous process
follicular cells: secrete steroid hormones
what are the two types of follicular cells and what hormones do they secrete?
- granulosa cells: secrete 17-beta-oestradiol (oestrogen)
- theca cells: secrete progesterone
hormones have endocrine and paracrine function ova development, uterus, breasts and bone
what is the role of the fallopian tubes?
- transport egg from ovary to uterus
- infundibulum with fimbriae help capture egg as it is released from ovary
- smooth muscles: inner circular muscle layer and outer longitudinal muscle layer for peristalsis
- highly folded mucosa which is ciliated and contains secretory cells for helping movement of ova
what are the 3 walls of the uterus?
- perimetrium: external serosa
- myometrium: thick inner muscle layer
- endometrium: changes over course of menstrual cycle
what are the components of the endometrial wall of the uterus?
- simple columnar epithelium
- compound tubular glands which are highly branched
- spiral arteries which move between glands and connective tissue of the lamina propria
- supporting tissue contains leukocytes and macrophages to form the stroma
- basal layer zona basalis: static layer
what is the functional layer of the uterus?
- endometrial layer can vary along cycle
- sheds during menses and builds thicker again
- when thick layer, fertilised egg is implanted
- if no fertilised egg is implanted, the thick layer sheds
what is the cervix?
- cervical canal connects uterus to vagina
- interior os and exterior os at its margins
- cervical glands secrete mucus to prevent microbes from reaching uterus
what is the vagina?
- birth canal (8-10cm)
- thin distensible wall with 3 layers:
- adventitia on outside
- muscularis: thick muscular layer
- mucosa: inner layer of stratified squamous epithelium rich in glycogen
- glycogen is fermented by bacteria to lactic acid to produce pH 3.5-4 which inhibits pathogens
- contains antigen-presenting dendritic cells
what are the two female cycles?
- ovarian
2. endometrial (menstrual)
what is the neuroendocrine control of the female cycles?
- hypothalamic-pituitary-gonadal axis drives menstrual cycle
- hypothalamic neurons release gonadotropin-releasing hormone (GnRH) once per hour
- hypophyseal portal system connects hypothalamus to anterior pituitary
- metabotropic GnRH receptor increases IP3, DAG, Ca2+ and exocytosis of FSH and LH
what is the hypothalamic-pituitary-gonadal axis?
- neurons in hypothalamus release GnRH
- GnRH binds to receptors in gonadotrophs within the anterior pituitary
- pituitary secrets FSH and LH to stimulate the ovary
what are the actions of FSH and LH on the ovary?
- theca release progesterone
- feedback to pituitary and hypothalamus
- positive/negative feedback - granulosa release oestrogen
- feedback to pituitary and hypothalamus
- positive/negative feedback
- inhibin negatively feeds back at anterior pituitary
- activin positively feeds back to antierior pituitary
how are the ovarian hormones produced?
- theca cells synthesise and secrete progesterone from cholesterol
- LH induces synthesis of progesterone - androstenedione diffuses from theca to granulosa cells
- granulosa cells convert testosterone to oestrogen via enzyme aromatase
- FSH and LH both stimulate this pathway
what are the actions of oestrogen and progesterone?
- develops ovum
- maintains corpus luteum which is derived from follicles which surround the ovum
- maintains pregnancy
what does the hypothalamic-pituitary axis control depend on?
- it is controlled by positive or negative feedback depending on the phase
how is the hypothalamic-pituitary axis controlled in the follicular phase?
- hypothalamus releases GnRH
- GnRH stimulates anterior pituitary to release FSH and LH which have positive effect on ovary
- oestrogen is released which has negative feedback on anterior pituitary and hypothalamus
how is the hypothalamic-pituitary axis controlled in the midcycle phase?
- feedback of oestrogen to hypothalamus is negative throughout cycle, except prior to ovulation when it is positive
- oestrogen now has a positive feedback on anterior pituitary and hypothalamus during ovulation
how is the hypothalamic-pituitary axis controlled in the luteal phase?
- progesterone secreted from ovary becomes major hormone of negative feedback to the anterior pituitary and hypothalamus
how do the ovarian and endometrial cycles overlap?
- during the follicular phase of ovarian cycle, the endometrial cycle is in the proliferative phase as the endometrial lining thickens
- after ovulation, endometrial cycle transitions to secretory phase
- in follicular phase, ovum is contained in a developing follicle
- during ovulation when the egg is released, the follicle is termed the corpus luteum and enters the luteal phase
how do hormones change across the ovarian and endometrial cycles?
- ovarian cycle is governed by FSH which peaks in day 12 and causes proliferation of theca and granulosa cells
- surge of oestrogen and progesterone after follicular stimulation
- critical level of oestrogen causes a switch to positive feedback in H-P axis which upregulates LH secretion from pituitary, leading into the secretory phase
what do oestrogen and progesterone control in the uterus?
- endometrium thickening
- feedback regulation of FSH and LH from anterior pituitary
- follicular phase: oestrogen causes cervical mucus to become copious, water and elastic to form channels in the follicular phase for sperm to be propelled through
- secretory phase: progesterone decreases and mucus thickens