reproductive systems Flashcards
what is sodium balance important in the maintenance of body fluids
Because sodium is the most abundant electrolyte in the ECF its the most influential factor affecting ECF osmolarity. Changes in sodium concentration, therefore, result n changes in osmolarity of the ECF which subsequently influences the fluid shift and plasma volume (therefore blood volume and pressure). To ensure that body fluids are balances (equal osmolarity between compartments) and blood volume and pressure are adequate, sodium concentration must be well regulated.
what is the strucute of the testes
they are suspended within the scrotum by a spermatic cord which consists of;
- testicular artery
- pampiniform venous plexus (cools blood before it reaches the testes)
- nerves and lymphatics
- ductus deferens
what is the cremaster muscle
it surrounds the testes and the spermatic cord and contracts to draw the testes closer when its cold
what’s the function of the testes
produce sperm and testosterone
what is the function of the epididymis
sperm maturation and storage
what is the function of the vas deferens
transport sperm from the epididymis to the ejaculatory duct which transports semen to the urethra
what is the function of the urethra
conducts either urine or semen to the outside of the body
what is the structure of the urethra
it is divided into 3 regions;
- prostatic urethra- portion passing through the prostate gland
- membranous urethra- portion passing through the pelvic floor
- spongy urethra- portion passing through the erectile tissue of the penis
what do accessory glands do
produce semen. there are 3 types of accessory glands
seminal glands (accessory gland)
produce an alkaline fluid (60% of semen) containing substances that nourish and enhance sperm activity
prostate gland (accessory gland)
produces a milky, slightly acidic fluid (30% of semen) containing citrate and various enzymes that help to activate sperm
bulbourethral glands (accessory gland)
produce an alkaline mucus that lubricates the glans penis and neutralises traces of acidic urine in the urethra
the function of the penis
delivers semen into the female reproductive tract
what is the structure of the penis
it is a copulatory organ. The root of the penis anchors it to the perineum, while the shaft (body) hangs freely and ends in the glans- enlarged tip of the penis. The skin of it forms a loose cuff around the glans, known as the prepuce or foreskin.
what are the 2 types of penis erectile tissue
- Corpus spongiosum: a single column of erectile tissue surrounding the urethra and forming the glans.
- Corpora cavernosa: paired columns of erectile tissue making up the majority of the penis.
- The erectile tissue is highly vascularized and engorges with blood when the male is sexually aroused. This engorgement of the erectile tissue with blood causes the penis to swell and stiffen which pulls the penis superiorly until the glans is pointing upwards and is near the umbilicus (belly button) when fully erect. The erection of the penis facilitates insertion of the penis into the female reproductive tract during sexual intercourse.
what are some of the substances in sperm and what are their functions
- fructose- provides energy source for sperm
- prostaglandins- thin the cervical mucus and stimulate reverse peristalsis of the uterus
- enzymes and hormones- enhance sperm motility
- immune chemicals- suppress female immune response and destroy bacteria
- coagulating enzymes- cause coagulation of the semen after ejaculation. this allows the semen and sperm to stick to the vagina walls
where are male and female genitalia found
within the urogenital triangle of the perineum
what is the function of ovaries
produce oocytes and the hormones estrogen and progesterone
where are the ovaries found
the pelvic cavity near the opening of the uterine (fallopian) tubes
what does the ovarian cycle do
encompasses the changes occurring in the ovaries each month including
- continued development of oocytes and ovulation
- development of follicular cells surrounding an oocyte and hormone production
what is the function of the uterine (fallopian) tubes
transport ovulated oocytes to the uterus and is the main site of fertilization
how are oocytes transported to the uterine tubes
The fimbrae of the infindibulum sweep ovulated oocytes into the uterine tube. Peristalsis and the sweeping action of cilia on the ovaries lining the tubes then sweep the oocytes towards the uterus. Fertilization most commonly happens in the ampulla (swollen, middle portion) of the uterine tubes.
what is the function of the uterus
nourishes and helps develop a growing baby and expels the baby at birth
what are the 3 regions of the uterus
- fundus- uppermost portion containing the bulk of the muscle tissue
- body- central portion surrounding the uterine cavity
- cervix- narrow, separates uterus from external environment
what is myometrium and endometrium lining the fundus and body
Myometrium- a thick layer of smooth muscle which generates the force necessary to expel a baby during labour and birth
endometrium- a layer of CT and epithelium that allows implantation, nourishment, and support for embryonic and fetal growth and development
what is the uterine cycle
refers to the changes that take place in the endometrium each month to prepare it to receive, retain and nourish a fertilized ovum. This cycle co-insides with the ovarian cycle and is regulated by the hormones produced during the ovarian cycle.
what is the function of the vagina and what are vestibular glands
copulatory organ that receives the penis and ejaculation, allows passage of the products of menstruation and forms the birth canal
vestibular glands: lubricate vagina and vestibule
what is the function of the breasts
production of colostrum and milk
what are mammary glands
The breasts contain the mammary glands which produce and secrete colostrum & milk to provide the necessary nourishment for newborns and infants. The mammary glands consist of numerous alveoli arranged into lobules which cluster to form lobes. Each lobe is drained by a lactiferous duct which opens at the nipple.
what is gametogenesis
the process in which the gametes- oocytes & sperm- are produced. Production of oocytes is known as oogenesis and production of sperm is known as spermatogenesis. Both of these processes involve mitotic AND meiotic cell division to generate haploid (n) daughter cells from diploid (2n) parent cells
what is mitosis
The first phase of gametogenesis in which there is complete replication of all chromosomes in the diploid (2n) parent cells (oogonia or spermatagonia) followed by cell division into two genetically identical diploid daughter cells (primary oocytes or primary spermatocytes).
what is meiosis 1
all chromosomes in the primary oocytes or spermatocytes are completely copied to generate sister chromatids. Maternal and paternal sister chromatids of the same chromosome number align and one sister chromatid of each pair will swap segments of DNA before the maternal and paternal sister chromatids are divided into two haploid (n) daughter cells
what is meiosis 2
the phase in which the secondary oocytes or spermatocytes divide into 2 haploid daughter cells by separating the sister chromatids. Each daughter cell now contains a unique half set of the individuals DNA.
what is oogenesis
it begins in the female fetus in utero, where mitosis of oogonia generate all the primary oocytes a female will ever have.
Each month after puberty, a handful of primary oocytes will re-start meiosis 1, but only a couple will complete it, giving rise to a polar body (contains genetic material but no cytoplasm or organelles) and a secondary oocyte which begin meiosis 2, but stop prior to ovulation.
the secondary oocyte will re-start and complete meiosis only if fertilization occurs, it will then divide into another polar body and the ovum which shares its genetic material with the fertilizing sperm.
all polar bodies creates will degenerate, therefore only one viable daughter cell (the ovum) is generated from a single parent primary oocyte
what is spermatogenesis
it begins at puberty and continues for life. each mitotic division results in 2 identical daughter cells: type A and type B daughter cell.
Type A stays within the testes to carry on mitosis generating new type A and type B daughter cell.
type B daughter cell becomes a primary spermatocyte which will undergo meiosis, generating four spermatids which undergo a process called spermatogenesis in which they physically transform into spermatozoa containing three distinct regions;
- head- contains the nucleus and is capped by the acrosome
- midpiece- contains numerous mitochondria for ATP production
- tail- flagellum that provides locomotion for sperm
what is the first phase of the ovarian cycle; follicular phase (days 1-14)
occurs prior to ovulation and involves the development of the primordial follicle into a tertiary follicle. the oocyte restarts and completes meiosis 1, then begins with meiosis 2 and halts and follicular development occurs along with the production of estrogen. LH and FSH levels were high at the beginning and then fall and estrogen rises
what is the second phase of the ovarian cycle; luteal phase (days 14-28)
occurs after ovulation and involves the development of the corpus luteum which produces estrogens and progesterone. if fertilization of the ovulated oocyte occurs, the corpus luteum will remain and continue to produce these hormones, but if fertilization does not occur the corpus luteum will degenerate into the corpus albicans and hormone production falls
what are the two zones of the endometrium (uterine cycle)
- stratum basalis- sits adjacent to the myometrium forming a base layer of the endometrium which remains relatively constant over time
- stratum functionalis- this functional layer undergoes cyclical changes, fluctuating between growth and development and loss of the layer
what is the menstrual phase of the uterine cycle (days 1-5)
shredding of endometrium (stratum functionalis) and blood
hormones: drop in estrogens and progesterone
what is the proliferative phase of the uterine cycle (days 6-14)
growth of endometrial tissue, blood vessels and glands
hormones: estrogens
what is the secretory phase of the uterine cycle (days 15-28)
further endometrial growth, coiling of arteries and secretion of glycogen
hormones: estrogens and progesterone but if they are not produced then ischemia occurs and the uterine cycle repeats
what is the HPG axis
Both gametogenesis and the female reproductive cycles are regulated by the hypothalamic-pituitary-gonadal axis. This cascade of hormones involves the release of GnRH from the hypothalamus, LH and FSH from the anterior pituitary gland and the release of gonadal hormones from the gonads.
This axis is regulated by negative feedback mechanisms, when rising levels of the gonadal hormones inhibit the release of GnRH, LH and FSH. When gonadal hormone levels are low then GnRH is free to start the hormonal cascade again.
the male HPG axis
the constant rise and fall in testosterone levels regulates the HPG axis hormones and their effects
the male HPG axis; gonadal activity initiated by the anterior pituitary gland
- LH: stimulates the interstitial cells of the testes to produce and secrete testosterone
- FSH: stimulates the spermatogonia to begin mitotic cell division and increases testicular cell receptivity
the male HPG axis: testosterone promotes spermatogenesis and spermatogenesis in the testes but also stimulates;
- libido and related behaviours (CNS effects)
- bone and muscle growth
- establishment and maintenance of secondary sex characteristics
- maintenance of male reproductive structures Additionally testosterone promotes the release of inhibin, another gonadal hormone which controls the rate of spermatogenesis through inhibiting GnRH & FSH. Inhibin levels increase when sperm count is high and decrease when sperm count is low.
the female HPG axis
While the female HPG axis works on the same basic principle as the male HPG axis, it is slightly more complicated in that regulation also involves positive feedback, as well as negative feedback, and this feedback occurs on a monthly basis. The hormonal activity of the female axis relates to the actions of oogenesis, the ovarian cycle and the uterine cycle.
the female HPG axis; initiated by the anterior pituitary gland
- LH-stimulates the restart of oogenesis, ovulation and formation of the corpus luteum & progesterone production
- FSH: stimulates follicular development and gonadal hormone secretion (estrogens & inhibin)
female HPG axis; estrogens and progesterone
estrogen-have similar effects as testosterone throughout the female body and additionally stimulates endometrial growth, including growth of the spiral arteries and endometrial glands. Estrogens also soften the cervix and thin cervical mucus.
progesterone-enhances endometrial growth dilates the spiral arteries and stimulates the secretion of glycogen from the endometrial glands. Progesterone also causes thickening of cervical mucus.
what happens when high estrogen levels result in a temporary switch to positive feedback within the HPG axis
the switch to positive feedback results in a large surge of LH which stimulates ovulation and supports the initiation of the luteal phase
