Reproductive System Flashcards
What are the 3 types of cells in the testes and what is their function?
- Interstitial cells - produce androgens
- Sertoli cells - aid spermatogenesis
- Spermatogonia - differentiate into sperm for reproduction
Where are male gametes produced?
Seminiferous tubules
Where do the male gametes go during ejaculation?
They are released into the epididymis which then joins the seminal vesicles to form the ejaculatory duct
How are the testes adapted to maintain a constant temperature?
- Temp maintained by scrotum
- High temp negatively affects spermatogenesis
- Smooth muscles of the scrotum contract and relax to move the testicles closer/further away from the abdomen
- Must be kept at a temp lower than core temp
Where are male gametes stored and matured?
Epididymis
What are the 3 accessory glands of the male reproductive system?
- Epididymis
- Vas (ductus) deferens
- Urethra
What are the 4 functions of testosterone?
- Stimulates adolescent growth spurt
- Development of reproductive organs
- Underlies sex drive
- Development of secondary sex characteristics
What are male germ cells called and where are they produced?
- Spermatogonia (diploid)
- Produced in germinal epithelium which lines the seminiferous tubules
What are the functions of the 3 main parts of the male gamete?
- Acrosome - allows sperm to penetrate follicle cell capsule and oocyte membrane
- Flagella - aids mobility
- Midpiece - contains mitochondria to provide energy for mobility
What is the mons pubis and where is it located?
Area of fatty tissue above the symphysis pubis, which is an oval piece of cartilage between the pubic bone
Which two parts of the female genitalia are covered in pubic hair?
Mons pubis and labia majora
Where is the vestibule and what are its components?
- Contained within the labia majora
- Consists of the urethral orifice, vaginal orifice, clitoris and greater vestibular gland
Describe the clitoris
- Homologous to the male penis
- Made up of sensitive erectile tissue
What are the external genitalia often referred to as?
Vulva
What is the function of the greater vestibular gland?
Produce mucus to lubricate the vagina during sexual intercourse
What does the duct system include?
Uterine tubes, uterus and vagina
How long does an oocyte take to reach the uterus?
3-4 days
Where does fertilisation take place?
Uterine (fallopian) tubes
How does the oocyte enter the fallopian tube?
When ovulation occurs, fluid currents carry the oocyte along which are created by undulating fimbriae
What are the 3 layers of the uterus?
- Endometrium
- Myometrium
- Perimetrium
What holds the uterus in place?
The uterosacral and round ligaments
Which layer of the uterus does the zygote implant in?
Endometrium
Describe the myometrium
- Smooth muscle
- Responsible for rhythmic contractions of labour
What is the other name for the perimetrium and what is it’s function?
- Visceral peritoneum
- Protects the uterus from rubbing against other structures in the pelvis
Describe the vagina
- A thin-walled tube
- Walls consist of elastic muscle fibres called rugae
- Enables it to stretch to accommodate the penis during intercourse and the baby during birth
What are the 2 main functions of the vagina?
- Provides a passageway for childbirth and menstrual flow
2. Receives penis during sexual intercourse
What is the hymen?
- A thin fold of vascular skin which partially closes the vagina
- Usually ruptures during the first episode of sexual intercourse
What exocrine and endocrine products do the ovaries produce?
Exocrine = ova Endocrine = oestrogen and progesterone
Describe the maturation of ovarian follicles
- Ovarian follicles contain an immature oocyte
- Oocyte grows and matures and a fluid filled area (antrum) develops; this is called a Graafian follicle
- When ovulation occurs, the ruptured follicle develops into a corpus luteum which releases progesterone
What are the 2 gonadotrophic hormones involved in puberty?
FSH and LH
Describe the initiation of sperm production
- GnRH released from hypothalamus in brain
- FSH released from anterior pituitary gland
- Seminiferous tubules start producing sperm
Where is LH released from and what does it cause?
- Anterior pituitary gland
- Causes interstitial cells to produce testosterone
Give 3 of the main secondary sex characteristics in males
- Larynx enlarges (voice deepens)
- Hair growth
- Skeletal muscle and bone weight increases
What are the 4 hormones involved in spermatogenesis?
GnRH, FSH, LH and testosterone
What effect does FSH have on the female reproductive system?
- Causes growth of primary follicles
- Follicle cells then release oestrogen in ovaries
- This causes the release of LH
What are the secondary sex characteristics in females?
- Enlargement of accessory reproductive organs
- Development of breasts
- Appearance of axillary and pubic hair
- Increased fat deposits (hips and breasts)
- Widening and lightening of pelvis
- Onset of menses (menstrual cycle)
What are the accessory reproductive organs in females?
- Uterine tubes
- Uterus
- Vagina
What is the name for the first period that a female gets?
Menarche
What 5 hormones are involved in oogenesis?
GnRH, FSH, LH, oestrogen and progesterone
What are the 3 stages of the ovarian cycle?
- Follicular phase
- Ovulation
- Luteal Phase
What occurs in the follicular phase?
- Release of FSH and growth of primary follicles
- Oestrogen released
- As oestrogen increases, FSH decreases
- 1st meiotic division
What occurs in ovulation?
- Critical level of oestrogen = LH released
- 2nd meiotic division (halted at metaphase II)
What occurs in the luteal phase?
- LH forms corpus luteum which secretes oestrogen and progesterone
- Progesterone and oestrogen cancel out FSH and LH
What are the 3 phases of the uterine cycle?
- Menstrual phase
- Proliferative phase
- Secretory phase
What occurs in the menstrual cycle?
- Functional layer of endometrium shed
- Oestrogen and progesterone low = FSH increases
What occurs in the proliferative phase?
- Oestrogen repairs functional endometrium
- Blood supply to endometrium increases
- Glands formed in spongy tissue
What occurs in the secretory phase?
- Corpus luteum secretes oestrogen and progesterone
- Blood supply increases
- Nutrients released to support the embryo
- FSH and LH no longer released
- Corpus luteum degenerates
- Cell death of functional endometrial layer
What are Interphase and Prophase I otherwise known as?
Foetal period
What occurs in Interphase I?
Primordial primitive germ cells differentiate into diploid oogonia and duplicate mitotically
What occurs in Prophase I?
- Homologous pairs
- Chromosomes condense
- Crossing over occurs
What occurs in Metaphase I?
- Spindles attach to homologous pairs
- Random assortment
What occurs in Anaphase I?
Homologous pairs are pulled apart but chromatids remain attached
What occurs in Telophase I?
Nuclear membrane reforms with 2 haploid cells
What are Prophase and Metaphase II otherwise known as?
Ovulation
What are Anaphase and Telophase II otherwise known as?
Fertilisation
What occurs in Prophase II?
- Chromosomes condense
- Nuclear envelope breaks
- Spindle forms
What occurs in Metaphase II?
Homologous pairs (2 sister chromatids) line up along the equator (metaphase plate)
What occurs in Anaphase II?
Sister chromatids separate and move towards opposite poles
What occurs in Telophase II?
- Nuclear membrane reforms
- Chromosomes decondense
- Cytokinesis
Which days of the menstrual cycle does ovulation occur in?
Day 13-15
Describe the 1st step of ovulation
- FSH stimulates primary follicle growth and meiosis resumes (prophase completed prior to birth)
- Results in larger follicle with fluid filled antrum that releases oestrogen
Describe the 2nd step of ovulation
Just prior to ovulation, the diploid cell undergoes its first meiotic division, producing a secondary oocyte contained in a Graafian follicle (2n) and a polar body (n)
Describe the 3rd step of ovulation
- Ovulation is instigated by a sudden surge in LH and FSH released from the anterior pituitary gland in response to a critical level of oestrogen
- The 2nd meiotic division is arrested in metaphase until fertilisation occurs
Describe the 4th step of ovulation
- The ruptured follicle develops into the corpus luteum under the influence of LH, which then secretes progesterone
- This increases the blood supply to the endometrium and causes glands to grow and secrete nutrients into the uterine cavity for the embryo
Describe the 5th step of ovulation
- If fertilisation does not occur, the corpus luteum degenerates as LH levels decline
- The blood vessels kink and contract, restricting oxygen and nutrients and resulting in cell death
- This then results in menstruation around day 28
Describe the process of fertilisation
Sperm + Ovum –> Zygote –> Morula –> Blastocyst –> Trophoblast + Inner cell mass
What does the trophoblast develop into?
- Placenta
- Chorion
What is another name for the inner cell mass and what does it develop into?
- Name = embryoblast
- Foetus
- Amnion
- Umbilical cord
What is the zona pellucida?
A thick membrane surrounding the ovum before implantation
What are the 3 germ cell layers called?
- Ectoderm
- Mesoderm
- Endoderm
How is pregnancy detected?
- Trophoblast cells secrete hCG
- Pregnancy tests are sensitive to the beta subunit of this hormone
What determines the sex of the foetus?
All foetuses are female unless testosterone is activated which causes it to differentiate into a male
Describe the prenatal development in an XX foetus
- Oestrogen causes external genitalia to form
- Walffian ducts passively regress
- Mullerian ducts passively develop into internal genitalia
Describe the prenatal development in an XY foetus
- SRY gene is activated which causes the development of the testes
- Testosterone is released which causes active development of Walffian ducts into internal genitalia and dihydrotestosterone into external genitalia
- Regression of Mullerian ducts
Give 3 female reproductive disorders
- PIDS (Pelvic Inflammatory Disease)
- Endometriosis
- Ectopic Pregnancy
Explain the effects of PIDS
- Affects uterus, ovaries and fallopian tubes
- Caused by bacterial infections or STIs
- Can increase risk of ectopic pregnancy
- Treatment = antibiotics (unless there are complications)
Explain the effects of Endometriosis
- Endometrium tissue found in places other than the womb (e.g. ovaries/ fallopian tubes)
- Can cause infertility
- Can’t be cured but can give pain relief, reduce endometrium growth by reducing oestrogen or perform surgery
Explain the effects of Ectopic Pregnancy
- Blastocyst implants in fallopian tube/ outside uterus
- Treatment = blastocyst removal
Give 3 male reproductive disorders
- Cryptorchidism
- Epididymitis
- Hydrocele
Explain the effects of Crytorchidism
- 1 or 2 undescended testicles
- Can cause infertility and increased risk of testicular cancer
- Treatment = operation
Explain the effects of Epididymitis
- Inflamed epididymis
- Usually caused by a UTI or STI
- Treated with pain killers and antibiotics
Explain the effects of Hydrocele
- Swelling of the scrotum (usually in infants and adults with injuries to their scrotum or STIs)
- Can cause infection/ tumour and reduce sperm production/ function
- Treatment = surgery in more severe cases
Describe the process of spermatogenesis
Spermatogonia A (2n) –> Mitosis –> Spermatogonia B (2n) –> Growth –> Primary Spermatocyte (2n) –> Meiosis I –> Secondary Spermatocytes (n) –> Meiosis II –> Spermatids (n)
Describe the process of oogenesis
Oogonia (2n) –> Mitosis –> Primary Oocyte (2n) –> Growth –> Primary oocyte (2n arrested in prophase I) –> Released monthly (meiosis I) –> Secondary oocyte + polar body (n) –> Ovum + 3 polar bodies
