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M101 > W24 The Reproductive System > Flashcards

W24 The Reproductive System Flashcards

1
Q

What are features of the reproductive system?

A
  • Produces male and female gametes
  • Oocyte
  • sperm
  • Enhances fertilisation of an oocyte by
    a sperm
  • Female: nurtures new individual until
    birth
  • Produces reproductive hormones –
    controls above processes
  • Birth: Biological Sex
  • Female (vagina)
  • Male (penis)
  • Intersex (variation)
  • Anatomy doesn’t always dictate
    gender identity
  • Covering biological sex
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2
Q

What makes up the male reproductive system?
Organs?
Ducts?
Glands?

A

Organs
- Testes
- Penis

Ducts
- Epididymis
- Ductus deferens
- Urethra

Glands
- Seminal vesicles
- Prostate

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3
Q

Describe features of the testes:
What produces testosterone?
What produces sperm?

A
  • Testes covered in
  • Fibrous connective tissue
  • (under skin- scrotum)

Each testis contains
* Connective tissue forms lobes
* Seminiferous tubules (produce sperm)
* Rete testis
* Efferent ductules
* Epididymis
* Ductus deferens
* Leydig cells (outside seminiferous tubule)
- Produce testosterone

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4
Q

What is Gametogenesis?
(2)

A

Formation of the male and female gametes

  • Gametes (ovum and spermatozoa)
    -Oogonium/primary oocytes and spermatogonium
    Splits into:
  • Females: oogenesis
  • Males: spermatogenesis
    -occurs in the gonads (ovary or testis)
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5
Q

Gametogenesis undergoes Meiosis.
Describe the process.

A
  • One cell undergoes two consecutive cell divisions
  • Four daughter cells, each half as
    many chromosomes as the parent cell
    Termed
  • meiosis I (reduction division, 23)
  • meiosis II
  • During fertilization, zygote receives 1 set of chromosomes (23) from each parent
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6
Q

What is the Seminiferous tubule?
What do Leydig and Sertoli cells produce?

A
  • Where sperm formed
    -Mature in lumen, immature on outside
  • Leydig cells (testosterone)
  • Sertoli cells (nourish the germ cells and produce hormones)
    -Germ cells partially embedded
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7
Q

What is Spermatogenesis?

A
  • Creation of sperm cells within the male gonads (testes)

Spermatogonia- Spermatocytes- Spermatids- Spermatozoa

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8
Q

What is the Seminiferous tubule?

A
  • Where sperm formed
    -Mature in lumen, immature on outside
  • Leydig cells (testosterone)
  • Sertoli cells (nourish the germ cells and produce hormones)
    -Germ cells partially embedded
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9
Q

What are the functions of the testes?

How long does sperm take to mature?

A
  • Exocrine – produce sperm
  • Endocrine – produce hormone
    Spermatogenesis
  • Process of sperm maturation
  • Involves both mitosis & meiosis
  • Takes ~ 74 days to complete (incl
    maturation)
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10
Q

What makes up the female reproductive system?

A

Ovary
Uterine tube/ fallopian tube oviduct
Uterus
Vagina

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11
Q

What are the 3 Uterine tissue layers?

A
  • Endometrium – vascular and glandular * Stratum compactum - cuboidal ciliated
    epithelium*
  • Stratum spongiosum - loose connective
    tissue** Stratum basale
    *Slough during menstruation
  • Myometrium – 3 layers of smooth muscle
  • Perimetrium - peritoneum
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12
Q

What are the major components of the fallopian tubes? (3)

A
  • Also known as: Uterine tubes or Oviducts
  • Each 10cm long (approx.)
  1. Isthmus – narrowing
  2. Ampulla – swelling – fertilization usually occurs here
  3. Infundibulum – collecting area with fimbrae
    -Fimbrae that collect egg when released from ovary
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13
Q

What is the ovary?

A
  • Outer: connective tissue – ovarian follicles
  • Oocyte (female sex cell)
  • Centre: blood vessels nervous
    tissue
  • Developing follicles (cellular
    structures)
  • Surrounding developing oocytes
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14
Q

Ovary: follicular development

A
  • Primordial follicles (present at birth)
  • Puberty:
    Primary follicles
  • Oocyte enlarges
  • Develops granulosa cells
  • Build up
    Secondary follicle
  • Fluid filled vesicles
  • Thecal cells
    Grafian follicle (mature follicle)
  • Inside are Ruptures and secondary oocytes surrounded by cells released during ovulation
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15
Q

What are follicles?

A

Small sacs filled with fluid

  • Primary follicle surrounded by
    granulosa cells
  • No. Layers of granulosa cells increase as maturation proceeds
  • Cells secrete oestrogen-rich fluid into space surrounding oocyte called Antrum
  • Outer layer of granulosa cells condenses into layer of theca cells
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16
Q

What is Oogenesis?

A
  • Occurs in the ovaries
  • Process of creation of an ovum (egg cell) from precursor cells
  • Begins prior to birth
  • primordial germ cells (oogonia) in foetal ovary
  • spans all of pre-reproductive & reproductive life
  • Similar process to spermatogenesis
  • Mitosis of primordial cells (oogonia)
  • (early) meiosis of primary oocytes
  • (late) meiosis of secondary oocyte
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17
Q

Steps of Oogenesis:

A

Primitive germ cells differentiate into
Oogonia which peform mitosis to become
Primary oocyte, early meiosis leads to
Secondary oocyte, late meiosis leads to
Ovum

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18
Q

Ovary: follicular and oocyte development

A
  • Follicle development 28 days
  • Hormonal control
  • Generally only one follicles forms a mature follicle
  • Remaining degenerate
  • Post ovulation
  • Forms corpus luteum
  • If pregnancy
  • Corpus luteum enlarges and persists (producing hormone)
  • If no pregnancy
  • Corpus luteum lasts 10-12 days then degenerates (becomes small white structure)
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19
Q

Which follicle ruptures at ovulation?
Grafian
Secondary
Primary

A

Grafian

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20
Q

Recap: the endocrine system
What are the major endocrine glands?

A
  • Adrenal glands
  • Hypothalamus
  • Ovaries and testes
  • Pancreas
  • Thyroid and parathyroid
  • Pineal gland
  • Pituitary gland
  • Thymus gland 29
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21
Q

Recap: the endocrine system
What are hormones?

A

A chemical substance produced by ductless glands within the endocrine system

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22
Q

What are the 3 classes of hormones?

A
  • Three general classes
  • Hormones derived from amino acids
  • Dopamine, epinephrine (tyrosine precursor)
  • Proteins and peptides
  • Insulin (peptide), growth hormone (protein)
  • Hormones derived from lipids
  • Prostaglandins (derived from phospholipids)
  • Steroids (derived from cholesterol)
  • Most RH steroids but stimulated by other classes
  • Reproductive hormones (RHs) are synthesised and secreted throughout a person’s
    lifetime at different levels, increasing at puberty and normally decreasing in old age
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23
Q

What are Reproductive hormones?
What are the 3 classes of reproductive hormones?
What do they interact with?

A
  • Commonly called sex steroids or steroid hormones
  • Produced mainly by the gonads (ovaries and testes)
  • Some production by placenta, adrenal glands

Three classes:
* Oestrogens
* Androgens
* Progestogens
* Interact with oestrogen (ER), androgen (AR) or progesterone (PR)
receptors respectively

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24
Q

Overview of major functions of
reproductive hormones

A
  • Bind to specific receptors in target tissues
  • AR, ER, PR
  • Exert a range of effects on both organs and the body as a whole
  • Primary role: maturation of reproductive organs, fertility and pregnancy
  • Secondary role: development of physical characteristics
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25
Q

Where is testosterone produced?

A

In Leydig cells
Sertoli cells

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26
Q

Reproductive hormones: molecular
action

A
  • Generic mechanism of action
  • Hormones enter cells
  • Hormones bind to an intracellular receptor
  • Conformation change and translocation
  • DNA binding (HRE’s)
  • Gene expression (or repression)
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27
Q

Endocrine function of gonads is regulated by

A

HPG axis
Hypothalamus, Pituitary, Gonad

28
Q

Where is the hypothalamus?
What does it release

A

Small structure at base of forebrain
It releases GnRH (Gonadotrophin Releasing Hormone) which is a peptide hormone
Stimulated and is released into the blood and reaches the pituitary

29
Q

What is the Pituitary gland?

A
  • Pea-sized gland located at the base of the
    skull ventral to the hypothalamus
  • Comprised of two elements
  • Posterior and anterior lobes
  • Anterior pituitary contains specialised cells
    (gonadotropes)
  • GnRH stimulates gonadotropes to
  • Produce gonadotrophins
  • glycoproteins
  • FSH (follicular stimulating hormone)
  • LH (Lutenising hormone)
  • hCG (human chorionic gonadotrophin)
30
Q

What are the 2 Gonadotropins?
How do they work?

A

LH and FSH
Luteinizing and Follicular stimulating hormones

Bind to different receptors expressed on cells within the ovary and testes

31
Q

LH main functions

A
  • ♀ acts on ovarian follicle INDUCING OVULATION (main)
  • ♂ acts on testes producing testosterone
32
Q

FSH main functions

A
  • ♀ Promotes ovarian follicle development
    & oestrogen production (main)
  • ♂ stimulates spermatogenesis in testes
  • Sertoli cells
33
Q

What are the 3 classes of hormones?

A

Oestrogens e.g. oestradiol
Androgens e.g. DHEA, DHT
Progestogens e.g. progesterone

34
Q

HPG axis:
What hormone does the hypothalamus secrete?
What 2 hormones does the pituitary gland release?

A

1.GnRH
2.LH and FSH
Luteinising and Follicular Stimulating Hormones

35
Q

Regulation of Reproductive Hormone
Secretion: Male reproductive System (6)

A
  1. GnRH stimulates secretion of LH and FSH from anterior pituitary
  2. LH stimulates testosterone secretion from Leydig Cells (interstitial cells)
  3. FSH stimulates Sertoli cells to increase spermatogenesis
  4. Testosterone
  5. Stimulates Sertoli cells
  6. Development of reproductive organs
  7. Testosterone: negative effect on Hypothalamus and Pituitary
  8. Sertoli cells secrete inhibin – negative feedback
36
Q
A
  • Puberty- ages 12-14
  • Before puberty- small amounts of testosterone secreted by the testes and the adrenal cortex (inhibit GnRH, LH and FSH)
  • During puberty there are developmental changes in the hypothalamus
  • Cause the hypothalamus and the anterior pituitary gland to become much less sensitive to the inhibitory effect.
  • Rate of GnRH
37
Q

The female reproductive cycle:
What 2 cycles does it consist of?

A
  • Reproductive cycle consists of ovarian and uterine cycles
    Ovarian cycle:
    -series of ovarian events that precede and follow oocyte maturation
  • controls oogenesis
  • Uterine cycle
    -Preparation of uterus to receive ovum
  • Mediated by reproductive hormones
38
Q

Stages of the menstrual cycle in order: (4)

A

Menses, Follicular Phase, Ovulation (proliferative phase), Luteal Phase (secretary phase)

39
Q

What happens during the ovarian cycle?

A
  • During each ovarian cycle, up to 20 primordial follicles are activated (by FSH) to begin the maturation process
  • Usually only one reaches full maturity, the remainder regress
  • The ovarian cycle can be divided into 3 phases:
  • Follicular phase
    (Secondary follicles develop and development of Graafian follicle)
  • Ovulatory phase
    (Release of mature follicle)
  • Luteal phase
    (Formation of corpus luteum)

If fertilisation doesn’t happen, corpus luteum degenerates and becomes corpus albicans (stops producing progesterone) and slowly disappears.

40
Q

Ovarian and endometrial cycle:
What happens in the Proliferative (follicular) phase?

A
  • Secondary follicles mature
  • Granulosa cells secrete oestrogens
  • Oestrogen: causes the epithelial cells of the endometrium to divide rapidly.
  • Endometrium thickens
41
Q

Ovarian and endometrial cycle
What happens in the Secretory (Luteal) phase?

A
  • The corpus luteum begins to secrete progesterone and smaller amounts of oestrogen.
  • Progesterone: causes the cells of the endometrium to become larger and to secrete a small amount of fluid.
  • Fullest development of endometrium
  • If no fertilisation – corpus luteum degenerates – progesterone drops
42
Q

What cells/structure in the ovary secrete oestrogen?
Granulosa cells?
Corpus luteum?
Theca cells?

A

Granulosa cells

43
Q

Are oogonia haploid or diploid?

A

Oogonia are tiny DIPLOID germ cells that pass through mitotic divisions and originate the primary oocytes.

Oocytes are haploid, anything before that are diploid

44
Q

Feed back mechanisms: overall

A
  • Oestrogen
  • Postive feedback before ovulation,
  • resulting in increased LH and FSH secretion;
  • Negative feedback (with progesterone) on the hypothalamus and anterior
    pituitary after ovulation, resulting in decreased LH and FSH secretion
  • Progesterone
  • Negative feedback (with oestrogen) on the hypothalamus and anterior
    pituitary after ovulation, resulting in decreased LH and FSH secretion
45
Q

Hormonal control of the reproductive cycle
Follicular Phase

A
  • Oestrogen (developing follicles) stimulates GnRH secretion from hypothalamus
  • GnRH triggers FSH and LH
  • FSH stimulates oestrogen secretion at an increasing rate from the developing follicles.
  • This positive-feedback loop produces a series of larger and larger surges of FSH and LH
    secretion
46
Q

Hormonal control of the reproductive cycle
Ovulation

A
  • Ovulation occurs in response to
    the large increases in LH levels
  • about day 14 of the menstrual
    cycle
  • This large increase in LH is also
    responsible for the
    development of the corpus
    luteum
47
Q

Hormonal control of the reproductive cycle
Luteal Phase

A
  • Corpus luteum begins to secrete progesterone and oestrogen
  • Progesterone: cells of the endometrium to become larger
  • Negative Feedback: Together, progesterone and oestrogen act on the hypothalamus and
    anterior pituitary gland to
    inhibit GnRH, LH, and FSH
    secretion.
  • LH and FSH levels decline
  • No stimulation of follicles
  • Corpus luteum degenerates -
    Lower progesterone

Inhibin has a smaller role, helps maintain steady levels

48
Q

Hormonal control of the reproductive cycle
Menses

A
  • Oestrogen and progesterone secretion is low
  • In response to declining progesterone levels, the endometrial lining of the uterus
    sloughs off, resulting in menses
  • The rate of LH remains low, and
  • The rate of FSH secretion increases as progesterone levels decline (negative feedback
    released)
  • Stimulates development of follicles
  • Start to release oestrogen
49
Q

When Fertilisation does not occur:

A
  • The egg lives for 12-24 hrs
  • Takes 5 days to reach Uterus
  • Fertilisation must occur in uterine tube
  • Endometrial development continues
  • Progesterone production
50
Q

Fertilisation

A
  • hCG from pituitary and later placenta maintains corpus luteum
  • Oestrogen and progesterone levels maintained
  • Endometrium doesn’t break down
  • Subsequently Placenta takes over progesterone and oestrogen
    production
51
Q

Contraception

A

Chemical Methods
* Synthetic oestrogen and progesterone in oral contraceptives * among the most effective contraceptives - 99.9% effectiveness.
* Synthetic steroids can have more than one action* Generally they reduce LH and FSH release from the anterior pituitary.
* Oestrogen and progesterone are present in high enough concentrations to have a negative-feedback effect on the pituitary* prevents the large increase in LH and FSH secretion that triggers ovulation
* Mini-pill
* contains only synthetic progesterone* reduces and thickens the mucus of the cervix
* Prevents sperm cells from reaching the oocyte

52
Q

what cells/structure in the ovary secrete androgens
Theca cells
Corpus luteum
Granulosa cells

A

Theca cells
(granulosa cells secrete oestrogens)

53
Q

Which hormone stimulates ovulation?
LH or FSH

A

LH

54
Q

What does FSH do?

A

Stimulates follicular development

55
Q

Which hormone triggers the LH surge?

A

Oestrogen

56
Q

Which hormones do pregnancy tests detect?

A

hCG- human chorionic gonadotrophin

57
Q

What are sertoli cells?
A structure that nuture the developing spermatozoa
A duct that transports spermatozoa
Location where spermatozoa are formed
Location where spermatozoa mature

A
58
Q

What is the function of the epididymis?
A structure that nuture the developing spermatozoa
A duct that transports spermatozoa
Location where spermatozoa are formed
Location where spermatozoa mature

A
59
Q

What is the function of the vas deferens?

A

A coiled tube that carries the sperm out of the testes

60
Q

Where are sperm cells produced?
Are spermatids haploid or diploid?

A

Graafian follicle

61
Q

Which follicle ruptures at ovulation?

A
62
Q

What are the important features of gametes?

A
63
Q

What are the 3 classes of RH?

A
64
Q

What is the corpus luteum?

A
65
Q

What does inhibin do?

A

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