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BIOM 3200 > The reproductive system > Flashcards

The reproductive system Flashcards

1
Q

spermatogonia vs spermatozoa

A

spermatogonia: the stem cells of sperm
spermatozoa: mature sperm, carries mans genetic material

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2
Q

spermatogenesis pt 1: how is the primary spermatocyte prepared

A
  1. spermatogonia are diploid stem cells that give rise to one daughter cell
  2. the daughter cell remains at the basement membrane as a stem cell
  3. a second daughter cell (primary spermatocyte) moves towards the inner lumen
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3
Q

spermatogenesis pt 2: how does the primary spermatocyte become spermatozoa

A
  1. primary spermatocyte undergoes first meiosis: DNA duplicates
  2. homologous chromosomes are separated into 2 daughter cells
  3. second meiosis: duplicate chromatids are separated into 4 daughter cells (spermatids) which will become the spermatozoa
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4
Q

oligospermia

A

Lower sperm count, leads to decreased fertility

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5
Q

What is immunological infertility - in men

A
  • the immune system attacks developing sperm because it does not recognize it as self
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6
Q

how do the Sertoli cells help the seminiferous tubules as an immunologically privileged site

A
  1. the blood-testis barrier creates tight junctions at the basement membrane, controls what gets through Sertoli cells
  2. produces FAS Logans which when binds to receptors on T-cells triggers apoptosis of the T-cell which prevents immune attacks on developing sperm
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7
Q

what is sperm life in the female reproductive tract

A

80 hours after ejactulation

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8
Q

what is capacitation

A

sperm structure is modified during passage through the reproductive tract so it can fertilize an egg
- alters the glycoside protein surface of the sperm under the influence of secretion of the tissues of the female reproductive tract

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9
Q

how do sperm survive in the genital tract

A
  • cervical mucus maintains metabolic requirements of sperm
  • while migrating though the tract, sperm are rapidly separated from the seminal plasma and resuspended in the female genital fluid
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10
Q

steps in capacitation

A
  1. epididymal: surface of the epididymal sperm contain proteins and carbohydrates
  2. ejaculated: these surface proteins are coated with seminal plasma proteins
  3. capacitated: when sperms are exposed to the female tract environment, these surface proteins are removed exposing the molecules that can bind the zona pellucid of the oocyte
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11
Q

how does fertilization happen

A

the sperm first penetrates the corona radiata and ending with the intermingling of maternal and paternal chromosomes after the sperm entered the egg
- the sperm must pass all the layers before genetic material can be released

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12
Q

what are the layers of the egg that the sperm must pass for fertilization

A
  1. corona radiata
  2. inner acrosomal membrane
  3. zona pellucida
  4. perivitelline space
  5. plasma membrane of the egg
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13
Q

what is viagra

A

a drug that helps relax muscles and arteries inside the penis which helps more blood reach it

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14
Q

what is an erection

A

a hemodynamic event where parasympathetic nerve-induced vasodilation of arterioles allows blood to flow into the corpora cavernosa

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15
Q

How do men get erections

A
  1. the neurotransmitter that mediates this is nitric oxide
  2. arterioles vasodilate and blood enters the corpus cavernosa
  3. the vein contracts causing less blood outflow
  4. there is an increase in intracavernosal pressure causing the erection
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16
Q

how do arterioles vasodilate

A

by smooth muscles relaxing

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17
Q

how does nitric oxide act as a neurotransmitter in erections

A
  • causes vasodilation of arterioles that allows blood to flow into the corpus cavernosa of the penis
    1. NO acts on vascular smooth muscle cell and activates GTP, producing cGMP
    2. cGMP causes Ca2+ channels in VSMC to close, Ca2+ concentration in the cytoplasm decreases
    3. VSMC relaxes, causing vasodilation of the penis and engorgment of the erectile tissue
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18
Q

How does viagra inhibit PDE to promote an erection

A

viagra inhibits PDE that catalyzes the breakdown of cGMP which increases the ability of cGMP and promotes the erection

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19
Q

how was viagra shown to cure jet lag in hamsters

A
  • viagra causes elevated levels of cGMP which temporarily speed up the internal body clock in the brain
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20
Q

prolactin axis

A

hypothalamus produces PRH - acts on the anterior pituitary - produces prolactin - acts on the breasts

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21
Q

structure of the human breast

A
  • the mammary gland has 15-20 milk lobes divided by adipose tissue
  • each lobe is subdivided into lobules, which contain alveoli (sacs) that secrete milk
  • alveoli secrete milk into secondary tubules which form into mammary ducts, then the lactiferous duct, then drain at the nipple
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22
Q

where does milk accumulate during nursing

A

the lumen of the mammary duct

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23
Q

why is milk production prevented during pregnancy

A
  • because estrogen is high, so the secretion of prolactin is inhibited
  • PIH (dopamine) is secreted from the hypothalamus instead of PRH
  • after birth, the placenta is gone so estrogen levels go down and there is an increase in prolactin
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24
Q

prolactin vs oxytocin

A

prolactin: stimulates milk production - anterior pituitary
oxytocin: releases milk - posterior pituitary

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25
Q

what are cues for oxytocin production to release milk

A
  • suckling
  • thought of the child
  • visual/ausitory cues (brain stimuli)
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26
Q

why is oxytocin made in both males and females

A

it is a neuropeptide that plays a role in attachment and affiliation in non-human mammals (trust)
- has a biological basis of prosocial approach behaviour

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27
Q

what determines biological sex

A

a particular gene on the Y chromosome induces the embryonic gonads to become testes
- biological females lack a Y chromosome - absence of this gene causes ovaries development

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28
Q

what is the SRY gene

A

a highly conserved gene found on the Y chromosome of animals - important for sex determination

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29
Q

sex differentiation

A
  • in the fetus, sex differentiation begins with the development of the gonad from a biopotential primordium
  • at 6 weeks it is undistinguishable but at 10 weeks can tell differentiation between males and females
30
Q

female sex differentiation

A
  1. in the absence of SRY protein - gonadal tissue develops into ovaries
  2. since there is no testosterone, there is no Mullerian inhibition factor (MIF) made since no Sertoli cells - Wolffian duct degrades but Mullerian duct is maintained
  3. absence of MIF allows the Mullerian duct to become Fallopian tubes, uterus and vagina
31
Q

male sex diffeerentiation

A
  1. presence of SRY proteins - gonadal tissue develops into testes
  2. presence of testosterone, so MIF is made in the Sertoli cells which cause Mullerian duct to degrade - the Wolffian duct is maintained
  3. testosterone allows Wolffian duct to become seminal vesicle, vas deferent and epididymis
32
Q

sex chromosomes

A
  • genetic females are XX - inherit one X from each parent
  • genetic males are XY - inherit one X from mother and Y from father
  • even with Y chromosome, must also have SRY or else fetus will develop into female
33
Q

Testes determination and insulin receptors in mice

A
  • mice are SRY positive and XY positive
  • noticed that if you mutate 3 insulin receptors in mice they develop ovaries and show female phenotype - not based on SRY in this case
34
Q

true hermaphrodites

A

an intersex condition where individuals have both ovaries and testes tissue - can be 46XX with SRY mascism

35
Q

pseudo hermaphrodites

A

a congenital condition where individuals have external genitalia of one sex and internal sex organs of the other
- an endocrine disorder
- actually male

36
Q

characteristics and development of pseudohermaphrodite’s

A
  • normal testosterone
  • defective 5a-reductase
  • inadequate levels of DHT
  • inappropriate exposure to androgens during early gestation therefore male external genitalia and prostate gland fail to fully develop during fetal development
  • at birth they appear female
  • at puberty testes secrete testosterone again which causes masculinization of the external genitalia, voice etc.
37
Q

heart attack gender gap

A

heart attacks strike younger in men but survival rates are worse in women

38
Q

what is puberty

A

rapid growth and development, with earlier and more obvious signs in girls
- activation of the HPG axis resulting in gonad maturation

39
Q

what influences irregular puberty

A
  • genetic variations in timing of onset of puberty
  • environmental factors (altitude)
  • nutrition (EDs)
  • chronic illness
  • synthetic hormones and other environmental chemicals
  • precocious puberty
40
Q

how is sexual maturation prevented by GnRH deficiency in children fixed

A
  • treat with GnRH pulses similar to those that occur naturally
  • if given steady infusions instead of pulses the child will still fail to mature sexually
41
Q

how are puberty and adolescence coupled?

A

through interactions between nervous system and gonadal steroid hormones

42
Q

what happens with hormones before ovulation

A
  • ovulation requires an LH surge - 2 days before LH increases 6-10 fold and FSH 2-3 fold
  • LH converts granulosa and theca cells to progesterone-producing cells
  • transport of ova to Fallopian tube, for humans takes 72 hours
43
Q

when can fertilization occur in the female?

A
  • sperm can survive up to 3 days in the female tract therefore can occur if intercourse takes place up to 3 days prior to the end of ovulation
  • however secondary oocyte following ovulation disintegrates 12-24 hours after ovulation if it doesn’t go into its division cycles
    SO between 3 days prior to - 1 day post ovulation
44
Q

amount of sperm in ejactulation

A
  • 2-6ml/ejactulate
  • about 10% sperm, 60% fluids from seminal vesicles and 30% from prostate
45
Q

where does fertilization usually happen

A

at the fallopian tube

46
Q

what barriers do sperm have to penetrate through to fertilize the egg

A
  1. outer layer granulose cells - corona radiata
  2. protective glycoprotein coat - zona pellucida
47
Q

polyspermy

A

fusing of sperm
- prevented by the formation of a secreted chemical barrier in mammals - in sos other species is electrical instead

48
Q

steps of egg transport in the female tract

A
  1. ovulation
  2. day 1 - fertilization
  3. days 2-4 - cell division
  4. days 4-5 - ~100 blastocysts reach the uterus
  5. days 5-6 - blastocyst implants
49
Q

what are blastocysts

A

a fertilized egg after 5-6 days that is now a rapidly dividing ball of cells
- the inner group of cells will become the embryo
- the outer group of cells will become the cells that nourish and protect it

50
Q

how does the blastocyst develop after fertalization

A
  1. zygote
  2. multi celled zygote (embryo)
  3. morula (12-16 cells)
  4. blastocyst (contains inner and outer cell mass)
51
Q

types of twins

A

dizygotic twins: develop from 2 separate oocytes fertilized at the same time - fraternal twins
monozygotic twins: 2 individuals developed from one fertilized oocyte, have identical genomes - identical twins
conjoined twins: monozygotic twins who’s bodies are joined to a varying extent

52
Q

how does implantation of the blastocyst occur

A
  • the trophoblast cells (outer cell mass) produce enzymes that allow blastocyst to eat its way into the endometrium so the placenta can form
  • trophoblasts secrete hCG to maintain the mothers corpus luteum - to make progesterone and promote pregnancy until the fetal placenta can take over
  • this produces enzymes to IMPLANT UTERUS WALL on 6th day after fertalization
53
Q

what is the cause of most lost pregnancies

A

failure of implantation in the uterus wall

54
Q

what are sites of ectopic pregnancy

A

major sites: ampullar, isthmic
minor sites: intramural, cervical, ovarian, infundibular
- pregnancy can continue in these regions (other than uterus)

55
Q

entropic pregnancy

A

implantation in a different site than the posterior wall of the uterine cavity
- pregnancies that won’t continue include tubal pregnancies and ovarian pregnancies

56
Q

placenta pervia

A

when the placenta partially covers the cervical canal if the embryo is implanted close to the cervix - will have normal embryonic development

57
Q

what do pregnancy tests detect

A
  • hCG concentration in the urine
  • at 10 weeks hCG concentration will be the highest
58
Q

how are hormones measures by immunoassay

A
  • tags antibodies specific to a hormone (hCG to detect pregnancy) which can detect levels in blood and urine
59
Q

what are some hormonal factors in pregnancy

A
  • estrogen levels gradually increase
  • progesterone levels gradually increase
  • hCG secretion peaks by 10 weeks then decreases - secreted by blastocyst, not the mother, to keep the corpus luteum until the placenta forms
60
Q

pregnancy recognition factors

A

dogs and cats - none needed (feel)
woman - hCG

61
Q

what keeps the pregnancy going before the placenta is formed

A

hCG (blastocysts)

62
Q

why is the corpus luteum needed to synthesize progesterone

A
  • placenta is not formed yet so needed until shift happened at 7 weeks
  • in early pregnancy, progesterone is needed to keep the endometrium intact
  • progesterone, estrogen and inhibit cause feedback suppression to pituitary
63
Q

what is the placenta

A
  • organ that provides oxygen and nutrients to the baby
  • a2-adrenoreceptors control vascular developmental the interface between mother and embryo
64
Q

properties of the placenta

A
  • fully developed at 3 moths
  • proper development of the placenta vascular system is needed for nutrient and gas exchange (e.g. O2/CO2)
  • preforms digestive, respiratory and renal system functions for the “parasitic” fetus
65
Q

what makes the placenta a unique endocrine gland

A

it is transient without extrinsic control. it makes…
hCG: maintains the corpus luteum
Estrogen: uterine myometrium (growth, oxytocin receptors), breast ducts
Progesterone: suppresses uterine contractions, cervical plug, milk glands
PTHrP: mobilizes mother’s bone calcium
CRH: fetal lung maturation and birth process

66
Q

How can contraceptives block unwanted pregnancies

A
  • block sperm transport (condoms, barriers)
  • suppress gametes (birth control pills - estrogen)
  • block implantation (IUD, morning after-pill, high dose hormones)
    *many prevent pregnancy but don’t protect against IUDs
67
Q

How does birth occur via hormone control (positive feedback loop)

A
  1. fetal adrenal gland secretes DHEAS and cortisol upon stimulation by CRH and ACTH
  2. cortisol stimulates the placenta to secrete CRH, producing the positive feedback loop
  3. DHEAS is converted by the placenta into estriol, which together with prostaglandins and oxytocin stimulate the myometrium of the uterus to undergo changes - leading to labour
68
Q

stages of labour in women time line

A

stage 1 - cervical dilation: 8h
stage 2 - fetal expulsion: 2h
stage 3 - fetal membrane expulsion: 1h or less

69
Q

time required for complete involution in women

A

40-45 days

70
Q

time required for resumption of complete ovarian activity in women

A

6-24 months

BIOM 3200 (7 decks)

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