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Human physiology > Reproduction 3 > Flashcards

Reproduction 3 Flashcards

1
Q

Where does fertilisation usually take place?

A

In the uterine tube

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2
Q

When must sperm be introduced to the female reproductive tract & why?

A

5 days before ovulation

  • Sperm viable for 5 days
    -Oocyte vibale for 12-24 hours
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3
Q

Sperm is initially incapable of fertilisation, what is required?

A

It requires ‘capacitation’

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4
Q

How do oocyte and sperm compare?

A

Oocyte is much larger than sperm cells

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5
Q

How does oocyte move in the uterine tube?

A
  • At ovulation, fluid movement causes oocyte to enter of uterine tube
  • Peristaltic contractions move oocyte toward uterus for several minutes
  • Activity of cilia move oocyte toward uterus for a few days
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6
Q

How long does it take for the oocyte to travel down the uterine tube?

A

Entire trip takes 4 days

Sperm must meet ovum during these 4 days

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7
Q

What happens if oocyte movement in the uterine tube goes wrong?

A

This is how an eptopic pregnancy occurs (sperm fetrilises the egg in the uterine tube

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8
Q

How does the sperm move in the unterine tube?

A
  • Millions of sperm deposited into the vagina during copulation
  • Swim to uterus
  • Survival time in reproductive tract usually abt 5 days
  • Only a few hundered sperm make it to uterine tubes
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9
Q

How many sperm need to break through the barrier of an oocyte?

A

Only 1

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10
Q

Where does sperm capacitation happen?

A
  • Deposited sperm cannot fertilise oocyte
  • Capacitation occurs in female reproductive tract
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11
Q

What happens during sperm capacitation?

A
  • Tail movement
  • Plasma membrane altered
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12
Q

What are the events of fertilisation? (Part 1)

A
  • Several sperm generally reach ovum & try preventing corona radiata
  • When through, bind top sperm-binding protein
  • Acromosome reaction triggered, with acromosomal enzymes released
  • Enzymes break thru zona pellucida allowing sperm to access oocyte
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13
Q

What are the events of fertilisation?

A
  • First sperm to access oocyte binds to receptor on oocyte plasma membrane
  • Sperm transported into cytoplasm = fusion
  • Sperm-binding proteins become inactivated & zona pelludica hardens preventing polyspermy
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14
Q

What happens in fertilisation?

A
  • Fusion stimulates 2nd meiotic division of oocyte = oocyte –> ovum
  • Sperm plasma membrane disintegrates
  • Chromosomes from sperm and ovum migrate to centre
  • DNA repliated - zygote
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15
Q

What do capiciated sperm release

A

enzymes from their acrosomes in order to penetrate their cells and son pelludisa surrounding the egg

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16
Q

What happens in the fusion of sperm and egg to form zygote?

A

Egg and sperm nuclei fuse to form zygoye nucleus & a second polar body is produced as well

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17
Q

What happens in early embryonic development and implantation?

A
  • Mitotic divisions - morula
  • Cell cleavage (no increase in overall size)
  • Totipotent up to 16-32 cell stage
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18
Q

What is a blastocyst?

A
  • Lost zona pellicuda
  • Outer cell layer = trophoblast –> will become fetal placenta
  • Inner cell mass –> willl become embryo
  • Fluid dilled cavity = blastocoele
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19
Q

What can happen in the development of the blastocyst?

A

At this stage quite alot of miscarrriages can happen

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20
Q

What happens in the implantation stage?

A

Occurs 6-7 days post fertilisation

Trophobast responsible for implantantation:
- Secretes enzymes that digest endometrial cellls to provide nourishment for embryo
- Secretes paracrines that stimulate decidual respone
- Infiltraes endometrial tissue to develop into placenta

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21
Q

What are the steps that happen during implantation?

A

1 - Ovulation

2 - Day 1: fertilisation

3 - Days 2-4: Cell division takes place

4 - Days 4-5: Blastocyst reaches uterus

5 - Days 5-9: Blastocyst implants

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22
Q

What happens when the Blastocyst Attaches to Endometrial Lining?

A

Endometrium swells, increases glycogen stores

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23
Q

What happens when the Trophoblast Penetrates Endometrium?

A

Trophoblast and endometrial cells will form placenta

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24
Q

What are the Disorders of Implantation?

A

Ectopic Pregnancy (1 in 300 pregnancies):

  • Fertilised ovum implants in the fallopian tube
  • Growth of fetus and placenta causes distension, bleeding and possible rupture
  • Treat with drugs to kill fetus (subsequently reabsorbed) or surgical removal
25
Q

What is gestation/preganancy?

A
  • Covers the period from conception to birth of the fetus * Approx 9 months
  • Consists of 3 (uneven) Trimesters
  • The first is dated from the day of the last period - i.e. 2 weeks before conception
26
Q

What are the 3 components of the blastocyst?

A
  • Single layered sphere of cells - Trophoblast - required for implantation and develops into the fetal placenta
  • Fluid filled cavity - Blastocoele - develops into the amniotic sac
  • Inner cell mass - develops into fetus
27
Q

After implantation what does the trophoblast form?

A

The two cell layer ‘chorion’

28
Q

What does the two layer ‘chrorion’ do?

A

Produces more digestive enzymes which produce more cavities - which allows development of placenta

29
Q

What are the stages of placenta development?

A
  • Fetal component –> Chorionic Villi
  • Maternal component –> Endometrial tissue
  • Blood flow to placenta –> Maternal uterine artery and vein & Fetal umbilical artery and vein located in umbilical cord
30
Q

What does the developing embryo float in & how does this help the embryo?

A

In the Amniotic fluid;

  • It obtains oxygen & nutrients from the mother thru the placenta & umbilical cord
31
Q

How is material exchanged into the placenta?

A
  • Some material is exchanged across placental membrane by diffusion
  • Other material must be transported
32
Q

Look at the diagram of the placenta (may have to laebel it)

A

:)

33
Q

What is the fetus like by 5 weeks?

A

By 5 weeks, placenta is functioning and heart is beating

34
Q

What are the 3 primary functions the placental serves?

A
  • Allows for the free exchange of energy, nutrients and waste products –> respiratory, digestive & renal functions
  • Provides an immunological barrier between mother and fetus
  • Secretes hormones that support the development of the fetus and prepare the mother to support the newborn child
35
Q

How does the placenta providing an immulogical barrier between the mother & fetus beneficial?

A

Prevents rejection of father’s proteins

36
Q

What are the placental hormones?

A
  • Human Choionic Gonadotropin (hCG)
  • Estrogen
  • Progesterone
  • Human Chorionic Somatomammotropin
  • Relaxin
  • Placental PTHrp (parathyroid hormone- related peptide)
37
Q

What is the role of Placental PTHrp (parathyroid hormone- related peptide) in the placenta?

A

Inc maternal plasma Ca2+ level for use in calcifying fetal bones –> if necessary promotes localised dissolution of maternal bone

38
Q

What is the role of Relaxin in the placenta

A
  • Softens the cervix in preparation for cervical dilation at parturition
  • Loosens the connective tissue between the pelvic bones
39
Q

What is the role of Human Chorionic Somatomammotropin in the placenta?

A
  • Believed to reduce maternal use of glucose and to promote breakdown of stored fat (like growth hormones) - more glucose and free fatty acids available to fetus
  • Helps prepare the mammary glands for lactiation
40
Q

What is the role of progesterone in the placenta?

A
  • Suppresses uterine contractions to provide a quiet environment for the fetus
  • Promotes formation of a cervical mucus plug to prevent uterine contamination
  • Helps prepare the mammary glands for lactation
41
Q

What is the role of estrogen in the placenta?

A
  • Stimulates growth of the myometrium, increasing uterine strength for parturition
  • Helps prepare the mammary glands for lactation
42
Q

What is the role of Human Chorionic Gonadotropin (hCG)?

A
  • Maintains the corpus luteum of pregnancy
  • Stimulates the secretion of testosterone by the developing testes in XY embryos
43
Q

Look at the hormonal changes during preganancy slide

A

I can’t insert the graphs

44
Q

How is ovulation prevented during pregnancy?

A

Progesterone inhibits GnRH, LH, and FSH release, preventing LH surge

45
Q

What develops in the fetus at 4 weeks?

A

Spinal cord & heart

(weight = <1g)

46
Q

What develops in the fetus at 8 weeks?

A
  • Head & Facial Features (eyes & nose)
  • Arms & Legs

  • All internal organs - heart beat detectable

-Reflexes develop

(weight = 3g)

47
Q

What develops in the fetus at 12 weeks?

A
  • Sexual differentiation complete
  • Development of bones
  • Fine hairs on body
  • Fingers & toes discernible
  • Splenic production of Red Blood Cells begins

(weight = 48g)

48
Q

What develops in the fetus at 16 weeks?

A
  • Superficial blood vessels observed
  • Ears & hearing develops
  • Lungs breathe amniotic fluid
  • Finger nails discernible
  • Facial expressions observed

(weight = 180g)

49
Q

What develops in the fetus at 20 weeks?

A
  • Skin sensitive to touch
  • Movement more coordinated - stretching, grasping & turning
  • Sebaceous glands operational

(weight = 500g)

50
Q

What develops in the fetus at 24 weeks?

A
  • Brain waves resemble that of newborn child and evidence of patterns of sleep & wake
  • Detects and recognises external sound

(weight = 1kg)

51
Q

What develops in the fetus at 32 weeks?

A
  • Thermoregulatory mechanisms partially operational
  • Deposition of adipose tissue
  • Plenty of movement
  • Lungs able to function ex utero

(weight = 2kg)

52
Q

What is the 10th & 90th percentile of appropriate size fr gestational age at birth?

A

10th = 5.5lbs

90th = 8.8lbs

53
Q

What are the maternal changes during the first trimester of pregnancy (weeks 1-14)?

A
  • Associated w a 10-25% increase in metabolic activity & 1-2 kg weight gain
  • Inc in Cardiac Output, Heart Rate, Respiration & Blood Volume
  • Inc in breast size (action of hormones)
  • Inc in uterus - presses on bladder
  • ‘Morning sickness’ and loss of libido
54
Q

What are the maternal changes during the second trimester of pregnancy (14-28 weeks)?

A
  • Increase in weight (approx 6 kg) - loss of waistline
  • Heartburn - progesterone-induced relaxation of oesophageal muscle
  • Constipation - progesteron-induced relaxation of intestinal muscle
  • General improvement in well-being
  • Feel movement of baby, return of libido, improved skin tone
55
Q

What are the maternal changes during the third trimester of pregnancy (29 weeks - birth)?

A
  • Deeper breaths - baby reduces abdominal movements of diaphragm
  • Braxton-Hicks contractions of the uterus - preparation for child birth
  • Tired and anxious
56
Q

What are the 3 disorders of pregnancy?

A
  • Pre-eclampsia & Eclampsia
  • Eclampsia = ‘like a flash of lightening’
  • Diabetes mellitus
57
Q

What is Pre-eclampsia & Eclampsia?

A

Elevated blood pressure in 15% of woman

  • Compromises blood flow to fetus
  • Requires plenty of bed rest and even sedation
58
Q

What is Eclampsia (‘like a flash of lightening’)?

A

Large and rapid increase in blood pressure associated with water and sodium retention

  • Life threatening to mother and fetus
  • Precipitated by fetal factor as blood pressure drops post parturition
  • Yreat aggressively with anti-hypersensitive agents or terminate pregnancy
59
Q

What is diabetes mellitus?

A
  • 1/350 pregnancies
  • Danger to both fetus and mother

Human physiology (43 decks)

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