2.1.2 (2 - fertilisation + prenatal dev)

Question 1

Ovulation

Answer 1

Release of eggs from the ovaries.

Question 2

Oxytocin

Answer 2

Natural hormone that stimulates contractions of the uterus in childbirth + afterwards.

Question 3

Fertilisation

Answer 3

The fusing of a sperm + egg cell. Marks the beginning of pregnancy (aka conception) - when the sperm penetrates an egg to result in a single cell called a zygote.

Question 4

Process of fertilisation

Answer 4

• Sperm is deposited in vagina + swims towards fallopian tubes (during SI).
• If ovum is present any sperm that reaches will be able to compete to break through ovum’s membrane.
• Done by releasing an enzyme that breaks down the outer barrier - once enters no more can.

Question 5

Stages of prenatal development

Answer 5

Germinal stage
Embryonic stage
Foetal stage

Question 6

Germinal stage

Answer 6

0-2 weeks (fertilisation to implantation)
DM - process of cell division begins (30 hrs after fert).
- Formation of placenta begins.

Question 7

Implantation

Answer 7

When cluster of cells that will become an embryo attaches itself to endometrium.

Question 8

Morula

Answer 8

A solid ball of cells created from a zygote.

Question 9

Blastocyst

Answer 9

Thin-walled hollow structure consisting of a cluster of cells making up an outer cells mass (will become the placenta) + inner cell mass (become the embryo).

Question 10

Embryonic stage

Answer 10

2-8 wks (implantation to 8th week)
DM - buds appear that will become limbs, heart begins to beat, embryo approx 1.5cm long, brain is now active.

Question 11

Cell differentiation

Answer 11

When cells take on specialised roles (eg. heart cells, skin cells, bone cells).

Question 12

Teratogens

Answer 12

Particularly influential during embryonic stage.
- Anything in the the environment of the embryo that can cause defects in development.

Question 13

Foetal stage

Answer 13

9-38wks (continues until birth) characterised by rapid growth.
DM - ears fully functioning + foetus can hear muffled sounds, fat laid down under skin to assist with life outside uterus, foetus assumes head down position in preparation for birth).

Question 14

The birth process

Answer 14

Dilation of the cervix
The birth
The afterbirth

Question 15

Dilation of the cervix (1st stage)

Answer 15

• Birth begins when strong muscles in the wall of uterus begin to contract (triggered by oxytocin).
• Pressure of baby’s head on the cervix leads to released of oxytocin + subsequent contraction of smooth muscles of uterus.

Question 16

The birth (2nd stage)

Answer 16

Begins when cervix is fully dilated (approx 10cm) up to delivery of the baby.

Question 17

The afterbirth (3rd stage)

Answer 17

• Expulsion of the placenta due to powerful contractions of the uterus.
• Injections of oxytocin may be given to constrict blood vessels + reduce bleeding from the uterus.

Question 18

APGAR scale

Answer 18

An indication of how well a neonate is coping with the physical challenges outside the uterus.
- Lower score may indicate that medical intervention is necessary.

Question 19

A - activity

Answer 19

• Absent (0)
• Flexed arms + legs (1)
• Active (2)

Question 20

P - pulse

Answer 20

• Absent (0)
• Below 100bpm (1)
• Above 100bpm (2)

Question 21

G - grimace (reflex irritability)

Answer 21

• Floppy (0)
• Minimal response to stimulation (1)
• Prompt response to stimulation (2)

Question 22

A - appearance (skin colour)

Answer 22

• Blue/pale (0)
• Pink body/blue extremities (1)
• Pink (2)

Question 23

R - respiration

Answer 23

• Absent (0)
• Slow + irregular (1)
• Vigorous cry (2)