Grade 12 Human Reproduction Part 6 Birth (Parturition) and Birth Control (Contraception) Flashcards
Define birth:
The expulsion of the foetus, its surrounding membrane and the placenta from the uterus
When is the baby usually ready for birth?
- Approx. 9 months after fertilization – baby ready for birth
- Placenta is less efficient at end of gestation period
What is distinctive about human birth?
1) Baby born helpless, relatively immature stage**
* In order to successfully leave mother’s body, human pelvis is narrower, narrower birth canal – bipedal and upright
* Relatively large brain at foetal stage
2) Baby usually born head-first
Discuss different birth options:
Vaginal childbirth
* Natural (drug free)
* With pain medication
Cesarean section (C-section)
* Process
* Abdomen and uterus of mother cut open
* Baby removed from uterus
* Cut stitched up
* Rrecommended if:
* Vaginal childbirth puts mother/ baby life at risk
* Complications (awkwardly positioned baby)
How does birth / parturition occur?
- Foetus moves into birthing position 2 – 3 weeks before birth
- High levels of oestrogen in mother’s blood just before birth
- This causes the hypophysis to release oxytocin (promotes contraction of the uterine wall)
- Birth process can take from a few hours to well over a day.
3 Stages of the Birth Process
Explain stage 1 of the Birth Process:
Dilation of cervix
* Myometrium contracts (muscular layer) – becomes more intense & frequent
* Amnion and foetus forced towards cervix
* Causes cervix of uterus to dilate (full dilation is about 10cm)
* “Water (amnion) breaks” due increased pressure & releases amniotic fluid through the vagina
Explain stage 2 of Birth Process:
Delivery of baby
* Cervix fully dilated – baby pushed out through vagina (uterine & abdominal muscles contract)
* Umbilical cord tied & cut immediately after birth
* Becomes naval/ belly button (part still connected shrivels up)
- Non-fused skull aids natural birth (*Flat bones of baby’s skull separated by connective tissue & not fused
Head changes shape to be able to pass through birth canal – process called moulding
Misshapen head of new-born returns quickly to normal )
Explain stage 3 of the Birth Process:
Expulsion of placenta – final stage
* 10 – 20 minutes after delivery
* Placenta with remaining umbilical cord detaches from uterine wall
* Afterbirth – uterine contractions forcing the placenta & co. out
* Short ( seldom longer than 15 minutes)
Study diagram on page 115 of your textbook to show birth of baby.
Discuss the process of breast feeding:
- Mammary glands are made up of milk-secreting cells
- Lactation - milk formation
- Oestragen and progesterone stimulate development of milk glands and ducts
- Prolactin, from pituitary, stimulates milk production
- Oxytocin, from hypothalamus, causes release of milk from glands and maintains flow of milk
What are the advantages of breast-feeding?
- Contains antibodies
- Contains nutrients
- Is free!
The Control of Human Fertility - What is birth control?
- Voluntary regulation of the number of births by preventing pregnancy.
- The prevention of fertilisation or implantation after sexual intercourse has taken place
- Not always 100% effective
- 100% effective when abstaining
List the four main methods of birth control:
- Natural methods
- Barrier method
- Chemical substances
- Surgical methods
How do contraceptives work?
- Prevent the egg from being released, which will prevent ovulation
- Prevent the sperm from reaching the egg, which **prevents fertilisation **
- **Prevent embryo implantation **or development
- **Other **methods
What natural methods of birth control exist?
**Withdrawel **- penis withdrawn from vagina just before ejaculation
Very unreliable method - small quantities of sperm-containing semen may be released prior to ejaculation. Ejaculation also difficult to control.
Rhythm method - Sexual intercourse restricted to SAFE days in the female’s menstrual cycle, when fertilisation is unlikely to occur = about 5 days before menstruation and 3 days after mestruation. Unsafe days 3 - 4 days before ovulation, ovulation and 3 - 4 days after ovulation.
To prevent sperm reaching the egg, the Barrier method is used as well as Sterilisation.
List the options under the** BARRIER method:**
- Male condom
- Female condom
- Cervical cap
- Diaphragm
- Intra-uterine device (IUD)
To prevent ovulation, the PILL is an effective contraceptive. Explain.
- Pill contains two hormones - oestrogen and progesterone.
- Prevent pregnancy by inhibiting ovulation and thus fertilisation.
- One of the most commonly used.
- Very reliable if taken daily
- Not suitable for all women.
- Does not protect against STDs.
*
One way to prevent the sperm from reaching the egg is through SERGICAL methods e.g. STERILISATION. Explain.
- Usually permanent.
- It does not affect the reproductive physiological processes and is not harmful.
- Is cheap.
Male sterilisation - VASECTOMY - Sperm duct is cut, preventing sperm from being expelled. Sperm made is broken down and absorbed back into body.
Female sterilsation - Tubal ligation. Fallopian tubes tied off which prevents egg and sperm meeting.
What is the condom used for?
- A barier device used during sexual intercourse.
- Reduce probability of pregnancy
- Reduce probability of spreading sexually transmitted infections (STI’s) such as gonorrhoea, syphilis, HIV
- Get male and female condom
What is the male condom?
- Thin rubber sheath that fits over erectile penis
- Capturing sperm in the female and thus fertilisation of the ovum
- Excellent and reliable method - especially if combined with spermicide.
- Prevents pregnancy of female
- Provides protection against sexually transmitted diseases (STD’s) e.g. HIV Aids
What is the female condom?
- Resembles an elongated balloon and is larger than male condom
- Captures sperm and prevents them entering cervix and fertilising the ovum
- Lines the vagina and also covers part of hte external vulva - provide some protection against STD’s
What is the cervical cap?
- Small, flexible rubber structure that is interserted before intercourse
- Fits over cervix and prevents entry of sperm
Another method to prevent sperm from reaching egg is a diaphragm. What is a DIAPHRAGM?
- Shallow, bendable cup
- Placed over the cervix before sex and left in palce for at least six hours after sex
- Prevents sperm from reaching egg
- Moderately effective.
- Effective if used with spermicide.
What is SPERMICIDE?
- Chemicals that kill sperm.
- Creams, foams and gels - put in vagina
- Often used with condoms
- Not effective if used on own - use with condoms.
