Pregnancy

Question 1

What are the main structures of a mature spermatozoa and what is their function?

Answer 1

1. Head- contains nucleus (haploid) and acrosome
2. Mid piece- contains lots of mitochondria to give the spermatozoa enough energy to move around the female reproductive tract
3. Tail- Flagellum used to help swim in a forward direction

Question 2

What is the acrosome?

Answer 2

Like a heat seeking missile, goes and seeks the egg

-also contains a bag of enzymes to degrade the zone pellucida

Question 3

What is a vassectomy and tube tying, and what is their purpose?

Answer 3

Vassectomy: cutting the vass deferens
-still producing sperm, just can’t be released

Tying tubes: Cutting and tying of Fallopian tubes
-all events still take place

Purpose is so that sperm and egg to not meet

Question 4

Where does fertilization take place?

Answer 4

In the first third of the Fallopian tube because the ovum only has a life span of 1 day

Question 5

What are the steps to fertilization?

Answer 5

1. Sperm reaches the zone pellucida
2. Acrosome reaction is triggered to release the enzymes in order to degrade that area of the zona pellucida
3. Sperm fuses with the ovum
4. Block polyspermy- triggering the cortical reaction from the ovum which releases its own enzymes to harden the rest of the zona pellucida so no other sperms can penetrate
5. Sperm head enters the cytoplasm of the ovum
6. Ovum finishes meiosis II to form the other polar body
7. The 2 nuclei fuse together to form a diploid
8. Zygote is created (via fertilization)
9. Rapid cell division (mitosis) begins

Question 6

When does the zygote move down the Fallopian tube?

Answer 6

Once fertilization occurs

-helped by the cilia that line this structure

Question 7

What happens to the zygote as it travels down the tube?

Answer 7

Multiple cell divisions (mitosis) occurs, going from a zygote to a morula, to a blastocyte

Question 8

When in the cycle does the zygote reach the site for implantation?

Answer 8

Around day 6 post fertilization

• in the luteal phase
• corpus luteum is pumping out hormones and uterus is secreting nutrients to help keep the baby and for the baby to survive

Question 9

What is a morula?

Answer 9

Forms around day 4 post fertilization

-it is a solid ball of cells

Question 10

What is a Blastocyte?

Answer 10

Formed around day 5 post pertilization. Is a hallow ball of cells with some fluid in it and made up of:

• inncer cells
• trophoblast cells

Question 11

What do inner cells and trophoblast cells turn into?

Answer 11

Inner cells become the baby

Trophoblast cells become the placenta

Question 12

How does the blastocyte implant itself into the endometrial lining?

Answer 12

Trophoblast cells contain an enzyme that is released to digest the endometrium. This creates/leaves holes where it can implant

Question 13

What is the function of a placenta?

Answer 13

Essential for baby to grow, provides:

• nutrients
• air
• gas exchange
• gets rid of wastes

Question 14

What is the placenta composed of?

Answer 14

Endometrial layer and the blood vessels from the baby

-blood vessel from baby grow into the endometrium

Question 15

What is the lacunae?

Answer 15

The spaces that the trophoblast make with their enzymes

• moms blood fills this space
• where gas and nutrient exchange takes place

Question 16

What are the chorionic villi?

Answer 16

When baby b mood vessels invades the lacunae

Question 17

Does the mom and baby share a blood supply?

Answer 17

No, blood from each is separate

• mom in lacunae
• baby in vessels

Question 18

Where does the baby live?

Answer 18

Floats in the amniotic sac filled with amniotic fluid

Question 19

What is Human chorionic gonadotropin (HCG)?

Answer 19

Hormones that start being made as soon as the blastocyte is formed
-made for 2-3 m months until placenta is fully formed

Question 20

What is the purpose of HCG?

Answer 20

Signals the corpus luteum to survive because the corpus luteum makes the hormones and supports the baby until the placenta takes over
-HGC is released through the blood