Pregnancy Flashcards
What are the main structures of a mature spermatozoa and what is their function?
- Head- contains nucleus (haploid) and acrosome
- Mid piece- contains lots of mitochondria to give the spermatozoa enough energy to move around the female reproductive tract
- Tail- Flagellum used to help swim in a forward direction
What is the acrosome?
Like a heat seeking missile, goes and seeks the egg
-also contains a bag of enzymes to degrade the zone pellucida
What is a vassectomy and tube tying, and what is their purpose?
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
Where does fertilization take place?
In the first third of the Fallopian tube because the ovum only has a life span of 1 day
What are the steps to fertilization?
- Sperm reaches the zone pellucida
- Acrosome reaction is triggered to release the enzymes in order to degrade that area of the zona pellucida
- Sperm fuses with the ovum
- 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
- Sperm head enters the cytoplasm of the ovum
- Ovum finishes meiosis II to form the other polar body
- The 2 nuclei fuse together to form a diploid
- Zygote is created (via fertilization)
- Rapid cell division (mitosis) begins
When does the zygote move down the Fallopian tube?
Once fertilization occurs
-helped by the cilia that line this structure
What happens to the zygote as it travels down the tube?
Multiple cell divisions (mitosis) occurs, going from a zygote to a morula, to a blastocyte
When in the cycle does the zygote reach the site for implantation?
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
What is a morula?
Forms around day 4 post fertilization
-it is a solid ball of cells
What is a Blastocyte?
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
What do inner cells and trophoblast cells turn into?
Inner cells become the baby
Trophoblast cells become the placenta
How does the blastocyte implant itself into the endometrial lining?
Trophoblast cells contain an enzyme that is released to digest the endometrium. This creates/leaves holes where it can implant
What is the function of a placenta?
Essential for baby to grow, provides:
- nutrients
- air
- gas exchange
- gets rid of wastes
What is the placenta composed of?
Endometrial layer and the blood vessels from the baby
-blood vessel from baby grow into the endometrium
What is the lacunae?
The spaces that the trophoblast make with their enzymes
- moms blood fills this space
- where gas and nutrient exchange takes place
