Reproductive Biology Quiz

Study Notes

Ovum

The female egg cell, known as the ovum, is the female gamete
It has two layers:
- The outer layer is called the corona radiata
- The inner layer is called the zona pellucida
It has a lifespan of 24 hours

Sperm Cell

Sperm cells are the male gametes
They are also known as spermatozoa
They have three parts:
- The head contains chromatin material
- The neck or mid-piece provides energy for movement
- The tail is responsible for motility
They have a lifespan of 48 to 72 hours (2-3 days) after ejaculation
There are two kinds of sperm cells:
- Gynosperm carries the X chromosome
- Androsperm carries the Y chromosome

Insemination

Fertilization is when the sperm and ovum unite, creating a fertilized ovum called a zygote
This occurs in the outer third portion of the fallopian tube
The process involves:
- Penetration
- Mitotic cellular division
- Chromosomal formation
- Capacitation
- Hyaluronidase
- Acrosin
Polyspermy occurs when more than one sperm cell enters the ovum

Zygote

The zygote travels from the fallopian tube to the uterus over 3-4 days
Zygotes can divide and create many daughter cells called blastomeres
A zygote with multiple blastomeres is called a morula

Blastocyst

The blastocyst contains two parts:
- An inner layer called the blastocele
- An outer layer called the trophoblast or trophoderm
The blastocele contains the following layers:
- Ectoderm
- Entoderm
- Mesoderm
The trophoblast is responsible for:
- Absorbing nutrients from the endometrium
- Secreting the hormone human chorionic gonadotropin (hCG) which keeps the corpus luteum alive and pumping out hormones

Implantation

Occurs 6 to 7 days after fertilization
Implantation bleeding may occur

Decidua

Refers to the endometrium after implantation
It functions as:
- The ideal site for implantation
- Provides easy access for the baby's birth at the end of gestation
- Prevents infection from the vagina and cervix
The decidua produces the following hormones:
- Prolactin
- Relaxin
- Corticotrophin Releasing Hormone (CRH)
- Growth Hormones
- Prostaglandin
- Oxytocin
- Endothelin-I

Fetal Membranes

Enclose the fetus and amniotic fluid
There are two membranes:
- Chorionic membrane - The outermost layer that separates the baby's amniotic sac from the wall of the uterus
- Amniotic membrane - The amniotic sac

Amniotic Fluid

The medium in which the fetus and cord float inside the amniotic membrane
The fetus contributes to amniotic fluid by:
- Active secretion from the epithelium of the amniotic membrane
- Transudation
- Fetal urination
The mother contributes to amniotic fluid by:
- Transudation from maternal circulation

Amniotic Fluid Removal

Amniotic fluid is removed or absorbed by:
- Absorption through the amnion to the maternal circulation
- Fetal swallowing, this is the main mechanism that controls amniotic fluid volume

Amniotic Fluid Characteristics

Normal volume is 500 to 1200 ml, averaging 1000 ml
Composition: 99% water and 1% solid particles
- Contains albumin, urea, uric acid, creatinine, lecithin, sphingomyelin, bilirubin, minerals, and suspended materials like desquamated epithelial cells and vernix caseosa
Color is clear and odorless to straw-colored
Green tinged or meconium stained can signify fetal distress
Golden colored amniotic fluid can signify hemolytic disease
Gray colored amniotic fluid can signify infection
Bloody amniotic fluid can signify vasa previa
Brownish, coffee or tea-colored amniotic fluid can signify fetal death
pH is 7.0 to 7.25, a normal to alkaline reaction
Specific Gravity - 1.005 to 1.025

Amniotic Fluid Functions

Protection of the fetus:
- From trauma, blows, and pressure
- From uterine contractions
- From sudden changes in temperature
- Of the cord from pressure
Promotes symmetrical musculoskeletal development by allowing freedom of movement
Acts as an excretion and secretion system
Source of oral fluid for the fetus who swallows it
Aids in the diagnosis of maternal and fetal complications through amniocentesis
Assists in labor by:
- Intact membranes aid in effacement and dilation of the cervix
- Once membranes rupture, the fluid washes the birth canal and serves as an antiseptic
- It acts as a lubricant, making the birth canal more slippery for passage of the fetus

Umbilical Cord or Funis

Function: Connection between the fetus and placenta
Main function: Transport oxygen and nutrients from the placenta to the fetus, and return unoxygenated blood and fetal waste products to the placenta
Blood vessels: Two arteries and one vein
Length: About 50-55 cm long and 2 cm in diameter
Appearance: Dull white and covered by amnion

Umbilical Cord Abnormalities - Short Cord

Short cord can lead to:
- Intrapartum hemorrhage due to premature separation of the placenta
- Delayed descent of the fetus during labor
- Inversion of the uterus

Umbilical Cord Abnormalities - Long Cord

Long cord can lead to:
- Wrap around the baby’s neck or body
- Prolapse of the cord before the baby is born
- A knot in the cord that could cut off the baby's blood supply

Description

Test your knowledge on the fundamentals of reproductive biology, including the structures and functions of ovum and sperm cells, as well as the process of insemination and fertilization. Explore the key concepts related to female and male gametes and their roles in human reproduction.

Reproductive Biology Quiz

Podcast Beta

Questions and Answers

Which hormone is primarily responsible for initiating uterine contractions during labor?

What is the main component of amniotic fluid?

What does green-tinged amniotic fluid typically indicate?

How does the mother contribute to the amniotic fluid volume?

Which of the following functions is NOT performed by amniotic fluid?

At what location does fertilization typically occur?

What is the primary function of the trophoblast during the development of the blastocyst?

Which structure plays a crucial role in preventing infection from reaching the fetus post-implantation?

What happens during the process of polyspermy?

Which type of gamete has a lifespan of 24 hours within the female reproductive system?