Module 5: Reproduction Flashcards
What are the key features of mammals?
Mammals are warm-blooded, reproduce sexually, have internal fertilization, and nourish their offspring with milk. They also tend to care for their young for extended periods.
What is the role of the placenta in placental mammals?
The placenta supplies oxygen and removes waste for the embryo, allowing it to grow inside the uterus.
How does the umbilical cord function?
The umbilical cord consists of two arteries and one vein that facilitate material exchange between the embryo and mother.
What distinguishes marsupials from placental mammals?
Marsupials give birth to underdeveloped offspring that continue to develop in a pouch, while placental mammals give birth to more developed young.
What are monotremes and how do they reproduce?
Monotremes lay soft-shelled eggs and nurse their young with milk; examples include echidnas and the platypus.
What hormonal changes occur during the first trimester of human pregnancy?
HCG rises rapidly, maintaining the corpus luteum and allowing progesterone secretion, which keeps the uterine lining receptive to the embryo.
What hormonal changes occur during the second trimester of pregnancy?
HCG levels decline, leading to a decrease in progesterone and oestrogen production by the corpus luteum; the placenta takes over hormone production.
How does oxytocin contribute to labour in the third trimester?
Increased oestrogen induces the formation of oxytocin receptors in the uterus, leading to contractions that help push the baby towards the cervix.
Describe ovulation in humans.
Ovulation occurs mid-cycle when a mature follicle releases an egg, ready for fertilisation.
What is the function of follicle-stimulating hormone (FSH)?
FSH stimulates follicles in the ovaries to grow and mature.
What is menstruation?
Menstruation is the disintegration of the endometrium, resulting in menstrual bleeding from the vagina.
Explain implantation in mammals.
Implantation occurs when a blastocyst attaches to the endometrium after travelling down the fallopian tube, allowing for embryonic development.
What is the corpus luteum?
This structure develops after a follicle ruptures and releases an egg during ovulation. It releases oestrogen and progesterone.
What is oestrogen?
A hormone produced by either a mature follicle or the corpus luteum. It stimulates the endometrium to thicken.
What is progesterone?
A hormone produced in women by the corpus luteum. It helps to maintain the endometrium.
What is the follicular phase?
The first half of the ovarian cycle, characterised by one follicle maturing. Oestrogen levels rise during this phase.
Which days of the menstrual cycle does the follicular phase occur in?
Days 1-14
What is the luteal phase?
The second half of the ovarian cycle, characterised by the corpus luteum producing oestrogen and progesterone.
What are hormones?
Chemical messengers that can travel in the bloodstream. These are often made of proteins or lipids and there are many different types.
What is an ovary?
A female reproductive organ that contains many follicles. Each of these follicles contains one immature egg cell inside it.
What is a follicle?
A small sac found in the ovary that contains one immature egg cell. As this structure grows and matures, it releases oestrogen.
Where is the follicle located on day 2 of the menstrual cycle?
The ovary.
Where is the follicle located on day 6 of the menstrual cycle?
The ovary.
Where is the ovum located on days 6-10 of the menstrual cycle?
In a follicle in the ovary.
Where is the ovum on day 14 of the menstrual cycle?
The fallopian tube.
When the egg reaches maturity, what happens to the follicle?
It bursts open and the remnants form the corpus luteum.
Where is the corpus luteum located?
In the ovary (only after day 16).
Which phase is characterised by its progesterone production?
The luteal phase.
What does FSH stand for?
Follicle Stimulating Hormone.
What does LH stand for?
Luteinising Hormone.
What is the function of FSH?
Primarily responsible for stimulating follicles to grow in the ovaries.
What is the primary function of LH?
High concentrations of LH trigger ovulation, and the remnants of the burst to form the corpus luteum.
Where are FSH and LH released?
The anterior pituitary gland.
Where is GnRH produced?
The hypothalamus, in the brain.
What is the function of GnRH?
It triggers the release of LH and FSH.
Does an increase in progesterone cause ovulation?
No.
Where are oestrogen and progesterone released?
The ovaries.
Which hormone does high levels of oestrogen stimulate?
GnRH.
What effect do low levels of oestrogen have on the pituitary gland?
They inhibit it, causing lowered levels of FSH and LH.
What effects do the combination of oestrogen and progesterone have?
They thicken and stabilise the endometrium for the first half of the luteal phase; they inhibit the production of GnRH.
How does a fertilised egg (zygote) grow?
Through a form of cell division called mitosis.
What is HCG?
Human Chorionic Gonadotropin, a hormone that sustains the corpus luteum, allowing the continued secretion of oestrogen and progesterone.
What hormone do blastocysts secrete?
HCG.
How do pregnancy tests work?
Pregnancy tests check for the presence of HCG, because this hormone is only secreted by a blastocyst. Hence, is only present in pregnant women.
Why are oestrogen and progesterone essential in pregnancy?
They maintain the endometrium to support embryonic development.
When do LH and FSH spike?
Day 14; ovulation.
When does oestrogen spike?
Day 14; during ovulation.
When does progesterone spike?
Day 21; mid-luteal phase.
What role does oxytocin play in lactation?
It stimulates the release of breast milk from storage.
What role does prolactin play in lactation?
It stimulates the production of breast milk.
What are the hormones responsible for producing milk?
Prolactin and Oxytocin.
What is the term used to describe an animal with both male and female sex organs?
Hermaphrodite.
What is the meaning of parthenogenesis?
A “virgin birth”.
What is the function of contractions?
They push the baby towards the cervix and out of the vaginal opening.
What is the biological name for flowering plants?
Angiosperms.
What part of the angiosperm produces pollen?
The anther.
What is the sticky part of the carpel called?
The stigma.
When the pollen fertilises an egg within a flower, what develops?
A seed.
What happens in a clownfish colony if the female is killed?
The largest dominant male changes sex to become the new female.
