Chapter 16 - Reproductive Cycles And Fertilisation Flashcards
What is the ovarian cycle?
A series of events that take place within the ovaries
What does the ovarian cycle include?
- the maturation of an egg
- the release of an egg into the uterine tube
- the development of follicles in the ovary
- the formation of the corpus luteum
How long does the ovarian cycle last for?
20 to 40 days with an average of 28 days
What is a primary follicle?
A single layer of cells that form a sphere around an immature egg
What happens to the follicles during puberty?
A layer of cells surrounds the developing egg that secrete to produce a fluid filled space that forces the egg to the edge of the follicle
What is a secondary follicle?
The follicle that develops during puberty
What is a Graafian follicle?
A matured follicle that produces a bulge on the surface of the ovary
How many days does it take for a primary follicle to develop into into a Graafian follicle?
10-14 days
What is ovulation?
The process of when the Graafian follicle burst and expels the egg into the uterine tube
What do beating cilia do during ovulation?
Create a current that sweeps the egg into the uterine tube
What happens to the ruptured follicle after ovulation?
- forms a clot
- clot is absorbed by the remaining follicle cells to form the corpus luteum
What does the corpus luteum do?
Secretes hormones that influence the development of the inning of the uterus
What is the corpus albicans?
A fibrous mass of scar tissue that is the degeneration of the corpus luteum
What happens if fertilisation occurs?
The corpus luteum continues to develop and the ovarian cycles cease
What is the menstrual cycle?
A series of events and changes that occurs in the uterus and to a lesser extent, the vagina
What is the endometrium?
The lining of the uterus
What are the stages of the menstrual cycle?
- menstruation
- preovulation
- ovulation
- secretion
- premenstruation
What is menarche?
When menstruation first begins
What is menopause?
When the menstrual cycle stops and the changes that occur at puberty are reversed
How many eggs reach maturity?
400 out of 400,000
What are the endocrine glands?
Glands that make
What is the time span of menstruation?
Days 1-4
What is the time span of preovulation?
Days 5-12
What is the timespan of ovulation?
Days 13-15
What is the timespan of secretion?
Days 16-20
What is the timespan of premenstruation?
Days 21-28
What occurs in menstruation?
Uterine bleeding and shedding of the endometrium
What occurs during preovulation?
- endometrial repair begins
- development of the ovarian follicle
- uterine lining thickens
What occurs during ovulation?
- rupture or mature follicle, releasing egg
What occurs during secretion?
- secretion of watery mucus by glands of endometrium, cervix and uterine tubes
- movement and breakdown of unfertilised egg
- development of the corpus luteum
What occurs during premenstruation?
- degeneration of corpus luteum
- deterioration of endometrium
What are secondary sexual characteristics?
Characteristics associated with a person’s sex but are not directly involved in sexual reproduction
What are male secondary sexual characteristics?
- pubic, armpit, chest and facial hair
- increase in size of larynx
- lengthening of vocal chords
- deepening of voice
What are female secondary sexual characteristics?
- enlarging breasts
- broadening of hips
- growth of pubic bones
- deposition of fat
- pubic hair
Follicle stimulating hormone - male
From: pituitary gland
Target organ: seminiferous tubules of testes
Effect: production of sperm
Follicle stimulating hormone - female
From: pituitary gland
Target organ: follicles of ovaries
Effect: maturation kid ovarian follicles
Human chorionic gonadotropin
From: placenta
Target organ: corpus luteum
Effect: maintenance of corpus luteum during early stages of pregnancy
Lactogenic hormone (prolactin)
From: pituitary gland
Target organ: breasts
Effect: production of milk in activated glands
Luteinising hormone - male
From: pituitary gland
Target organ: interstitial cells of testes
Effect: stimulates secretion of testosterone
Luteinising hormone - female
From: pituitary gland
Target organ:cells of ovaries
Effect: stimulates secretions of oestrogen and progesterone
Oestrogens
From: ovarian follicle and corpus luteum
Target organ: various
Effect: development of female reproductive system, development of secondary sexual characteristics
Oxytocin
From: pituitary gland
Target organ: uterus, breasts
Effect: stimulates contraction of smooth muscle, promotes contraction of muscles cells surrounding breast lobules
Progesterone
From: corpus luteum
Target organ: uterus, placenta, breasts
Effect: maintenance of endometrium, development and maintenance of placenta, development of milk secreting glands
Testosterone
From: interstitial cells of testes
Target organ: various
Effect: development of male reproductive system, development of male secondary sexual characteristics
What is insemination?
The process in which sperm is released into the vagina at the entrance of the uterus
Where does the sperm go once it is in the vagina?
The spree travel through the cervix and the body of the uterus into the uterine tubes
Where do spermatozoa reach?
The upper third of the uterine tubes
Why are large numbers of spermatozoa required?
Because sperm mortality is high and many sperm are required to supply enough enzymes to break down the acids holding the corona radiata together
How many sperm reach the uterine tubes?
A few thousand out of hundreds of millions
Where does fertilisation occur?
When the egg is a third of the way down the uterine tube
What is the mature egg surrounded by?
A layer of follicle cells called the corona radiata
What holds the corona radiata together?
Acids
What do the tips of sperm contain?
An enzyme capable of breaking down the acids holding the corona radiata together
What is the cycle of the ovarian follicle?
Primary follicle - secondary follicle - Graafian follicle - corpus luteum - corpus albicans
