Flashcards in Human Reproduction Deck (62):
Give the function of the scrotum
Contains the testes
Give the function of the testes
Contains seminiferous tubules where spermatogenesis occurs
Give the function of the epididymis
Where the spermatozoa mature
Give the function of the vas deferens
Connects the epididymis to the urethra
Give the function of the seminal vesicle
Produces a secretion that aids the mobility of spermatozoa
Give the function of the prostate gland
Produces a secretion that neutralises the alkali of the urine
Give the function of the urethra
Tube that carries the urine and spermatozoa out of the body
Give the function of the penis
Intermittent organ used to insert spermatozoa into the reproductive system of the female
Give the function of the ovary
Oogenesis occurs here
Give the function of the oviduct (fallopian tube)
Site of fertilisation, where spermatozoa fuses with an oocyte. After fertilisation a zygote is formed which moves down the oviduct to the uterus
Give the function of the uterus
Embryo plants in the endometrium and develops in the uterus
Give the function of the vagina
During copulation, spermatozoa are deposited at the top of the vagina
What do gametes contain?
Haploid number of chromosomes
One chromosome from each homologous pair
What is gametogenesis?
Production of gametes
Where are sperm produced?
State the four stages of spermatogenesis
1- GERMINAL EPITHELIAL CELLS undergo MITOSIS to form SPERMATOGONIA
2- SPERMATOGONIA undergo MITOSIS to form PRIMARY SPERMATOCYTES
3- PRIMARY SPERMATOCYTES undergo MEIOSIS 1 to form haploid SECONDARY SPERMATOCYTES. They then complete MEIOSIS 2 to form SPERMATIDS
4- SPERMATIDS mature to form SPERM
What is a sperm cell comprised of?
Give the function of the nucleus in a sperm cell
Contains the DNA
Give the function of the acrosome in the sperm cell
Release enzymes which digests the zona pellucida
Give the function of the mitochondria in sperm cells
Release energy (ATP) for the flagellum to propel the sperm
Give the function of sertoli cells
Nourish and protect sperm in the seminiferous tubules
Give the function of the interstitial cells
What is testosterone?
Hormone involved in stimulating the process of spermatogenesis
When does the first stage of oogenesis occur?
What is the first stage of oogenesis?
OOGONIA divide by MITOSIS to form PRIMARY OOCYTES ( begin meiosis 1 but stops at prophase 1)
GERMINAL EPITHELIAL CELLS divide to form FOLLICLE CELLS which surround the PRIMARY OOCYTE
When does the second stage of oogenesis occur?
Once a month once the girl reaches puberty
What is the second stage of oogenesis?
Follicles begin to develop, only one matures into a Graafian follicle
Primary oocyte completed meiosis 1 to form a haploid secondary oocyte and a polar body
Why does only one follicle develop into a graafian follicle?
In oogenesis there is an uneven splitting of cytoplasm.
The developed follicle has to have enough cytoplasm to provide nourishment for the developing embryo
What happens to the graafian follicle?
Moves to the surface of the ovary where it releases the secondary oocyte (ovulation)
What happens after ovulation in terms of oogenesis?
The secondary oocyte begins meiosis 2 but stops at metaphase 2
What happens at fertilisation? (Oogenesis)
Sperm cell enters the oocyte.
Secondary oocyte completes meiosis 2, forming an ovum and a second polar body
How are zygotes formed (oogenesis)?
Nucleus of the sperm fuses with the nucleus of the secondary oocyte to form the zygote
During copulation, where are spermatozoa ejaculated from?
They travel up the vas deferens and out through the urethra
Once spermatozoa is ejaculated, where does it travel?
Swim through the cervix, along the lining of the uterus and into the oviduct where they meet the secondary oocyte
What is capacitation?
Physiological changes to spermatozoa to complete fertilisation
What must occur before a sperm cell can fertilise an oocyte?
What are the two reactions which occur during capacitation?
What is the acrosome reaction?
The acrosome membrane ruptures and hydrolase enzymes are released. Enzymes digest through the zona pellucida to allow sperm to enter the oocyte
What is the cortical reaction?
Contents of the cortical granules fuse with the cell memrane of the oocyte which causes to zona pellucida to modify
Fertilisation membrane forms, preventing polyspermy
What is polyspermy?
Entry of additional sperm into the oocyte
What happens to the zygote after fertilisation?
Stimulates the secondary oocyte to complete meiosis 2
Haploid nucleus from each gamete forms a diploid nucleus of the zygote
Zygote divides by mitosis to form a blastocyst
What is a blastocyst?
Hollow ball of cells
What does the rapid division of the zygote cause?
What is a trophoblast?
Outer layer of a blastocyst formed when it reaches the endometrium
What does the trophoblast consist of?
chorion- develops chorionic villi to absorb nutrients through the endometrium
Amnion- forms the amniotic sac
What are the female hormones involved during pregnancy?
LH (luteinising hormone)
FSH (follicle stimulating hormone)
State when each of the hormones are at their peak levels
FSH- before ovulation
LH- during ovulation
Progesterone- after ovulation (if fertilisation occurs)
Oestrogen- during ovulation
What is the role of FSH?
Stimulates the maturation of a follicle in the ovary. Positive feedback on oestrogen
Where is FSH secreted?
Anterior pituitary gland
What is the role of oestrogen?
Positive feedback on LH
Triggers the repair of the endometrium
Where is progesterone secreted from?
What is the role of progesterone?
Causes further development of the endometrium
What is the role of LH?
Cause ovulation to occur and the graafian follicle to develop into the corpus luteum
What happens to the hormones if implantation doesn’t occur?
FSH and LH levels fall, causing the corpus luteum to degenerate
Progesterone levels fall and the endometrium breaks down
What hormone is released when implantation occurs, and what is its role?
Human chorionic gonadotrophin
Maintains the corpus luteum for the first 16 weeks
What hormones do the placenta secrete?
Progesterone and oestrogen
Progesterone suppresses the uterine wall’s to contract
Oestrogen stimulates the growth of the uterus and the mammary glands
What happens to FSH and LH during pregnancy?
They are inhibited
What happens to oestrogen and progesterone at birth?
Oestrogen levels increase
Progesterone decreases to allow uterine walls to contract
What 2 other hormones occur at birth?
Oxytocin- stimulates contractions and allows milk to be released from the mammary glands
Prolactin- stimulates mammary glands to produce milk
Both released by the anterior pituitary gland
What os the placenta?
Organ which connects the developing foetus to the wall of the uterus via the umbilical cord
What are the 4 functions of the placenta?
•Exchange of gases and nutrients- countercurrent blood system between foetal and mother’s blood to allow for diffusion
•Provides a barrier to protect foetus from high BP from mother
•Protection from the mother’s immune system
•Secretion of horomones