Reproduction in Humans Flashcards
What is the function of the scrotum?
It keeps the ballsack at low temperature so sperms can develop properly.
What are the peepee glands and their functions?
Prostate gland, Cowper’s gland, and seminal vesicle; they secrete a fluid that mixes with sperms and produces semen as a result..
What happens during menstruation?
The uterine lining breaks down and flows from the uterus out of the body through the vagina.
What happens during the follicle stage?
The primary follicle develops into a Graafian follicle. The follicles secret oestrogen, which causes repair and growth of the uterine lining, making it thick and spongy with blood vessels.
What happens during ovulation?
The Graafian follicle ruptures and releases the egg into the oviduct. As a result, the corpus luteum forms from the remains of the follicle. The corpus luteum secretes progesterone and some oestrogen.
What happens during the corpus luteum stage?
Progesterone maintains the uterine lining by causing it to thicken further and be richly supplied with blood capillaries, in order to prepare it for the implantation of the embryo. Ovulation is inhibited.
What happens if no fertilisation occurs?
The egg and corpus luteum breaks down. Progesterone is not secreted, causing the thickened uterine lining to break down as it cannot be maintained. The uterine lining flows from the uterus with some blood through the vagina.
What happens if fertilisation occurs?
The fertilised egg becomes a zygote, which develops into an embryo. The embryo embeds itself in the uterine lining and secretes a hormone which prevents the corpus luteum from breaking down until the placenta is formed.
What happens during fertilisation?
The egg is usually surrounded by a few layers of follicle cells. The acrosome of the sperm releases an enzyme to break down the egg membranes and disperse the follicle cells. The haploid sperm nucleus fuses with the haploid egg nucleus, forming a zygote.
How does implantation occur?
The cilia lining the inner surface of the oviduct sweep the fertilised egg or zygote along the oviduct with help from peristaltic movements. The zygote divides by mitosis to form the embryo. The embryo takes about five days to reach the uterus, floats freely for about 2 days, and eventually sinks in the uterine lining.
How is the placenta developed?
Soon after implantation, villi begin to grow from the embryo into the uterine lining. The villi and uterine lining in which the villi are embedded make up the placenta.
How is the amniotic sac developed?
The amniotic sac begins to develop at about the same time as the placenta. It encloses the embryo in the amniotic cavity, containing amniotic fluid.
Why is the fetal blood system not continuous with the mother’s blood system?
The blood pressure of the mother would kill the fetus. Furthermore, the blood group of the fetus may not be the same as the mother’s.
What are the functions of the placenta?
It allows oxygen and dissolved food substances to diffuse into the fetal blood. It also allows metabolic waste or excretory products to diffuse into the mother’s blood. Protective antibodies from the mother diffuse into the fetal blood. Progesterone can be produced to maintain the uterine lining.
What are the functions of the umbilical cord?
The umbilical cord attaches the fetus into the placenta. It contains two umbilical arteries that transport deoxygenated blood and metabolic waste products from the fetus to the placenta, and one umbilical vein that transports oxygenated blood and food from the placenta to the fetus.
