Human Reproduction and Development

Comprehensive question-and-answer flashcards covering human male and female reproductive systems, gametogenesis, menstrual and ovarian cycles, fertilization, early embryonic development, and gestational structures.

What are the two primary functions of the testis in the male reproductive system?

The testis produces sperm by spermatogenesis and secretes the hormone testosterone.

What are the functions of the epididymis and the vas deferens?

The epididymis stores sperm temporarily, while the vas deferens carries sperm from the epididymis to the urethra.

What are the specific functions of the seminal vesicle and the prostate gland?

The seminal vesicle secretes fluid supplying spermatozoa with nutrients for motility energy. The prostate gland secretes a milky alkaline fluid that protects sperm by neutralizing the acidity of the vagina and urethra, and aids sperm motility.

What is the function of Cowper's gland?

It secretes a fluid that neutralizes the acidity of the urethra so that sperm can remain active, and aids in motility.

What temperature is required for healthy sperm production, and what occurs if a man wears tight underwear?

A temperature of $35^\circ\text{C}$ is required. Wearing tight underwear causes scrotal temperatures to rise higher than normal, resulting in the production of unhealthy sperm cells, a low sperm count, and reduced fertility.

What are the roles of the fallopian tubes, ovaries, and cervix in the female reproductive system?

The fallopian tubes are the site of fertilisation and conduct eggs into the uterus. The ovaries produce ova by oogenesis and secrete sex hormones (oestrogen and progesterone). The cervix allows sperm to enter and menstrual blood to leave the uterus.

What are the primary physical changes during puberty in males versus females?

In males (under testosterone): hair growth, initiation of sperm production, stronger muscular development, and enlargement of the penis and testes. In females (under oestrogen): breast development, pubic and armpit hair growth, widening of pelvis and hips, and the start of menstruation.

How does spermatogenesis proceed in the male reproductive system?

Under the influence of testosterone, diploid cells in the seminiferous tubules of the testes undergo meiosis to form four haploid sperm cells.

Describe the sequence of oogenesis from ovarian diploid cells to a mature ovum.

Under the influence of oestrogen, diploid cells in the ovary undergo mitosis to form follicles. At puberty, under FSH influence, one cell inside a follicle undergoes meiosis; only one of the four resulting cells survives to form a mature haploid ovum in a monthly cycle.

What key events occur in the ovarian cycle and the uterine cycle during the menstrual cycle?

The ovarian cycle involves Graafian follicle development, ovulation, and corpus luteum formation. The uterine cycle involves changes in the thickness of the endometrium and menstruation.

How does the negative feedback mechanism work if fertilisation occurs?

High levels of progesterone from the corpus luteum enter the blood and inhibit pituitary gland FSH secretion. Low FSH levels prevent ovum development in a Graafian follicle, meaning no ovulation occurs.

How does the negative feedback mechanism work if fertilisation does not occur?

The corpus luteum disintegrates, causing progesterone levels to decrease. This stimulates the pituitary gland to secrete more FSH, which in turn stimulates another follicle to produce another egg.

What is fertilisation, and what role does the acrosome play?

Fertilisation occurs in the fallopian tubes when the haploid nucleus of a sperm cell fuses with the haploid nucleus of an ovum to form a diploid zygote. The acrosome releases enzymes that break down the outer membrane of the egg cell.

How does a zygote develop into a blastocyst?

The zygote divides by mitosis to form a solid ball of cells called the morula, which undergoes further mitotic divisions to become a hollow ball of cells called the blastocyst.

What occurs during implantation and how is gestation defined?

Implantation is the process where the blastocyst embeds itself into the endometrial lining, and the chorion develops chorionic villi that embed into the endometrium. Gestation is the period during which the embryo develops inside the mother's uterus until birth.

What is the function of the chorion in embryonic development?

The chorion forms finger-like projections called chorionic villi, which together with the uterine wall (endometrium) make up the placenta.

What are the four protective functions of the amnion and amniotic fluid?

The amnion protects the embryo from dehydration, protects the foetus against temperature fluctuations, acts as a shock absorber, and allows free foetal movement for growth and development.

What are the main functions of the placenta during gestation?

The placenta facilitates gas exchange, prevents infections, physically attaches the foetus to the uterine wall, exchanges soluble materials, protects the foetus from the mother's immune system, and secretes progesterone after $12$ weeks.

What are the distinct functions of the umbilical artery and umbilical vein?

The umbilical artery carries deoxygenated blood with nitrogenous waste away from the foetus to the placenta, while the umbilical vein carries oxygenated blood with dissolved nutrients from the placenta to the embryo.