Human Reproductive System

Comprehensive Q&A flashcards covering the Matric Life Sciences Human Reproductive System notes.

What is puberty?

Puberty is the stage of development during which a child's body physically matures into an adult body capable of sexual reproduction, marked by the growth of sex organs and sex cell production.

At what age does puberty typically begin in boys and girls according to the lecture notes?

Puberty usually begins at $11\text{--}13\text{ years}$ in boys and from $10\text{--}11\text{ years}$ old in girls.

Which hormone released by the hypothalamus triggers the pituitary gland to secrete FSH and LH at the start of puberty?

Gonadotropin-releasing hormone (GnRH).

What are the roles of FSH and LH during puberty in females?

FSH stimulates follicle development in the ovary to initiate the menstrual cycle, while LH triggers ovulation and the subsequent production of progesterone.

What are the roles of FSH and LH during puberty in males?

FSH stimulates spermatogenesis, while LH stimulates testosterone secretion from the testes.

What is the average maximum annual height increase during puberty growth spurts for females compared to males?

Females grow up to $12\,\text{cm}$ a year, while males grow up to $10\,\text{cm}$ a year.

What specific medical terms refer to breast development, pubic/armpit hair growth, and onset of menstruation during puberty?

Breast development is thelarche, pubic and armpit hair growth is pubarche, and the onset of menstruation is menarche.

What are the three structural columns of erectile tissue that make up the shaft of the penis?

Two columns of corpus cavernosa on the upper part, and one smaller column of corpus spongiosum surrounding the urethra on the lower part.

What are the functions of the fluid secreted by the prostate gland?

It is a milky alkaline fluid that gives semen its characteristic smell, ensures maximum motility of sperm, and protects sperm against the low pH (acid) in the urethra and vagina.

What is secreted by the seminal vesicles and what function does it serve?

They secrete a yellowish sticky substance providing fructose, which serves as the main source of food energy for sperm.

What functions do the Cowper's glands perform in the male reproductive system?

They contribute to greater sperm motility, clear the urethra of urine residue, and lubricate the head of the penis.

What is the epididymis and what are its primary functions?

It is a long, convoluted tubule about $5\,\text{cm}$ long formed by seminiferous tubules; it stores sperm, allows sperm to mature until ready for fertilisation, and secretes mucous to facilitate sperm movement.

Why are the testes located outside the main body cavity within the scrotum?

To keep the temperature of the testes $2 - 3\,^\circ\text{C}$ lower than body temperature, which is required for optimal sperm production.

What is the function of Sertoli cells in the seminiferous tubules?

Sertoli cells nourish developing sperm cells through spermatogenesis in response to FSH.

Where are Leydig cells located and what is their primary function?

Leydig cells are located in the interstitial layer outside the seminiferous tubules and are activated by LH to secrete testosterone.

What are the structural components of a mature sperm cell and their functions?

The head contains a haploid nucleus and an acrosome with enzymes to penetrate the ovum; the middlepiece contains spiral-shaped mitochondria for energy; the tail enables movement.

What are the three distinct layers of the uterine wall?

1. Serous layer (membranous)
2. Muscular layer (myometrium)
3. Endometrium (mucous membrane lining)

What are the functions of the Fallopian tube (oviduct)?

It transports the egg cell from the ovary to the uterus and is the site where fertilisation typically occurs.

What is a Graafian follicle?

A mature ovarian follicle that contains a mature egg cell, produces oestrogen, and ruptures during ovulation to release the egg.

What is the corpus luteum and what function does it perform?

It is the remnant of the Graafian follicle after ovulation; it secretes progesterone and oestrogen to maintain endometrium thickness for embryo implantation.

How does elevated testosterone level regulate its own production via negative feedback?

High testosterone levels signal the hypothalamus and pituitary gland to inhibit FSH and LH release, which reduces Leydig cell stimulation and lowers testosterone production back to normal.

How does high sperm count regulate spermatogenesis through negative feedback?

When sperm count is too high, Sertoli cells produce inhibin, which inhibits FSH secretion from the anterior pituitary and slows down spermatogenesis.

What happens during Day 1 to Day 5 of the menstrual cycle?

The menstrual cycle begins with low hormone levels; the endometrium lining of the uterus breaks away and is shed from the body during menstruation.

What occurs on Day 14 of a standard 28-day menstrual cycle?

Ovulation occurs (release of the ovum from the ovary), driven by high levels of LH and oestrogen, while the endometrium continues to thicken.

How long can an ovum and a sperm cell survive in the female reproductive tract?

An ovum can survive for about $24\text{ hours}$, whereas sperm cells can survive for $2\text{--}3\text{ days}$.

What defines the transition from an embryo to a foetus during gestation?

The developing human is an embryo for the first $8\text{ weeks}$, and becomes a foetus after $3\text{ months}$ when all organs are present.

What are the dimensions, mass, and surface area of a full-term placenta?

At term, the placenta weighs almost $500\,\text{g}$, has a diameter of $15\text{--}20\,\text{cm}$, a thickness of $2\text{--}3\,\text{cm}$, and a surface area of almost $15\,\text{m}^2$.

What is the chorionic villus and what is its role in the placenta?

It is the basic structural unit of the placenta, consisting of vascular finger-like projections of foetal tissue surrounded by chorion that maximize contact with maternal blood for gas and nutrient exchange.

When does the placenta replace the corpus luteum in producing progesterone to sustain pregnancy?

The corpus luteum produces progesterone until about $12\text{ weeks}$ of gestation, after which the placenta takes over.

What is the function of the amniotic fluid during pregnancy?

It cushions the foetus against mechanical blows, allows easier foetal movement, promotes muscle and skeletal growth, aids lung development via inhalation/exhalation, and contributes to GI tract formation when swallowed.

How does blood composition differ between the umbilical arteries and the umbilical vein?

The two umbilical arteries carry deoxygenated, nutrient-depleted blood with metabolic wastes from foetus to placenta; the single umbilical vein carries oxygenated, nutrient-rich blood from placenta to foetus.

What roles do oxytocin and prolactin play in labour and lactation?

Oxytocin stimulates uterine contractions during labour and triggers milk release from breasts; prolactin stimulates milk production in the mammary glands after birth.

What is Colostrum and why is it important for a newborn?

Colostrum is a pre-milk substance secreted by mammary glands during pregnancy and early post-birth; it is rich in antibodies and nutrients to sustain the infant before milk production begins.

How does a vasectomy work as a method of contraception?

It is a surgical procedure that cuts, seals, or blocks the vas deferens, preventing sperm from being transported from the epididymis to the urethra.

How do copper IUDs prevent pregnancy?

Copper IUDs release copper ions into the uterus that act as a spermicide to prevent fertilisation.

What is Foetal Alcohol Syndrome (FAS) and what are its symptoms?

FAS is a lifelong condition caused by maternal alcohol consumption during pregnancy, leading to poor growth, abnormal facial features, small head/brain size, and central nervous system damage resulting in mental and behavioral impairments.

What adverse effects does maternal smoking during pregnancy have on the baby?

Inhaled nicotine and carbon monoxide cross the placenta, lowering oxygen, raising foetal heart rate, increasing risks of miscarriage/stillbirth, premature birth, low birth weight, and respiratory issues.

According to the hormonal control diagram, what effect does high testosterone have on the hypothalamus and pituitary gland?

High testosterone inhibits hormone production in the hypothalamus and pituitary gland, reducing LH and FSH secretion to decrease testosterone production.

What medical condition is depicted in the brain on the right side of this image compared to the normal brain on the left?

Foetal Alcohol Syndrome (FAS) brain.