UNIT 3: The Human Reproductive System Flashcards
penis
muscular organ through which urine and semen travel. It can also fill with blood, becoming erect. This occurs during sexual arousal, enabling the penis to be inserted into the vagina.
sperm ducts
there are 2 sperm ducts that carry sperm from the testes to the urethra.
prostate gland
exocrine gland located just underneath the bladder. It secretes fluid contributing to semen.
cowper’s gland
pair of exocrine glands that also secrete fluid contributing to semen.
seminal vesicles
pair of exocrine glands that also secrete fluid contributing to semen.
epididymis
sperm storage organs that are located on top of each testis. Sperm mature in the epididymis before being released during sexual intercourse. If sperm is not released, it is broken down and absorbed by the cells of the epididymis.
testes
pair of exocrine and endocrine glands located outside of the body in a sac called the scrotum. They are responsible for producing sperm (exocrine secretion) and the hormone testosterone (endocrine secretion). Testosterone is produced by the testes in response to luteinising hormone (LH), which is secreted by the pituitary.
scrotum
pouch in which each testis are located. They hold the testes outside the body as sperm production required a temperature of 35
sperm production
The testes produce sperm in response to the hormone follicle-stimulating hormone (FSH, which is secreted by the pituitary).
Sperm are produced by meiosis.
Sperm are highly specialised cells containing three parts: head, midpiece and tail
Sperm: head
contains the nucleus with 23 chromosomes (human haploid number) and an acrosome - needed to penetrate the egg cell at fertilisation.
Sperm: midpiece
contains many mitochondria that produce energy needed for movement of the sperm cell towards the egg cell.
Sperm: tail
responsible for propelling the sperm cell
vulva
consists of a number of external genital organs, forming the entrance to the vagina and function in sexual arousal.
vagina
muscular organ approximately 7cm long. It is also known as the birth canal and receives the penis during sexual intercourse.
cervix
located at the top of the vagina - it is the junction between the vagina and uterus.
uterus (womb)
muscular organ responsible for holding the developing embryo/foetus/baby during pregnancy. The internal lining of the uterus is called the endometrium and undergoes a series of changes throughout the female’s 28 day menstrual cycle.
fallopian tubes
also known as the oviducts, they form the tubes that carry the egg / fertilised egg from the ovaries to the uterus.
ovaries
2 exocrine and endocrine organs located within the abdomen at the end of the fallopian tubes. They release 1 egg (exocrine secretion) per menstrual cycle and hormones progesterone and oestrogen (endocrine secretion) directly into the bloodstream.
egg cell development
- eggs are present in the female ovaries at birth.
- eggs begin to be ovulated (released from the ovary) at puberty in the female (about the age of 13).
- usually only 1 egg is released (ovulated) per 28 days (the length of the female menstrual cycle).
meiosis
a nuclear division leading to 4 daughter cells each with half the chromosomes as the parent cell.
role of meiosis in gamete formation
Meiosis is required for gamete formation so that following fertilisation, the new individual will have the correct number of chromosomes in its cells. Meiosis also created variation in the gametes, so that no 2 gametes are the same genetically, and therefore, no two offspring are the same (unless they resulted from the same zygote).
secondary sexual characteristics
those features that distinguish males from females, but are not part of the reproductive system.
male secondary sexual characteristics
- facial hair
- pubic hair
- enlarged larynx
- broad shoulders and chest
- large musulature
female secondary sexual characteristics
- pubic hair
- breasts
- wide hips
role of testosterone
Produced in the male body by the testes in response to the pituitary hormone luteinising hormone (LH). It functions in maintaining male secondary sexual characteristics and plays a role in the production of sperm
role of oestrogen
Produced in the female body by the ovaries in response to follicle stimulating hormone (FSH). It functions in the formation and maintenance of female secondary sexual characteristics and the repair of the endometrium during the menstrual cycle.
role of progesterone
Produced in the female body by the ovaries (corpus luteum) following ovulation. It functions in maintaining the endometrium during the menstrual cycle and during pregnancy. Inhibits FSH / LH and prolactin
menstrual cycle
a series of changes that occur in the female reproductive tract over the period of 28 days.
It begins in the female at puberty and continues every 28 days until menopause (approx. age 45).
It can be divided into 3 separate phases:
- follicular phase and menses
- ovulation
- luteal phase
follicular phase and menses
- this phase begins with menses - which is the shedding of the lining of the uterus (endometrium) - usually occurring over the first 5 days of the cycle.
- it is caused by low levels of estrogen and progesterone.
- low levels of the female sex hormones removes the inhibition of these hormones on the pituitary and therefore, follicle-stimulating hormone (FSH) levels begin to increase once again.
- As FSH increases, new follicles begin to form within the ovaries and they start secreting estrogen.
- Eventually, one of these follicles becomes dominant and is called the Graafian follicle.
- The Graafian follicle continues to grow from days 6-13, increasing in size and secreting increasing amounts of estrogen.
- Increasing amounts of estrogen helps to repair the lining of the uterus.
- Increasing amounts of oestrogen also inhibits FSH secretion from the pituitary, ensuring no further follicles develop during the cycle.