Studied by 22 people
How is the structure of the male and female reproductive systems adapted for their functions?
The Male Reproductive System
The male reproductive system consists of several key components:
Prostate gland: Produces fluid called semen that provides sperm cells with nutrients
Sperm duct: Sperm passes through the sperm duct to be mixed with fluids produced by the glands before being passed into the urethra for ejaculation
Urethra: Tube running down the centre of the penis that can carry urine or semen. A ring of muscle in the urethra prevents them from mixing
Testis: Contained in a bag of skin (scrotum) and produces sperm (male gamete) and testosterone (hormone)
Scrotum: Sac supporting the testes outside the body to ensure sperm are kept at a temperature slightly lower than body temperature
Penis: Passes urine out of the body from the bladder and allows semen to pass into the vagina during sexual intercourse
Diagram of the male reproductive system
The Female Reproductive System
The female reproductive system consists of several key components:
Oviducts: Connects ovary to the uterus, lined with ciliated cells to push released ovum, fertilisation occurs here
Ovaries: Contains ova (female gametes) that mature and develop when hormones are released
Uterus: Muscular bag with soft lining where fertilised egg (zygote) implants to develop into foetus
Cervix: Ring of muscle at the lower end of the uterus to keep the developing foetus in place during pregnancy
Vagina: Muscular tube leading to inside of woman's body, where male's penis enters and sperm are deposited during intercourse
Diagram of the female reproductive system
What are the roles of oestrogen and progesterone in the menstrual cycle?
The Menstrual Cycle
The menstrual cycle is one of the secondary sexual characteristics that starts in early adolescence in females (around age 12)
The average menstrual cycle is 28 days long
Ovulation occurs around day 14, with the egg traveling to the uterus
If the egg is not fertilised, menstruation (period) begins due to the breakdown of the uterine lining
Menstruation lasts around 5 - 7 days and signals the beginning of the next cycle
After menstruation finishes, the lining of the uterus starts to thicken again in preparation for possible implantation in the next cycle
Changes in the lining of the uterus during the menstrual cycle
Hormonal control of the menstrual cycle
The menstrual cycle is controlled by hormones, two of which are oestrogen and progesterone
Oestrogen levels rise from day 1 to peak just before day 14
This causes the uterine wall to start thickening and the egg to mature
The peak in oestrogen occurs just before the egg is released
Progesterone stays low from day 1 – 14 and starts to rise once ovulation has occurred
The increasing levels cause the uterine lining to thicken further; a fall in progesterone levels causes the uterine lining to break down (menstruation / ‘period’)
Changes in the levels of oestrogen and progesterone in the blood during the menstrual cycle
What are the roles of FSH and LH in the menstrual cycle?
Roles of FSH & LH in the Menstrual Cycle
In addition to oestrogen and progesterone, the menstrual cycle is controlled by FSH and LH
Both of these hormones are released from the pituitary gland in the brain
FSH (follicle-stimulating hormone) causes an egg to start maturing in the ovary
It also stimulates the ovaries to start releasing oestrogen
LH (luteinising hormone) is released when oestrogen levels have reached their peak
LH causes ovulation to occur and also stimulates the ovary to produce progesterone
Changes in the levels of the pituitary hormones FSH and LH in the blood during the menstrual cycle
Interaction between all four of the menstrual cycle hormones
The pituitary gland releases FSH to develop an ovarian follicle
The follicle produces an egg and oestrogen
Oestrogen stimulates uterine lining growth and inhibits FSH production
High oestrogen levels trigger LH release from the pituitary, causing ovulation (around day 14)
The follicle becomes the corpus luteum, producing progesterone
Progesterone maintains the uterine lining
If the egg isn't fertilised, the corpus luteum breaks down, progesterone levels drop, and menstruation occurs
If pregnant, the corpus luteum continues producing progesterone until the placenta develops, which then maintains progesterone production throughout pregnancy
Diagram showing where hormones involved in the menstrual cycle are made and act
What is the role of the placenta in the nutrition of the developing embryo?
The Placenta
After fertilisation in the oviduct the zygote divides to form an embryo, and travels to the uterus
Upon reaching the uterus the embryo implants in the uterine lining, where it continues to develop
A structure called the placenta forms at the implantation site
In the placenta the mother’s blood comes into very close proximity to the blood of the fetus
The umbilical cord connects the embryo’s blood supply to the placenta
The role of the placenta is to enable exchange of substances between the mother's blood and that of the fetus
Substances that travel from the mother's blood to the fetus include:
oxygen
nutrients, e.g. glucose, amino acids and mineral ions
Substances that travel from the fetus' blood to the mother include:
carbon dioxide
urea
The placenta is an efficient exchange surface because it has:
a large surface area
a thin wall for efficient diffusion
The placenta also acts as a barrier to toxins and pathogens, although not all are stopped from passing through, for example:
nicotine and alcohol can pass across the placenta
virus particles can pass across the barrier
The placenta allows exchange of substances between the fetus and the mother
How is the developing embryo is protected by amniotic fluid?
Amniotic Fluid
In the uterus the developing embryo is surrounded by amniotic fluid
Amniotic fluid is contained within the amniotic membrane, also known as the amniotic sac
The amniotic fluid protects the embryo during development by cushioning it from bumps when the mother moves around
The foetus in the uterus is protected by amniotic fluid
What are the roles of oestrogen and testosterone in the development of secondary sexual characteristics?
Secondary Sexual Characteristics
Secondary sexual characteristics are the changes that occur during puberty
Their development is controlled by the release of hormones
Oestrogen in females
Testosterone in males
Female secondary sexual characteristics
Female Effects of Oestrogen | |
 | Development of breasts |
Body hair grows | |
Menstrual cycle begins | |
Hips get wider |
Male secondary sexual characteristics
Male Effects of Testosterone | |
 | Growth of penis and testes |
Growth of facial and body hair | |
Muscles develop | |
Voice breaks | |
Testes start to produce sperm |
Some changes occur in both males and females, including growth of sexual organs and growth of body hair
Emotional changes also occur due to the increased levels of hormones in the body
These include more interest in sex and increased mood swings
Note 
Flashcard (46)