reproduction in humans Flashcards
name the parts of the male reproductive system
Testicles, epididymis, scrotum, vas deferens (sperm duct), seminal vesicles, urethra, penis
what are the testicles?
oval organs that lie in the scrotum, most men have 2 testes which makes testosterone +generate sperm cells
what is testosterone?
primary male sex hormone.
responsible for the development and maintenance of secondary sexual characteristics in males
what is scrotum?
It is the loose pouch-like sac of skin behind the penis which contains testicles, nerves and blood vessels.
where is the scrotum located?
outside of the main body cavity so its temperature is slightly lower than body temperature for the normal sperm development
what is the vas deferens? (sperm duct)
is a long muscular tube that travels from the epididymis into the pelvic cavity, to just behind the bladder. transports mature cells to the urethra in prep for ejaculation
what is epididymis?
a long coiled tube that rests on the back of each testicle . It transports and stores sperm cells that are produced in the testes. it brings the sperms to maturity
what are the seminal vesicles?
sac-like pouches which are attached to the vas deferens near the base of the bladder. stores sperms temporarily before they are released through the urethra.
produces sugar-rich fluid(fructose) provide sperm w energy + help sperm with mobility. Prostate gland also secretes this. makes up most of vol of semen
what is the urethra?
tube that carries urine from bladder to outside body. in males, expels semen when he reaches climax of sexual intercourse. flow of urine is blocked, only allowing semen to be released
what is the penis?
male organ for sexual intercourse.
consists of internal chambers made up of special sponge-like erectile tissue which has thousands of large spaces that fill with blood during sexual arousal–> becomes rigid and erect in order to enter and deposit semen into the vagina (happens at the climax of sex)
what are the parts of female repro system?
ovaries, fallopian tubes/oviducts, uterus/womb, uterine lining(endometrium), cervix, vagina
what are the ovaries?
produce of ova/eggs and hormones like progesterone and oestrogen. mature eggs released is ovulation
what are fallopian tubes/oviducts?
two tubes from ovaries to uterus. ovum usu fertilized while in the oviduct, then it implants in the endometrium when it reaches the uterus
what happens when ovum matures?
the follicle and ovary’s wall rupture allowing the ovum to be released
what is the uterus/womb?
muscular organ where the foetus develops during pregnancy. provides mechanical protection, nutritional support and waste removal. contractions in muscular walls when ejecting foetus at birth
what is uterine lining/ endometrium
site of embryo implantation. fertilized ovum> embryo, develops into foetus and gestates until childbirth. egg does not embed in wall> menstruation and egg is flushed away
what is the cervix?
narrow, circular muscle at lower end of uterus, joins w top of vjj
what is the vagina?
muscular tract leading from uterus to exterior of body. semen frm male is deposited here during sex
what is sexual reproduction in humans (gametes)
the fusion of nuclei of 2 gametes
what are gametes?
repro cells that contain half the amt of genetic material compared to norm body cell. 2 gametes differ in structure and come from diff parents
what do gametes need?
- motility to meet and unite (sperms are motile ad small)
2. food to nourish developing embryo(eggs that contain food)
what does the sperm head contain?
- nucleus that carries one haploid set of chromosomes
- small amount of cytoplasm
- an acrosome that contains enzymes for breaking down part of the egg membrane for sperm penetration.
what else does the sperm contain?
- numerous mitochondria in the middle to provide energy for it to swim to egg
- a tail
what does the ovum contain?
- large nucleus containing one haploid set of chromosomes
- large amount of cytoplasm which may contain a small amount of yolk
- cell surface membrane that is surrounded by an outer membrane
what are hormones?
chem substances produced in minute quantities by endocrine glands> transported in bloodstream to target organs > exert effects
Four main hormones in the female repro cycle
- Follicle stimulating hormone (FSH)
- Luteinising hormone (LH)
- Oestrogen
- Progesterone
Purpose of these hormones
ensure that endometrium is ready for implantation of fertilised embryo
what is the menstrual cycle made up of?
Ovarian cycle
Uterine cycle
what is the follicle stimulating hormone? (FSH)
stimulates the development of follicles in ovaries to secrete oestrogen
what is the luteinising hormone? (LH)
^ in LH triggers ovulation + initiates conversion of residual follicle into a corpus luteum. CL produces progesterone and some oestrogen to prep endometrium for possible implantation
what do primary follicles consist of?
consists of a potential egg cell surrounded by a layer of smaller cells known as follicle cells.
what happens to primary follicles?
A primary follicle may develop into a Graafian follicle that contains a mature egg surrounded by follicle cells and a fluid-filled space > ready to be released
when does ovulation occur?
Ovulation occurs when the Graafian follicle ruptures and releases the egg into the oviduct funnel
what happens after ovulation in the ovary?
the ruptured Graafian follicle develops into a corpus luteum. hormones produced to prep endometrium
functions of oestrogen (secreted by follicles in ovaries)
main: repair and growth of uterine lining
1. promotes development and maintenance of female repro structures (esp endometrium)
2. assists in control of fluid and electrolyte balance within body, skin retains moisture
3. prep follicles for release of egg
4. ^ conc will inhibit FSH production, prevent maturation and development of more follicles + stimulate pituitary gland to secrete LH
functions of progesterone
- thicken and maintain uterine lining , supply w rich network of blood capillaries in prep of implantation
- inhibits ovulation and FSH production
- if no preg, levels will decrease and lead to menstruation
stages in the menstrual cycle
- menstrual flow stage
- follicle stage
- ovulation
- corpus luteum stage
what happens during menstrual flow stage?
uterine lining breaks down and flows out through vjj
follicle stimulating hormones are secreted into bloodstream by anterior pituitary gland
what happens during the follicle stage?
FSH stimulates follicles to:
- develop into graafian follicles
- secrete oestrogen
high levels of oestrogen will inhibit production of FSH and prevent further maturation and development of follicles
+ stimulate pituitary gland to secrete luteinising hormone
what happens during ovulation?
surge in level of LH results in ovulation and initiates conversion of ruptured graafian follicle into progesterone and some oestrogen, which will repair and maintain the uterine lining
what happens during corpus luteum stage?
progesterone stimulate uterine lining to thicken further with a rich supply of blood capillaries
progesterone will inhibit production of FSH and LH and ovulation
what happens when there is no ovulation?
progesterone levels drop and the uterine lining will detach itself and leave via the vjj
what happens after ovulation?
inside the oviduct, egg is carried along by cilia towards the uterus
fertilisation occurs if sperm are present
what happens when no fertilisation occurs?
- egg breaks down
- LH production inhibited due to high levels of progesterone
- Lh levels drop, corpus luteum breaks down, no more progesterone is produced
- uterine lining cannot be maintained and breaks down> menstruation
what happens when fertilisation does occur?
- fertilised egg develops into zygote before developing into embryo
- embryo implants itself into endometrium
- embryo secrete hormone, prevents corpus luteum from breaking down and continue producing progesterone and oestrogen, a placenta is formed
- contnues to secrete hormones until placenta takes over
what is the placenta made out of?
made up of villi which grows from the embryo and into the uterine lining, villi contains the blood capillaries of the embryo
Functions of placenta
- Allows oxygen and food substances, and protective antibodies to diffuse from mother’s blood to foetal’s blood
- allows for metabolic waste products or excretory products to diffuse from foetal blood to mother blood
- produces progesterone which maintains the uterine lining during pregnancy
what attaches embryo to placenta?
umbilical cord
functions of umbilical cord
- 2 umbilical arteries which transport deoxygenated blood and metabolic waster products from foetal blood to placenta
- 1 umbilical vein transport oxygenated blood and food substances from placenta to foetal blood
what is in the amniotic cavity?
Amniotic sac encloses foetus in the amniotic cavity and amniotic fluid fills the cavity
functions of amniotic fluid
- supports and cushions the foetus b4 birth
- shock absorber
- protects foetus from physical injury as fluid is not compressible
- allow foetus to move, allowing for muscle development
- lubricates and reduces friction in birth canal during birth
how is HIV transmitted?
semen, vaginal fluid and blood
how does HIV destroy an immune system?
destroys lymphocytes, not able to produce sufficient antibodies to fight infection. mild infections may be fatal
