Human Reproduction Flashcards
what are testes
male gonad
gonad
organ that produces sex cells in animals
how are testes developed
developed in body but a few weeks before birth descend into scrotum
what temp is sperm kept at and why
35 - ideal for sperm production
role of seminiferous tubules
lined with sperm producing cells
what is between tubules & its function
interstitial cells - produce testosterone
how is epididymis formed
all seminiferous tubules combine
role of epididymis
sperm are stored and matured here
another name for sperm duct
vas deferens
relationship between sperm duct and urethra
epididymis ➡️ sperm duct which brings sperm to ➡️ urethra which carries sperm and urine ➡️ out of body
glands in male body
seminal vesicle
prostate gland
cowper’s gland
role of glands in body
produce seminal fluid
what does the production of seminal fluid do for the body
nourishes sperm and provides a medium for swimming
how is semen produced
seminal fluid and sperm
role of penis
release sperm into vagina
how is sperm produced
produced by meisos
meiosis
type of cell division
- cell divides and forms 4 daughter cells with half the number of chromosomes as parent cell
how many chromosomes in parent cell
46
how many cells in daughter cell
23
sperm producing cells are ________
diploid
diploid
cells containing 2 sets of 4 chromosomes
how many chromosomes do normal body cells contain
46
symbol for diploid cells
2n
describe haploid cells
- meiosis halves number of chromosomes so sperm cells are called haploid
- contain one set of chromosomes
what does the acrosome in sperm cells contain
contains digestive enzyme
nucleus of sperm cell contains:
23 chromosomes
what does the collar of sperm cell contain
contains many mitochondria
role of flagellum in sperm cell
causes sperm to swim
when are sperm cells produced
puberty
puberty
beginning of sexual maturity
name male hormone
testosterone
role of testosterone
develops primary and secondary male sexual characteristics
what do primary sexual characteristics dictate
presence of reproductive parts
what do secondary sexual characteristics dictate
features distinguishing males from females (apart from sex organs)
name some secondary male characteristics
body, facial and pubic hair
enlarged larynx - causes breaking of voice
increased muscular and bone development- wider shoulders
growth spurt
increased secretion of sebum in skin
role of ovaries
production of eggs and female hormones
how are eggs in body produced
meiosis
what surrounds egg in ovary
graafian follicle
role of graafian follicle
produce oestrogen
what is corpus lutuem also known as
yellow body
role of corpus lutuem
secretes progesterone
process of egg production in ovaries
- at birth female foetus contains all potential eggs from birth, they are diploid cells.
- after puberty, a number of eggs are produced monthly by meiosis.
- one egg continues to grow and the rest die off
- the egg is surrounded by graafian follicle
- when mature, follicle forms a swelling on the outside of ovaries
- this swelling bursts at ovulation to release egg
- after ovulation, follicle fills with yellow cells and become corpus luteum
how long is the menstrual cycle
28 days
role of menstrual cycle
produce egg and prepares body for pregnancy
how long do women partake in the menstrual cycle
begins at puberty, ends at menopause
menopause
end of a woman’s reproductive life
what occurs day 1 - 5 of menstrual cycle
- old lining of endometrium breaks down and sheds, loss of blood and tissue (menstruation/period)
- new egg is produced in ovary by meiosis and surrounded by graafian follicle
menstruation/period
loss of blood and tissue
what occurs day 6 - 14 of menstrual cycle
- developing graafian follicle produces oestrogen
- this causes the endometrium to build up again to prepare for implantation
- it also prevents the development of more eggs
what occurs day 14 of menstrual cycle
(ovulation) graafian follicle bursts which releases egg into the fallopian tube
what occurs day 14 - 28 of menstrual cycle
- graafian follicle turns into corpus lutuem
- this causes endometrium to thicken further and also prevents formation of new eggs
- on day 16, egg dies if its not fertilised
- days 12 - 16 are the fertile period
- at around day 22, if fertilisation doesn’t occur corpus lutuem will begin to degenerate, resulting in reduced progesterone levels
- as a result, on day 28, the endometrium breaks down
- cycle repeats
when is the fertile period of a menstrual cycle
days 12 - 16
ovum
egg
ova
eggs
how long can sperm live in female body
7 days
what is the reason for the fertile period beginning on day __ ? name day and explain
- day 14
- sperm may already be present in body
name the hormones in menstrual cycle and list their order
FSH
oestrogen
LH
progesterone
how is FSH produced
by pituitary gland days 1 - 5 of cycle
meaning of FSH
follicle stimulating hormone
role of FSH
stimulates a few potential eggs to develop (surrounded by graafian follicle), usually one survives
what can FSH be applied in
- fertility treatments as it can stimulate the production of eggs
- often lots develop causing multiple births
how is oestrogen produced
graafian follicle in ovary days 1 - 5 of cycle
roles of oestrogen
- develop endometrium
- inhibits FSH, this ensures no further development of eggs
application of oestrogen
contraceptive pills
meaning of LH
luteinising hormone
how is LH produced
is produced by pituitary gland days 14 - 28 of cycle
role of LH
causes ovulation
how is progesterone produced
remains of graafian follicle develop into corpus luteum which produces progesterone days 14 - 28 of cycle
role of progesterone
- maintains structure of endometrium
- inhibits production of FSH (stops development of eggs)
- inhibits LH which stops further ovulation and pregnancies
- prevents contractions of uterus
name a menstrual disorder
fibroids
what are fibroids
- a benign tumour in uterus wall caused by overproduction of cells
- common between ages 35 - 45
benign
non - cancerous
cause of fibroids
- uncertain
- may be induced by oestrogen (e.g. in contraceptive pill)
prevention and treatment for fibroids
- large fibroids: surgically; hysterectomy/ anti - oestrogen tablets
hysterectomy
removal of uterus
symptoms of fibroids
- large fibroids: heavy and prolonged periods
- anaemia
- miscarriage/infertility
name stages of copulation
arousal, copulation and orgasm
what occurs during sexual arousal
- penis gets erect
- vagina becomes lubricated
what occurs during copulation
- penis is inserted and moved inside vagina
what occurs during orgasm
- sperm is ejaculated
- contraction of vagina and uterus
what occurs during insemination
- sperm released into female
- contractions of uterus and fallopian tubes move sperm to tubes within minutes
- if egg is present, chemical chemotaxis releases to attract sperm
where does fertilisation occur
fallopian tube
what occurs during fertilisation
- sperm swim up to egg, many die due to acidic conditions in vagina
- acrosome from sperm penetrates egg and loses tail in the process
- nuclei of egg and sperm fuse which forms zygote
- membrane of egg undergoes chemical change, this prevents other sperm cells entering
what is implantation
embedding of fertilised egg into endometrium, 6 - 9 days after fertilisation
what happens during implantation
- zygote turns into embryo
- amnion (membrane) develops around embryo, this secrets amniotic fluid which acts as a shock absorber
- after implantation, placenta forms
sequence of development from fertilised egg
(2 months)
zygote
morula
blastocyst
embryo
(7 months)
foetus
baby
what happens day 1 of human embryo development
(early development of zygote)
- fertilisation occurs
- zygote contains 46 chromosomes, half from the egg and half from the sperm
what happens day 3 of human embryo development
- zygote rapidly divides (mitosis)
- forms morula
morula
solid ball of cells
what happens day 5 of human embryo development
- blastocyst is formed
- outer layers of blastocyst form trophoblast, develops into membrane surrounding embryo (placenta & amnion)
blastocyst
hollow ball of cells
what happens day 10 of human embryo development
(embryonic development)
- inner cell mass of blastocyst form germ layers of embryo
- each layer gives rise to specific structures in the developing embryo
- mesoderm is divided into an inner and outer layer
name the germ layers of an embryo
ectoderm (outside)
mesoderm (middle)
endoderm (inside)
what is a coelom and its function?
the gap dividing inner and outer layer of mesoderm
it allows complex organs to develop (ie heart, lungs, kidneys)
germ layers
basic layers of cells in blastocyst that cause the formation of all adult tissues and organs
name the germ layers and the organ/organ system that they produce?
ectoderm - nails, skin, hair, nervous system
mesoderm - muscles, skeleton, excretory system, respiratory system, circulatory system, reproductive system
endoderm - inner lining of digestive, respiratory and excretory systems, liver and pancreas
what is amnion in contact with when first formed
embryo
what happens at the 4th/5th week of human embryo development
- fluid begins to accumulate within amnion (amniotic fluid)
- heart forms and starts to beat
- brain develops
- limbs start to form
what is the primary function of amnion and amniotic fluid
protection of embryo for its future development
what happens at the 6th week of human embryo development
- eyes are visible
- mouth, nose and ears begin to form
- skeleton is in early stages of development
what happens at the 8th week of human embryo development
- major body organs are formed
- sex glands have developed into testes/ ovaries
- bone begins to replace cartilage
- embryo has taken on a recognisably human form
- referred to as a foetus
- no new organs formed
what happens at the 12th week of human embryo development
- nerves and muscle co-ordinate allowing arms & legs to move
- foetus sucks it’s thumb, urinates and releases faeces into amniotic fluid
- gender can be seen in scans
gestation period
time from fertilisation to birth
how long is the gestation period
38 weeks/9 months
process of placenta formation:
- forms from combination of tissues of uterus and embryo
- after implantation a membrane (chorion) surrounds amnion and embryo
- chorionic villi emerge from chorion and invade endometrium, this allows for the transfer of nutrients from menstrual blood to fetal blood
- combination of chorionic villi and endometrium form placenta and is fully operational 3 months into pregnancy
- placenta allows for exchange of nutrients, wastes, gases, antibodies and hormones between blood of mother and embryo
- produces progesterone
chorion
a membrane
why cant the blood of the mother and the blood of the embryo mix
- blood groups may be incompatible
- blood pressure of mother’s system may damage embryo
function of umbilical cord
- connects embryo with placenta
- takes blood from embryo to placenta and back again
- must be cut at birth to separate baby from mother
what does the umbilical cord contain
blood vessels which circulates the blood between embryo and placenta
whats another name for birth
parturition
explain process of birth and labour
- hormones oestrogen and progesterone are produced throughout pregnancy by corpus luteum in the first 3 months and then by placenta
- immediately before birth placenta stops making progesterone, this causes the walls of the uterus to contract
- pituitary gland releases hormone oxytocin, this causes further contractions of the uterus
(labour) (stage 1) 12 hrs
- contractions of the uterus pushes foetus towards cervix, this causes cervix to dilate
- contractions cause amnion to break, this releases amniotic fluid through vagina (water break)
(pushing) (stage 2) 20m to 1hr
- foetus passes through cervix and birth canal headfirst
- Umbilical cord is tied and cut, this leaves a scar and becomes the navel (bellybutton)
(afterbirth) (stage 3) 10m - 15m
- baby is born
- uterus contracts again and expels after birth (umbilical cord and placenta)
what is the endocrine gland’s function
produces and releases hormones into blood (ductless glands)
materials pass from baby to mother
waste, salt, CO2, urea
materials passed from mother to baby
food, oxygen, hormones, viruses, alcohol and drugs, antibodies
lactation
the secretion of milk by the mammary glands
process of lactation
- colostrum produced first days after birth
- milk production is triggered by the release of prolactin by pituitary gland
benefits of breastfeeding
- colostrum and breast milk provide essential antibodies to protect
babies from infection - ideal balance of nutrients for baby
- easier to digest than milk (less fat)
- helps mother recover (uterus contracts faster)
- reduces risk of breast cancer
birth control
methods employed to limit number of children born
contraception
- deliberate prevention of fertilisation/pregnancy
- achieved by preventing egg from meeting
forms of mechanical contraception
- condoms
- Use of diaphragms (female), stops sperm from entering uterus
what can contraception also protect against
STD/STI’s
forms of chemical conception
- the pill, contains oestrogen and progesterone which prevent against ovulation, hence contraception
- spermicide, chemical that kills sperm
- the bar, inserted under skin in arm
form of surgical contraception
- fallopian tubes and sperm ducts can be cut and tied
forms of natural contraception
not having sexual intercourse during the fertile period of menstrual cycle
natural methods of contraception try to identify the time of ovulation based on:
- monitoring body temperature, which slightly rises after ovulation
- Mucus secreted in cervix, which texture changes after ovulation
methods of preventing implantation
- pills
- coils/ IUDs, which are inserted into womb
infertility
inability of a couple to achieve conception
male infertility disorders include:
- low sperm count, which is a low number of sperm per ml of seminal fluid
- low sperm mobility, arises if movement of sperm is slow/not in a straight line, or both, sperm may have difficulty passing through cervical mucuos or penetrating shell of egg
- endocrine gland failure, which is when the testes fail to produce sperm
Causes of low sperm count
- persistent use of drugs (eg alcohol, cigarettes, anabolic steroids)
- abnormalities in sperm production/obstruction of tubes that sperm travels through
- stress
treatment of low sperm count
- change in diet
- change in lifestyle (eg stopping alcohol consumption/smoking)
- reduction in stress levels
female infertility disorders
- blockage in fallopian tubes, which is when the scarring of the tube can block the passage of the egg to the uterus
- endocrine gland failure, which is a failure of ovaries to produce an egg
causes of blockage in the fallopian tube
- fragments of uterus lining may spread to fallopian tube
- Inflammation due to infection
treatment of blockage in the fallopian tube
IVF ( in vitro fertilisation)
what is IVF
- a method of treating infertility, when eggs are removed from an ovary and fertilised outside of the body
- during IVF, fertility drugs are given to the female to stimulate the ovaries to produce more than one egg
process of IVF
- eggs are taken from females body and into the laboratory
- sperm sample is taken from male
- eggs and sperm and mixed together
- sample is placed in an ideal condition for fertilisation
- main aim of procedure is to obtain a zygote, if successful zygotes development will be monitored closely
- developing embryo can be placed back into females body for implantation
stem cells
- primary source to develop into many different types of body cells
- obtained from embryos and bone marrow
describe fallopian tube
- muscular and approximately 12 cm long
- site of implantation
- funnels at tips of tube catch egg after released from ovary
- egg moves along tube by cilia and muscular peristalsis
- egg is either fertilised or dies
another name for uterus
womb
describe uterus
- muscular structure, approximately the size of a fist
- site of implantation
- forms placenta
- outer wall made of involuntary muscle
- inner lining of uterus is called the endometrium
- the lining of the endometrium thickens each month with cells and blood vessels to nourish embryo
- The opening of the uterus is called the cervix
describe vagina
- elastic muscular tube, 10 cm long
- allows entry of sperm
- birth canal for babies exit
- lined with cells that produce mucuos, which protect against entry of pathogens
pathogens
disease causing organisms (e.g. bacteria/fungi)
