Human Reproduction Flashcards
The human reproductive systems are composed of 3 structural levels of organisation, one is a pair of?
structures in both males and females to produce sex cells
The human reproductive systems are composed of 3 structural levels of organisation, they have a series of?
transport tubes
The human reproductive systems are composed of 3 structural levels of organisation, a number of what?
glands to secrete hormones that could control human reproduction
The testes produce? Called?
male sex cells (gametes) called sperm
The ovaries produce? Called?
female gametes called eggs
Whats a gonad?
an organ that produces sex cells in animals
Male gonads are the?
testes
In the testes, the temperature is maintained at what degrees to allow what?
35 degrees Celsius allowing meiosis to occur producing sperm
The cells between the tubules produce what hormone?
testosterone
Each testis consists of a?
mass of tubules
Mass of tubules are lined with? What then occurs here to produce what?
diploid sperm producing cells, meiosis occurs producing haploid sperm
Function of epididymis?
store sperm
/
allow sperm mature
/
transport sperm from testes to sperm duct
Tubules in the testes combine to form?
epididymis
Where is epididymis located?
outside each testis
If sperm is not released from epidermis what happens?
they are broken down and taken back into bloodstream (reabsorption)
The epidiymis leads into the?
sperm duct
A vasectomy is a form of what? What does it involve?
an operation to cut the sperm duct, a form of male sterilisation
Sperm duct function?
carry sperm to the urethra
Wheres the urethra located?
tube located in the centre of the penis
Two functions of urethra?
releases semen or urine
Prostate gland and Cowper’s glands produce a liquid called?
seminal fluid
What is semen?
a liquid made of seminal fluid and sperm
What is ejaculation?
the release of semen
Sperm is produced by?
meiosis
Sperm-producing cells are?
diploid
Sperm cells are first produced in?
the testes
Whats the name of the tip of the penis?
glans
Whats the foreskin?
a fold of skin partially covering the glans
At puberty what two hormones are produced by the male pituitary gland?
FSH,
LH
What does FSH do?
causes the diploid sperm-producing cells in the testes to divide by meiosis and produce sperm
What does LH do?
stimulates the testes to produce testosterone
During puberty, FSH and LH are produce by?
the male pituitary gland
What are androgens?
male hormones
An example of an androgen is?
testosterone
Testosterone is produced where, when and in what size amounts?
by testes in small amounts before puberty
Testosterone causes?
primary male sex characteristics
What are secondary sexual characteristics?
features that distinguish males from females apart from the sex organs themselves
Give examples of secondary male characteristics.
- deep voice
- body hair
- enlarged muscles
- enlargement of penis
- wide shoulders
Definition of infertility?
the inability to produce offspring
Whats the main type of infertility in males?
low sperm count
Give causes of low sperm count.
- persistent smoking
- alcohol abuse
- anabolic steroids
- mumps
Give corrective measures for low sperm count.
- IVF
(- changes in diet and lifestyle)
Ovaries produce?
eggs and female hormones
Eggs are produced by?
meiosis
Each potential egg is enclosed in a cluster of cells forming a? Where is this?
follicle in the ovary
After puberty about __ eggs are produced by meiosis each month, usually ___ continues to grow and the rest die off.
20 eggs, usually 1 continues to grow
After meiosis, a haploid egg is surrounded by? What does this produce?
graafian follicle, producing oestrogen
The follicle matures, forming what and where?
forms a swelling on the surface of the ovary
How is the egg released?
follicle bursts at ovulation
Definition of ovulation?
is the release of an egg from the ovary
Whats a Graafian follicle?
fluid filled sac plus haploid egg
After ovulation, what happens the follicle? What does it become? What does this secrete?
follicle fills with yellow cells and becomes the corpus luteum. this secretes progesterone
Progesterone is secreted by?
corpus luteum
Where does insemination occur?
upper vagina
Where does fertilisation occur?
fallopian tube
Where does ovulation occur?
ovary
Where does implantation occur?
endometrium
Give the 4 places in order for the pathway of egg.
ovary
abdomen
fallopian tube
uterus
Fallopian tubes have what at their ends? What does this do?
funnels that catch the egg after ovulation
The egg is moved along the fallopian tube by?
cilia and muscular peristalsis
In the fallopian tube what are the 2 fates of the egg?
can be fertilised or dies
Another word for uterus?
womb
The outer wall of the uterus is made of?
involuntary muscle
The inner lining of the uterus is called the?
endometrium
The lining of the uterus thickens with what each month? Why?
thickens with cells and blood vessels in order to nourish the embryo in the event of pregnancy
The opening into the uterus is called the?
cervix
Two functions of the vagina?
birth canal,
insemination
What are labia?
the folds of skin that protect the vagina
The vagina is lined with?
mucous producing cells
Definition of the menstrual cycle?
a series of events that occurs every 28 days on average in the female if fertilisation has not taken place
When does the menstrual cycle begin and end?
begins at puberty and ends at menopause
What is menopause?
when ovulation and menustration stop happening in a female
What happens on the days 1-5 in menstrual cycle?
the endometrium breaks down and is shed from the body.
loss of blood and tissue through vagina (menstruation/period).
new egg formed by meiosis which is surrounded by the Graafian follicle.
FSH released
What happens on the days 6-14 in menstrual cycle?
developing graafian follicle produce oestrogen which causes the endometrium to thicken/repair/build up, as well as preventing other eggs from developing
What happens on day 14 in menstrual cycle?
ovulation occurs when graafian follicle bursts, releasing the egg from the ovary.
egg passes into abdomen of female and on into the funnel of fallopian tube.
egg is then moved along the fallopian tube.
What happens on the days 14 -28 in menstrual cycle?
remains of the graafian follicle develops into the corpus luteum (yellow body).
this makes the hormone progesterone which maintains the endometrium, and thicken even more, as well as preventing other eggs forming.
if fertilisation has not taken place, corpus luteum starts degenerating which results in reduction in progesterone levels causing the endometrium to break down
reduction in progesterone levels, causing the lining of the uterus to break down
FSH =
Oestrogen =
LH =
Progesterone =
pituitary,
ovary/graafian follicle,
pituitary,
corpus luteum
Corpus luteum makes what hormone?
progesterone
Whats menstruation?
the discharge of the endometrium and the unfertilised egg
Oestrogen causes what and when?
Progesterone does what and when?
Both of these hormones prevent?
- the endometrium to thicken in the first half of the cycle
- progesterone continues this process in the second 14 days
- prevent eggs from developing
High levels of oestrogen cause what in females during puberty?
cause the primary female characteristics, the growth of sex organs
Combination of oestrogen and progesterone at puberty causes what in females?
secondary female characteristics
Give 3 secondary female characteristics.
- maturing and elargement of the breasts
- widening of the pelvis
- growth of pubic and underarm hair
Whats infertility?
inability to produce offspring
Whats an example of female infertility, whats it due to?
Give a cause and corrective measure for this.
failure to ovulate due to endocrine gland failure
caused by hormone imbalance/levels,
treatment could involve hormone supplements or surgery
FSH
- produced by?
- produced when in the cycle?
- function?
produced by pituitary gland
produced early in cycle (days 1-5)
stimulates a few potential eggs to develop
OESTROGEN
- produced by?
- produced from what days?
- 3 functions?
produced by the graafian tube/in ovary
produced from days 5-14
1) causes endometrium to repair/thicken
2) inhibits FH by negative feedback
3) stimulates LH
LH
- produced by?
- produced on what day?
- 3 functions?
produced by the pituitary gland
produced on day 14
1) causes ovulation
2) causes remains of graafian follicle to develop into the corpus luteum
3) corpus luteum makes progesterone
PROGESTERONE
- produced by?
- produced what days?
- 4 functions?
produced by corpus luteum (in ovary)
produced from days 14-28
1) maintains endometrium
2) it inhibits FSH
3) inhibits LH
4) prevents contractions of the uterus
Name a menstrual disorder, its cause and prevention/treatment.
fibroids
cause is uncertain, may be an abnormal hormonal response
treated with surgery if big and if small they are just frequently examined, or HRT/hysterectomy
What are fibroids?
benign tumours in/of the uterus
Name the 3 stages of copulation.
sexual arousal
copulation
orgasm
Whats sexual arousal?
male: flow of blood into penis to increase and the blood flow out to decrease, tissue fills with blood and becomes erected.
female: vagina becomes lubricated, elongated and wider
What’s copulation?
the act of sexual intercourse
What is an orgasm?
the physical and emotional sensations experienced at the peak of sexual excitement
What is ejaculation?
the release of semen from the penis
What is insemination?
the release of semen into the vagina, just outside the cervix
What is chemotaxis?
if ovulation has occured and an egg is present, it releases a chemical that attracts the sperm
Definition of fertilisation?
occurs when the nucleus of the sperm fuses with the nucleus of the egg, forming a diploid zygote
Where does fertilisation usually take place?
fallopian tube
How long can sperm survive for in the female system?
up to 7 days
What is implantation?
the embedding of the fertilised egg into the endometrium/lining of the uterus
Implantation happens how long after fertilisation?
6-9 days
Zygotes grow to form?
embryo
During implantation what devleops around the embryo?
a membrane called the amnion
What does the amnion do?
secretes amniotic fluid which surrounds and protects the embryo
What is in-vitro fertilisation?
involves removing eggs from an ovary and fertilising them outside the body
After implantation, the embryo forms an outer membrane called? What does this do
chorion, which surrounds the amnion and the embryo
Tissues involved in formation?
endometrium and embryonie/ embryo tissue
Name the 3 functions of the placenta?
transfer (exchange)
barrier (prevents bloods from mixing)
hormone production
Describe the function of placenta ‘transfer’.
placenta allows nutrients/gases/waste/some hormones be exchanged between the blood of the mother and the embryo, mainly by diffusion
Describe the function of placenta ‘barrier’. Give 2 reasons why it is essential.
blood of mother and embryo do NOT mix
1) blood groups might not be compatiblem leading to damage o RBC’s.
2) blood pressure of mother’s system could cause damage to the embryo as it is higher
Describe the function of placenta ‘hormone production’.
placenta produces progesterone, oestrogen and prevents contraction of uterus
The fertilised egg/zygote has how many chromosomes?
46
In relation to the early development of zygote, most of the cytoplasm and mitochondria comes from where?
egg - mother
Definiton of a morula?
a solid ball of cells formed from a zygote by mitosis
After about how many days does a morula form? (Early development of zygote)
3
What happens the zygote during the first three days of early development?
divides rapidly by a series of mitotic divisions to produce 2 cells, then 4-8-16 etc
During the first three days of early development zygote, what is the mitotic divisions called/doing?
cleavage
Definition of a blastocyst?
(or blastula) is a hollow ball of cells formed from a morula
Give explanation of day 5 of early development of zygote.
outer cells of the BLASTOCYST form the trophoblast, this will later form the MEMBRANES around the embryo. the INNER CELLS of the blastocyst will later form the EMBRYO
On day 5 of early development of zygote, the outer cells of the blastovyst form from the? These will llater form what?
trophoblast, these will later form the membranes around the embryo
On day 5 of early development of zygote, the inner cells of the blastocyst will later form?
the embryo
On day 5 of early development of zygote, the blastocyst is pushed down what into what?
down fallopian tube into the uterus
What are germ layers?
basic layers of cells in the blastocyst from which all adult tissues and organs will form
What are the three primary germ layers called?
ectoderm,
mesoderm
endoderm
For ectoderm, name an organ or system produced.
- skin
- hair
- nails
For mesoderm, name an organ or system produced.
- skeleton
- muscles
For endoderm, name an organ or system produced.
- inner lining of digestive system
- liver and pancreas
Give points on embryonic development - week 8.
- tail has diminished
- face and main body organs are formed
- bone begins to replace cartilage
- embryo is recognisable as a human, now called a foetus
Give one point on embryonic development - week 8 onwards.
- foetus grows and refines structures already formed
Give points on embryonic development - end of 3rd month/12 weeks.
- nerves and muscles become coordinated
- foetus urinates into the amniotic fluid
- external sex organs have formed and gender can be seen (in scans)
Function of amniotic fluid?
protection - shock absorber
Gestation definition?
the length of time spent in the uterus from fertilisation to birth
In humans gestation lasts how long?
38 weeks/9 months from the date of fertilisation
Name 4 points on birth.
contractions, delivery, afterbirth, waterbreak/cervix dilates/change in hormone levels
During pregnancy what hormone is produced in greater and greater amounts?
progesterone
During birth, the placenta acts as?
an endocrine gland
What stops producing progesterone just before birth?
pancreas
What happens to the walls of the uterus when progesterone levels are low?
begin to contract
During birth, the pituitary gland is producing what hormone?
oxytocin
Function of oxytocin?
causes stronger reactions of the uterus muscle, resulting in the onset of labour
Labour begins when the uterus what?
starts to contract involuntarily
How many stages of birth are there?
3
How long does each stage of labour last?
1 = 12 hours typically
2 = 20 minutes to an hour
3 = 5 to 30 minutes
STAGE 1:
- contractions of the uterus push the foetus down towards where?
- what is expelled along with some blood
- the membranes around the foetus break to allow?
- cervix
- a mucous plug
- the loss of about 1 litre of amniotic fluid
STAGE 2:
- what dilates to allow baby be born?
- what way does baby come out?
- Explain umbilical cord in this stage.
- the cervix
- head first
- still attached but then clamped/tied then cut
Definition of lactation?
the secretion of milk by the mammary glands of the female
STAGE 3:
- what are being expelled?
- uterine contractions and placenta
Breasts produce a thick, yellow fluid called what after first few days of birth?
colostrum
Once the baby is born, a hormone called X is produced by X, this stimulates___.
prolactin by the pituitary gland
this stimulates milk production
Give 4 biological benefits of breastfeeding.
- ideal balance of nutrients
-supply of antibodies - breast milk is sterile
- causes the uterus to contract
(correct temperature, bonding, contraception, psychological wellbeing)
Definition of birth control?
refers to the methods taken to limit the number of children that are born
Definition of contraception?
is the deliberate prevention of fertilisation or pregnancy
What are the 3 (+1) methods of contraception?
natural, mechanical, chemical
(+ surgical)
Explain natural contraception.
involves not having intercourse at those times in the menstrual cycle when pregnancy is possible
3 examples of natural contraception?
withdrawal, abstinence, rhythm
What are spermicides?
substances that kill sperm
4 examples of mechanical contraception?
condoms, diaphragm, coil, tube ligation
Explain mechanical contraception.
involves using mechanical barriers to prevent sperm reaching the egg
Explain chemical contraception.
involves the use of spermicides to kill sperm or hormones to prevent egg formation or ovulation
Give 5 examples of chemical contraception.
pill, hormonal, vaginal ring, spermicide, implant
