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YEAR 2 BIO > sexual reproduction in humans > Flashcards

sexual reproduction in humans Flashcards

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Biology 101 flashcards
1
Q

what do males and females have in common

A
  • pairs of gametes producing organs called gonads
  • system of ducts which connect the gonads to other parts of the body
  • structures of copulation - bring gametes together without passing through air
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2
Q

what are the male parts of the reproductive systems

A 
scrotum 
prostate 
testes 
erectile tissue 
epididymus 
pubic bone
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3
Q

what is the scrotum

A

the sac of skin that surrounds the testicle

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4
Q

what is the prostate

A

joined to initial region of the urethra. secretes alkaline fluid which forms part of the semen and neutralises ruin acidity

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5
Q

what is the testes

A

found inside scrotum and located in a pouch. produces testosterone and sperm

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6
Q

what is the erectile tissue

A

erect due to being engorged by blood. exists in places such as corpora cavernosa

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7
Q

what is the epipididymus

A

long coiled tube that rests on each testes. transports and stores sperm

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8
Q

what is the pubic bone

A

lower front of hip bone

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9
Q

what are the female parts of the reproductive systems

A 
fallopian tube 
ovaries 
cervix 
vagina 
uterus
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10
Q

what is the fallopian tube

A

oviducts. narrow and muscular. ovary -> uterus

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11
Q

what are the ovaries

A

contain 70,000 follicles (only 500 mature) ovum released at puberty stimulated by hormones

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12
Q

what is the cervix

A

narrow end of uterus leads to muscular canal called vagina

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13
Q

what is the vagina

A

uterus to exterior of body. accommodates penis during sex

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14
Q

what is the uterus

A

pear shaped structure with muscular walls supplied with blood vessels

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15
Q

what do both males and females have in their reproductive systems

A

bladder

urethra

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16
Q

what is the bladder

A

sac in pelvic cavity serves as a reservoir for urine

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17
Q

what is the urethra

A

passes through centre allows urine (And semen) to pass out of body but not at the same time

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18
Q

what do the testes do

A

testes produce sperm by spermatogenesis
sperm form in SEMINFOROUS TUBULES
seminiferous tubules also contain INTERSTITIAL CELLS which produce testosterone
hang outside abdominal cavities in a sac called the scrotum
optimum temp is 34 degrees

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19
Q

how do you transfer sperm

A

system of tubes carry the sperm from testes to penis
pass from seminforous tubules through the epididymus and vas deferens into the urethra
urethra acts as an exit route for both sperm and urine

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20
Q

what is the prostate gland and what does it do

A

secretes a milky white fled that neutralises the acidity of any traces of urine and helps protect sperm from acidic secretions in female body also helps with sperm mobility

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21
Q

what do the seminal vesicles/Cowper’s gland do

A

seminal vesicles combine with vas deferent via a duct before it joins the urethra, secretes a thick mucus which nourishes the sperm
Cowper’s gland secretes a lubricant
sperm along with secretions added make up the sperm released during an orgams

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22
Q

what do the ovaries do

A

2.5 cm long. contains sac like follicles which develop in the germinal epithelium.
surrounds and nourishes an oocyte which undergoes meiotic division to form an egg cell
born with 200,000-400,000 follicles only 200-400 complete development, the rest degenerate

23
Q

what is ovulation

A

one egg cell every 28 days released

24
Q

what are the fallopian tubes and what do they do

A

egg cell leaves ovary passes through a small space and is caught up in the infundibulum which leads to the uterus
cilia sweep the egg cell towards the uterus if fertilisation occurs it takes place high up in the oviduct. a fertilised egg (zygote) develops into a multicellular embryo which passes to the uterus
the embryo embeds itself into the endometrium (a mucus membrane that lines the muscular walls of the uterus) which is richly supplied with blood vessels
if the egg is not fertilised it will degenerate and leave the body during menstruation, along with the endometrium

25
Q

what is spermatogenesis

A
  • spermatogonium are found near or at the basement membrane
  • they have a high rate of cell division by mitosis to produce spermatogonia (still genetically identical )
  • the spermatogonia grow to form primary spermatocytes which have completed s-phase
  • the primary spermatocytes separate the homologous pairs of chromosomes in meiosis 1 to form the haploid secondary spermatocytes
  • the secondary meiotic division causes secondary spermatocytes to form the sister chromatids called spermatids.
  • the spermatids are found in association with the sertoli cells which nourish the spermatids as the differentiate into spermatozoa and which protects them from the immune system of the male.
26
Q

what do sertoli cells

A

come into contact with blood supply so can get glucose and oxygen needed but the spermatozoa are protected from the blood supply. sertoli cells diffuse nutrients to spermatozoa.

27
Q

what is the rate of formation of sperm

A

high and continuous throughout the life of the sexually mature male
the average number of spermatozoa in ejaculated semen is 3.2x10^7 ml^-1

28
Q

what is the process of oogenesis

A

oogonium divide by mitosis to produce many oogonia
each oogonia grows within the follicle of cells. meiosis begins but stops in prophase 1. the oogonia are found within the primary follicles (formed from the germinal epithelium)
400,000 primary follicles present in the ovary prior to puberty
during puberty primary oocytes undergo the first meiotic division to form haploid secondary oocytes.
the first polar body does not progress beyond metaphase 2.
the secondary oocyte begins the secondary meiotic division but does not progress to the end of meiosis until fertilisation takes place

29
Q

step by step of spermatogenesis

A

1) mitosis
2) cell growth
3) reduction division and meiosis
4) meiosis 2
5) cell differentiation

30
Q

step by step of oogenesis

A

1) mitosis
2) cell growth
3) reduction division and meiosis
4) meiosis 2

31
Q

what is the mature sperm

A

the acrosome is a thin cap over the nucleus of the sperm. the acrosome vesicle contains the enzymes required to digest its way through the ovum wall
haploid nuclei containing the paternal chromosomes
the mid section of the sperm contains many mitochondria which synthesis ATP to provide energy for the movement of the flagellum
protein fibres add longitudinal rigidity and provide a mechanism of propulsion

32
Q

what is the mature egg

A

the haploid nuclei sits inside a cell with a large volume of cytoplasm
during follicle development unequal division of the cell during meiosis produces the 1st polar body that can be seen outside the plasma membrane this will not develop.
the ZONA PELLUCIDA surrounds the structure and is composed of glycoproteins. with the cortical granules they will be involved in the acrosome reaction at fertilisation
around the outside are the follicle cells

33
Q

why do egg cells release a specific signal

A

release a specific signal, normally a polypeptide which acts as a signal to the sperm to the egg and not other cells
the chemical signals are species specific
the restoration of the diploid numbers occurs and mechanisms that prevent polyspermy

34
Q

what is the acrosome reaction

A

the acrosome release proteases which digest the cells of the corona radiata
the corona radiata is a thick loose grouping of cells in a gelatinous matrix
on contact with the zona pellucid, the acrosome membrane repulses and releases another protease, across, which hydrolyses the zona pellucida around the secondary ovum

35
Q

what is the cortical reaction

A

cortical vesicle fuses with the plasma membrane, releasing enzymes that destroy the sperm binding proteins of the Zona Pellucida to prevent polyspermy
reaction of the oocyte that produces the fertilisation membrane when sperm attaches to 2nd oocyte, the smooth endoplasm reticulum releases calcium ions into the cytoplasm. they make the cortical granules fuse with the cell membrane
the zona pellucida is chemically modified and expands and hardens making a fertilisation membrane, which is impossible for more sperm to penetrate.
stimulates the completion of meiosis, divides and expels the polar body
the chromosomes combine and forms a diploid zygote
caused an embryo until week 10 when organs develop

36
Q

what is capacitation

A

sperm can only fertilise the oocyte after a process has taken place
the removal of cholesterol and glycoproteins from the cell membrane over the acrosome in the sperm head. over several hours, the membrane becomes more fluid and more permeable to calcium ions

37
Q

what is FSH

A

made in the pituitary gland

stimulates one egg cell to develop

38
Q

what is oestrogen

A

made in the follicle

stimulates rebuilding of the uterus wall

39
Q

what is LH

A

made in the pituitary gland

stimulates follicle to burst and release the ovum

40
Q

what is progesterone

A

made in the corpus luteum

completes development of uterus wall. promotes glycogen storage

41
Q

what happens in the menstrual cycle and when are the hormones released

A

in the 1st week of the cycle the pituitary gland is stimulated and releases FSH
FSH stimulates a potential egg cell in the ovary
the cells around the ovum also develops. this is a follicle
follicle cells = produce oestrogen
oestrogen stimulates rebuilding of uterus wall

42
Q

in the start of the cycle, what is the level of oestrogen and what effect does it have

A

initial concentration is low

low concentration of oestrogen has a negative feedback on the secretion of FSH

43
Q

as the cycle continues, what is the level of oestrogen and what effect does it have

A

as follicle grows is produces larger conc of oestrogen
at a certain threshold its effects reverse.
it now has a positive feedback effect on secretion of FSH from pituitary
also stimulates pituitary gland to release luteinising hormone

44
Q

what does a peak in LH cause

A

causes follicle to burst and release ovum
follicle reforms to become structure called corpus luteum
LH stimulates corpus luteum to produce progesterone

45
Q

when must fertilisation occur

A

within 2 days of ovulation
embryo takes three days to reach uterus and implant
if no embryo implants within a week the corpus luteum starts to break down
progesterone and oestrogen concentrations fall uterus wall breaks down
FSH no longer inhibited, so begins to rise
cycle beings again

46
Q

what happens if fertilisation occurs

A

hCG produced by embryo –> detected on a pregnancy test

corpus luteum continues to make progesterone for next 2-3 weeks while the implanted embryo establishes a placenta

47
Q

what is the blastocyst

A

after fertilisation the zygote divides mitotically until a hollow ball of cells, the blastocyst is produced
it takes three days to reach the uterus and a further three or four days to become implanted in the lining of the uterus

48
Q

what is the trophoblast

A

the outer layer of cells of the blastocyst called the trophoblast develops into the embryonic membranes, the chorion and the amnion

49
Q

what is the chorion

A

develops villi which grow into the surrounding uterus tissue from which they absorb nutrients
increase surface area = villi
also secretes hCG which prevents breakdown of corpus luteum. hCG that is used as the basis of most pregnancy tests

50
Q

what is hCG

A

an immobilised enzyme

51
Q

what is the placenta

A

villi form part of the placenta which is connected to the foetus by the umbilical cord
amnion develops as a membrane around the foetus and encloses the amniotic fluid, a watery liquid which protects the foetus by cushioning it from physical damage
placenta is a GLAND, EXCHANGE SURFACE AND A BARRIER

52
Q

what are the hormones released during pregnancy

A

placenta produces oestrogen and progesterone which maintains the uterus walls so corpus luteum can now degenerate
progesterone inhibits oxytocin so uterus does not contract
oestrogen causes growth of uterus and mammary glands
o and p also inhibit FSH and LH
they also inhibit prolactin so no milk is made

53
Q

what are the hormones released after birth

A

progesterone levels decrease
oxytocin and prolactin are released by pituitary gland
oxytocin causes contraction of the uterus which leads to the delivery of the baby and placenta
prolactin causes synthesis of milk in the mammary gland

YEAR 2 BIO (11 decks)

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