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human biology > test 3 (sex cells and shit) > Flashcards

test 3 (sex cells and shit) Flashcards

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1
Q

what is mitosis?

A
  • cell division
  • for growth and repair
  • in somatic cells
  • a continuous process
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2
Q

what are the phases of cell division?

A
  • G1 (first growth phase) new proteins produced, grows and carries out normal tasks
  • S phase (synthesis phase), DNA duplicates
  • G2 (second growth phase), preparation for cell division
  • M phase (mitotic phase), cell divides into 2 daughter cells
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3
Q

what is interphase?

A

-G1-S phase

dna forms copies of itself during the S phase

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4
Q

what is prophase?

A
  • 2 pairs of centrioles become visible early on
  • centrioles move to piles
  • centrioles begin to produce spindle (microtubules)
  • nuclear membrane breaks down
  • chromatin tightly coils and chromosomes become visible
  • chromosomes are made of two chromatids joined at centromere
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5
Q

what is metaphase?

A
  • chromosomes line up down equator of cell

- centromere attached to a spindle fibre

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6
Q

what is anaphase?

A
  • chromosomes seperate at centromere
  • chromatids pulled by spindle fibres to poles of cell
  • move away from equator to poles
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7
Q

what is telophase?

A
  • chromosomes form tight groups at each pole
  • nuclear membrane forms
  • nucleolus appears
  • spindle fibres disappear
  • the cell is pinched into two daughter cells
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8
Q

what is cytokinesis?

A
  • division of the cytoplasm
  • furrow develops between the two nuclei
  • furrow deepens and cuts cytoplasm in half, results in two daughter cells
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9
Q

how is meiosis different to mitosis?

A
  1. parent cell divides twice
  2. four daughter cells are produced in meiosis (2 in mitosis)
  3. chromosome number is haploid (diploid crops divide to become haploid cells)
  4. the daughter cells are not genetically identical
  5. only occurs in sperm and ova
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10
Q

difference in anaphase 1 (meiosis + mitosis)

A
  • in mitosis, the centromere divide so that each chromatid becomes a chromosome
  • in meiosis, the chromatids are not split apart, instead the whole chromosome moves
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11
Q

interphase 2

A
  • there is no interphase 2 in meiosis

- dan does not double in preparation for the second division

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12
Q

what is prophase 2?

A
  • chromosomes condense and become visible

- spindle fibres start to form

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13
Q

what is metaphase 2?

A

-chromosomes line up down equator and spindle fibres attach

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14
Q

what is anaphase 2?

A

-chromosomes are split at the centromere and sister chromatids are pulled to opposite poles

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15
Q

what is telophase 2?

A
  • spindles disappear
  • nuclear membrane forms
  • cytokinesis - cytoplasm is split
  • 4 non-identical daughter haploid cells
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16
Q

what is spermatogenesis?

A
  • all stages occur in testes continuously after puberty
  • spermatogonia begin dividing by mitosis
  • daughter cells grow and become primary spermatocytes
  • final stage occurs when the spermatic matures into spermatozoa
  • takes 72 days
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17
Q

what is sperm?

A
  • microscopic
  • tail is used to propel cell forwards
  • the head contains nuclear material and enzymes
  • the middle has mitochondria
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18
Q

what is oogenesis?

A
  • millions of egg mother cells (oogonia) develop before birth in the ovaries
  • these cells divide by mitosis and will become ova
  • oogonia grow into primary oocytes
  • at birth, ovum is still in prophase 1
  • 1 per month matures metaphase 2
  • meiosis is complete if fertilised
  • produces 1 viable ovum and up to 3 polar bodies
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19
Q

gonads:

A
  • two testes
  • site of spermatogenesis
  • works best at 35°C
  • testes can contract/ expand depending on weather
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20
Q

testis:

A
  • lobules filled with tiny tubes
  • tubules lined with cells that produce sperm
  • interstitial cells lay in between the seminiferous tubules— produce testosterone
  • larger tubes join to form ducts
  • ducts lead out of testes via epididymus —> vas deferens
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21
Q

epidiymus:

A

-sperm stored here for up to a month

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22
Q

vas deferens:

A

-carries speed away from testes and connects to urethra

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23
Q

semen:

A

-require:
a water medium to swim
a nourishing environment that provides sugars they need to fuel their journey
protection against acidic conditions of vagina

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24
Q

ovaries:

A
  • made up of a connective tissue (stroma- made up of a layer of germ cells)
  • endocrine glands secrete oestrogen and progesterone
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25
Q

the ovarian cycle:

A
  • development of follicles and corpus luteum
  • at birth 400,000 immature eggs- only 400 mature
  • these eggs rest until puberty encased by primary follicles (single cell layer)
  • length 28 days
26
Q

ovarian cycle: secondary follicle

A
  • cells surrounding the egg enlarge, divide and secrete —> a fluid filled space around egg (now secondary follicle)
  • more fluid accumulated within follicle —> enlarges and moves to surface of ovary
  • now the mature follicle (14 days)
27
Q

how is the corpus luteum formed?

A
  • mature follicle bursts—> egg is swept down fallopian tube via cilia
  • ovulation occurs (release of egg)
  • the ruptured mature follicle collapses and forms a blood clot —> absorbed by follicle cells and enlarged to form corpus luteum
28
Q

corpus albican:

A
  • if no fertilisation, corpus luteum reaches max development 8-10 days
  • then degrades and becomes corpus albican
29
Q

menstrual cycle: (5 steps)

A
  • menstruation: 1-4 days —> uterine bleeding, shedding of endometrium
  • pre-ovulation: 5-12 days —> endometrial repair begins; development of ovarian follicle; uterine lining thickens
  • ovulation: 13-15 days —> rupture of nature follicle, releasing egg
  • secretion: 16-20 days—> secretion of mucus by endometrium glands, cervix and uterine tubes, movement and breakdown of unfertilised egg, development of corpus luteum
  • premenstruation: 21-28 days —> degeneration of corpus luteum, deteriorating of endometrium
30
Q

hormone regulation- endocrine glands

A
  • secrete hormones into extracellular fluid

- the secretion enters the blood transport system via capillaries

31
Q

hormone regulation : pituitary gland

A
  • secrete hormones that stimulate reproductive system

- secretes gonadatrophins

32
Q

follicle stimulating hormone FSH

A

-in females, stimulates the development and maturation of the follicle

33
Q

lutenising hormone LH

A
  • promotes final maturation, ovulation and formation of corpus luteum
  • during development, the follicle secretes oestrogen —> FSH reduces as oestrogen increases
34
Q

corpus luteum:

A
  • secretes progesterone + oestrogen
  • as progesterone increase, LH decreases
  • maintained by human chorionic gonadatropin (HCG)secreted by placenta
  • once placenta starts to secrete progesterone and oestrogen, (3 months into pregnancy) corpus luteum is no longer needed and starts to degenerate
35
Q

progesterone:

A
  • maintains endometrium
  • develops and maintains placenta
  • develops milk secreting glands in breasts
36
Q

hormone regulation in males: pituitary gland

A

secretes gonadotropin

37
Q

hormone regulation in males: FSH

A

stimulates epithelial tissue of seminiferous tubules to produce sperm

38
Q

hormone regulation in males: LH

A

stimulates cells in testes to secrete testosterone

39
Q

hormone regulation in males: testosterone

A

important for speed maturation and mate reproductive organ maintenance

40
Q

other hormones secretes from the pituitary gland:

A
  • prolactin (lactogenic hormone)-> production of milk

- oxytocin -> stimulates the concentration of the uterus and promotes contraction of muscle cells in the breasts

41
Q

fertilisation:

A
  • ovum is surrounded by corona radiata
  • sperm contain and enzyme in the acrosome capable of breaking down the corona radiata
  • sperm enters ovum, tail is absorbed and head moves thorough cytoplasm in form of male pronucleus
  • this mutates the completion of meiosis II and the nucleus of ovum becomes a female pronucleus
  • the 2 pronucleus fuse and form a zygote
42
Q

development of embryo: amnion/amniotic fluid

A 
amnion
-surrounds embryo
-secretes amniotic fluid into the cavity it forms
-expands as the embryo grows
-ruptures just before birth (water) 
amniotic fluid
-shock absorber
-maintains temperature
-allows embryo to move freely
43
Q

development of embryo: chorion

A
  • forked from outer blastocyst
  • becomes placenta
  • amnion fuses with chorion as it grows
  • chorionic villi protrude into endometrium and allow grander of nutrients from maternal to foetal blood
44
Q

development of the placenta

A
  • development from chorion- fully developed by 3 months has 5 functions
  • develops as blastocyst implants
  • contains blood vessels
  • pools of maternal blood surround villi
45
Q

the umbilical cord:

A
  • 2 arteries (carry blood to chorionic villi)

- 1 vein (carries blood from placenta to foetus

46
Q

changes for pregnant mother:

A
  • enlargement of breasts (hormones for milk-secreting tissue development)
  • increase in heart and blood volume (40%)
  • extra blood flow (placenta, kidneys)
  • increased urination
  • emotional changes (hormonal)
  • weight gain
  • hormone changes promote energy to covert to fat
  • water retention
47
Q

how to maintain a healthy pregnancy?

A
  • increase diet by 850kj
  • increase calcium, iron and folic acid
  • regular exercise
48
Q

disruptions to normal foetal development:

A
  • genetics, mutations or environmental factors
  • chemicals and drugs that cause physical defects
  • maternal diet (lack of folate can cause spina bifida)
49
Q

how to diagnose foetal health:

A
  • ultrasounds
  • fetoscopy (telescope size of a needle through uterine wall, foetal blood sampling)
  • chorionic villus sampling for genetic disorders (9-19 weeks)
  • electrocardiography (heart monitoring)
50
Q

labour preparations:

A

changes in hormones prepare the body for labour and child birth

  • pelvis ligaments soften
  • sensitivity in uterus increases
  • strengthened contractions of uterine muscles
  • foetus positions head in mothers pelvis
  • cervix softens, shortens and starts to open
51
Q

the first stage of labour:

A
  • contractions come in waves from top of uterus to cervix (like peristalsis) every 30 minutes
  • with each contraction, muscle fibres of the uterus shorten and pull on the cervix
  • this shortens cervix until it no longer protrudes into the vagina, begins to open
  • dialation allows for foetus to move deeper into pelvis
  • cervix fully dialated at 10cm
52
Q

the second stage of labour:

A
  • begins with breaking of waters
  • lasts 20mins-2 hours
  • contraction of the uterus and abdominal muscles push the foetus through the vagina
  • babies head turns towards mothers back
  • eventually head stretches the vagina and perineum
  • birth
53
Q

third stage of labour:

A
  • after birth
  • baby begins to breath
  • baby is connected to placenta
  • amnion, chorion and placenta still in uterus
  • umbilical cord is cut
  • baby covered in vernix (a waxy protective layer that washes off)
  • uterus contracts and pushes out placenta and other membranes
  • placental blood vessels constrict
  • uterus contractions squeeze uterine blood vessels shut, blood clot forms
54
Q

changes in the baby at birth:

A
  • infant becomes self supporting
  • lungs don’t function before birth- receives oxygen from placenta
  • alimentary canal doesn’t function
  • circulatory changes need to occur
55
Q

foetal circulation:

A
  • foetal blood is carried to and from placenta by blood vessels in umbilical coed
  • some blood (returning to foetus) flows through liver into inferior vena cava
  • other blood bypassed liver via ductus venosus to inferior vena cava
56
Q

foetal circulation: blood returning to foetus enters right atrium through:

A

1) right ventricle to lungs: considerable resistance due to collapsed lungs
2) right ventricle to ductus arteriosus to aorta - ductus arteriosus is a kung bypass to pulmonary artery to aorta
3) right atrium to left atrium through foremen ovale - foremen ovale is an opening between the two chambers

57
Q

circulation after birth:

A
  • lungs and liver must become fully functional
  • slap on bum initiates first breath or clamping umbilical cord
  • flap of foremen ovale is forced against wall of atrium by increased blood pressure, closing the opening (hole in heart is caused by failure to close)
  • ductus arteriosus is left as fibrous tissue
  • ductus venosus is constricted and closes
58
Q

changes to mother after birth:

A
  • puerperium (8 weeks)- mother reproductive organs slowly return
  • uterus begins to contract
  • discharge from shrinking uterus (breaking down of tissue)
  • blood volume decreased
  • slow pulse and body temperature
  • emotional changes
  • return of menstruation can be delayed up to 6 months (breastfeeding) or 10 weeks (not breastfeeding)
59
Q

milk production:

A
  • 16-25 loves
  • loves divided into lobules
  • lobules made up of alveoli
  • loves and lobules surrounded by fatty connective tissue
  • lobules ducts opens into spaces which act as reservoirs for milk
60
Q

lactation:

A
  • initiation and maintenance of milk secretion
  • increases hormones during pregnancy causes changes in breast
  • loves become more complex
  • colostrum is the first secretion (watery + yellow, contains little to no fat, high antibody content that is absorbed through infants intestine)
61
Q

milk let down reflex:

A
  • automatic response on suckling
    1) nerves in nipples stimulated- message sent to brain
    2) brain instructs pituitary gland to release oxytocin
    3) oxytocin triggers contraction of small muscles around lobules- milk is then ejected into ducts
    4) suckling infant can then draw milk through the nipple
62
Q

puerperium:

A

reproductive organs return to non- pregnant start- takes 8 weeks

human biology (14 decks)

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