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Human Reproduction Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what are humans in relation to sex

A

unisexual, with 2 separate sexes, female and male

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2
Q

what makes up the male reproductive organs

A

Primary sex organs - the testis
Ducts - epididymis, sperm duct (vas deferens), urethra
Accessory glands - prostrate gland
external genitalia - the penis

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3
Q

What does the scrotum contain

A

the testis

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4
Q

What are the functions of the scrotum

A
  1. temperature regulator - lower temp is needed for the formation of fertile sperm (2 to 3 degrees lower than body temp)
  2. houses and protects the testis
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5
Q

what are the testis

A

2 oval structures suspended outside the body in the scrotum

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6
Q

where are the testis during the embryonic stage

A

in the abdominal cavity just below the kidneys. before birth they descend into the scrotum

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7
Q

what do the testis consist of

A

many compartments, which contain the seminiferous tubules (these total to about 250 m in each testis)

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8
Q

what lines the tubules in the testis and what is between them

A

germinal epithelium lines them, between the tubules are groups of endocrine cells, the interstitial cells

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9
Q

what functions do the testis have

A

they produce

  1. sperm - by the germinal layer
  2. testosterone - by the interstitial cells
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10
Q

what ducts are found in the male reproductive organs

A
  1. epididymis
  2. sperm duct
  3. urethra
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11
Q

what is the epididymis

A

a highly convoluted tubule about 5m long

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12
Q

what is the epididymis formed from

A

the seminiferous tubules that join to form it

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13
Q

what are the functions of the epididymis

A

immature sperm cells enter the epididymis where they:

  1. mature - to become motile and fertile
  2. are stored for several months
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14
Q

what is the sperm duct

A

a continuation of the epididymis. it leaves the scrotum, passes through the prostrate gland and then enters the urethra

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15
Q

what is another name for the sperm duct

A

vas deferens

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16
Q

what is the function of the sperm duct

A

pushes mature sperm forward by strong peristaltic waves, from the epididymis into the urethra (ejaculation)

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17
Q

what is the urethra

A

the duct at the end of the uro-genital system leading to the exterior

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18
Q

what is the function of the urethra

A

it forms a common duct for the transportation of semen and urine, although these 2 processes never occur together

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19
Q

what is the prostrate gland

A

a plum-sized gland surrounding the urethra at the base of the bladder

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20
Q

what is the function of the prostrate gland

A

secretes a fluid that aids the transport of the sperm and contains enzymes that make sperm more active (this fluid makes up about 1/3 of the semen)

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21
Q

what is the Cowper’s gland

A

2 glands found at the base of the penis

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22
Q

what is the function of the Cowper’s glands

A

these glands produce an alkaline mucous-like fluid when sexually aroused. This fluid:

  1. neutralizes acidic urine that may still be in the urethra
  2. lubricates the urethra and external urethral opening to protect sperm from the mechanical damage during the ejaculation
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23
Q

what is the penis

A

the organ through which the urethra passes down

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24
Q

what does the penis consist of

A

special spongy tissue (erectile tissue).
running the length of the penis there are 3 sections of erectile tissue. 2 are situated on the dorsal side, the corpus cavernosa, and one on the ventral side, the corpus spongiosum

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25
Q

label a cross section of a penis

A

page 91

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26
Q

What is the primary mechanism that brings about an erection

A

the dilation of dorsal and central arteries supplying blood to the penis. This allows more blood to fill the three spongy erectile tissue chambers, causing the penis to lengthen and stiffen

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27
Q

why are erections necessary

A

without it sperm cannot be transferred to the females vagina during sexual intercourse

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28
Q

what protects the head of the penis

A

foreskin

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29
Q

what is the function of the penis

A

it deposits semen with sperm into the females vagina during copulation.

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30
Q

what is distinctive about the human penis

A
  • the human male is the only mammal that has no erectile bone (baculum) in the penis, it relies entirely on engorgement (filling up) with blood to reach its erectile state
  • the human penis is not attached to the abdominal wall but hangs free, this is in contrast to other mammals where the penis is stored internally until erect
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31
Q

what does semen consist of

A
  • sperm from the testis

- seminal fluid from the sperm duct and accessory glands eg. prostrate

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32
Q

what is the average volume of semen for an ejaculation

A

2.5 to 5 ml

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33
Q

whats the difference between ejaculation and erection

A

erection - stiffening of the penis

ejaculation - expulsion of semen

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34
Q

whats the difference in the female reproduction tract

A

it is much more complex because it produces ova, female hormones and it prepares the female body to sustain a developing fetus

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35
Q

what do the female reproductive organs include

A

ovaries
accessory organs - fallopian tubes, uterus and vagina
external genitalia - vulva

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36
Q

what are the ovaries

A

two almond shaped organs found in the pelvic cavity and held in position by ligaments

  • a germinal epithelium layer surrounds each ovary
  • primary follicles (tiny sac-like structures) containing an immature egg are embedded in the outer layer.
  • a primary follicle develops into a mature follicle (graafian follicle)
  • after ovulation the graafian follicle forms the corpus luteum
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37
Q

why are the total number of eggs determined at birth

A

because a female is born with these primary follicles

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38
Q

what are the functions of ovaries

A
  1. form and release eggs

2. production of oestrogen and progesterone

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39
Q

what are the fallopian tubes

A

muscular tubes lined with cilia. they stretch from each ovary to the uterus. each ends in a funnel shaped structure (the infundibulum) that has finger-like outgrowths (the fimbria)

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40
Q

what are the functions of the fallopian tubes

A
  1. provide a pathway between the uterus and ovary for eggs, sperm and the zygote
  2. are the site of fertilization and initial cell division of the zygote
  3. enable the egg or developing zygote to move towards uterus - by the action of muscles and cilia
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41
Q

what is the uterus

A

a hollow, pear shaped thick-walled, muscular organ. It is situated between the bladder and the rectum . During pregnancy it enlarges considerably but soon after birth almost returns to its original size

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42
Q

what is the lower part of the uterus and what does it do

A

the cervix, it projects into the vagina. normally its opening is only millimeters in diameter, allowing menstrual blood to leave the body and sperm to gain access. It must therefore dilate hugely during the birthing process.

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43
Q

what prevents miscarriages

A

the sphincter muscles of the cervix, which keep the uterus closed during pregnancy

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44
Q

what does the uterine wall consist of

A
  1. myometrium - a thick involuntary muscle layer (walls need to be thick so they can stretch when a baby develops)
  2. endometrium - a lining that is richly supplied with blood vessels
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45
Q

what role does progesterone play in relation to the endometrium

A

at ovulation it causes the endometrium to thicken to prepare for the implantation of the blastocyst

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46
Q

what happens to the endometrium if fertilization doesn’t occur

A

the upper layer of the endometrium becomes detached and is passed out together with the unfertilized egg. This occurs roughly every 28 days and is known as fertilization

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47
Q

what are the functions of the uterus

A
  1. its the organ in which the blastocyst implants, develops and grows
  2. the contraction of the myometrium enables the baby to be pushed out during birth
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48
Q

what is distinctive about the human uterus

A

they have a simplex uterus in which there is no separation between the horns and thus is still a singe cavity

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49
Q

what is the vagina

A

(birth canal) is a muscular passage between the uterus and the outside of the body - it has elastic, folded walls which allows it to stretch during intercourse and childbirth, the pH of the vagina is normally quite acidic which helps keep the vagina healthy and free from infection

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50
Q

what are the functions of the vagina

A
  1. its the place where sperm are deposited during intercourse
  2. forms a birth canal during birth
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51
Q

what is the vulva

A

it forms the external genitalia and plays no part in the reproductive process

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52
Q

what is the clitoris

A

a small mass of erectile tissue, found at the anterior end of the vulva. it is the female counterpart of the male penis and plays a role in sexual excitement of the female

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53
Q

what is puberty

A

the process of physical and psychological changes that lead to, the development of secondary sex characteristics as well as an immature individual becoming capable of reproduction

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54
Q

what effects the age at which puberty begins

A

genetics

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55
Q

around when does puberty begin

A

girls - 11 and 14

boys - 14 and 16

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56
Q

how do climates effect puberty

A

in warmer climates it usually begins sooner and it colder climates 1 to 2 years later

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57
Q

how does puberty start

A

the pituitary gland (stimulated by the hypothalamus) releases ganodatropins which initiates puberty

  • FHS stimulates ovaries to secrete oestrogen
  • LHS stimulates testis to produce testosterone

Testosterone and oestrogen then initiates changes to the gonads and to other parts of the body

the results of changes to the gonads are called primary sexual characteristics (as they influence the process of reproduction) other physical changes are referred to as secondary sex characteristics (as they have nothing to do with reproduction)

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58
Q

what physical changes occur in girls during puberty

A
  • breast development (10-12 yrs)
  • hair growth in pubic area and armpits (11-12 yrs)
  • increase in size of ovaries and priamry follicles
  • widening of pelvis and thus hips (provide wider birth canal)
  • deposition of fat on thighs, hips, upper arms and buttocks
  • start of the menstrual cycle (12-18 yrs)
  • first menstrual bleeding (menarche) occurs 2 yrs after breasts start to develop
  • menstruation is unique to humans and close primate relatives such as chimpanzees
  • ovulation (occurs after the 1st year of menstruation is 80% of girls)
  • growth spurt lasting 2 to 3 yrs
  • possible acne as skin gets oilier
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59
Q

what physical changes occur in boys during puberty

A
  • enlargement of testis and penis (max size reached about 6 yrs after the onset of puberty)
  • hair growth in the pubic area and armpits (13-14 yrs)
  • increase in size of larynx, deeper voice
  • enlargement of skeletal muscles and broadening of shoulders (by end of puberty bones are heavier and muscle mass doubles)
  • sperm production begins
  • growth spurt of 2 to 3 years occurs
  • acne can occur (more common in boys that in girls)
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60
Q

what are some distinctive human sexual activitues

A
  • human males are sexually fertile all the time
  • menstruation
  • mating in humans is not confined to the period of time when ovulation occurs
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61
Q

draw and label the life cycle of humans

A

page 96

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62
Q

what is gametogenesis

A

the formation of mature gametes (sperm and eggs) by the reproductive glands (gonads)

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63
Q

how does gametogenesis work

A

it involes meiosis (nuclear division) which results in a halving of the number of chromosomes (from 46, in body cells, to 23, in the gametes) this is to ensure that the number of chromosomes in the fertilized egg return to 46 after fertilisation

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64
Q

what is spermatogenesis

A

the sequence of events during which mature, haploid sperm are produced from the germinal epithelium in the seminiferous tubules of the testis

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65
Q

what hormone is essentail for making sperm

A

testosterone

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66
Q

elaborate on spermatogensis throughout a males life

A
  • it begins at puberty between 14 and 15 yrs old and continues throughout life
  • everyday a healthy adult male makes about 400 million sperm, this large number increases the chance of fertilisation
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67
Q

what are the different phases of spermatogenesis, elaborate on them

A
  1. Multiplying phase - the diploid (2n) spermatogonia of the germinal epithelium divide repeatedly by mitosis to form new spermatogonia (2n)
  2. growth phase - some spermatogonia mature and grow in size to develop into primary spermatocytes
  3. reduction phase - the primary spermatocytes undergo the first meiotic division (reduction division) each forming 2 haploid spermatocytes (n) with 23 chromosomes. These undergo the second meiotic division, resulting in 4 haploid spermatids (small round cells)
  4. differentiation phase - during this phase the spermatids lose cytoplasm and unnecessary cell organelles and differentiate into immature sperm
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68
Q

draw and label a spermatogenesis diagram

A

page 97, slide 15

69
Q

how long does spermatogenesis take

A 
72 days (from the primary spermatocyte to immature sperm)
the immature sperm are moved into the epididymis where they mature, becoming motile and fertile, and can be stored for several months
70
Q

summarise spermatogenesis in a sentence

A

diploid cells in the seminiferous tubules of the testis undergo meiosis to form haploid sperm cells

71
Q

draw, label and annotate a diagram of the structure of sperm

A

page 97

72
Q

how long can sperm survive after ejaculation

A

48 hours in the female reproductive tract as it obtains nourishment from seminal fluid and female secretaion

73
Q

what is oogenesis

A

the production of haploid, mature eggs in the follicles of the ovaries

74
Q

what are the differences in the sequence of oogenesis compared to that of spermatogenesis

A
  • no. of eggs is determined before birth
  • the mature eggs are not formed continuously throughout life (starts at puberty, stops at menopause)
  • oogenesis occurs in a menstrual cycle, an egg reaches maturity every 28 days while sperm are produced daily
75
Q

what are the phases of oogenesis (elaborate)

A
  1. multiplying phase - before birth, germ cells from the germinal epithelium which surrounds the ovary, sink in and divide by mitosis to form the primary follicles (each follicle has a large central cell, the oogonium (2n), surrounded by a single layer of cells, the theca)
  2. growth phase - from puberty the primary follicles start periodically growing and developing to form graafian follicles. within each graafian follicle the oogonium grows into a primary oocyte
  3. reduction and maturity phase - the primary oocyte (2n) undergoes meiosis resulting in an egg (n)
    - there is no splitting of the cell during meiosis. of the 4 haploid nuclei one will form the nucleus of the egg, the other 3 will degenerate
    - mature graafian follicles move periodically to the surface of the ovary, where they burst, releasing the mature egg and surrounding follicle cells (a process called ovulation)
76
Q

what is ovulation

A

the release of a mature egg from a graafian follicle in the ovary every 28 days. The egg survives for 24 hours after ovulation

77
Q

summarise oogenesis in 2 sentences

A

diploid cells in the ovary undergo meiosis to form a primary follicle consisting of haploid cells. One cell develops into an ovum contained in a graafian follicle

78
Q

label and draw a diagram of oogensis

A

page 99, slide 15

79
Q

draw, label and annotate the strcture of an egg

A

page 99

80
Q

elaborate on the menstrual cycle

A

its length ranged from 21 - 35 days (28 days being the average), it includes the uterine and ovarian cycles. these cycles occur from puberty until menopause and are controlled by the endocrine system

81
Q

what does the ovarian cycle consist of

A
  1. development of the graafian follicle (follicular phase)
  2. ovulation (ovulatory phase)
  3. formation of the corpus luteum (luteal phase)
82
Q

explain 1. development of the graafian follicle

A

1st phase, primary follicles mature and get ready to release an egg cell
FHS stimulates this process
during this process the primary oocyte follicle undergoes meiosis and develops into a haploid egg cell (ovum)

83
Q

explain 2. ovulation

A

LH stimulates the rupturing of the graafian follicle which allows an egg to be released
this takes place on about day 14 of the cycle

84
Q

explain 3. formation of the corpus luteum

A

after ovulation the remains of the graafian follicle (under the influence of LH and FSH) changes into glandular tissue called the corpus luteum (this structure produces large amounts of preogesterone and oestrogen)

85
Q

what makes human ovulation unique

A
  1. human females can be sexually active at any time, not just when they’re going to ovulate
  2. there arent any external signs or sexual excitement to signal ovulation
86
Q

label changes in the ovary durin ovarian cycle diagram

A

page 100

87
Q

what is the uterine cycle

A

series of changes in the endometrium and is regulated by hormones

88
Q

what are the 2 main phases of the uterine cycle

A
  1. changes in the endometrium - oestrogen (secreted from maturing follicles) starts the repairing of the endometrium, days 6-14 of the menstrual cycle
    - progesterone and oestrogen (from the corpus luteum) cause the endometrium to thicken becoming more glandular and vasuclar to be suitable for the implantation of a fertilised egg
  2. menstruation - high levels of oestrogen and progesterone trigger negative feedback, stopping LH and FSH release, as a result the corpus luteum degenerates and progesterone secretion stops
    - with no hormone to maintain the endometrium the lining breaks down and is shed (menstruation)
    - the detached tissue and blood pass out through the vagina as menstrual flow for 3-7 days
89
Q

Menstrual cycle changes in ovary and uterus, diagram and graphs

A

page 102

90
Q

how does hormonal control (negative feedback) work

A
  • under the influence of FSH, a primary follicle develops into a graafian follicle and causes the ovaries to produce oestrogen
  • oestrogen then stimulates the pituitary glands to produce LH
  • LH causes the graafian follicle to form the corpus luteum, which secretes progesterone
  • the increases progesterone and oestrogen levels activate a negative feedback mechanism which stops the pituitary from secreting FSH and LH
  • as there is no FSH a graafian follicle will not develop and no oestrogen, and later progesterone will be produced by the ovary
  • because of the low levels of oestrogen and progesterone the secretion of FSH and later LH, will no longer be supressed and the whole cycle starts agaun
91
Q

what is menopause

A

when the ovaries stop producing oestrogen and progesterone at about age 46-54, as a result the ovaries stop releasing eggs and menstruation stops

92
Q

what does menopause cause

A
  • hot flushes
  • mood changes
  • atrophy (degeneration of the reproductive organs)
  • bone mass loss
  • increasing risk of cardiac disease

some doctors prescribe HRT (hormone replacement theory) of low dose oestrogen-progesterone preparations in order for women to cope during menopause

93
Q

what is the difference between aquatic animals and humans in regards to fertilisation

A

with humans sperm must be transferred as close to the egg as possible, whereas with aquatic animals the sperm and ova are simply released into the water and fertilisation occurs externally

94
Q

whats the difference between copulation and fertilisation

A

copulation - transfer of sperm into the vagina of the female when the male organ (the penis) is inserted and sperm are deposited near the cervix

only after copulation can fertilisation occur

fertilisation - the fusion of the sperm nucleus with the eg nucleus to form a diploid cell known as zygote

95
Q

how sperm get to ova label diagram

A

page 105

96
Q

what is gestation

A

the time between conception (fertilisation) and birth, during which the embryo and then the fetus develops in the uterus. Usually gestation lasts about 280 days, 40 weeks

97
Q

what are the stages of prenatal development

A
  1. early development (0 to end of 2 months)
    - fertilisation
    - blastocyst and implantation formation
    - embryo formation
  2. later development (3 months to birth)
98
Q

where does fertilisation occur

A

in the fallopian tubes

99
Q

where does the sperm go after being deposited in the vagina

A

through the cervix, uterus and into the fallopian tubes until they reach the egg

100
Q

how does the egg get to the fallopian tubes

A

it is sucked into the fallopian tubes by the action of fimbriae

101
Q

where in the fallopian tube does fertilisation occur

A

usually in the top part (outer third)

102
Q

explain the fertilisation process

A
  1. thousands of sperm surround the egg
  2. hydrolytic (splitting molecules using water) enzymes break down the follicle cells
  3. only one sperm penetrates the membrane of the egg, the tail is discarded
  4. the nuclei of the sperm and egg fuse forming a diploid zygote
  5. a fertilisation membrane forms immediately which prevents other sperm from entering the egg
103
Q

draw and label a diagram of the process of fertilisation

A

page 106

104
Q

what happens after fertilisation (blastocyst formation and implantation)

A
  1. the diploid zygote divides immediately by mitosis to form two cells
  2. each of these divides repeatedly until a solid ball of cells (the morula) is formed
    - the morula develops into a hollow, fluid filled ball of cells called the blastocyst
    - the outer cells forming the wall of the blastocyst form a layer known as the trophoblast (tropho=relates to feeding)
  3. an inner cell mass develops from the trophoblast
  4. these changes take place as the developing embryo moves along the fallopian tube towards the uterus (it moves by a combo of peristaltic waves and rhythmic beating of the tubes cilia)
  5. after a few days in the uterus the blastocyst sinks into the thickened, highly vascular endometrium (called implantation and occurs about 20 days after fertilization)
105
Q

what takes place after implantation (formation of the embryo)

A
  1. inner cell mass forms the;
    - embryo (the future baby)
    - amnion (membrane that becomes fluid filled)
    - yolk sac (forms part of the umbilical cord)
  2. trophoblast develops villi that grow into the endometrium to form the placenta
106
Q

label a young embryo diagram

A

page 107

107
Q

what layers does the embryo develop into

A
  1. ectoderm (outer layer)
  2. endoderm (inner layer)
  3. mesoderm (between the endo and ecto)
108
Q

what comes from these embryo layers

A

all the different tissues and organs of the body will form from these layers by further cell division or differentiation, during this time all major organs appear

109
Q

how much does the embryo grow during the differentiation period

A

1.5mm - 30mm

110
Q

what can cause embryological malformations

A
  • drugs
  • viruses (german measles)
  • environmental factors (pesticides)
111
Q

how long does the embryonic phase last

A

third week until the eighth week after fertilisation

112
Q

how long does the later development or foetal period last

A

9th week to the end of pregnancy

113
Q

what changes occur during the foetal period

A

only some differentiation occurs

the main change is rapid growth of the body

114
Q

what happens as the fetus approaches full term

A
  • bones ossify
  • adipose (fat) tissue is formed
  • antibodies enter the fetus via the placenta to fight diseases
  • the fetus usually turns so that the head is fcaing down towards the cervix
115
Q

what is an ultrasound

A

a type of technology that uses high-pitched sound waves that cannot be heard by the human ear, the sound bounces off solid structures, eg. the embryo and fetus, therefore these echoes form an image and give the doctor a view of the growing fetus and info of:

  • fetal size, age, growth
  • an early diagnosis of any complications
116
Q

what is the difference between an embryo and a fetus

A

embryo - refers to the developing zygote until 8 weeks

fetus - after the organs have develped from 9 weeks until birth

117
Q

label a diagram of a young fetus

A

page 111

118
Q

what is the placenta

A

temporary disc shaped organ, richly supplied with maternal and fetal blood vessels. it connects with the fetus with its mothers blood at the end of the umbilical cord

119
Q

why dont the fetal and mothers blood mix and what would happen if they did

A

because the fetal capillaries have thin walls

if the blood mixed it could cause a blood clot resulting in the death of the fetus

120
Q

how do substances therefore move between the mother and fetal blood

A

by diffusion

121
Q

what are the functions of the placenta

A
  1. oxygen and dissolved food substances such as glucose, amino acids, fatty acids, ions and vitamins pass from the mom to the fetal blood system for nutrition and respiration
  2. fetal waste products of metabolism, eg. urea and carbon dioxide pass into the maternal blood system for excretion
  3. some maternal antibodies pass to the fetus providing temporary passive immunity to certain diseases (results in the child being immune to most diseases during the 1st 6 months)
  4. the placenta acts as a barrier (micro filter) preventing many pathogenic microorganisms and drugs from entering the fetus from the mother. (some pass through, german measles, HIV and syphilis)
  5. the placenta also has endocrine functions
122
Q

what are the endocrine functions of the placenta

A
  1. after 3 months of pregnancy the placenta takes over the function of secreting progesterone and oestrogen from the ovaries (corpus luteum)
    - these hormones are essential for maintaining the pregnancy
    - progesterone prevents menstruation which would cause the loss of the fetus
  2. late in pergnancy it secretes relaxin, a hormone which relaxes joints and ligaments to assist in the delivery of the baby
  3. in early pregnancy the placenta secretes human chorionic gonadotropin which is the basis of many pregnancy tests
123
Q

what is the amnion

A

a membrane that surrouds the developing fetus and embryo, it secretes a fluid called amniotic fluid that fills the amniotic cavity

124
Q

what is amniotic fluid

A

consists of about 99% water, fetal cells and waste products

the cells contain fetal genetic info

125
Q

what are the functions of amniotic fluid

A

its essential for developing fetuses
1. supports the fetus - allowing it the freedom to move easily and so prevent malformations due to gravity or pressure

  1. it cushions and protects the fetus from damage
  2. provides a medium in which to practice breathing and swallowing movements
  3. it holds urine as it is released from the fetus
  4. it protects the fetus against changes in temperature and dehydration
126
Q

what is the umbilical chord

A

a flexible cord extending from the fetuses abdomen to the placenta, it joins the fetus to its mother and contains two umbilical arteries and a single umbilical vein

127
Q

what are the functions of the umbilical cord

A
  1. umbilical arteries - carries waste (carbon dioxide and other excretory waste) away from fetus, these waste products diffuse into the mothers blood and are excreted
  2. umbilical vein - brings oxygenated blood and nutrients (glucose and amino acids) to the fetus from the mother
128
Q

how long is the first trimester and what changes occur

A

first 12 weeks (during this time risk of birth defects and miscarriages are highest)

  • menstruation stops
  • woman experiences tiredness, mood swings, cravings or distaste for certain foods
  • nausea or morning sickness, which occurs in 70% of women and can occur at any time of the day
  • breasts become tender and swollen
129
Q

how long is the 2nd trimester and what changes occur

A

weeks 13 to 28

  • women have more energy
  • morning sickness lessens, eventually disappearing
  • uterus starts expanding, visible baby bump will appear
  • moving of fetus can be felt (4th month)
  • patches of darker skin can appear on the face (mask of pregnancy)
130
Q

how long is the 3rd trimester and what changes occur

A

weeks 29 to 40

  • final weight gain takes place (fetus will be gaining about 28g per day)
  • women will feel more frequent stronger movements of the fetus
  • many women find breathing difficult
  • breast become tender and may leak colostrum (watery pre-milk fluid)
  • uterus muscles begin contracting (help the mom prepare for birth)
  • mothers abdomen changes shape, drops down, due to the fetus turning in a downward position for birth, fetal head descends into pelvic cavity (breathing becomes easier, reduces bladder capacity, often backache)
131
Q

what is birth

A

expulsion of the fetus, placenta and surrounding membranes from the uterus

132
Q

why does birth take place

A

the placenta becomes less effective

133
Q

what is distinctive about birth in humans

A
  1. the human baby s born relatively immature and very helpless, but if it grew any larger it wouldnt be able to leave the body succesfully because:
    - human birth canals are much narrower than other mammals as we are upright and bipedal which requires a narrower pelvis
    - the brain is much larger than that of other primates, it enlarged any more it wouldnt pass through the birth canal
  2. the baby is usually born head first, the head is the largest diameter of the babies body
134
Q

how does birth occur

A

for a normal birth the fetus must lie with its headpoiting downward towards the cervix

just before birth, very high levels of oestregen in the mothers blood cause the hypophysis to release the hormone oxytocin, which promotes contraction of the uterine wall

entire birth process may take from a few hours to well over a day

135
Q

what are the 3 stages of birth

A
  1. dilation of the cervix
  2. delivery of the baby
  3. expulsion of the placenta
136
Q

explain 1. dilation of the cervix

A
  • Myometrium starts contracting
  • This forces the amnion and foetus towards the cervix
  • Cervix and uterus start to dilate
  • When the cervix is fully dilated, the amnion breaks under pressure, passing
    ‘water’ through the birth canal
137
Q

explain 2. delivery of the baby

A
  • Powerful contractions of uterus and abdominal muscles push the baby out
    head first
  • Umbilical cord tied and cut
  • Fontanelles allow for the head to change shape as it is forced through the birth
    canal
138
Q

explain 3. expulsion of the placenta

A
  • 20 min after delivery
  • umbilical cord + placenta come away from uterine wall
  • contractions force it out
139
Q

what are the birth options

A

vaginal childbirth (natural birth(

cesarean section

140
Q

what are mammary glands

A

organs in female mammals that produce milk to feed young offspring

in humans mammary glands are in the breasts and made up of milk secreting cells

141
Q

what is lactation

A

milk production

142
Q

label diagram of mammary gland

A

page 116

143
Q

explain the lactation process

A
  • during pregnancy oestrogen and progesterone stimulate the growth and development of the milk ducts in the breasts
  • after birth prolactin from the pituitary gland stimulates the mammary glands to produce milk
  • a second hormone (oxytocin) from the hypothalamus causes the release of milk from the glands
144
Q

why is breast feeding favoured above bottle feeding

A

it contains antibodies which can help a baby fight infections, it contains all the nutrients in the perfect proportions for optimal growth and it is cheap and easy

145
Q

how do contraceptives work

A
  1. prevent egg being releases (prevent ovulation)
  2. prevent sperm reaching egg (prevent fertilisation)
  3. prevent embryo implantation or development
146
Q

what is an example of preventing ovulation

A

The pill, which contains oestrogen and progesterone that prevent pregnancy by inhibiting ovulation and therefore fertilization

147
Q

give an example of preventing fertilisation

A
  1. sterilisation - (vasectomy in men) the sperm duct is cut, preventing sperm from being expelled, the sperm that are made eventually break down and get absorbed back into the body
    - (tubal ligation in women) the fallopian tubes are tied which prevents the egg and sperm from meeting
  2. condom - a physical barrier used during sex, reduces the possibilty of STI’s
  3. spermicide - chemicals that kill sperm, usually used with condoms because alone they’re not very effective
  4. diaphragm - a shallow bendable cup placed over the cervix before sex and left in place for at least 6 hours after sex
148
Q

give an example of preventing embryo implantation and development

A

MAP (morning after pill) - must be started within 72 hours of having sex, the oestrogen progesterone combo confuses the hormonal signals

UID (intrauterine device) - object made of copper, stainless steel or plastic, inserted into the uterus, prevents implantation of the blastocyst

RU 486 (mifepristone) - a pill, taken within the first 7 weeks of pregnancy, it blocks the the action of progesterone so that if implantation occurs then the endometrium disentergrates resulting in miscarriage

149
Q

what are some other methods of contraception

A

Injectables (3 month injection) - contains progesterone

rhythm method - unprotected sex during the ovulation period is avoided

150
Q

when is the incidence of STI’s highest

A

15-29 yrs of age

151
Q

give examples of STI’s

A
  1. caused by viruses - HIV/Aids, genital warts, genital herpes
  2. caused by bacteria - gonorrhoea, syphilis
  3. caused by fungi - thrush
152
Q

what are some symptoms of Aids

A
  • loss of appetite
  • rapid weight loss
  • diarrhoea lasting longer than a month
153
Q

what is syphilis

A

most commonly caused STI after aids

caused by tears in mucous membranes in the genital areas

154
Q

how is syphilis transmitted

A

sexually or to the fetus

155
Q

how is syphilis diagnosed

A

blood tests

156
Q

what are some symptoms of syphilis

A
  • small bump on penis, vagina or cervix that develops into a painless sore or ulcer
  • skin rash and mild fever
  • damage to many organs can occur after ten or more years
157
Q

how do you treat syphilis

A

antibiotics

158
Q

what is gonorrhoea

A

casued by bacterium that live and breed in the moist, warm linings of the reproductive and urinary tubes

159
Q

what are symptoms of gonorrhoea

A

in women

  • panful urination and sex
  • cloudy, yellowish vaginal discharge
  • starts in the cervix, 50-60% of women dont know because they don’t have symptoms at first

in men
- yellowish urethral discharge and painful urination
- testicles are painful
85% of infected men symtoms develop within 2-10 days of being infected

160
Q

what is the treatment for gonorrhoea

A

antibiotics
It is important to:
- retest the infected person once the antibiotics are finished
- treat all sexual partners of the infected person
- abstain from sexual activity until gonorrhoea has cleared up

161
Q

what are the complications of gonorrhoea

A
  • infection can spread resulting in pelvic inflammatory disease, this can damage reproductive organs and can lead to infertility
  • in pregnant women there’s an increased risk of an ectopic pregnancy, a miscarriage or premature birth
  • during childbirth the bacteria may pass from a mother to her baby, this could lead to pneumonia or a serious eye infection that can cause blindness in the baby
  • re-infection with gonorrhoea is common
162
Q

how to avoid or prevent the transmission of STI’s

A
  • abstain from sex
  • abstain from alcohol and drugs
  • choose sexual partners carefully
  • use a condom
  • don’t ignore symptoms
163
Q

what are the possible causes of male infertility

A
  1. damage to the testis, due to mumps, chemo, trauma or surgery
    - testicular damage can lead to a low sperm count or poor sperm quality
  2. sometimes the sperm ducts can be blocked due to an infection
  3. most cases however don’t have identifable causes
164
Q

what treatment can help male infertility

A
  • if sperm count are too low due to incorrect levels of LH and FSH, hormone injections are given
  • surgical inervention can be attempted to clear blocked sperm ducts
165
Q

what causes female infertility

A
  • problems with ovulation (viable eggs are not made)
  • blocked oviducts that prevent egg and sperm from meeting
  • problems with the uterus (fibroids) which can prevent the implantation of blastocyst
166
Q

how can female infertility be treated

A
  1. fertility drugs
    - in general these drugs cause the release of hormones that trigger or regulate ovulation
  2. surgical treatments
    - unblocking fallopian tubes, removing fibroids, clearing up endometriosis
  3. assisted conception
    - artificial insemination = sperm donor
    - in vitro fertilisation (IVF) = egg donor
    - gamete intra-fallopian transfer (GIFT)
    - intra-cytoplasmic sperm injection (ICSI)
167
Q

what is surrogacy

A

when a women carries a baby on behalf of future parents who are medically unable to do so

this can be done by IVF or artificial insemination , meaning the embryo and resulting baby will not be genetically related to the surrogate mother

  • the surrogate surrenders any parental rights
  • surrogacy must be approved by a high court
  • surrogacy may not be done for commercial gain
168
Q

what is fetal alcohol syndrome (FAS)

A

a pattern of birth defects, learning and behavioural problems affecting children whose mothers consumed alcohol during pregnancy

there are currently an estimated 2 million people in SA with FAS

during pregnancy the alcohol freely crosses the placenta and causes damage to the developing embryo or fetus

169
Q

what are some features of FAS

A

phyysical features:

  • short
  • low birth weight
  • poor weight gain
  • microcephaly

other features become more evident as the child grows:

  • poor attention span
  • poor motor skills
  • slow language development
  • hyperactivity disorder
  • learning disabilities or mental retardation
  • poor social skills

there is no treatment

Biology (11 decks)

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