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Human Biology > Chapter 10.2 + 11 > Flashcards

Chapter 10.2 + 11 Flashcards

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1
Q

what are gametes?

A

sperm and ova produced in the ovaries and testes

they’re the result of meiosis

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2
Q

what is haploid vs diploid

A

haploid = daughter cells with half the number of chromosomes that were present in the original cell.

diploid = number of chromosomes in body cells.

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3
Q

define meiosis

A

the production of gametes with half the usual number of chromosomes.

the process involves two divisions, but chromosomes only duplicate once.

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4
Q

mitosis and meiosis differences

A

mitosis = one duplication of chromosomes and one nuclear division. meiosis = one duplication of chromosomes and two nuclear divisions.

mitosis = produces two diploid cells. meiosis = produces 4 haploid cells.

mitosis = homologous chromosomes do not pair. meiosis = homologous chromosomes pair.

mitosis = chromosomes do not change their genetic makeup. meiosis = genetic makeup of chromosomes can be changed through crossing-over.

mitosis = produces new cells for growth and repair. meiosis = produces haploid gametes for sexual reproduction.

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5
Q

explain variation in daughter cells and what it is a result of

A

a characteristic of meiosis where it is able to produce daughter cells that vary in their genetic information (offspring will differ from each other).

result of:

  • crossing over
  • non-disjunction
  • random/independent assortment
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6
Q

what is crossing over

A

when homologous chromosomes are paired, the chromatids may cross, break and/or exchange segments.. resulting in a new combination of alleles along the chromosome.

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7
Q

when does crossing over occur and what does it ensure?

A

occurs in prophase I.

ensures chromosomes passed on to the offspring are not exactly the same as those inherited from parents.

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8
Q

explain non-disjunction

A

failure of paired homologous to seperate during the first meiotic division or failure of chromatids to seperate during the second meiotic division.

  • severe and distinctive birth defects can occur
  • often miscarriage occurs early in pregnancy
  • daughter cell receiving an extra or lacking a chromosome.
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9
Q

what is a trisomy?

A

inheritance of an extra copy of a chromosome

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10
Q

what is trisomy 21?

A

down syndrome.

  • characteristic facial appearance
  • variable degrees of intellectual disability
  • physical abnormalities
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11
Q

what is trisomy 13?

A

Patau syndrome.

  • intellectual disability
  • a small head
  • extra fingers or toes
  • cleft palate and/or lip
  • abnormalities of the ears and eyes
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12
Q

what is trisomy 18?

A

Edwards syndrome.

  • intellectual disability
  • defects in eyes, ears, hands and head
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13
Q

what is a monosomy?

A

where an individual is missing a chromosome

- severe malformations and often miscarriage results

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14
Q

what is partial trisomy and monosomy?

A

when only part of the chromosome is missing.

- partial trisomy 21 can result in many of the same symptoms as Down syndrome.

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15
Q

explain random/independent assortment

A

any single human egg receives one of two possible chromosomes 23 times (also occurs in sperm cell).

thus, when a sperm fertilises an egg, the resulting zygote contains a combination of genes arranged in an order that has probably never occurred before and never will again.

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16
Q

what is cancer?

A

cancer is a malignant growth, where cells uncontrollably divide.

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17
Q

define tumour

A

an abnormal tissue mass resulting from the uncontrolled division of cells.

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18
Q

define malignant

A

tumour cells can spread to other parts of the body, known as metastasis.

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19
Q

define benign

A

abnormal tissue that is not able to invade normal tissue. however they grow and put pressure on surrounding tissue.

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20
Q

what are 6 causes of cancer

A
  1. carcinogens
    - environmental factors that can trigger malignant tumours
  2. UV radiation
    - sunburn + exposure from sunlight
    - skin cancer
  3. X- rays
    - exposure is limited in Australia
  4. ionising radiation
    - radium and ores of uranium
    - hiroshima + nagasaki
  5. viruses
    - HPV linked with cervix cancer
  6. chemical carcinogens
    - alcohol, asbestos, soot and tar, organic solvents in glues and paints and tobacco tar.
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21
Q

3 most common cancers found in women

A

lung, breast and bowel (colorectal)

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22
Q

3 most common cancers found in men

A

lung, prostate and bowel (colorectal)

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23
Q

cervical cancer

A

caused by human papilloma virus (HPV), transmitted by genital skin contact during intercourse.

usually clears up in 8-14 months and goes by unnoticed.

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24
Q

tests for cervical cancer

A

a Pap smear. involves collecting cervical cells and examining them under a microscope.

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25
Q

breast cancer

A

most common type of cancer in Australian women.

tests = mammography (x-ray of breast tissue) - capable of detecting tumours as small as 1cm in diameter.

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26
Q

bowel cancer

A

when a malignant tumour develops in the large intestine, colon or rectum. symptoms are hard to detect.

tests = faecal occult blood test (FOBT) - detects traces of blood in faeces. blood can be traced to polyps or bowel cancer through colonoscopy.

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27
Q

what are polyps?

A

small growths in the colon or rectum and may become cancerous.

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28
Q

gametes

A

a sperm or egg cell

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29
Q

gonads

A

a sex organ; testis or ovary

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30
Q

zygote

A

a fertilised egg from which a new individual develops

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31
Q

primary sex organs

A

responsible for the reproduction of gametes (gonads)

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32
Q

secondary sex organs

A

organs essential for reproduction, but do not produce gametes (vagina and penis)

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33
Q

what are testes responsible for and explain them

A

responsible for the production of spermatozoa (sperm).

they’re held and supported in a skin-covered pouch called the scrotum.

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34
Q

what do smooth muscle fibres in the scrotum do?

A

smooth muscle fibres in the wall of the scrotum move the testes closer or further away from the body as sperm production and development must take place at 2ºC below normal body temperature.

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35
Q

epididymis

A

highly folded tubule (5-6m in length) allowing space for sperm storage and time for maturation.

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36
Q

vas deferens (sperm duct)

A

epididymis tubule continues to become the vas deferens, carrying sperm away from testis. joins urethra under the bladder.

37
Q

sperm

A

for transfer into a females body, and to reach the egg for fertilisation, sperm must be in liquid (semen/seminal fluid).

38
Q

semen

A

nourishes and aids the transport of sperm and is a mixture of secretions from three glands:

  • seminal vesicles
  • prostate gland
  • bulbo-urethral glands

urethra carries sperm and semen through penis to a slit-like opening at the tip

39
Q

what are the seminal vesicles?

A

a pair of pouch-like organs about 5cm in length located behind the urinary bladder.

they secrete thick fluid that is rich in sugars and makes up about 60% of semen volume.

40
Q

what is the prostate gland?

A

a single gland, shaped like a doughnut where the two vasa deferntia join the urethra.

it secretes a thin, milky, alkaline fluid that also becomes apart of semen.

41
Q

what are the blubo-urethral glands?

A

two small yellow glands each about the size of a pea located just below the prostate on either side of the urethra.

secrete clear mucus which is carried to the urethra by a duct from each gland.

secretion acts as a lubricant and much precedes the emission of seminal fluid.

42
Q

what do the female gonads consist of?

A

two ovaries. responsible for the production of ova (eggs).

each ovary is an almond-shaped gland approximately 3cm in length

43
Q

what does each ovary contain?

A

a mass of connective tissue called the stroma which is surrounded by a layer of cells containing numerous germ cells, each composed in a follicle. as a follicle matures, it moves to the surface of the ovary and ruptures.

44
Q

explain the pathway of the egg once it ruptures

A

expelled into funnel-like opening of uterine tube (aka fallopian tubes). there are two uterine tubes, extending from each ovary. these tubes carry an egg from the ovary to the uterus.

the funnel like opening near the ovary is fringed with finger-like projections called fimbriae, which help guide the egg into the uterine tube.

the lining of the tube contains cilia whose movement carries the egg towards the uterus.

contraction of smooth muscles in the wall of the uterine tube also aids this movement of the egg.

45
Q

explain the structure and location of the uterus

A
  • hollow, pear-shaped organ situated behind the bladder and in front of the rectum.
  • wall of the uterus is made up of smooth muscle with soft mucosal lining (endometrium) playing a role in embryo development.
46
Q

explain the structure and location of the cervix

A
  • neck of the uterus, separating it from the vagina
47
Q

explain the structure and function of the vagina

A
  • it is a muscular canal leading to the outside of the body and is capable of considerable stretch in the formation of the birth canal
  • receives male penis during sexual intercourse
48
Q

explain the structure and function of the hymen

A
  • a fold of tissue partially covering the external opening of the vagina
49
Q

the vulva refers to the region of the female reproductive system consisting of…?

A
  • labia majora
  • labia minora
  • clitoris
50
Q

explain the labia majora

A

two flesh folds of skin, made up of fat and fibrous tissue, containing glands that produce an oily secretion. outer surfaces are pigmented and inner surfaces are smooth.

51
Q

explain the labia minora

A

beneath and between the labia majora are two smaller folds of skin, pinkish in colour, without fat and lacking hair. they surround the space into which the urethra and vagina open.

52
Q

explain the clitoris

A

the upper end of the labia minora surround the clitoris, a structure equivalent to the penis of a male. it contains erectile tissue, blood vessels and nerves, it is very sensitive to touch becoming engorged with blood when stimulated.

53
Q

what is gametogenesis?

A

the development of gametes, from meiosis to mature gametes.

54
Q

what are the two types of gametogenesis?

A

spermatogenesis- formation of spermatozoa in the testes

oogenesis- formation of ova in the ovary

55
Q

where does spermatogenesis occur?

A

the seminiferous tubules of each testis.

56
Q

how long does the process of spermatozoa take?

A

72 days and occurs continuously after puberty.

57
Q

how long is a human sperm and what do they consist of?

A

about 0.06mm long and contain a head, neck, middle piece and tail.

58
Q

explain the head of the sperm

A

made up of nuclear material with a fluid-filled tip (acrosome).

  • the fluid are enzymes which is important if sperm reaches egg. it breaks down the layer of cells surrounding the egg so that fertilisation can occur.
59
Q

explain the middle of the sperm

A

contains mostly mitochondria, providing a place for respiration to occur to provide the sperm with energy for movement.

there is a limited amount of cytoplasm surrounding the mitochondria, sperm have a short survival period, receiving their nourishment from semen in which they’re suspended.

60
Q

explain the tail of the sperm

A

capable of contractile motions to propel the cell forward.

61
Q

what features of the human reproductive system depend on the endocrine glands?

A

the menstrual and ovarian cycles.

the glands empty their secretions, called hormones, into the extracellular fluid surrounding the cells making up the gland. the secretion then passes into capillaries to be transported by the blood to the target audience.

62
Q

what is the pituitary gland?

A

a small organ lying in a pit in the bone below the brain and above the roof of the mouth. some of the hormones it secretes affects parts of the reproductive system

63
Q

what are the two gonadotropic hormones secreted by pituitary gland?

A
  1. follicle-stimulating hormone (FSH)

2. luteinising hormone (LH)

64
Q

explain the follicle-stimulating hormone

A

stimulates the development and maturation of the follicle in females. during this development, the ovarian follicle secretes its own hormone, oestrogen, increasing the bloods level of oestrogen and decreasing FSH secretions.

65
Q

explain the luteinising hormone

A

promotes the final maturation of the ovarian follicle, ovulation, and the formation of the corpus lute which secretes another ovarian hormone, progesterone and oestrogen. there’s a gradual decrease in the production of LH as progesterone levels in the blood increase.

66
Q

other than the follicle-stimulating hormone and the luteinising hormone, what are two other secretions from the pituitary gland?

A

prolactin and oxytocin

67
Q

explain prolactin

A

has a direct effect on the breast of women. important in the preparation and maintenance of milk production along with other hormones.

68
Q

explain oxytocin

A

causes uterine contractions, promotes the movement of milk in the breast and has a role in the movement of sperm and the production of testosterone in the testes.

69
Q

what is the ovarian cycle?

A

the series of events taking place within the ovary including the maturation of an egg and its release into the uterine tube.

70
Q

what is the duration of the ovarian cycle?

A

ranges from 20-40 days, with the average spanning 28 days. 30% of females have a cycle 27-28 days in length.

71
Q

what is a primary follicle?

A

immature eggs surrounded by a single layer of cells within the ovary

72
Q

what happens when a female matures sexually at puberty?

A

some of the primary follicles which contain a primary oocyte undergo further development.

73
Q

what happens during the first half of the ovarian cycle?

A

the levels of FSH and LH slowly increase, prompting the growth and maturation of follicles over a 10-14 day period.

74
Q

explain the steps that each follicle that develops goes through

A
  1. cells forming the wall of the follicle begin to enlarge and divide, creating a layer of cells around the primary oocyte.
  2. secretions from these cells create a fluid-filled space that gradually forces the oocyte to the edge of the follicle. it is now referred to as a secondary follicle.
  3. as more fluid accumulates within the follicle, it continues to enlarge and gradually moves towards the surface of the ovary.
  4. on reaching the surface, it produces a bulge that looks like a swollen blister on the surface of the ovary. at this stage it is referred to as a mature follicle.
75
Q

what happens as the follicles grow?

A

they release oestrogen and a low level of progesterone.

at around day 14, the level of oestrogen is high enough to stimulate a spike in the LH and FSH. the surge of LH causes the ovulation of the most mature follicle.

76
Q

how many secondary follicles complete development?

A

several follicles commence development but usually only one will complete development. the others normally break down to be reabsorbed into the ovary.

77
Q

what happens at ovulation?

A
  • the mature follicle bursts and expels the oocyte. beating cilia within the open end of the uterine tube creates a current sweeping the egg into the uterine tube.
78
Q

what happens following ovulation?

A
  • the ruptured follicle collapses and the blood within forms a clot. the clot is gradually absorbed by the remaining follicle cells which enlarge and change colour to form a creamy-coloured body (corpus luteum).
79
Q

what does the corpus luteum secrete?

A

oestrogen and progesterone. progesterone influences the development of the lining of the uterus, preparing it for implantation if fertilisation occurs. it also inhibits the release of FSH and LH, preventing other follicles from developing.

80
Q

what happens if fertilisation does not occur?

A

the corpus luteum reaches its maximum development about 8-10 days following ovulation.

it then begins to degenerate into a fibrous mass of scar tissue (corpus albicans) which eventually disappears. another ovarian cycle then begins due to the reductio of progesterone and oestrogen.

81
Q

what happens if fertilisation does occur?

A

the corpus luteum continues to develop and the ovarian cycle ceases.

82
Q

what is the corpus luteum maintained by?

A

human chorionic gonadotropin which is a hormone produced by the developing placenta in a pregnant woman.

corpus luteum begins to degenerate as placenta begins to secrete oestrogen and progesterone on its own. degeneration is slow and the corpus luteum is still present in the ovary at childbirth.

83
Q

when do ovarian cycles resume after birth?

A

after breast-feeding of the baby has ceased.

84
Q

what is the menstrual cycle?

A

the cycle of changes occurring in the uterus and to a lesser extent, the vagina. involving changes to the lining of the uterus (endometrium), closely associated with changes in the ovarian cycle.

changes occur in preparation of a fertilised egg needing to embed itself in the endometrium.

85
Q

what happens in the first stage of the menstrual cycle?

A

(this stage occurs while the follicle is still maturing in the ovarian cycle).

progesterone causes the endometrium of the uterus to become thicker and softer. there is also an increase in the number of blood vessels and mucus-secreting glands.

after ovulation the endometrium continues to thicken and glands within it begin to secrete a watery mucus, rich in glycogen.

86
Q

what happens if the egg is not fertilised by a sperm?

A

the corpus luteum degenerates, reducing the amount of progesterone, resulting in its breakdown.

87
Q

what is ‘menstruation’?

A

when blood from broken-down capillaries, mucous secretions and cell debris from the uterine lining are lost through the vagina, about 14 days after ovulation.

88
Q

what is a menarche?

A

a females first menstruation, marking the commencement of puberty. unless interrupted by pregnancy, she will have a menstrual cycle about once a month until menopause.

89
Q

what is menopause?

A

the time when the processes that occurred at puberty are reversed. taking place over a period of years between ages 45-55 and eventually ceases the menstrual cycle.

Human Biology (14 decks)

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