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Anatomy and physiology 1 > final exam > Flashcards

final exam Flashcards

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1
Q

When can the oocyte be fertilised?

A

Once the oocyte is ovulated it remains viable for 12 to 24 hours and the chance of pregnancy after that drops to almost zero after that.

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2
Q

How much can a sperm survive ?

A

it usually survives at least 48 hours after the ejaculation

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3
Q

Where does fertilisation occurs ?

A

Fertilisation occurs in the uterine tube or fallopian tube. Once ovulation has occurred, the secondary oocyte its swept into the fallopian tube by the fimbriae.

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4
Q

what environment has the sperm has to go through ?

A

it has to survive the acidic environment of the vagina, pass the cervical mucus to reach the uterus. They are propelled by their tail and uterine contractions during intercourse.

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5
Q

What causes cervical contractions ?

A

oestrogen, prostaglandins and orgasm which help sperms disperse throughout the uterine cavity

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6
Q

What process does the sperm has to overcome before ferilisation?

A

Capacitation

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7
Q

Capacitation?

A

It is a biochemical process where acrosomal membrane thins and becomes fragile so the enzymes can be released at the right time to allow penetration.

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8
Q

How do sperms know where to go ?

A

sperm receptors, respond to chemical stimuli and smell of the ovum.

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9
Q

the mature oocyte secretes..

A

a chemoattractant called allurin

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10
Q

which layers does the sperm need to penetrate with help of ……….. enzymes.

A

the protective layers called CORONA RADIATA AND ZONA PELLUCIDA using enzymes within the acrosome.

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11
Q

where are sperm capacitated?

A

in the uterine tube

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12
Q

which layer has to be penetrated to trigger the acrosomal reaction

A

The zona pellucida, the sperm head binds to the sperm receptor opening Ca channels which triggers the arosomal reaction.

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13
Q

What do acrosomal enzymes do ?

A

They digest holes in the zona pellucida.
once the path is cleared out the sperm whips back and forth rocking the sperm head to the oocyte plasma membrane.

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14
Q

what happens when the sperm binds to the oocyte plasma receptors ?

A

The sperm and the oocyte plasma membrane fuse and the cytoplasmatic contents spill into the oocyte.

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15
Q

What is the cortical reaction?

A

exocytosis from the cotical granules causes the zona pellucida to harden and sperm- binding receptors are clipped of by ZONL INHIBITORY PROTEINS. Also when the oocyte binds to the sperm it sheds taking all the receptors off

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16
Q

Pronucleus ?

A

Sperm nucleus and the ovum nucleus then both swell forming male pronucleus and the female pronucleus: two nuclei contained within the same cell membranes.

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17
Q

first phase of fertilisation ?

A

the paternal and maternal chromosomes from the pronuclei combine and intermix. The now diploid and called a zygote

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18
Q

What is cleavage?

A

produces fast mitotic division after fertilisation. cells become smaller.

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19
Q

Morula ?

A

16 cells have formed

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20
Q

4-5 days of ovulation which phase ?

A

blastocyst forms with the degenerating of the zona pellucida

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21
Q

how does a blastocyst looks like ?

A

is a single layer hollow ball of about 50 cells encircling a fluid filled cavity with dense ,mass of cells together at one side

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22
Q

What does the inner cell mass and develops into ?

A

a foetus

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23
Q

What makes the foetal portion of the placenta ?

A

Trophoblast

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24
Q

after how many days does placentation happens after fertilisation ?

A

6 days, it implants closer to the cervix, it may later separate

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25
how pregnancy supported ?
-Corpus luteum need to continue to produce hormones or menstruation will happen -
26
What does trophoblast make ?
they make chrorionic gonadotropin peaks around the 8 weeks. HCG acts like a luteinising hormone
27
What does HCG stimulates ?
it stimulates the corpus luteum to produce oestrogen and progesterone up until about 8-10 weeks of gestation. AFTER THAT IT IS RESPONSABILITY OF THE PLACENTA
28
After fertilisation, the zygote goes through a rapid period of cells divisions called
Cleavage
29
What is the specialised mitotic division does the zygote undergo?
cleavage
30
What are the levels human chorionic gonadotropin hormone during pregnancy ?
HCG is detectable after one week of fertilisation and they continue to rise until the eight week, after that they begin to decline reaching their lowest level at the fourth month of gestation,
31
How long is the embryonic period ?
It is the the first 8 weeks after conception during which every major organ system is being developed an
32
When is the oocyte considerate a zygote ?
When the chromosomes of the pronuclei intermix, Fertilisation is accomplished and now the cell is considerate to by a zygote and its ready to for the first cleavage division.
33
When does embryonic development begins?
With fertilisation continues with the embryo floats through the uterine tube, into the uterine cavity and implants into the uterine wall.
34
what are blastomeres ?
the first cleavage of zygotes produces identical cells, only after 36 hours after fertilisation
35
when is the zygote considerated Morula
after 72 hr and the ovum now has 16 cells
36
In which phase is the uterus while the embryo is moving towards the uterus ?
secretion phase of the uterine cycle is now providing rich in glycogen into the cavities to sustain the embryo until implementation.
37
After how many days after ovulation does the embryo becomes blastocyst ?
usually 4-5 days after the ovulation, and then hatches from degenerating the zona pellucida
38
what part in the blastocyst develops into a foetus?
The dense mass or the inner cell mass called the embryo blast is what will be become the foetus
39
How can you identify a blastocyte ?
it is a fertilised egg that has a single layer hollow ball of about 50 cells encircling a fluid filled cavity with a dense group of dense cells at one side.
40
How is it called the thin outer layer of cells in the blastocyst, and whats its function ?
Trophoblast accomplish implantation and forms the foetal part of the placenta by sticking to the endometrium and start to digest the endometrial wall
41
Where is the best spot for the blastocyte to implant
the fondus, as if it implantates in close to the cervix it is possible that it will not be able to receive blood supply and die
42
What hormone indicates that fertilisation happened and that the corpus luteum need to keep releasing progesteron?
The trophoblast produce human chorionic gonadotropin hormone wihch signals the corpus luteum to keep releasing estrogen and progesterone
43
At what time does the production of progesterone and estrogen the responsability of the placenta ?
After 8 or 10 weeks the the HCG hormone concentration declines at the 4th months of gestation. The corpus luteum degenerates and the ovaries remain inactive until after birth
44
In which two layers do the trophoblast divide into ?
cytrotrophoblast - that retains the cells boundaries -Syncytiotrophoblast- it loses its plasma membrane and forms cytoplasmatic mass. The syncytiotrophoblasts actively invade the endometrial wall breaking down capillaries, and as the endometrium is eroded, the blastocyst burrows into the lining.
45
After what day implantation is completed ?
day 12 after ovulation, the epithelial surface is successfully restored and the blastocyst has fully invades the endometrial lining.
46
In which two layers does the inner mass differentiates ?
Into a bilayered embryonic disc consisting of the amnion , a transparent membranous sac, and its contents, the amniotic fluid.
47
What is the amnion?
it is a bag with amniotic fluid that provides an buoyant environment to protect the developing embryo against the physical trauma and helps to maintain a constant homeostatic temperature.
48
After the complete implantation of the blastocyst how many layers does the embryo disc transforms to ?
it transforms into 3 layers: the ectoderm, the outermost layer, the mesoderm , the middle layer, ant the endoderm, the innermost layer.
49
What does the ectoderm eventually becomes to ?
the nervous system
50
What does the mesoderm transforms to ?
It ends up being the muscles
51
What does the endoderm differentiates into ?
Into the epithelial lining of the hollow organs in the gut .
52
What does placentation means ?
It refers to the formation of the placenta. This originates from both embryonic and endometrial tissues. Some of the cells from the original inner cell mass
53
What does the embryonic and endometrial tissues become during placentation?
they transform into the chorion, Chrionic vili are structures that contact the maternal blood in the lacunae. some chorionic vili are invaded by newly forming blood vessels which extend to embryo as the umbilical arteries and vein.
54
What does the the part that lies beneath the embryo becomes ?
decidua basalis
55
What does the the part n of the endometrium that surrounds the uterine cavity side of the embryo becomes ?
decidua capsularis.
56
What two structures form the placenta ?
the chorionic vili and the decidua basalis together form the placenta.
57
At the ending of which month does the umbilical arteries carry waste filled blood from the foetus ?
The third month
58
What runs from the foetus to the placenta ?
oxygen, carbon dioxide and waste exchanges occur at the placenta.
59
What is Organogenesis ?
is the formation of the body organs systems.
60
what organs systems are developed in the ectoderm?
The neural system including the brain and the spinal cord
61
what organs systems are developed in the endoderm?
The endoderm also produces the epidermis of the skin, hair and nails. The innermost layer produces epithelia lining of the digestive, respiratory and reproductive tracts.
62
what organs systems are developed in the mesoderm?
differeientiates into structures developed from connective tissues such as cartilage, bone, skeletal, smooth and cardica muscles
63
What substance allows the pelvic ligaments to stretch in readiness for parturituion?
Relaxin
64
What are Braxton Hicks contractions?
They contractions in the uterus due to the stretching of the smooth muscle. described as false labor. The purpose of this contraction is to push the head of the baby on to the cervix to prepare for delivery
65
What makes the uterine smooth muscle more irritable ?
The rising of oestrogen levels from the placenta induce more oxcytocin receptors to be formed in the uterine smooth muscle, making it irritable
66
what is the function of prostaglandins before labor ?
Some foetal cells produce oxytocin causing the placenta to release some prostaglandins, which stimulate more vigorous contractions of the uterus and assist the cervix to become thin and soft just pror to labor.
67
What fires afferent impulses to the hypothalamus that stimulate the release of oxytocin from the posterior pituitary gland?
When the cervix starts to get soft and starts to dilate it fires afferent impulses to release oxytocin and start uterine contractions.
68
What is parturition ?
it is the process of delivery or labour. and it is divided in three stages
69
What are the three stages of parturition ?
stage I: dilatation stage cervix 10 cm in diameter Stage II: Expulsion stage, which lasts from full dilation to delivery of the infant. Stage III: is the delivery of the placenta and all the attached membranes
70
what effect does the high levels of oestrogen and progesterone have on the mammillary glands ?
they prepare the breast tissue and stimulate the hypothalamus to produce prolactin releasing hormone.
71
what kind of receptors are needed for the stimulation of oxcytocin ?
mechanoreceptors in the nipples by suckling infant sends afferent impulses to the hypothalamus to release the hormone oxcytocin from the posterior pituitary gland
72
what is the function that oxytocin has on the nipples?
they activate letdown reflex, which causes the ejection of milk from the mammary glands.
73
what is spermatogenesis?
it is the sequence of events involved in the production of sperm , or the male gamates.
74
when does spermatogenesis begins ?
it starts in puberty and takes place in the seminiferous tubules of the testes.
75
what is spermatogonia ?
They are stem cells with a diploid number of chromosomes. this cells remain near the basement membrane if the seminiferous tubules and undergo mitosis almost continuously.
76
what is the difference between daughter cells before puberty and after puberty?
After puberty each mitotic division of spermatogenia results in 2 distinctive cells
77
what is the difference between cell type A and B
Type A remains attached to the basement membrane to maintain the pool of mitosing germ cells, and type B daughter detaches from the basement membrane ans is pushed toward the lumen where it differentiates into primary spermatocyte, destined to produce 4 sperm.
78
what are sustenocytes or sertoli cells ?
Setoli cells are tightly surrounded by spermatocytes and provide nourishment for them. they are a site of action for testosterone, follicle stimulating hormone and the release of inhibin
79
Where does the miotic divisions of spermatocytes occur?
It occurs between the seroli cells and progressively moving towards the lumen
80
what happens in meiosis I spermatogenesis ?
From a diploid primary spermatocyte produces two haploid cells called secondary spermatocytes
81
What happens in meiosis 2 spermatogenesis?
allows the sister chromatids in a secondary spermatocyte to separate and form 2 haploid cell spermatids
82
How phase it is considerate to be after meiosis II
its considerate it to be early spermatids and marks the ending of spermatogenesis
83
What does late spermatogenesis involves ?
the late development of the late spermatid into sperm. the process is called spermiogenesis.
84
What happens when the spermatid progresses to the lumen ?
The spermatid changes from a roud spherical shape undergoing spermiogenic activity, to the lengthy shape that reflects the final spermatozoa.
85
What does every sperm contains?
It contain a head with acrosomal cap containing enzymes, a mid-piece and a tail.
86
In summary what process need to happen during spermatogenesis ?
-meiosis 1 -Meiosis 2 -Spermatogenesis
87
How long does spermatogenesis take ?
approximately 70 days to complete for each sperm, yet 400 million sperm are produced in a day

Anatomy and physiology 1 (2 decks)

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