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yr.11 Human Biology > Reproduction > Flashcards

Reproduction Flashcards

(64 cards)

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1
Q

Erection

A

penis becomes enlarged and firm
Sexual excitation initiates blood flow

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2
Q

ejaculation

A

Rhythmic contraction of epididymus, vas deferens, seminal vesicle, prostate gland
propels contents of the ducts and glands into the urethra and then out the body

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3
Q

Semen

A

provide nourishment
Neutralises acidic nature of urethra and female vagina, protecting sperm.

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4
Q

insemination

A

Sperm travel through cervix and body of uterus into uterine tubes
quickly reach upper portions of uterine tubes, often a few minutes
Along wt swimming, contractions in uterus walls and uterus tubes help sperm reach egg faster

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5
Q

sperm mortality

A

Death rate of sperm is high
only few 1000s reach uterine tube

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6
Q

Ova

A

Has two layers around it: corona radiata and zona pellucida

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7
Q

corona radiata

A

Follicle cells held together by cementing materials that contain acid
outer layer

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8
Q

Zona pelucida

A

glycoprotein matrix surrounding the plasma membrane of oocyte
Inner layer

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9
Q

Acro some (fertilisation)

A

acrosome of sperm head uses enzymes to break down acid in cementing material holding cells of corona radiata together.
1 acrosome’s enzymes are inefficient therefore 1000s of sperm needed to loosen layer to allow 1 sperm to reach egg.

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10
Q

Once sperm through corona radiata

A

encounters zona pellucida and initiates acrosomal reaction.
Release of digestive enzyme from acrosome, breaking down glycoprotein matrix of zona pellucida, giving access to plasma membrane of Oocyte, preventing entrance of any more sperm. This ensure only one haploid cell joins wt Oocyte.

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11
Q

once sperm entered oocyte

A

Tail is absorbed, head begins to move through cytoplasm to form male pronucleus, the haploid nucleus of sperm.
entrance of sperm stimulates secondary Oocyte to complete 2nd meiotic division.
Nucleus of Oocyte develops into female pronucleus, haploid nucleus of Oocyte, fuses with male pronucleus, forming single diploid nucleus.
Oocyte is now referred to as zygote.

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12
Q

Blastocyst formation (after fertilisation)

A

zygote travels down uterine tube and begins to divide by mitosis

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13
Q

Blastocyst

A

6 days after fertilisation, zygote has reached uterus and developed into blastocyst.
Hollow ball of cells that surround a cavity filled wt fluid
at one side is inner membrane (group of 30 cells), embryoblast. Inner cell mass composed of stem cells, differentiation develops embryo.

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14
Q

Implantation

A

blastocyst remains free within cavity pf uterus for 2-3 days then sinks into soft endometrium, to become firmly attached to wall of uterus.
Enables the blastocyst to gain nourishment for growth and development by absorbing nutrients from glands and blood vessels of uterine lining

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15
Q

hormone production

A

Blastocyst development depends on endometrium being maintained.
high levels of oestrogen and progesterone stop break down of endometrium, ceases menstrual cycle.
Corpus luteum secretes hormones until placenta is able to produce them, usually after 8-12 weeks.
1st 2 months referred as embryonic period, after 2 months embryo reffered to as foetus

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16
Q

Cell differentiation

A

cells making up inner cell mass of blastocyst are stem cells.
Genes and chemicals and contact wt other cells causes differentiation

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17
Q

totipotent stem cell

A

Has potential to create any type of cell necessary for embryonic development

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18
Q

pluripotent stem cells

A

Cells of inner cell mass
able to give to many, but not all, cell types necessary for foetal development

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19
Q

Multipotent stem cells

A

pluripotent that has undergone further specialisation
Give rise to cells that have particular function

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20
Q

primary germ layer

A

3rd week of development
Inner cell was undergoes changes as cells change to multipotent
resutlts in formation of 3 primary germ layers: Ectoderm, Mesoderm, Endoderm

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21
Q

Ectoderm

A

outermost germ layer
Form outer parts of body
(Eg. Skin, hair, mammary gland, nervous system)

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22
Q

Mesoderm

A

middle germ layer
Allows formation of stomach and intestines
(eg. Skeleton, muscles, connective tissue, heart, blood)

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23
Q

Endoderm

A

Innermost germ layer
(eg. Lining of digestive system, lungs, thyroid)

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24
Q

Embryonic membranes

A

4 embryonic membranes form: amnion, chorion, Yolk sac and Allantois
Lie outside embryo and serve to protect and nourish it as it develops

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25
Amnion
First membrane to develop 8th day it surrounds embryo, enclosing cavity within which it secretes amniotic fluid, fluid is shock absorber, protecting baby, and helps maintain constant temp, and allowing foetus to move freely Expands during growth, usually bursting at childbirth
26
chorion
Formed from outer cells of blastocyst together with layer of mesodermal cells surrounds embryo and other 3 embryonic membranes Amnion fuses with inner layer of chorion as it expands eventually becomes main part of foetal portion of placenta
27
Yolk sac and Allantois
2 of the other membranes Form outer structure of umbilical cord
28
placenta
Foetal and maternal tissues formed in first 3 months of gestation, foetal portion develops from chorion placenta supplies nutrients to, and removes wastes from, the foetus Also serves as endocrine gland
29
chorionic villi
Small, branching, finger-like projections develops from chorion and contain blood vessels, grow into endometrium Mother and foetal blood don’t mix, therefore exchange of materials occurs through diffusion and active transport number of villi provide large surface for exchange
30
Umbilical cord
contains umbilical vein and artery Vein carries blood from placenta through cord to foetus Artery carries blood from foetus through cord to chorionic villi
31
blood passage from mom to baby
Uterine arteries -> chorionic villi -> umbilical vein -> foetus -> umbilical artery -> chorionic villi -> uterine veins
32
Gestation
time embryo or foetus is carried in uterus About 280 days
33
embryo to foetus (1st month)
After 1 month embryo is under 4mm long development of muscle segments on either side of the tube that is to become brain and spinal cord
34
Embryo to foetus (4th week)
arm/leg buds start to appear
35
Embryo to foetus (8th week)
all organs present Recognisable human form 3cm length, 1g Head half size of embryo, eyes appear as slits, moved from side to front of head jaw almost developed
36
Foetal development (16th week)
uterus expands Foetus 18cm long, 100g posture more erect Heart beats 120-160 bpm
37
foetal development (20th week)
Foetus is 25cm long, 300g foetal movement clearly felt
38
Foetal development (24th week)
mother shows obvious signs of pregnancy Foetus grown 27-35cm long, 565-680g
39
foetal development (28th week)
Foetus os 38cm long, 1000g moves around rigorously in uterus Brain enlarged in males, testes descend into scrotum
40
Foetal development (32 weeks)
foetus is 41-45cm long, 1800-2200g
41
Foetal development (36th week)
46-48cm, 2700g Circulatory system fully developed, ready for birth
42
foetal development (40th week)
Pregnancy at full term foetus occupies all space in uterus, no room to move 50cm long, 3400g, males 100g more Head smaller in proportion to body nose well formed
43
Shortly before birth
head moves inside curved shape of pelvis Growth is slow, placenta begins to fail and becomes more fibrous
44
late stages of pregnancy
Antibodies diffuse into placenta, give baby immunity to same diseases as mum after 6 months affects of antibodies begin to decrease, baby builds own immunity
45
Pregnant mother changes
growing abdomen, growing uterus pushes organs upwards and outwards Enlargement of breasts, hormones create milk-secreting tissue increase is size of heart and blood volume Greater blood volume results in increased blood flow to kidneys, therefore more urine production uterine presses on bladder, less liquid can be contained Emotional stated affected by hormonal imbalances
46
parturition
Process by which foetus is expelled from mother’s body at end of gestation proceeded by a sequence of events called labour
47
Prior to labour
several hormone changes, changes cause ligaments in pelvis to soften, also increases response of uterus to stimuli, strengthening contractions. Before labour begins cervix softened, shortened in length, begins to open
48
first stage of labour
Dilation of cervix waves of contractions travel from upper part of uterus downward towards cervix, muscle fibres shorten wt each contractions Cervix is 10cm when full dilation and head of baby pushed into dilating cervix, passage called birth canal. complete dilation marks end of first stage of labour
49
Second stage of labour
involves delivery of foetus Membrane surrounding foetus bursts, gushing liquid from vagina Baby’s head turns to face mother’s back, distension stimulates mother to contract uterus once head emerges, head turns to face mother’s hips, allowing shoulders and rest of body to move more easily Pressure on head may change its shape, no brain damage, head returns to shape in a few days
50
third stage of labour
Contractions continue and placenta and remains are expelled, called afterbirth umbilical cord clamped in 2 places and then cut between clamps
51
Baby first breath
if baby doesn’t breath on its own doctor will slap its bottom. If this is unsuccessful umbilical cord is cut causing a buildup of CO2 in body stimulating lungs to breath.
52
Ductus Venosus
Before birth Vein bypasses liver and enters inferior vena cava as blood is already filtered by mom.
53
Ductus Arteriosus
Lungs collapsed therefore causes resistance to blood flow, little blood reaches lungs. Ductuce Arteriosus provides pathway from right ventricle into aorta, bypassing lungs
54
Foramen Ovale
Blood in right atrium may flow directly into left atrium through oval opening between both chambers because blood from mom already oxygenated.
55
Closing of special vessels
after lungs expand no more resistance to blood flow therefore blood in arteriosus decreases, closing after a few weeks later More blood returns from the lungs therefore pressure in aorta increases, pushing flaps of Foramen Oval against aorta walls, eventually completely shutting. due to loss of placenta, blood need filtration through liver, therefore Ductus venosus contracts and eventually closes
56
Following birth
45 breathes per min, for 2 weeks, rate gradually slows Heart rate 125-130 bpm, high rate due to need for oxygen for muscular activity, to keep warm due to environment being cooler then uterus number of RBC increases
57
Maintaining healthy pregnancy (diet)
increase energy uptake, 850kj more per day At least 65g of protein daily increase folic acid essential for normal cell division and manufacture of proteins Increase calcium for bone growth, teeth, heart, nerve and muscular development increase fluoride prevents future dental problems Increase vitamin A normal growth of cells
58
literiosis
Cause: contaminated foods potential to cause miscarriage Avoidance: eat freshly cooked foods, avoid packaged foods
59
Healthy pregnancy (exercise/weight)
exercise level should be maintained to same level as before pregnancy 0.5kg weight added per week, due to uterus and blood volume increase
60
Teratogens
agent that causes physical defects in the developing embryo
61
Foetal alcohol syndrome
describes effects of foetal exposure to alcohol
62
Smoking
increased rate of miscarriage, baby born lighter than supposed to
63
Thalidomide
morning sickness pill that formed deformities in babies, in legs and arms
64
Rubella
viral infections contracted by school-aged children If contracted by pregnant mother baby may be born deaf, blind or heart malfunctions

yr.11 Human Biology (10 decks)

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