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Human Biology > Pregnancy & Birth > Flashcards

Pregnancy & Birth Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Define Ejaculation

A

when the contents of the ducts and glands are propelled into the urethra then out of the body

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2
Q

What is in the ejaculated material and what reactions accompanies an ejaculation?

A

The ejaculated material consists of fluid/semen which contains sperm. Accompanying the ejaculation is a rapid heartbeat, an increase in blood pressure and breathing rate, and intensely pleasurable sensations. This is referred to as an orgasm

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3
Q

Define Insemination

A

The process where the sperm are released into the vagina

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4
Q

Where and how does the sperm travel after it is within the vagina?

A

Once within the vagina, the sperm travel through the cervix and uterus, into the uterine tubes.
- This occurs very quickly
- Muscular contractions of the uterus

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5
Q

What is sperm mortality?

A

Sperm mortality is the death rate of sperm. Of the hundreds of millions of sperm deposited into the vagina, only a few thousand reach the uterine tubes, one reason why a large number of sperm are required for fertilsation to occur

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6
Q

Define Fertilisation + where it occurs

A

Fertilisation is the fusion of a sperm and egg, and occurs in the uterine tubes when the egg is one third of the way down the tube.

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7
Q

The two layers that surround the mature egg (secondary oocyte):

A
  • CORONA RADIATA consists of follicular cells held together by an acid.
  • ZONA PELLUCIDA a glycoprotein matrix surrounding the plasma membrane of the oocyte
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8
Q

How does the sperm break through the corona radiata and zona pellucida?

A
  • The acrosome on head of the sperm contain an enzyme that breaks down the acid. The many sperm work together to break down the corona radiata.
  • When the acrosome meets the zona pellucida, the ACROSOMAL REACTION occurs, causing digestive enzymes to be released that break down the glycoprotein matrix
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9
Q

What occurs once the sperm enters the egg?

A
  • The formation of the fertilisation membrane is stimulated, preventing entrance of any more sperm
  • the entrance of the sperm stimulates the secondary oocyte to complete the second meiotic division
  • Sperm’s tail is absorbed and head begins to move through the cytoplasm in the form of a MALE PRONUCLEUS.
  • nucleus of the egg develops into the FEMALE PRONUCLEUS which fuses with the male pronucleus to form a single nucleus with the diploid number of chromosomes.
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10
Q

Cleavage

A

The process by which a zygote repeatedly divides by MITOSIS.

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11
Q

What is a morula + where does it travel

A

A solid, spherical mass of cells formed after 3 days of cleavage. Travels down fallopina tube into uterus.

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12
Q

What is a blastocyst?

A
  • Between days 4-6, the morula further divides into a BLASTOCYST
  • The blastocyst is a hollow ball of cells with fluid in the middle and a mass of ~30 stem cells at one side of the cavity called the INNER CELL MASS
  • The outer layer of cells of the blastocyst are known as TROPHOBLASTS and eventually become part of the placenta
  • The inner cell mass will develop into the EMBRYO
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13
Q

What is implantation?

A
  • When the blastocyst sinks into the soft endometrium to become firmly attached to the wall of the uterus.
  • Occurs around day 7 and enables the blastocyst to gain nourishment for growth
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14
Q

3 primary germ layers

A

ECTODERM: Outermost layer of cells – will give rise to the body’s outermost layers of skin, central and peripheral nervous systems, eyes, inner ears.

MESODERM: Middle layer of cells – heart and a primitive circulatory system, bones, muscles, kidneys, much of the reproductive system, stomach and intestines

ENDODERM: Inner layer of cells – will become a simple tube lined with mucous membranes. The lungs, digestive tract lining and thyroid.

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15
Q

4 embryonic membranes and function

A
  • Amnion
  • Chorion
  • Allantois
  • Yolk sac
    function is to provide embryo nourishment as it develops
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16
Q

What is the amnion?

A
  • First membrane to develop
  • secretes amniotic fluid
  • cushions foetus, protecting it form injury
  • maintains a constant temp
  • allows foetus to move freely - developing joint and muscle movement
  • as foetus grows, the amnion grows with it
  • ruptures just before childbirth expelling amniotic fluid
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17
Q

What is the chorion

A
  • surrounds embryo and other 3 embryonic membranes
  • as amnion enlarges it fuses with outer layer of chorion
  • Eventually chorion becomes the main part of the foetal portion of the placenta
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18
Q

What is the placenta + functions

A
  • The placenta is a disc-like organ which grows over the surface of the uterus.
  • The job of the placenta is to supply food and oxygen to the foetus and to remove wastes such as urea, uric acid, and ammonia.
  • acts as an endocrine gland and so secretes a number of hormones necessary for maintaining pregnancy.
  • Allows the transport of antibodies from mother to foetus, so foetus is immune to diseases mother is immune to.
  • exchange of CO2 and O2
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19
Q

What are chorionic villi?

A

Finger-like projections that develop from the outer layer of cells of the early embryo;grow to form part of the placenta

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20
Q

Do foetal + maternal blood mix to exchange materials. If not then how do they exchange them?

A
  • Foetal and maternal blood do not mix
  • Exchange of materials takes place via diffusion and active transport
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21
Q

Umbilical cord structure + function

A
  • Attaches the foetus to the placenta
  • 2 UMBILICAL ARTERIES inside the cord- carry blood to the capillaries of the chorionic villi from the foetus
  • A single UMBILICAL VEIN carries blood from the placenta through the cord back to the foetus
22
Q

How does blood flow to and from placenta on the maternal side?

A

Mothers blood enters placenta through the UTERINE ARTERY, flows through blood spaces where exchange of substances occurs and leaves again through the UTERINE VEIN.

23
Q

What is the embryonic period with small timeline?

A
  • Embryonic period - first 2 months of pregnancy
    4 WEEKS - brain, heart, liver begins to form, heart begins to beat
    5-6 WEEKS - arm + leg buds form, eyes, lips, nose start to form. neural tube closes, if doesnt close then spina bifida
    7 WEEKS - major organs have all begun to form, embryo has developed its own blood type. eyes have retina + lens. major muscle systems developed and embryo able to move.
    8 WEEKS - everything fully developed or nearly developed.
24
Q

What can cause disruptions to foetal development?

A

Infections
Maternal Diet
Alcohol
Smoking
Chemicals

25
Q

Parturition

A

the process by which the foetus is expelled from the mothers body at the end of gestation

26
Q

What occurs in preparation for labour?

A
  • Foetus settles its head in the mother’s pelvis
  • Cervix has softened and shortened in length, likely to have opened a little
  • knees drawn up to abdomen and legs crossed
  • One side of head pressed against mother’s bladder, the other her bowel
27
Q

What occurs in first stage of labour

A
  • In final 3 months of pregnancy- uterus undergoes weak, irregular contractions, gradually become stronger and more frequent
  • When the contractions are strong and every 30 mins, they are known as Labour Pains.
  • Dilation of Cervix, time from the onset of labour until the complete dilation (or opening) of the cervix
  • the waves of contraction travel from the upper part of the uterus downwards toward cervix
  • with each contraction muscle fibers of the uterus shorten a small amount- pulling on the cervix
  • at the same time cervix is opened- cervical dilation allows foetus to move more deeply into the pelvis
  • eventually cervix is completely dilated (usually about 10cm)
  • uterus, cervix and vagina form a single, curved passageway called the BIRTH CANAL
  • foetus will pass thru birth canal by contractions of the uterus and voluntary contractions of the abdominal muscles of the mother
  • end of first stage is marked by complete cervical dilation
28
Q

What occurs in the second stage of labour?

A
  • The stage lasts 20 minutes - 2 hours
  • Begins with the bursting of the membrane surrounding the foetus and a gush of fluid from the vagina (waters breaking)
  • Foetus head stretches the vagina as it moves through the dilated cervix- this distention of the vagina stimulates the woman to contract her abdominal muscles
  • With each contraction head advances a small amount (between contractions retreats a little)
  • mother has increased pulse rate + sweating from effort
  • Once head emerged- turns sideways again to face mother’s hips, this rotation allows shoulders and rest of body to move more easily through birth canal
  • Pressure on baby’s skull as it passes through birth canal may push it out of shape- no brain damage occurs as skull bones are pliable and separated by joints
  • Head of foetus is down in 90% of cases- allows foetus to begin breathing before completely free of birth canal
29
Q

What occurs in third stage of labour?

A
  • Baby begins to breathe with its own lungs even though still connected via umbilical cord
  • Umbilical cord clamped, tied in two places and cut between the ties
  • Baby born covered in waxy material called
    VERNIX- protective layer
  • AFTERBIRTH: uterus continues to contract - 5 minutes after delivery of the placenta, other membranes and remains of umbilical cord are expelled
30
Q

How long is the average pregnancy

A

265 days

31
Q

3 trimesters of pregnancy

A
  • 1st Trimester –
    The process of forming organs from the 3 primary germ layers (Wk 1-12)
  • 2nd Trimester –
    Period of continued growth and development; rapid increase in foetal length (Wk 13 -28)
  • 3rd Trimester –
    Period of most rapid growth and development due to deposition of subcutaneous fat. (Wk 29 – birth)
32
Q

When is foetal period?

A

Wk 9 - Birth

33
Q

Foetal development at 3 months

A

Forelimbs well developed, outer ear completed, eyelids closed, bone marrow forms; blood cells form in bone marrow, sex distinguishable

34
Q

Foetal development at 4 months

A

Arms and hands fully formed, skeleton completed, ears stand out from head, exercising of muscles evident

35
Q

Foetal development at 5 months

A

Fine hair covers body, gripping reflexes are developed, increased growth

36
Q

Foetal development at 6 months

A

Respiratory movements, digestive glands begin to function, tooth buds evident, eyebrows and eyelashes

37
Q

Foetal development at 7 months

A

Period of greatest growth, all systems functional except respiratory system

38
Q

Foetal development at 8 months

A

Accumulation of fat beneath skin, growth slowed

39
Q

Foetal development at 9 months

A

Eyes open, nose well formed, sucking and grasping reflexes apparent, fine body hair is shed

40
Q

Developing foetus requirements

A

Foetus requires oxygen and nutrients delivered and carbon dioxide and wastes removed

41
Q

Physical effects on mother during pregnancy

A
  • Uterus 5x’s in size
  • Shortness of breath because growing baby forces stomach, liver and intestines upwards crowding the mother’s lungs giving her less room to breathe
  • Increase in heart size, HR, and blood volume
  • Physiological anaemia (tiredness, lethargy, breathlessness during physical activity
  • low blood pressure in early pregnancy due to progesterone causing slight relaxation in blood vessels, dilating them
  • Muscles in gastrointestinal system relax slightly, slowing the rate food moves along the gut. This maximises the absorption of nutrients into the mother’s blood, which is good for the foetus, but the mother may also experience nausea or constipation.
  • Need to urinate often due to increased blood flow to kidneys
  • Mood changes as a result of hormone balances changing
  • Breast enlargement as a result of hormones causing development of milk-secreting tissue in the breasts
  • In second trimester, breats begin to produce colostrum. It is rich in proteins and maternal antibodies, and should be fed to newborn babies.
42
Q

What do pregnant mothers have to increase in their diet

A
  • Iron – due to the increased production of RBC and increased blood volume
  • Calcium – normal bone growth, teeth, heart, nerve & muscle development
  • Vitamin A – normal growth of cells, especially in the last 10 week of pregnancy
  • Folic acid (folate) – normal cell division & manufacture of proteins
  • Fluoride – if it isn’t in drinking water, mothers need to increase fluoride intake to prevent dental issues with foetus
43
Q

What is Listeriosis and how is it avoided?

A
  • Listeriosis is an infection by the bacteria Listeria monocytogenes that causes miscarriages and stillbirths.
  • Avoid eating foods that have not been freshly prepared or cooked e.g. pre-packages salads, soft cheeses, raw or smoked seafood
44
Q

What is average mother’s weight increase during pregnancy?

A

The expected increase in weight of the mother in an average pregnancy is 9-12 kg

45
Q

Disruptions to normal foetal development

A
  • Congenital Disorders: defects or diseases that are present at birth
    -Inheritance of defective gene
    -Mutations (gene or chromosome)
    -Environmental factors (smoke/drugs/alcohol)
  • Teratogenic Agent (Teratogen): one that causes physical defects in developing embryo
    -Some Antibiotics, Anticoagulants, anticonvulsants, thyroid drugs
    -Thalidomide
    -LSD
    -Marijuana
46
Q

Rubella

A

Rubella: viral infection, skin rash and joint pain
If contracted by mum can have huge consequences for child:
- If infected during first 10 weeks: deaf, blind, heart defects, brain damage

47
Q

What does a lack of folate before and during pregnancy cause?

A

Spina Bifida: vertebrae around spinal cord doesn’t develop

48
Q

Foetal Alcohol syndrome

A
  • causing by binge drinking in early pregnancy
  • Lower than normal birth weight
  • Slow growth before and after birth
  • Small head
  • Defects of heart/organs
49
Q

3 different pathways of blood entering the right atrium from the inferior vena cava

A
  1. It can flow from the right atrium to the right
    ventricle and then to the lungs in the usual way.
    However the lungs are not functioning at this stage so there is considerable resistance to blood flow and little blood actually reaches the lungs
  2. Alternatively, blood can flow through the DUCTUS ARTERIOSUS which allows the blood to flow directly from the pulmonary arteries to directly to the aorta, bypassing the lungs completely.
  3. However most of the blood passes directly from the right atrium to the left atrium through an oval shaped hole between the two chambers called the FORAMEN OVALE.
50
Q

Why are ductus arteriosus and foramen ovale pathways beneficial to foetus?

A

The ductus arteriosus and foramen ovale alternative pathways are beneficial to the foetus, as the blood coming from the placenta is already highly oxygenated, so it is unnecessary for it to pass through the lungs when it can flow more efficiently straight to the developing foetal
tissues.

51
Q

What occurs after birth?

A
  • The first breath of life is triggered by the shock of birth.
  • If this does not occur, a slap on the baby’s bottom provides enough stimulus.
  • As the lungs expand with the first breath, they no longer give resistance to blood flow, so the blood flow through the ductus arteriosus begins to decrease.
  • As larger amounts of blood return to the heart from the lungs, the pressure in the left atrium increases, which causes the flap of the foramen ovale to close over against the wall of the right atrium which blocks the passage
  • As blood no longer flows through the umbilical vessels, the ductus venosus is no longer used, so it gradually constricts until it is permanently closed off.
  • All blood then must flow through the liver before it reaches the heart.
52
Q
A

Human Biology (16 decks)

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