Week 1 - Pregnancy + Development of the Foetus Flashcards
(96 cards)
1
Q
What are the 8 stages of life?
A
- Germinal
- Embryo
- Foetus
- Neonate
- Infant
- Child
- Adolescent
- Adult
2
Q
When does the GERMINAL stage of life occur?
A
From conception to 2 weeks (14 days)
Occurs up until IMPLANTATION during which the Zygote begins to rapidly divide.
3
Q
When does the EMBRYO form?
A
Between the 2nd week - 8th week
4
Q
When does the FOETUS form?
A
From the 8th week - Birth
5
Q
What is a neonate?
A
A neonate is a baby that is 1 month old (after birth)
6
Q
What is an infant?
A
An infant is a baby between the age of 1 month - 2 years old
7
Q
What is a child?
A
A child is aged between 2 and up until they hit PUBERTY.
8
Q
What is an adolescent?
A
When someone has hit puberty - 20 years old
9
Q
What is the definition of growth?
A
The physical element. It is the increase in size. From 2 single cells to one big cell which can multiply and produce many.
10
Q
What is the prenatal period?
A
From Fertilization to Birth
11
Q
When is the postnatal period?
A
From Birth to Death
12
Q
What is the definition of pregnancy?
A
The presence of a developing offspring in the uterus. It tends to last around 38 weeks and is divided into trimesters that last around 3 months each!
13
Q
What is Fertilisation?
A
- The union of a secondary oocyte and a sperm cell
- Results in a new cell called a Zygote
- Located in the UTERINE TUBE
14
Q
When does Fertilisation occur?
A
Between 12 and 24 hours after conception
15
Q
What are the stages of Fertilisation (conception)?
A
- An egg is typically ovulated each month and enters the fallopian tube
- After sperm deposition into the vagina, it moves through the uterus and into the fallopian tube
- The PROSTAGLANDINS in semen stimulate the lashing movement of the sperm tails for swimming, causing muscular contractions of the uterus and fallopian tubes. This aids sperm movement (making it a shorter journey).
- Under influence of EOSTROGEN, a women’s uterine secretions go from being mucousy and acidic - watery and allow easy sperm transport through female tract.
- Sperm reaches the upper portion of the fallopian tube within 1 hour.
- Many sperm may reach the egg, but only one can fertilise it.
- With the aid from the ACROSOMAL ENZYMES in the sperm head, sperm erod the CORONA RADIATA (layer surrounding the oocyte).
- Sperm bind to the ZONA PELLUCIDA (membranes directly surrounding the oocyte) and digest a specific protein.
- Only the 1st sperm head is allowed to puncture the egg cell membrane
- Following PENETRATION, hardening of the ZONA PELLUCIDA, prevents the entry of additional sperm cells
- The sperm cells NUCLEUS, swells and becomes the MALE PRONUCLEUS.
- The secondary oocyte completes MEIOSIS ll and its nucleus becomes the FEMALE PRONUCLEUS.
- PRONUCLEI of EGG and SPERM unite, completing Fertilisation.
- Fertilisation results in the formation of a ZYGOTE.
16
Q
What is the correct order of the developing foetus, starting from conception and ending with the foetus?
A
Oocyte - Zygote - Morula - Blastocyst - Embryo - Foetus - Baby
17
Q
When does Fertilisation end?
A
When the Zygote is produced (24 hrs after conception).
18
Q
When does the Embryonic Stage occur?
A
The period between fertilization and the 8th week.
19
Q
What happens during the embryonic stage?
A
The placenta forms, major organs form, and external structures appear.
20
Q
What is the period of CLEAVAGE (Mitosis)?
A
- The period of cleavage takes place during the embryonic stage.
- Takes place 30 hours AFTER Zygote formation
- Mitosis begins (aka cleavage)
- Cells divide rapidly, become smaller and smaller with each division as the Zygote moves down the fallopian tube to the uterus.
21
Q
What happens during the Embryonic Period (Part 1)?
A
- 30 hours after Zygote formation, Mitosis occurs. This is also known as cleavage because cells divide rapidly, becoming smaller and smaller with each division as the Zygote moves down the fallopian tube to the uterus.
- The trip down the fallopian tube takes about 3 days; by then the mass has developed into a solid ball of 16 cells called a MORULA.
- The Morula stays in the uterine cavity for approximately 3 days, unattached.
- The morula then forms a hollow mass, called a Blastocyst.
- The Blastocyst implants into the endometrium of the uterus by the end of the 1st week.
- At this point, the cells are PLURIPOTENT stem cells, which can give rise to more stem cells and several types of specialized cells, eg. liver.
22
Q
What happens during the Embryonic Period (Part 2)?
A
- During implantation, certain inner cells of the blastocyst organize into the inner cell mass (embryoblast), which gives rise to the embryo proper, the body of the offspring.
- The cells of the wall of the Blastocyst develop into the Trophoblast, which becomes supporting structures of the embryo.
- Trophoblast cells send out extensions, microvilli, which invade the endometrium.
- Endometrial growth surrounds the blastocyst, resulting in implantation into the lining of the uterus.
- The Trophoblast secretes the hormone human chorionic gonadotropin (hCG) which maintains corpus luteum for the production of hormones during early pregnancy.
- The Trophoblast enzymes breakdown the tissue of the endometrium, obtaining nutrients for the embryo.
- The chorionic villi develop, irregular spaces called LACUNAE form around between the villi, and fill with maternal blood.
- Embryonic blood vessels extend through the connecting stalk, attaching the embryo to the developing placenta.
23
Q
What happens during the Embryonic Period (Part 3)?
A
- As the placenta forms from the CHORION, another membrane develops around the embryo, called the AMNION.
- The Umbilical cord forms and connects the umbilicus stalk between the embryo and mother.
- The Yolk sac and Allantois (2 additional membranes) form during development.
24
Q
What is the Chorion Membrane and its function?
A
- The outermost foetal membrane
- It develops from an outer fold on the surface of the yolk sac, which lies outside the zona pellucida.
- Function: protect and nurture the embryo
25
What is the Amnion and its function?
- Starts forming in the 2nd week
- It attaches around the edge of the inner cell mass or embryonic disc
- Amniotic fluid prevents compression of the embryo, it cushions the embryo from the mother's movements and maintains a stable temperature.
26
What is the Umbilical Cord?
- Forms from portions of the Amnion, enveloping tissues on the underside of the embryo, mainly the connecting stalk between the embryo and mother.
- The umbilical cord connects the umbilicus of the embryo to the placenta.
Function: Is to exchange blood between the embryo and the placenta.
27
What are the 2 additional membranes that form during development?
Yolk Sac: Forms during the 2nd week, produced blood cells, and gives rise to cells that will develop into sex cells.
The Allantois: Forms during the 3rd week, produces blood cells and umbilical blood vessels.
28
What is the placenta?
The placenta is an organ that develops in the uterus when pregnant. It functions in gas exchange and delivery of nutrients from the mother to the embryo.
29
Where does the placenta form from?
An area where the chorion is in contact with the uterine wall.
The embryonic part consists of chorion and chorionic villi
the maternal part consists of decidua basalis of the uterine wall, where the villi are attached.
30
What is the function of the placental membrane?
Separates the embryonic blood from the maternal blood
| Performs the exchange of nutrients, O2, wastes, and CO2 between the embryonic and maternal blood.
31
What is the definition of Gastrulation?
- The movement of cells in the embryonic disk that form multiple layers
- It is the period of time where the birth and development of organs occur
32
What are the layers of the embryonic disc?
Outer Ectoderm and Inner Endoderm
33
What is the name of the layer formed when the Ectoderm and Endoderm fold?
The middle layer - known as the Mesoderm
34
What is Organogenesis?
Organogenesis is the phase of embryonic development that starts at the end of gastrulation and continues until birth. During organogenesis, the three germ layers formed from gastrulation form the internal organs of the organism.
35
What is the name given to a 2-week old embryo that has all 3 primary germ layers?
A Gastrula
36
What are the 3 primary germ layers?
Ectoderm, Mesoderm and Endoderm
37
What is the function of the Ectoderm layer?
- Gives rise to the Nervous System
- Portions of special sensory organs, the Epidermis and Epidermal accessory organs and the linings of the mouth and anal canal.
38
What is the function of the Mesoderm Layer?
- Forms all types of muscle tissue, bone tissue, bone marrow, blood, blood and lymphatic vessels, internal reproductive organs, kidneys, connective tissues and epithelial linings of the body cavities.
39
What is the function of the Endoderm layer?
Produces the epithelial linings of the digestive tract, respiratory tract, urinary bladder and urethra.
40
What is the timeline of the Embryonic Period?
Fertilisation Occurs: 12-24hrs after conception
Zygote is formed: 12-24 hrs after conception
Cleavage occurs: Between 30hr-3days after conception
Morula formed: 3rd-4th day after conception
Blastocyst formed: 5th day - 2nd week after conception
Gastrulation occurs: End of the 2nd week, germ layers formed
41
What occurs during the 4th week of the Embryonic Stage?
```
By the 4th week, the embryonic disc forms the cylindrical neural tube, which will develop into the nervous system.
The heart (primitive, mass of cells) is beating, the head and jaws appear, and the limb buds form.
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42
What occurs during the 5th-7th weeks of the embryonic stage?
The head grows quickly, the face develops its features, limbs elongate and the fingers and toes form.
By the end of the 7th week, major internal organs have formed.
43
When does the embryonic stage end?
At the end of the 8th week.
44
When does the foetal stage occur and for how long?
Begins at the end of the 8th week, lasts until birth
45
What occurs during the foetal stage?
Growth is rapid, body proportions change considerably; the embryo is now called a foetus.
Existing structures grow and mature, and only a few parts appear
The body enlarges, the limbs grow to the relative size that they will maintain through development, and the bones ossify.
46
What happens at the end of the 12th week?
External reproductive organs are distinguishable as Male or Female.
47
What happens during the 4th month of development?
The body grows quickly, the lower limbs lengthen skeleton continues to ossify.
The foetus is covered by LANUGALL which is hair, and this covers the whole body.
Activity is starting to increase and the foetus may start kicking its legs a little.
48
What happens during the 5th month of development (the 2nd part of the fetal stage)?
Growth slows down, the mother may feel the fetus move, fine hair appears, dead epithelial cells and sebum covers the skin, and lower limbs reach proper proportion.
49
What happens during the 6th month?
The foetus gains weight, eyebrows and eyelids form, the skin is wrinkled, translucent and reddish.
50
What happens during the 7th month?
Subcutaneous fat is deposited, skin gets smoother, and eyelids open.
51
What happens in the final trimester of pregnancy (in regard to foetal development)?
Brain cells form rapidly, and organs grow and mature as the foetus greatly increases in size.
About 266 days after fertilisation, the aby is fully term and ready for birth.
52
When does the CNS form in the developing foetus?
Between weeks 3-38.
| It is very sensitive to toxins that might get across the barrier.
53
When does the heart form in the developing foetus?
Between weeks 3-8.
It is vulnerable between week 3 and 8.
After that, the heart tends just to grow in size.
54
When do the arms and legs form in the developing foetus?
Between weeks 4 and 8.
We start to see the arm and leg bonds.
We see the Limb Limberts from week 4 onwards.
55
When do the eyes form in the developing foetus?
Between week 4 to TERM.
| Start to develop early and are extremely sensitive to anything.
56
When do the ears form in the developing foetus?
Between weeks 4 and 20.
| They are not quite as sensitive to being exposed to toxins in comparison to your eyes.
57
When does the external genitalia form in the developing foetus?
Between weeks 7 and 16.
From around week 12, we can tell what sex the developing foetus is.
Sensitive all the way through the pregnancy in regards to exposure to toxins.
58
When do the teeth and palate form in the developing foetus?
Between weeks 7 and 16.
59
What does an Apgar Score check?
```
Colour of baby
Muscle Tone
Heart Rate
Reflex Response
Respiratory Effort
```
60
What is a poor Apgar Score?
0-2
61
What is a fair Apgar Score?
3-7
62
What is a good Apgar Score?
8-10
63
Why is the foetus highly vulnerable during Organogenesis?
This is a time where their organs are developing, making it more vulnerable to influences from the outside world.
64
What is a healthy baby?
A baby that is born at TERM - Between 37 and 39 wks
| At a healthy weight of 2.5-4kgs
65
If a baby is born small (at term) what are they at a higher risk of?
Heart problems, lower intelligence, poor academic performance, poor social skills and behavioural problems.
66
If a baby is born larger than average weight and size, what are they at a higher risk of?
Perinatal mortality, obesity, and metabolic disorders
67
What is Pharmacokinetics?
```
It describes the time course of the movement of a drug into, around, and out of the body.
Absorption (into)
Distribution (around)
Metabolism (out of the body)
Excretion (out of the body)
```
68
What 3 factors influence Pharmacokinetics?
Physio-chemical properties of the drugs
- Physiological factors
- Patient-specific factors
69
What is the Blood Brain Barrier (BBB) and its function?
A dynamic interface that separates the CNS from the Vascular System.
highly selective semipermeable border of endothelial cells that prevents solutes in the circulating blood from non-selectively crossing into the extracellular fluid of the central nervous system where neurons reside.
Location: surrounds most of the blood vessels in the BRAIN.
70
What is the Physiological Barrier in the kidney?
It plays a crucial role in maintaining water and electrolytes balance in the body.
This is achieved through a complex system of blood filtration followed by reabsorption and secretion.
71
What Important Transporter acts as a Physiological Barrier?
P-glycoproteins (P-gp)
This is found in the brain, gut and kidneys
Transfers drugs/compounds out of the body.
72
What are the Physiological Barriers in the body that prevent free access of drugs to certain organs when distributed?
The Blood Brain Barrier (BBB)
Barried in the Kidneys
Transporters - P-glycoproteins (P-gp)
The Placental Barrier.
73
What is the function of the placenta?
Connected to the foetus by the umbilical cord (made up of blood vessels and connective tissue)
It acts as a barrier between the mother and foetus
The placenta ensures that substances cannot simply transfer between the maternal and foetal bloodstream
Nutrients and O2 can cross over the plaenta via diffusion
The Placental barrier is quite spongy (porous) and may allow chemical substances to cross.
74
What are the physio-chemical properties of alcohol?
Alcohol (C2 H5 OH)
| It is an AMPHIPHILIC molecule which means that alcohol possesses both LIPOPHILIC and HYDROPHILIC (like water) properties
75
How is alcohol eliminated in the adult?
90% of alcohol gets eliminated by the liver; the remaining 10% by the lungs, skin and urine.
76
How is alcohol eliminated in the foetus?
In the foetus, liver enzymes are not fully developed, slowing down alcohol elimination.
Mostly, the foetus relies on the mother's capacity to eliminate alcohol.
77
What is Nicotine?
A liquid alkaloid
78
What are the Physio-chemical properties of Nicotine?
It can readily cross membranes (skin; airways; measurable plasma levels)
The absorption of Nicotine through Lipidic membranes depends on the pH (and the nature of tobacco).
79
Where does Nicotine bind to in the body?
Acetylcholine receptors (AChRs)
80
How is Nicotine eliminated in the adult?
It is mostly metabolized by the liver, via an essential class of enzymes called CYPs.
81
How is Nicotine eliminated in the foetus?
Liver enzymes are not fully developed, slowing down Nicotine elimination.
Mostly, the foetus relies on the mother's capacity to eliminate Nicotine.
82
What are the 2 classes of Acetylcholine receptors (AChRs)?
```
Nicotinic acetylcholine receptors (nAChRs)
Muscarinic receptors (mAChRs)
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83
Which receptor does Nicotine specifically bind to?
Nicotininc acetylcholine receptors (nAChRs).
84
How many subunits make up each Nicotinic and Muscarinic receptor?
5 subunits.
85
What do Nicotinic acetylcholine receptors do in the skeletal muscle when distributed?
They trigger muscle contraction
86
What do Nicotinic acetylcholine receptors do in the autonomous ganglion when distributed?
They relay autonomous signals.
87
What do Nicotinic acetylcholine receptors do in the brain when distributed?
Together with Muscarinic receptors (mAChRs) they are involved in an enormously complex array of functions, including memory, the reward pathway and sleep.
88
What is Epilepsy?
An abnormal, excessive, paroxysmal, hypersynchronous discharge of cerebral neurons, caused by brain abnormality and that cannot be attributed to any other diseases.
89
Paroxysmal discharges are known as...
seizures.
90
What anti-epileptic drugs are there?
```
Phenytoin, Sodium Valporate
Benzodiazepines
Ethosuximide
Phenobarbiton
Vigabactin, Tiagibine, Topiramate
Lamotrigine
```
91
What can cause Infertility in females (prior to conception)?
```
Undernutrition
Low body weight
Overnutrition
Obesity
Diet
Alcohol
Caffeine
```
92
What can cause infertility in male (prior to conception)?
```
Overnutrition
Obesity
Diabetes
Reactive Oxidative stress
Alcohol
Polyunsaturated Fatty Acids (PUFA)
Antioxidants (vit C and E)
Selenium (decreases the ability of sperm to move)
Lycopene (caretanoid, from tomatoes)
Isoflavones
Phthalates (man made chemicals added to plastics)
```
93
What are Teratogens?
Substances that are potentially harmful from about 10-14 days.
Once the embryo is embedded in the womb and there is a connection between the embryo and mother's blood supply.
Example, alcohol
94
How much caffeine is recommended in the 1st trimester of pregnancy?
200mg caffeine per day
95
What are Dietary Mutagens?
Substances that are found in food that causes DNA damage either directly or through oxidative stress.
96
What is Oxidative stress?
is an imbalance between free radicals and antioxidants in your body. Free radicals are oxygen-containing molecules with an uneven number of electrons. The uneven number allows them to easily react with other molecules.
