Hehi Test 1 Genetics, Conception, And Fetal Development

Front 1

Genes

Back 1

coded sequences of information by which cellular organisms regulate their embryologic development, metabolic functioning, growth and reproduction.

Front 2

- Chromosomes

Back 2

small, threadlike strands of DNA and proteins (contains thousands of genes lined up in a specific sequence)

Front 3

- DNA

Back 3

composed of deoxyribose (a five carbon sugar), a phosphate group and nitrogen containing base subunits (purines and pyrimidines)
- Purines - adnenine and guanine
- Pyrimidines - thymine and cytosine

Front 4

Human DNA - double stranded spiral - consists of:

Back 4

- Genetic information
- 46 chromosomes/23 chromosome pairs
- 22 pair of autosomes
- 1 pair of sex chromosomes
• X
• Y

Front 5

Karyotype:

Used to determine:

Back 5

pictorial analysis of the number, form, and size of an individual’s chromosomes

Used to determine:
determines sex of a child
presence of chromosomal abnormalities

Front 6

Mitosis:

Meiosis:

Back 6

single cell division, new cells have same # of chromosomes

germ cell division in which new cells decrease chromosome number by half.

Front 7

Autosomal Chromosomal Abnormalities

Common Types:

Back 7

occurs during meiosis when a pair of chromosomes fails to separate and one resulting cell contains both chromosomes and the other contains none
- Trisomy 21 - Downs syndrome
Risk w/ mothers age: 25yo 1 in 1250; 40yo 1 in 100
- Trisomy 18 – Edwards Syndrome
- Trisomy 13 – Patau Syndrome

Front 8

2 types of Sex Chromosome Abnormalities

Back 8

- Turner’s syndrome (X) females – appear as female but lacking sex organs, may have external organs.

- Klinefelter’s syndrome – (XXY) – males – poorly developed 2ndary sex characteristics, small testes. Usually infertile, tall, and effeminate.

Front 9

Conception:

3 Periods and Weeks Gestation for each

Back 9

union of a single egg and sperm; marks the beginning of pregnancy; 1st of last menstrual cycle is day 1.

– Preembryonic Period (weeks 1-3)
– Embryonic Period (weeks 4 to 8)
– Fetal Period (weeks 9 to 40)

Front 10

Prembrionic Period

Back 10

(Weeks 1-3)
- Ovulation
o Release of Ovum from the ruptured ovarian folicle
o High estrogen levels – increase motility of fallopian tubes
o Cilia – propels ovum through the tube to the uterine cavity
o Fertile – 1-2 days after ovulation

- Ejaculate
o Sperm – 200 to 500 million sperm. Swim towards ovum. 4-6 hours to reach ovum.
o Viability -in reproductive system for 24-72 hours.

Front 11

Fertilization
takes place in:
Summary of

Back 11

Ampulla (outer 1/3 of fallopian tube)
Zygote travels to uterus -> Cleavage:cellular replication (3-4 days) -> Implantation: attachment to endometrium (6-10 days after conception)

Front 12

Decidua

Back 12

what uterine lining is called when implantation occurs

Front 13

Chorionic villi:

becomes:

Back 13

fingerlike projections that grow into the endometrium. Very vascular – provides nutrients and oxygen.

becomes: fetal side of the placenta, contains the major umbilical vessels

Front 14

Amnion

Back 14

forms the wall of the amniotic cavity
cells produce amniotic fluid

Front 15

Cotyledons

Back 15

15-20 sections of the placenta (look like cauliflower) meaty and vascular

Front 16

Placenta
- developed by __wk., grows until__
Main Function:
Other functions:

Back 16

developed by wk 12; grows until wk 20.
Main: diffusion of gases and nutrients to baby.
Other:
• Respiration:diffusion of oxygen from maternal blood to fetus
• Nutrition: carbohydrates, water, fats, proteins and mineral pass from maternal blood into the fetal system
• Excretion: end products of fetal metabolism cross the placenta into maternal circulation
• Protection
• Endocrine: barrier that protects fetus from harmful substances
secretes - estrogen, progesterone, HCG, human placental lactogen
• Immunity: to diseases (smallpox, diphtheria, measles) passed to the fetus from maternal antibodies

Front 17

Embryonic Period 3 Major Developments

Back 17

(weeks 4 - 8)
1) Organogenesis – external organs and organ systems formed. Rapid formation, potential for malformations.
2) Primitive circulatory system - heartbeat begins end of 3rd week
-4 chamber heart - 4th and 5th week
-complete development by end of embryonic period
3) Umbilical cord -5th week

Front 18

Umbilical cord
Function of umbilical vein and arteries:

-How long at term gestation:
-Wharton's jelly:
-Nuchal cord:

Back 18

Vein: blood to fetus, O2 blood from mother to baby
2 Arteries: blood from fetus to mother (chorionic villi)

•1% umbilical cords contain only 2 vessels
•term gestation = 30-90 cm long
•Wharton’s jelly - connective tissue – yellowish stringy – protects vessels in the cord.
•nuchal cord – cord around the neck

Front 19

Fetal Period

Back 19

(weeks 9 - 40)

Front 20

Placenta
development and structure

Back 20

Begins to form at implantation

Front 21

Fetal circulatory system
Ductus venosus
foramen ovale
Ductus arteriosus

Back 21

O2 blood from placenta → umbilical vein → fetal liver → ductus venosus (bypasses liver) → inferior vena cava → mixture with deoxygenated blood in vena cava → right atrium → foramen ovale (blood from RA to LA)→ LA → LV → aorta → major organs → RV → pulmonary artery → lungs → LA → ductus arteriosus (bypasses the lungs) → aorta

Front 22

Priority organ systems for the fetus in order.

Back 22

Brain
Heart
Adrenal Glands (release epi and NE in times of stress to optimize CO in the fetus
Respitory, Liver, Kidneys

Front 23

3 special characteristics that enable the fetus to obtain sufficient oxygen from the maternal blood.

Back 23

- Hgb carries 20-33% more O2 then maternal Hgb.
- Hgb concentration is 50% greater then that of the mother.
-**FHR is 110-160 bpm making CO per unit of body weight higher then that of an adult.

Front 24

Fetal pO2

Back 24

20-32 mmHg

Front 25

Fetal Lung maturity
respiratory track begins wk__ to wk __
Surfactant present wk __, secreted by__, lines___. Function:
- Fetal lung maturity weeks: __ to __. How is maturity measured?

Back 25

Embryonic period to childhood, biggest problem in preterm babies,
- Respiratory tract begins week 5 continues to week 17
Surfactant: wk 32, alveolar cells, alveoli, expands lungs. (synthetic available)
- Fetal lung maturity: 35 – 37 weeks
Measuring fetal lung maturity L/S ratio = 2:1
* Lecithin (alveolar surfactant)
* Sphingomelin (pulmonary phospholipid remains constant in amt)
When ratio is 2:1 respiratory function will take place.
In diabetic mother lung maturity may be delayed beyond 37wks.
Fetal stress will progress the production of Lecithen and accelerate lung maturity.

Front 26

Oligohydramnios

Polyhydramnios

Back 26

low amniotic fluid
May discover that baby does not have kidneys, or low function. Has patient ruptured membranes?

Large amounts of amniotic fluid

Front 27

Renal system of fetus
kidney formation during wk __
Urine begins during __
Function of Amniotic Fluid

Back 27

kidney formation during wk 5
Urine 3rd month
AF - bathes and coats the organ system keeping tissues soft and flexible

Front 28

Quickening:
wks gestation it occurs

Back 28

16 - 20 weeks fetal movement is perceived by mother, felt earlier in subsequent pregnancies.

Front 29

Neurologic and Sensory systems
movements type and wk.

Sound at wk__
Taste ___
Vision__

Back 29

11-12 weeks - respiratory movements, moves extremities, changes position

Purposeful movements - response to firm touch on mothers abdomen
- Sound - 24 weeks
-fetal acoustic stimulation
- Taste- 5th month-sweetener added to AF causes fetus to swallow twice as fast
- Vision - 7th month

Front 30

Gastrointestinal system of fetus
- Mature by __ wks
- Swallows AF by

Back 30

36 wks

swallows amniotic fluid by 5 month

Front 31

Meconium

What can cause meconium to pass in utero?

Back 31

fetal waste. Dark, green sticky. Normally passes w/in 48hours after delivery. If passed in utero can be swallowed and get into baby’s lungs (Meconium asperation syndrome – can be fatal to baby). Can be a sign of baby stress.

Mec. in utero: breech or fetal hypoxia

Front 32

Hepatic system
Major source of energy?
Why are coagulation factors NOT synthesized?

Back 32

- Glycogen stores - 9-10 weeks – major source of energy
- Iron can store for 5 months
- Coagulation factors II, VII, IX, and X not synthesized b/c of lack of vitamin K in sterile fetal gut.
-persists for several days after birth
-prophylactic administration of vitamin K after delivery

Front 33

Endocrine system of the fetus

Back 33

Adrenal cortex is formed in the 6th wk. Produces hormones by the 8-9th wk. At term it believed that aids in initiation of labor by lowering the maternal progesterone and stimulating production of prostaglandins.

(Insulin produced by 20th week.)

Front 34

Reproductive system
Begins in wk__

Back 34

7th week – XX chromosomes ovaries formed. Y chromosomes testes formed
External genitalia indistinguishable until week 12.
- Male
- Female

Front 35

What 2 immunoglobulins are availabe to the fetus? How? function?

Back 35

IgG - crosses only Ig that crosses the placenta; provides passive acquired immunity to specific bacterial toxins.
IgM - fetus produces by end of 1st trimester; produced in response to blood group antigens, and some viruses.
(IgA - provided by colostrum)

Front 36

Musculoskeletal System of fetus
Bones and muscles develop at wk__
Function of fontanels?

Back 36

6th week
Fontanels - allow bones of skull to mold and move through the birth canal.

Front 37

Integumentary system
Begins at wk__
Vernix
subcutaneous fat appears at wk__

Back 37

Begins at wk 4 as a single layer of cells.

mucous white, protects skin of the fetus, thick at 24wks, becomes scant at term.
-after 32wks subcutaneous fat deposited under dermis, skin becomes less wrinkled

Front 38

Dizygotic Twins

Back 38

- Fraternal Twins
- 2 mature ova are produced in one ovulation both fertilized by separate sperm
- 2 amnions, 2 chorions, 2 placentas
fraternal twins - different genes

Front 39

Monozygotic Twins

Back 39

Identical Twins – 50% mortality rate – often have a donor and recipient – one has fluid overload the other is deficient
- develop from one fertilized ovum- divides
- same sex with one genotype
- 2 amnions, 2 chorions, 1 placenta – usually
- genetic link is on female side.