Anatomy and Physiology: Conception & Pregnancy Flashcards
1
Q
Pelvis
A
- Protection of the pelvic structures
- Accommodation of the growing fetus
- Anchorage of pelvic support structures
- Divided into false & true pelvis
- false pelvis is above the linea terminalis (inlet)
- true pelvis is below
2
Q
Spermatogenesis
A
- Complete spermatogenesis takes 74 days, producing 300-400 million/day
- upon ejaculation (3-5 ml), most sperm do not survive more than 48 hours within the female reproductive tract - only 50,000 - 100,000 reach the ovum
- the alkaline nature of sperm protects them from vaginal acidity
- Composition of Semen: 60% seminal vesicular fluid, 30% prostatic fluid, 10% sperm and spermatic duct secretions
3
Q
How does the scrotum maintain temp?
A
- The scrotum maintains a temperature 2-3 degrees lower than the body, which is critical for spermatogenesis
- Cremaster muscle contracts and relaxes testes closer and further from the body
- Dartos muscle contracts scrotum to be wrinkled, which decreases its surface area
- Pampiniform plexus: vein network cools arterial blood
4
Q
Oogenesis
A
Primary oocyte: 2 million are formed during fetal development
Secondary oocyte: develops and starts meiosis monthly
- Second meiosis is only completed when fertilized = zygote
- optiman fertility is 17-28 years old and starts to decrease at 35
5
Q
Menstrual Cycle
A
- purpose is to prepare the uterus for pregnancy
- Starts 14 days after ovulation (usually every 28 days)
- Hypothalamic-pituitary cycle
- Ovarian cycle
- Endometrial cycle
6
Q
Hypothalamic-Pituitary Cycles
A
- End of cycle = decrease in Progesterone & Estrogen from hypothalamus
- The release of Gonadotropin-releasing hormone (GnRH) stimulates LH & FSH
- Luteinizing Hormone: rupture of follicle and conversion of ovum to the corpus luteum
- Follicle Stimulating Hormone: starts at menstruation causing ovum to mature
7
Q
Unterine/Endometrial Cycle
A
- Proliferative Phase: estrogen causes proliferation of ovarian mucosa until ovulation
- Secretory Phase: progesterone causes maturation and secretion by uterine glands - until about 3 days prior to onset of menses
- ischemic phase: blood supply to lining stops and lining prepares to slough
8
Q
Ovarian Cycle
A
- Follicular phase: 1-30 ova develop, estrogen increases = one ovum released
- Ovulation - day 14 mature ovum
- Luteal phase: the follicle develops into the corpus luteum, increased progesterone maintains the uterine lining
- Ischemic Phase: progesterone falls
9
Q
Fertilization and Implantation
A
- fertilization can happen anywhere in the fallopian tube
- Not every fertilized ovum = a pregnancy
- implantation happens between 6 and 10 days after conception
10
Q
Implantation
A
- implantation occurs 6-10 days post-fertilization
- trophoblast: secretes enzymes to burrow into endometrium
- trophoblast develops chorionic villi to act as vascular processes for O2/nutrients and CO2/waste disposal
- Endometrium terminal decidua - under chorionic villi is the decidua basalis
- Prefers anterior or posterior fundal height
- chorionice villi are tiny projections of placenta tissue that look like fingers and contain the same genetic material as the fetus
11
Q
Trophoblast
A
a thin layer of cells that helps a developing embryo attach to the wall of the uterus, protects the embryo, and forms a part of the placenta
12
Q
Decidua basalis
A
the portion of the decida that is related to the chorion and participates with it in the formation of the placenta, becoming the maternal component of the fully formed placenta
- endometrium decidua: connecting to growing lump of cells. wants to implant on the front or back of uterus
13
Q
Gestational Age
A
- Weeks of pregnancy is always counted from the women’s last menstrual period (LMP)
- Since ovulation doesn’t occur until Day 14, the moment fertilization occurs, the zygote is already considered to be at 2 week gestational
- When the women misses her fist period (approx day 28), the embryo has been developing for 2 weeks but is considered 4 weeks gestational age
14
Q
Naegle’s Rule
A
first day of LMP, add one year, subtract three months, add seven days
15
Q
3 phases of Fetal Development
A
Pre-embryonic
Embryonic
Fetal
16
Q
Pre-embryonic
A
- Conception to Day 14
- Prior to placental function, it is a cavity that forms, helps transport maternal nutrients and oxygen to the embryo via diffusion
- Creates blood cells and plasma
- Cellular replication, blastocyst formation, initial development of embryonic membranes, primary germ layers
- During embryongenesis, three germ layers form as the source of all embryo tissues and organs: ectoderm, mesoderm, endoderm
17
Q
Embryonic
A
Day 15 until week 8 (post conception)
-Teratogens are the biggest threat
- All organ systems and structures are in place
- babies grow head down.
18
Q
Fetal
A
- Week 9 until birth
- “viability” = able to survive outside the uterus
- current age of viability is 24-25 weeks (50-50 will survive)
19
Q
Special Fetal Circulation
A
- Fetal Shunts
- ductus arteriosus = fetal circulatory pathway where fetal blood bypasses the lungs because fetal lungs do not provide gas exchange
- ductus venosus = fetal circulatory pathway where fetal blood oxygen-rich blood from the umbilical vein (placenta) bypasses fetal liver and enters inferior vena cava
- foramen ovale = an opening between fetal atria were deoxygenated blood from the fetal legs and abdomen and returning from the fetal lungs flows into the left ventricle and to the aorta - Heart beat rate is faster (110-160 bpm)
- Higher hemoglobin concentration in circulation (additional RBCs, 50% greater)
- Hemoglobin has higher affinity for oxygen (20% to 30% more oxygen)
- this oxygen-rich blood heading to upper fetal head and torso first causes cephalocaudal growth
- Fetus loves hemoglobin and O2 because it is growing so fast
20
Q
Fetal Shunts
A
- Ductus Venosus = LIVER
- Foramen OVALE = Over the top of the fetal heart - so from R atrium to L atrium
- Ductus Arteriosus = “into the major ARTERY” the Aorta, bypassing fetal lungs
- Purpose:
1. bypassing fetal lungs
2. route oxygenated blood into circulation quicker
Venous: a little blood goes in the liver, bypasses most the blood because the mom is doing the function of the liver for the fetus - there is blood going through fetal lungs but will not grow or develop them
21
Q
Umbilical Cord
A
- Umbilical VEIN - carries oxygenated & nutrient rich blood into fetal circulation
- Umbilical Arteries - carry blood from EMBRYO to the placenta where it releases wasted & gains nutrients & oxygenated blood “Away”
- Wharton’s Jelly connective tissue on cord that prevents compression
22
Q
Membranes
A
Starts at implantation
- Amnion
Inner membrane
Fills with amniotic fluid
- Chorion
Contains placenta
Outer membrane
23
Q
Amniotic Fluid
A
- believed secreted by the amnion, maternal vessels in the decidual & fetal vessels in placenta
- Babe swallows and urinates fluid (week 11)
- Babe “breathes in” fluid into lungs
Volume increases during pregnancy - peaks around 2 wks before due date
Volume - 700-1000 mL at term
Polyhydramnios = too much (>2L) stress on the membranes
Oligohydramnios = too little (<300ml) too cramped. can’t grow right, there is not enough nutrients
24
Q
Role of Amniotic Fluid
A
- maintains a constant temperature for the fetus
- provides oral fluid for babe to practice breathing and swallowing
- cushions the fetus from trauma
- allows freedom of movement for musculoskeletal development
- prevents the fetus from becoming entangled in amnion or cord
25
Placental Development
Begins at implantation - structurally complete at 14 weeks
- chorionic villi burrow into decidua basalis
- series of functional units called "cotyledons"
- chorionic villi & deciduous basalis form the placenta
chorionic villi are tiny projections of placental tissue that look like fingers and contain the same genetic material as the fetus
- decidua basalis is the portion of the decidua that is related to the chorion and participates with it in the formation of the placenta, becoming the maternal component of the fully formed placenta
26
Placental Function: Manufacturing Warehouse
production of various proteins
stores proteins, calcium, iron
27
Placental Function: Endocrine Function
- Manufacturers hormones (takes over production from the maternal endocrine system)
28
Placental Function: Transport Function
- Delivery of oxygen, nutrients, excretion of wastes, CO2
- Heat transfer
29
Placental Hormones: Human Chorionic Gonadotropin
- "pregnancy hormone" detected in home pregnancy tests
- signals to body that pregnancy has taken place
30
Placental Hormones: Human placental lactogen (hPL)
- Stimulates maternal metabolism to supply nutrient for fetal growth
- increases resistance to insulin & facilitates glucose transport across placenta
31
Placental Hormones: Estrogen
uteroplacental blood flow - frowth
32
Placental Hormones: Progesterone
Relaxation and maintenance
- by week 9, placenta has taken over hormone production
-symptoms associated with first trimester is because her body is producing all these hormones
- hormone levels are still high when she has placenta, but she isnt producing them. her body is producing them through a supplemental structure
33
Factors of Uteroplacental Blood Flow
Maternal blood pressure
- Too high - can damage small capillaries
- Too low - insufficient perfusion
Maternal position
- not flat on back. weight of uterus compresses maternal vena cava in 3rd trimester
- left lateral provides best blood flow - pillow under right hip
Lifestyle choices
- smoking, cocaine, contraindicated medications
High BP not enough oxygenation. 24-25 weeks surfactant and alveoli develop in the fetus and this is why this is the age of viability. We cannot do artificial lung function. Lungs are essential. Lungs are the last organ to become independent.
34
1st Trimester
conception until 12 weeks (13-14 weeks)
"Organogenesis"
- very small baby. A whole lot is happening at the cellular level. Called a fetus, all the exciting stuff is happening on the inside. More important to do organs and body systems first
35
2nd Trimester
- 13-26 weeks
- Growth and development
- mature of all organ systems at the end you are at viability
36
3rd Trimester
- 27 weeks - Birth (40-42 weeks)
- Term: considered 37+1 -42 weeks
- bulking. getting big and chunky
37
Teratogens (any substance that can cause abnormal fetal development)
- Hot tubs/baths (amniotic fluid is temp stable environment that is prime for development of cells. Don't want to poach your baby)
- Medications
- Toxoplasmosis (a chemical toxin that exists in certain things (cat litter) teaching option.
- Occupational Hazards (something you're exposed to regularly in your work environment. Noise)
- X-Rays (most pregnant women do not get x-rays)
- chemicals (beauty products)
- Alcohol/smoking
- Infectious diseases
- Live Immunizations
38
Signs of Pregnancy: Presumptive
Changes felt by the woman (amenorrhea, fatigue, breast changes)
39
Signs of Pregnancy: Probable
those changes observed by an examiner(ballottement, pregnancy test)
- Human chorionic gonadotropin is the earliest biochemical marker for pregnancy
- production begins as early as implantation
- can be detected in maternal serum or urine as soon as 7 to 8 days before the expected menses
40
Signs of Pregnancy: Positive
those signs attributed only to the presence of the fetus (hearing fetal heart tones, visualizing the fetus, palpating fetal movements)
41
Key points
- Dilation of renal pelves and ureters during pregnancy increases the risk of UTI
- Balance and coordination are affected by changes in joints and in the woman's center of gravity as pregnancy progresses
- Decreased smooth muscle tone during pregnancy contributes to heartburn, reflux, and constipation
- endocrine changes are essential to maintaining pregnancy and promoting fetal growth
- During pregnancy maternal blood pressure remains the same or decreases slightly
- Heart rate increases 10 to 15 beats/minute by 32 weeks of gestation and persists until term
- Respiratory rate is unchanged during pregnancy, although tidal volume and minute ventilation increase by 30% to 50%
- Pregnancy is a hypercoagulable state with increased risk for thrombotic diease
- Physiologic anemia of pregnancy results from an increase in plasma volume greater than the increase in RBC
