Physiology of pregnancy Flashcards
Fertilised egg =
Zygote
Length of human pregnancy =
38 weeks
When is pregnancy clinically measured from?
Last menstrual period
If measured from LMP, when is fertilisation and implantation?
Fertilisation = week 3 Implantation = week 4
T1 =
Week 1 - 12
T2 =
Week 13 -26
T3 =
Week 27 - 40
Fetus in T1 =
Fertilisation
Implantation
Initial development
Placentation
Mother in T1 =
Weight gain
Nausea/vomiting
Fetus in T2 =
Nervous system Pain Spine straightens Pain Proportions change
Mother in T2 =
Placental growth Hypervolemia Cardiac remodelling Breast remodelling Bump Quickening
Fetus in T3 =
Growth Fat deposition brain electrical activity Blood cells Lungs
Mother in T3 =
Braxton-hicks
Tiredness
Restricted breathing
Lactation
HR in mother
Increases
Blood vol in mother
Increases
Bp in mother
Stays same, decreases slightly
HTC in pregnancy
Decreases. Blood volume increases, RBC increase but can’t keep up
Fetal HR rises until
Week 12 (end of T1)
Fetal HR in T1 =
160-180 bpm
Fetal HR after T1
140 bpm
Trophoblasts change into =
Syncitiotrophoblasts
Cytotrophoblasts
By what day is the blastocyst fully implanted?
day 9
Implantation coincides with which phases of uterine and ovarian cycle?
Luteal phase
Secretory phase
Syncytium is a
Multicellular structure. Outer layer of trophoectoderm cells lose cell membrane and make a large, multi-nucleated structure
Cytotrophoblasts =
Unicellular structure. Single nucleated.
Tropoblastic lacunae are found in …
The syncytial trophoblasts
Lacunae are originally filled with …
Clear liquid that provides histotrophic support
Lacunae become filled with what later?
Maternal blood
What produces hCG in weeks 3-4
Syncitiotrophoblasts
Progesterone and oestrogen contribute to what symptoms of early pregnancy?
Suppression of menses Tender breasts Fatigue Nausea Constipation
Ectoderm =
- Epidermis
- Nervous system
- Cornea and lenses
- Nasal, oral and anal epithelium
- Pituitary gland
Mesoderm =
- Heart
- Muscles
- Bones
- Connective tissue
- Blood
- Urogenital organs
- Lymphatics
Endoderm =
- Respiratory epithelium
- GI tract
- GI organs (liver, pancreas)
- Urogenital epithelium
Pluriblasts become …
Epiblast and hypoblast
Epiblasts =
Precursors of ectoderm
Hypoblasts =
Precursors of endoderm
Yolk sac membrane is formed from …
Mesoderm and endoderm
Allantois is the precursor to …
Umbilical cord
Amnion formed from =
Mesoderm and ectoderm
Chorion =
Trophoblasts and mesoderm
How are spiral arteries remodelled?
Infiltrated by syncitio and cytotrophoblasts
Why are maternal spiral arteries remodelled?
Decrease BP to not harm embryo
What forms in the lacunae to link maternal blood to foetal blood?
Villi
Primary villi =
Solid trophoblast (syncitiotrophoblast)
Secondary villi =
Invasion with mesoderm
Tertiary villi =
Fetal blood vessels penetrate villi
How long does the placenta take to fully develop?
12 weeks
Villi at week 3 =
Primary stem villi penetrated by mesoderm. Blood bessels and CT develop from mesoderm to become teritary villi
Villi at week 9 =
Tertiary stem villi lengthen form mesenchymal villi
Villi at week 16 =
Maximum length. Forms immature intermediate villi
Villi at week 32 =
Secondary branches form - terminal villi.
Final structure.
Placenta is covered by …
Cytotrophoblasts
Outside/inside: Chorion, Amnion
Chorion = outer Amnion = inner
Fetal Hb chains =
2x alpha
2x gamma
Foetal RBCs are
Nucleated
Hormones produces by placenta:
- Progesterone
- oestrogen
- hCG
Somat-mammotrophin
hCG acts to
Maintain CL
Stimulate thyroid
Oestrogens cause:
Weight gain
Breast remodelling
Relaxation of pelvic ligaments
Progesterones cause:
- Decidualization
- Increase uterine secretions
- Decrease uterine contraction
Feeling baby kick is called
Quickening
Oestrogen effect on fluid:
- Increase NO, decrease endothelin 1
- Increase angiotensin II, renal re-absoption and aldosterone
Progesterone effect on fluid:
- Increase vasodilation
- Decrease peripheral resistance
- Increase aldosterone
- Increase thirst centre
Cardiac remodelling:
HR increases
Stroke vol increases
Size of heart increases
Lungs: what decreases?
Vital capacity
Lungs: what increases?
Tidal volume
What hormone increases tidal volume?
Progesterone, relaxes ligaments
Renal system =
Kidneys enlarge Ureters enlarge Decrease bladder tone Increase reflux Urinary stasis
Increased urinary stasis leads to:
Increased UTIs
Progesterone and breast =
Growth of alveoli and ducts
Oestrogen and breast =
Stimulate growth and development of milk ducts
HPL and breast =
Breast, nipple and areola enlarge
What is produced from breast in T3?
Colostrum
Average weight gain during pregnancy =
24 lb (11 kg)
Additional caloric intake =
100-300 calories
Weight gain in T1
Ideally 2-4lb per week
Weight gain in T2-T3
Ideally 1 lb per week