Lecture 1: Phys and Pathophys Flashcards
What is the HPO Axis?
Hypothalamic Pituitary Ovarian Axis
What are the 4 roles of the HPO Axis?
- Development of sexual characteristics
- Coordinating regular periodic body changes
- Function of cervix, vagina, and breasts
- Maintenance of pregnancy
What is the role of the hypothalamus in the HPO axis?
- GnRH production and release (pulse)
- Binds to anterior pituitary
What is the role of the pituitary in the HPO axis?
- Release of FSH and LH
- FSH and LH go to ovary
What is the main role of FSH and LH in the HPO axis in relation to follicles?
Folliculogenesis
Theca and granulosa cells
What is the role of FSH and LH in the ovary?
- Production of steroids (estrogen, progesterone, androgens)
- Gonadal peptides (activins, inhibins, follistatins)
- Growth factors
What is the role of estrogen in the HPO axis?
- Induce surge of LH to release oocyte
- Proliferation of endometrium tissue
- Secondary sex characteristics development
- Libido
- Thickening of vaginal wall and lubrication
- Reduced cholesterol/atherosclerosis
- Reduced acne
What is the role of progesterone in the HPO axis?
- Maintenance of pregnancy
- Decrease uterine contractility
- Promote breast development/differentiation
- Once it falls, menses occurs and lactation occurs
What do activins do?
- Stimulate FSH secretion
- WBC production/embryo development
What do inhibins do?
Inhibit FSH secretion
What do follistatins do?
- Regulate gonadotropin secretion
- Inhibits activins
What is a relaxin?
- Relax pubic symphysis
- Inhibit uterine contractions
- Development of mammary gland and follicular development
Relax and INhibit
What is the positive feedback loop of the HPO axis?
- High estrogen => increased GnRH and LH
- High activin => more gonadotropic function
What is the negative feedback loop of the HPO axis?
- Progesterone inhibits GnRH and LH
- Inhibin inhibits FSH secretion
- Follistatin inhibits FSH secretion
- Lactation increases dopamine and alters release of GnRH
- Estrogen (moderate) decreases LH
- Estrogen decreases FSH
How does puberty tend to vary between sexes?
- Females occur 8-13 (earlier)
- Males occur 9-14
What are the stages of puberty?
- Andrenarche (prior to puberty)
- Thelarche: Breast development (First event of puberty)
- Pubarche: pubic and axillary hair
- Menarche: first menstrual cycle
Thelarche also includes:
Estrogen => duct growth
Progesterone => lobule and alveoli growth
What counts as day 1 of a normal menstrual cycle?
Beginning of flow
What is the average menstrual cycle duration?
28d, +/- 7d
What are the two main phases of the menstrual cycle?
- Ovarian cycle => Follicular phase => ovulation => luteal phase
- Uterine cycle => proliferative phase => secretory phase => menses
How does FSH and LH change during the ovarian cycle in the follicular phase?
- FSH Rise > LH Rise
- Inhibin B production due to FSH starts to inhibit FSH via neg feedback
- Midfollicular phase 6d later, making 1 dominant follicle and other atretic follicles.
What two things occur as a dominant follicle matures?
- LH receptor development
- Estrogen release
As estrogen is released from the maturation of a dominant follicle, what occurs?
- Increased GnRH pulses
- LH surge
- Ovulation
What happens during ovulation in the ovarian cycle?
- Occurs around day 14 with mature follicle rupture as it goes to oviduct.
- Corpus hemorrhagicum occurs as follicle fills with blood.
- Mittelschermz can occur
Ovulation pain due to blood being an irritant
What is the corpus luteum?
- Granulosa and theca cells of follicle make yellowish, lipid-rich luteal cells.
- Makes estrogen and progesterone when stimulated by LH
- Negative feedback inhibits FSH and LH
After it spits out the ovum
If there is no pregnancy, what happens to the corpus luteum?
- FSH and LH decrease
- Atrophy of corpus luteum 3-4d premenses into atrophic corpus albicans
What triggers menses?
Declining levels of progesterone as corpus luteum atrophies and ceases to release progesterone
What is the phase of the uterine cycle following menses and what occurs?
- Proliferative phase
- End of menses, where only the stratum basale remains of the endometrium.
- Days 5-16: Estrogen from developing follicles will regenerate endometrium, forming the stratum functionale.
- Uterine glands lengthen without secreting anything
The rebuilding of the endometrium, not revascularization.
When does the secretory phase of the uterine cycle occur and what occurs?
- 14d, post ovulatory
- Estrogen and progesterone from the corpus luteum vascularize the endometrium and develop uterine glands.
- However, once the corpus luteum regresses, spasms and ischemia of the endometrium occur with decreasing progesterone and estrogen.
- Hemorrhage occurs as breakdown of endometrium occurs.
Image of ovarian and uterine cycle
Medcomic image of uterine and ovarian cycle
LH causes ovulation
What occurs in the cervix during the menstrual cycle?
- Estrogen thins and alkalizes mucus to enhance sperm survival
- Dries like a fern-like pattern on slide
- Progesterone thickens mucus and does NOT cause a fern-like drying pattern.
When is cervical mucus thinnest?
At time of ovulation
When is cervical mucus thickest?
Day 21, which is after ovulation and during pregnancy
What kind of epithelium is present from endocervix to ectocervix?
Columnar
Cervical ectopy
Why does squamous metaplasia occur with rising estrogen levels in puberty?
Cervical os uncoils and exposes some columnar and the acidic environment results in squamous metaplasia.
What lifestyle habit accelerates metaplasia of the cervix?
Smoking
What medication can reverse/persist cervical ectopy?
OCPs
May increase susceptibility to STIs as columnar is weaker than squamous.
How do the two main steroid hormones affect ciliary beat frequency in the fallopian tubes? (CBF)
- Progesterone: reduces CBF
- Estrogen: increases CBF
Estrogen Enhances
How do the main steroid hormones affect muscles?
- Progesterone: reduce spasms, relax smooth, antagonizes insulin effects on glucose metabolism
- Estrogen: improves skeletal contractility
- Both help protein metabolism
Estrogen Enhances
What is the effect of ovarian hormones on skin?
- Maintain collagen and moisture
- Increased healing and growth
- Increased skin pigmentation
What is the effect of ovarian hormones on fat?
- Increased fat deposition: pear shape
- Progesterone: mediator of fat gain in pregnancy
What is the effect of ovarian hormones on sodium/water balance?
- Estrogen: retention
- Progesterone: excretion
Estrogen Enhances retention
Image of anatomy when pregnant
What CV changes occur during pregnancy?
- Upward and Lateral shift of PMI
- Increased heart size, SV, CO and +15 HR
Multiple gestation = more HR increase
What is supine hypotensive syndrome and the tx?
- Hypotension, bradycardia, and syncope when laying down.
- Tx: Lateral recumbent positions
How does BP change in pregnancy?
- Minor arterial decrease
- Widened PP
- Increased LE venous pressure, potentially leading to edema and varicosities
- PVR/SVR will decrease due to more vasodilators
Where does blood flow increase to during pregnancy?
- Uterus
- Kidneys
- Breasts
- Skin
What murmur is MC in pregnancy?
Split S1 or loud S3 at the left sternal border
90% of pts, generally normal
What does pregnancy decrease the threshold of for heart rhythm?
Reentrant SVT
What EKG changes may occur in pregnancy?
- Left axis shift
- ST Depression
- T-wave flattening
What happens to the rib cages in pregnancy?
Upward displacement
What happens to the lungs and ventilation in pregnancy?
- More tidal volume due to less dead space
- Increased O2 consumption
- Mild respiratory alkalosis
- No change in RR
- Increased dependence on diaphragm
What happens to the kidneys in pregnancy?
- Renal hypertrophy
- Dilation of vessels => increased flow and GFR and creatinine clearance and renin activity
- Upward and flattening of bladder, decreased tone (increasing capacity)
What might be seen in urine during pregnancy?
- Glucosuria
- Urinary protein loss
What happens to the GI system in pregnancy?
- Upward stomach and bowels
- Increased salivation and gum hypertrophy
- Decreased intestinal transmit time
- Slowed gallbladder emptying
- GERD and decreased gastric emptying
- Decreased albumin, increased ALP from placenta
What electrolyte binds to albumin primarily?
Calcium
What occurs to blood volume in pregnancy?
- 50% increase in plasma volume
- Estrogen = elevates volume via water retention and RAAS stimulation.
Estrogen Enhances
What heme changes occur in pregnancy?
- Increased RBC
- Anemia due to increased volume
- Increased EPO requires more iron
- WBC increase
- Plts increase in both production and consumption, resulting in net decrease.
What coagulation changes occur in pregnancy?
- Increased clotting factors
- Decreased protein S
- Net effect: procoagulant state
What happens to immune function in pregnancy?
Decreased.
Also means autoimmune conditions like SLE require LESS tx during pregnancy since immune system is depressed.
How does the pituitary gland change during pregnancy?
- Enlargement
- Increased GH
- 10x prolactin, going down after delivery.
How does the thyroid gland change during pregnancy?
- Increased thyroid hormone production without thyromegaly
- hCG is similar to TSH structurally, so low TSH can be masked.
How does the parathyroid gland change during pregnancy?
- Decreased 1st tri, increased 2nd and 3rd tri.
- Decreased Ca due to increased volume
- Vit D increased
How does the adrenal gland change during pregnancy?
- Increased ACTH and free cortisol
- Increased aldosterone (Na retention)
What ophthalmologic changes occur during pregnancy?
- IOP: decrease
- Cornea: increased thickness, decreased sensitivity, may see krukenberg spindles
- Transient loss of accommodation
- No actual visual changes
Spindles: brownish-red opacity on posterior cornea
What hyperpigmentation/skin changes can occur during pregnancy?
- Linea nigra on abdomen (black line)
- Melasma (mask of pregnancy), uneven darkening in cheeks, worsened by sun exposure
- Also seen in OCP use
- Stretch marks/striae gravidarum (MC in abdomen)
something like SLE should be DECREASING during pregnancy, so thats how u differentiate between melasma vs lupus malar rash
What rashes/vascular skin changes can occur in pregnancy?
- Spider angiomas
- Palmar erythema
- Cutis marmorata (mottled appearance)
- Varicosities
MC in white women
What nail change occurs during pregnancy?
Brittle and horizontal grooves (Beau’s lines)
What hair changes occur during pregnancy?
Increased thickness and growth
How does metabolism vary in pregnancy?
- More fatigued
- Increased appetite/thirst, esp by breastfeeding
- Increased weight on avg of 12.5g/27.5lbs
- Increased fat & water retention
- Hyperinsulinemia and insulin resistance
- Increased protein metabolism
How do electrolytes vary in pregnancy?
- Na & K decrease slightly, diluted by volume
- Ca and Mg decrease
- Phosphate minimal change
- Iron decreases, requiring supplemental
What additional nutrients should pregnant women be supplemented with?
- Iron
- Folic acid
- Calcium
- Zinc
How much more cal should a pregnant women eat daily? Lactating?
- Pregnant: 300kcal more daily
- Lactating: 500kcal more daily
Jensen said shes seen it in PPP
How much protein should a pregnant woman consume daily?
1g/kg/d + 20g/d in 2nd half of pregnancy
60-80g/d for an average pregnant women
If a pregnant women is anemic, how much iron should they be consuming daily?
60-120mg/d
Might need if not getting enough in diet.
What does folic acid supplementation prevent?
Neural tube defects
0.4mg/d, increased to 1mg/d depending on T1DM or 4mg/d if hx of NTD in previous
What is the function of the placenta?
- Release of hormones & enzymes to maternal bloodstream
- Transport all fetal nutrients
- Acts as fetal lungs
What controls arterial bleeding in a pregnant woman?
Uterine wall contraction
What substance characteristics make a drug likely to cross the placenta?
Small size and albumin-bound
Warfarin and salicylates are NONOs
Mother has less albumin, so the gradient is increased.
What does the placenta secrete?
- hCG
- Proteins
- Steroids: DHEAS and estriol
- Control intrauterine growth and vital organs
What common substances do not cross the placenta?
- Heparin
- Insulin
Large molecular size and/or charge
What occurs in weeks 1-4 of gestation?
- Zygote formation from sperm and egg
- Morula forms as zygote splits.
- Enters uterus 3-5d post fertilization
- Blastocyst formation, forming inner embryo and outer supportive tissues
- Days 6-7: implant and invasion of endometrium
- Day 10: Fully encased
Days 6-7 is peak of progesterone
Zygote > Morula > Blastocyst
What occurs to the outer cell group of a blastocyst?
Becomes chorionic villa and eventually the placenta.
What are the 3 layers of the inner embryo?
- Endoderm: Epithelial linings
- Mesoderm: connective tissue and muscles and bones
- Ectoderm: Skin, teeth, outer epithelium, nervous system
Inner to outer.
What organs begin to develop at week 5 in an embryo?
- Brain
- Spinal cord
- Heart
- GI Tract
AKA the most important minus kidneys
What begins to develop at weeks 6-7 for an embryo?
- Eyes, ears, bones
- Limb buds
- Heart beating
Brain also splits into its 5 areas
What should occur by week 9 of gestation?
All major organs should begin development
Milestone
What should occur by week 10 of gestation?
- Embryo is now a fetus
- Fetal heart tones (FHT) audible by Doppler
When is a fetus’s gender potentially distinguishable?
Around weeks 11-14
What occurs in weeks 11-14 of a fetus?
- RBC production in liver
- Urine production
- Ossification of bone centers
What milestones occur around week 15-18 of a fetus?
- Lanugo (fine hairs)
- Movement
- Meconium (first poop)
- Fat accumulation
When are fetal movements generally felt by a mother?
Week 19
Also when a fetus can begin hearing
What is the midpoint of pregnancy?
Week 20
By this time, movements may be felt, all major organs are under development, and bony structure is progressing.
FHT and gender are distinguishable.
What week is generally considered good survivability for a preemie? Why?
Around week 26 or later
Lungs are usually mature enough to survive
What should occur by week 26 in a fetus?
- Alveoli formation
- Hand/startle reflex
What is the main milestone that should occur around weeks 27-30 in a fetus?
Production of surfactant
When in gestation is the biggest risk for major congenital defects?
Week 16 and earlier.
1st trimester
What layer forms most of the GU system?
Intermediate mesoderm
What is required to generate a functional Male GU tract?
Functional Y chromosome
What are the 4 stages of GU development for an embyro?
- Genetic: chromosomes
- Gonadal: Expression of genes by testis determining factor (TDF) on Y chromosome
- Ductal: Mesonephric = male, paramesonephric = females
- Genital: Duct development into specific genitalia
What hormone suppresses paramesonephric ducts for male development?
Antimullerian hormone
Paramesonephric = mullerian
What hormone develops wolffian/mesonephric ducts?
Testosterone
Testosterone develops, antimullerian suppresses.
M for male
If we have release of antimullerian hormone without testosterone, what will occur in an embryo?
Suppression of both ducts.
Define agenesis and agonadism
- Agenesis: no formation of gonads ever
- Agonadism: Initial formation but later degeneration
What are streak gonads?
Primordial gonad formation without differentiation.
What is the precursor to urogenital structures?
Cloaca
Male: bladder, urethra, penis
Female: bladder, urethra, vagina
Define vaginal agenesis, atresia, and septa
- Agenesis: no development
- Atresia: lower part is only fibrous (aka closed)
- Septa: Either transverse or longitudinal
What do the mesonephric ducts become for a male?
- Epididymis
- Ductus deferens
- Ejaculatory ducts
What might the paramesonephric ducts become in a male?
May persist as appendix testis
Through what structure do the testes descend through?
Inguinal canal, going down to the scrotum
What happens to the mesonephric ducts in a female?
Mostly regression, but small amount becomes trigone of bladder
What happens to paramesophric ducts in a female?
- Midline: Uterus
- Distal: oviducts
What can happen to the clitoris in development?
- Agenesis: atresia or lack of tubercle formation
- Bifid/double: failure of fusion
- Hypertrophy: intersex disorders