Term
| What are the 6 ways substances move across the placenta? |
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Definition
Simple diffusion (O2, CO2)
Facilitated diffusion (Glucose)
Active transport
Bulk flow (d/t hydrostatic or osmotic gradient)
Pinocytosis
Phagocytosis |
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Term
Which type of drug is more susceptible to transfer across the placenta: protein bound drugs or free?
What are other ways drugs move across the placenta? |
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Definition
Free, nonprotein bound drugs move easier.
Concentration gradients, molecular weight, lipid solubility, and drug ionization (remember ion trapping!) |
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Term
| What is the range for autoregulation in the uterus? |
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Definition
| No range! The uterine vessels are maximally dilated, so there's no autoregulation. Blood flow is dependent on mom's MAP. |
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Term
| How does normal uterine blood flow compare to the gravid uterine blood flow? |
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Definition
| Normal blood flow is 100 ml/min, while the gravid uterine blood flow is 700 ml/min (10% CO) |
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Term
| Where does the majority of uterine blood flow go? |
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Definition
| The majority enters the sinuses, while the rest supplies the myometrium (uterine muscle). |
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Term
| True or false: Uterine blood vessels can be vasoconstricted. |
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Definition
| True, dat! Vasoconstriction occurs through alpha adrenergic action. |
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Term
What is the equation for uterine blood flow?
Which dead guy's law is this? |
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Definition
Uterine flow = (uterine arterial pressure-uterine venous pressure) / uterine vascular resistance
Ohm's law |
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Term
| How do gas changes, such as hypercarbia or hypoxia affect uterine blood flow? What about hypocarbia or respiratory alkalosis? |
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Definition
| Hypercarbia and hypoxia do not change uterine flow dynamics. No definitive word on hypocarbia, but hyperventilation shifts the oxyhemoglobin curve to the left, increasing affinity. |
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Term
| 6 factors reduce uterine blood flow. What are they? |
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Definition
Uterine contractions
Hypertonus
Hypotension
Hypertension
Vasoconstriction
Exogenous vasoconstrictors |
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Term
| How do uterine contractions decrease blood flow? |
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Definition
| They increase the venous pressure, reducing flow. They can also reduce arterial flow. |
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Term
What causes uterine hypertonus?
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Definition
| abruptio placenta, tetanic contractions, or over stimulation with oxytocin. |
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Term
| How might regional or general anesthetics be protective of the fetus? |
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Definition
| Maternal stress or pain stimulates the release of catecholamines, leading to vasoconstriction and increased uterine vascular resistance, which decreases uterine blood flow. Anesthesia blocks the sympathetic outflow, potentially improving blood flow to the uterus. |
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Term
How much oxygen does the fetus have?
What is the oxygen consumption of the fetus?
How much time does this give baby if oxygen delivery is cut off? |
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Definition
42 ml
21 ml/min
2 min, although in reality, the baby can survive as long as 10 minutes until irreversible brain damage sets in. |
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Term
| What might result in loss of oxygen supply to baby? |
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Definition
| maternal cardiac arrest, severe hypotension, hemorrhaging, placental abruption, complete cord compression, cord wrapped around baby's neck, prolapse cord |
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Term
| How does prolonged labor potentially affect mom's catecholamine stores? |
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Definition
| They can become depleted. |
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