Physiology Chapter 83 Fetal And Neonatal Physiology

Front 1

when does the heart begin to contract? what is the rate?

Back 1

during the first week. begins ~65 bpm and increases to about 140 bpm before birth

Front 2

when are most of the reflexes of the brainstem/spinal cord developed?

Back 2

by the 3rd/4th month but some cerebral cortex tracts are still developing and dont fully mylenate until about a year after birth

Front 3

when do fetal kidneys begin to excrete urine?

Back 3

during second trimester. fetal urine accounts for roughly 70-80% of amnionic fluid

Front 4

what is oligohydraminos

Back 4

severe reduction of amnionic fluid often due to failure of renal control systems or kidney development

Front 5

what is meconium

Back 5

residue composed of mucus and swallowed amnionic fluid that begins to pass through GI tract in the last 2 to 3 months

Front 6

when is calcium accumulation in the fetus highest? why?

Back 6

last 4 weeks of gestation

rapid ossification of the fetal bones

Front 7

where is the most iron (1/3rd) stored in the fetus

Back 7

liver

Front 8

what does the fetus need B12 and folate for

Back 8

proper red blood cell and nervous tissue development

Front 9

what does the fetus need vitamin C for

Back 9

formation of bone matrix and fibers of CT (particularly collagen)

Front 10

What is vitamin D needed for in the fetus

Back 10

absorption of calcium from the GI tract. needed for normal bone growth

Front 11

what do fetuses need vitamin E for

Back 11

we dont know, but they definitely need it. (without it spontaneous abortion occurs)

Front 12

what is vitamin K needed for in fetus

Back 12

used for formation of factor VII PT and other coagulant factors.

neonates are given vitamin K when born as they do not build up their own stores for at least a week.

lack of vit K can increase risk of hemorrhage

Front 13

what is the effect of labor anesthetics that cross the placenta

Back 13

can cause slowing of respiration in the infant

for this reason doctors must use minimal anesthetic to prevent hypoxia in newborn

Front 14

what are common causes of hypoxia during birth

Back 14

1. compression of umbilical cord

2. premature separation of the placenta

3. excessive contraction of the uterus

4. excessive anesthesia of the mother

Front 15

How long can a neonate remain hypoxic after birth

Back 15

can survive up to 10 minutes (adults only 4)

however longer hypoxic states are associated with CNS issues

Front 16

how do the lungs expand at birth?

Back 16

high surface tension from viscous fluid filling the lungs is overcome by tremendous first inspirations (60mmHg of negative intrapleural pressure overcomes the 25mmHg of surface tension)

each progressive breath becomes easier

Front 17

how does circulation occur prior to birth?

Back 17

oxygenated blood returns through umbilical veins to ductus venosus bypassing the liver and entering the right atria, passing through the foramen ovale and then out through the aorta to the body. the blood of the superior vena cava passes through to the RV and pulmonary artery, then is shunted via the ductus arteriosis to the aorta.

Front 18

what major changes occur at birth that trigger circulatory adjustments?

Back 18

loss of placenta, inflation of lungs. This results in reduction of resistance in the pulmonary circulation and redirection of the (55%) of blood that had been passing through the placenta increasing systemic vascular resistance

Front 19

What is the effect of birth on pulmonary arterial pressure, right ventricular pressure, and right atrial pressure

Back 19

all are reduced

Front 20

what closes the foramen ovale?

Back 20

high Left atrial pressure relative to low right atrial pressure

Front 21

what closes the ductus arteriosis

Back 21

increased systemic vascular resistance (increased aortic pressure) causes back flow into the pulmonary artery and vasoconstriction

Front 22

what chemicals can cause patent ductus arteriosis

Back 22

prostoglandins (which induce vasodilation)

Front 23

how do infants sustain themselves until sufficent breast feeding occurs?

Back 23

they cannot undergo significant gluconeogenesis due to incomplete liver development

they rely on stored fats for the first few days

Front 24

how do differences in respiratory volumes effect the stability of blood gasses in the infant

Back 24

the tidal volumes are smaller and the FRC is smaller so the minute respiratory volume is higher (relative to weight)

this causes cyclical increases/decreases in the infants blood gasses when respiration is altered

Front 25

what are normal blood pressures for neonates

Back 25

70/50 rising to 90/60 over the next few months

Front 26

why do some infants have jaundace

Back 26

poor ability of neonatal liver to process bilirubin. this is refered to as physiological hyperbilirubinemia

Front 27

what is the most common serious cause of abnormal fetal jaundace

Back 27

eryhtroblastosis fetalis due to Rh incompatibility with the mother (who is negative) and sends antibodies through the placenta which attack the childs blood cells

Front 28

is there a tendency toward acidosis or alkylosis in the newborn? why?

Back 28

higher metabolic rate increases acid (CO2) production.

also kidneys havent developed ability to fully concentrate urine.

as such acidosis and dehydration are 2 common problems in newborns

Front 29

slow progression of the liver to full function provides the following deficits for neonates

Back 29

1. poor conjugation of bilirubin (jaundice)

2. low plasma protein concentration (edema)

3. poor gluconeogenesis (low blood sugar)

4. impaired clotting factor formation (tendency for hemorrage

Front 30

if a mother has untreated T2DM what can happen to the infant?

Back 30

hypertrophy and hyperfunctioning of islet cells which can cause severe drop in blood sugar (20mg/dl)

Front 31

what is hypoproteinemic edema

Back 31

edema resulting from low colloid osmotic pressure, often seen in premature neonates

Front 32

what can low calcium in the neonate cause

Back 32

hypocalcemic tetany

Front 33

what is a risk of excess oxygen treatment in the premature infant?

Back 33

excess oxygen therapy to treat respiratory distress can lead to blindness as the oxygen will prevent growth of blood vessels in the retina. when the o2 therapy stops a period of rapid angiogenesis followed by fibrosis blocks light transmission to retina this is called retrolental fibroplasias