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Details Title: Labor and Delivery Description: 5.1.07 Total Flash Cards: 88 Created: 05/01/2007 13:03:42	To study from this set of flash cards, or to create your own your own study flash cards, register HERE. If you are already a registered user, CLICK HERE.
Cards Term what is labor? Definition Regular uterine contractions that cause thinning and dilatation of the cervix Result in delivery of the fetus. Term What is important for labor? Definition What is important for labor? Adequate pelvis Cervical change Cooperative fetus uterus Term when should labor begin? Definition around 40 weeks (280 days), term--anywhere between 37 weeks and 41 weeks and 6 days Term what are the 3 bones of the pelvis? Definition illium, ishium, and pubis Term what divides the true pelvis from the false pelvis? Definition the linea terminalis Term what are the 3 planes of the TRUE pelvis? Definition Pelvic inlet AP diameter = conjugate Transverse diameter; Midplane AP diameter Transverse diameter = bispinous distance = an important landmark for ensuring that the fetus's head gets through. Pelvic outlet AP diameter Transverse diameter = bituberous distance Term what are the 3 things that make up the cervix? Definition 1. Smooth muscle 2. Collagen 3. Glycosaminoglycans Term how is collagen composed? Definition Collagen Unit = tropocollagen = triple helix of collagen chains Synthesized in connective tissue cells Crosslinks exist between the chains Term what are the 2 types of GAGs? Definition Glycosaminoglycans = Dermatan (hydrophobic) Chondroitin Term What is necessary for cervical dialiation? Definition the collagen must be broken down, tissue btw the collagen must absorb water. Term what is cervical effacement? Definition Collagen chains are broken down by the process of: Hydrophobic GAGs are replaced by more hydrophilic hyaluronic acid to absorb water to become soft. Cervical smooth muscle contraction causes the cervical tissue to be pulled upward and be incorporated into the lower segment of the corpus. The cervix is dialating and being usurped into the uterus. Term what is an incompetant cervix? Definition predialation--maybe the collage isn't firm enough. Put a stitch into the internal os. Term what does a pregnant cervix look like in comparison to a non pregnant cervix? Definition non preg--organized collagen, pregnant - disorganized collagen. again, during preg, GAGs change, absorb the water, allowing cervix to dialate and for fetus to come out. Term describe the smooth muscle cells of the myometrium of the uterus. Definition The smooth muscle cells are arranged in spiral bundles which continue to the upper portion of the cervix. The majority of the myometrium is smooth muscle (contrast to cervix). Though they are in close proximity to each other, there is no direct contact between individual muscle cells until the end of pregnancy when gap junctions appear. Muscle cells spiral and are arranged in bundles. Thick + thin filaments Gap junctions Term what is the point of gap junctions? Definition once 1 smooth muscle contracts, they all contract (like dominos). So, muscles do not contract via neural inneration-they contract via horomones. Term what contractile proteins are necessary for contractions? Definition Contractile proteins Actin (thin filament) Myosin (thick filament) (both of which come together and are regulated by phosphorylation), Tropomyosin, Skeletin Term what regulatory proteins are necessary? Definition Calmodulin Cyclic adenosine monophosphate (cAMP) Enzymes -- (de)phosphorylation Term what does cAMP do? Definition phosphorylates MLCK Term what does calmodulin do? Definition when it binds to Ca, it allows MLCK to be dephosphorylated, and activated. Term what is in the myosin head? Definition Head Globular 2 pair of light chains ATP hydrolysis Actin binding Term what is in the myosin tail? Definition Tail Helical 2 heavy chains Term what is actin comprised of? Definition Composed of helically arranged polymers with Tropomyosin interspersed inbetween Term what happens to make actomyosin? Definition actin and myosin form actomyosin by using myosin ATPase and Mg. myosin globular head attaches to actin; cross bridge between thick and thin filaments; filaments slide past each other. This is how the smooth muscles of the uterus contract. Term why is phosphorylating key for the actin myosin interaction? Definition In order for actin and myosin to interact, the light chain of actin must be phosphorylated. Term what enxyme is responsible for phosphorylation? Definition Myosin light chain kinase (MLCK) = the enzyme responsible for phosphorylation. Activated by DEPHOSPHORYLATION and Ca-calmodulin complex Term what phosyphorylates MLCK Definition The enzyme responsible for phosphorylating MLCK is a cAMP-dependent protein kinase which is dependent on Adenylate cyclase Term Should myosin and actin be phosphorylated or not in order to be activated? Definition phosphorylated Term go over the steps of actomyosin binding. Definition look at your notes Term what does Ca bind to? Definition calmodulin Term why would you want to prevent uterine contractions from happening? Definition to stop preterm labor--so prevent Ca from entering the cell. Term what factors cause labor? Definition we don't know. we do know that cortisol is important, progesterone decreases, and estrogen increases. Term what do we know from sheep. Definition That the fetus can initiate labor: the fetal cortisol activates 17-alpha hydroxylase, which converts progesterone to estrogen, which induces contractions Term why do we not understand how humans work? Definition human placentas DO NOT have 17-alpha hydroxylase. So the placenta can't convert progesterone to androgens, the precursor of estrogen Term what do humans have instead? Definition a shuttle system bwn the fetus and the placenta that results in transfer of DHEA from the fetus to the placenta. DHEA is transferred from the fetal adrenal to the fetal liverr where it is converted to 16 OH DHEAS. 16 OH DHEAS is then taken to the placenta where it is metabolized into estrogen. Term in order for labor to start, what must decrease? Definition progesterone Term does estrogen directly cause myometrial contractoins? Definition no, not directly. Instead, estrogens upregulate myometrial gap junctions Term what horomone does the uterus have a lot of ? Definition Prostaglandins. Term what are the precursors of PG? Definition arachadonic acid- Term what does oxytocin do? Definition potent uterine stimulant Term what is 1 example of how estrogen indirectly causes contration? Definition OT gene is upregulated by estrogen Term what is decidua Definition maternal tissues that get shed with the pregnancy Term where is Ox found? Definition in the fetal plasma as well as maternal plasma and tissues (decidua) Term where are OT receptors found? Definition in the myometrium Term how do you make PGs? Definition phospholipids-->aa--.PG Term what does Ox and PG do? Definition they act as receptor agonists for creating contraction Term what are 2 important enzymes? Definition Pl-A2, and COX2 Term what must you have progesterone for? Definition estrogen synthesis Term where does progest come from? Definition cholesterol Term what does E do? Definition upregulates gap juncitons and OT receptors Term who releases CRH? Definition CRH is released by the hypothalamus, placenta, amnion, chorion, and decidua. Term Cortisol has what type of effect on CRH in an adult brain? In placenta? Definition There are two feedback loops for CRH secretion: Cortisol (adrenal)  CRH (decidua/plac/mbs) Prostaglandins (decidua/mbs)  CRH (decidua/troph/mbs) ** Cortisol has a positive feedback effect on fetal HPA (vs. negative feedback normally seen in adult!!) Term who upregulates CRH? Definition cortisol (adrenal), and prostaglandins (decidua) Term what enzyme is missing in the placenta? Definition 17-alpha hydroxylase Term what does OT do? Definition stimulate PG receptors, also stimulates prostaglanding creation. these both go to make smooth muscle contractions. Term what enzyme does PGE2 stimulate in the cervix? Definition PGE2 stimulates collagenase--which is required for collagen breakdown--for cervical dialation. Term what 2 things does cortisol stimulate? Definition PL-A2 (for PGs) and Cox2 Term what do you need for labor? Definition In order to have labor, the uterus has to contract and the cervix has to dilate! Term What causes uterine contractions/cervical ripening? Definition Uterine ctx Prostaglandins (E2, F2) Anything that increases intracellular Ca (e.g., activation of phosphotidyl inositol in membranes) Gap junctions Increase oxytocin receptors Term Cervical ripening/effacement Definition Collagenase, elastase (i.e., metalloproteases) Term How do you induce labor? Definition PG--activates collagenase. progesterone might reduce chance of PRETERM labor. Term what are the cardinal movements? Definition how the fetus navigates through the pelvis during labor. . Starts in false pelvis, head, is floating.engagement, flexion, descent, turn head, extension (now in perineum) Term what is engagement? Definition when you can feel the baby at the level of the ischial spine, the kid is engaged. Descent of the biparietal diameter below the pelvic inlet. Clinically assessed when doing a cervical check – palpate for the presenting part below the ischial spines (“0” station). Term Above the ischial spine Definition negative stations Term what is flexion? Definition passive response of the fetal head to soft tissues of the pelvis Term descent Definition downward passage of the presenting part Term what is the lie? Definition Lie – relation of long axis of fetus to longitudinal axis of mother. Term what are 3 common presentations? Definition Presentation – part of the fetus in the birth canal Cephalic Breech Shoulder Term what are 2 common positions? Definition Position – relation of a reference point on the presenting part to the maternal right or left Vertex ~ occiput Face ~ chin (mentum) Breech ~ sacrum Term what is stage 1 labor? Definition closed--->fully dialated (latent phase--long time, little dialation), (active phase-->quick dialation), Term stage 2 Definition fully dilated --> delivery Term stage 3 Definition placenta Term what are stations? Definition relationship of presenting part to ischial spines (-5-->+5) Term what are 2 things you find on a vaginal exam? Definition the sagittal suture, and the fontanelles (soft area, where sutures come together) Term what are the 3 potential problems in labor? Definition Dystocia is defined as abnormal labor that results from what have been categorized classically as abnormalities of the power (uterine contractions or maternal expulsive forces), the passenger (position, size, or presentation of the fetus), or the passage (pelvis or soft tissues). The term "cephalopelvic disproportion" has been used to describe a disparity between the size of the maternal pelvis and the fetal head that precludes vaginal delivery. Because dystocia can rarely be diagnosed with certainty, the relatively imprecise term "failure to progress" has been used, which includes lack of progressive cervical dilation or lack of descent of the fetal head or both. The diagnosis of dystocia should not be made before an adequate trial of labor has been achieved. A more practical classification is to categorize labor abnormalities as slower-than-normal (protraction disorders) or complete cessation of progress (arrest disorders). Term what is involved in labor management? Definition Progress Cervix – dilation, effacement Fetus – station Fetal well being – fetal heart tracing Pain control Intravenous narcotics Regional (epidural, pudendal block) Delivery Want to avoid lacerations Episiotomy Term when can myosin bind? Definition when it's phosyphorylated Term what does actin look like it its relaxed state? Definition actin fibers are bound by a complex made up of troponin-tropomysoin. Term what is involved in the actin myosin binding? Definition Ca, Calmodulin (the calcium bidning protein), cAMP, myosin light chain kinase Term what does Ca do? Definition 1. ca binds to the troponin -tropomyosin complex--resulting in this complex being unbound from the actin. as a result, cross bridges form and contractions occur.. also, ca binds to calmodulin. this complex can bind to the enzyme MLCK. Term what does MLCK do? Definition when activated, MLCK phosphorylates myosin light chans so that actin can attach and contractions can occur. Term how is MLCK inactivated? Definition when MLCK is phosphorylated by a cAMP dependent protein kinase Term how can you physiologically describe labor? Definition the myometrium being released from inhibitory effects of pregnancy Term what is necessary for the initiation of labor in humans? Definition progesterone withdrawl Term what does the fetal adrenal gland have lots of Definition cortisol Term what are myometrial contractractions mediated through? Definition ATP-dependent binding of myosin to actin Term what is the key modulator of myometrial contractility? Definition ca Term PGs have what type of action? Definition paracrine/autocrine Term what type of PGs will there be an increase of? Definition PE and PF