Module 9: Reproductive System Flashcards Preview

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Flashcards in Module 9: Reproductive System Deck (224)
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211

Maternal adaptations to pregnancy (Decrease)

Decrease in:
- Total Peripheral Resistance
- Total Pulmonary Resistance
- Serum creatine
- Hematocrit
- Platelet count
- Intraocular Pressure (IOP)
- Potassium and Sodium

212

• Birth of the baby
• Toward the end of pregnancy, uterus becomes progressively more excitable  strong rhythmical contractions that the baby is expelled
• Intense contractions responsible for parturition due to:
– Progressive hormonal changes that cause increased excitability of the uterine musculature
– Progressive mechanical changes

PARTURITION

213

Phases or Parturition

Phase O (Quiescence) - Progesterone; prelude to parturation; from implantation to few weeks before delivery

Phase 1 (Activation) - Estrogen; Preparation for labor; occurs in the last 6-8 weeks of pregnanct

Phase 2 (Stimulation) - Oxytocin; Process of Labor

Phase 3 (Involution) - Oxytocin; Parturient recovery

214

OXYTOCIN AND UTERINE CONTRACTIONS

- Uterine muscle increases oxytocin receptors >> increased responsiveness
- Increased rate of secretion at the time of labor
- Labor is prolonged in hypophysectomized animals
- Irritation or stretching of the uterine cervix, as occurs during labor, can cause a neurogenic reflex through the paraventricular and supraoptic nuclei of the hypothalamus signals neurohypophysis to increase secretion

215

“Positive feedback” theory of parturition

- squeezing of the uterus on the baby's breech >> push the uterus downward >> stretch out the cervix >> stimulation of more vigorous contraction
- oxytocin from the uterus and mother's pituitary >> stimulate the uterus to contract and also stimulate placenta to make Progesterone >> stimulation of vigorous contraction

216

“Positive feedback” theory of parturition (2)

1. Baby's head stretches the cervix
2. Cervical stretch excites fundic contraction
3. Fundic contraction pushes the baby down and stretches the cervix more
4. Cycle repeats over and over again

217

- characterized by regular uterine contraction that lead to cervical effacement and dilatation

Labor

218

Stages of Labor

Stage 1: Latent Phase (Effacement)
Active Phase (Activation)

Stage 2: Descent

Stage 3: Expulsion

219

(Lactation)

- begins at puberty due to estrogen stimulation >> increased during pregnancy due to estrogen, progesterone and prolactin

Breast development

220

(Lactation)
- secreted by anterior pituitary, starting from 5th wk of pregnancy until birth, then cycles

Prolactin

221

(Lactation)
- 1st milk , contains same proteins and lactose as milk, but no fat

Colostrum

222

• Initiated by precipitous drop in estrogen and progesterone after delivery
• Prolactin surges each time mother nurses baby due to nerve impulses from nipples to hypothalamus
–without nursing stimulation, no prolactinsurge, and loss of milk production
• inhibits FSH, LH and thus lactation interferes with reproductive function

Lactation

223

When not nursing, hypothalamus produces __

prolactin-inhibitory hormone

224

• ACTION
–Milk EJECTION
–Uterine Contraction (basis for Nipple Stimulation)
• Used to induced labor and reduce postpartum bleeding
• STIMULI
–Sucking
–Orgasm
–Dilation of cervix
• In males: for contraction of vas deferens during ejaculation

Oxytocin