Parturition and Lactation Flashcards
What is parturition?
Process of giving birth. Involves the softening and dilation of the cervix and initiation of powerful contractions.
The first stage of labour can be split into two parts. What are these parts.
Initial (latent) phase - contractions develop and cervix softens. Active phase - regular contractions (Every 3 minutes) and steady dilation of the cervix (3-10cm).
What are the 3 tissues involved in parturition.
Uterus, cervix and the placenta.
What is the role of the hormone oxytocin during parturition.
The two main actions of oxytocin in the body are contraction of the womb (uterus) during childbirth and lactation. Oxytocin stimulates the uterine muscles to contract and also increases production of prostaglandins, which increase the contractions further. This results in the placenta being expelled out.
What are the 3 stages of cervix preparation?
Quiescence, activation and stimulation.
What is quiescence?
When the cervix is closed to form a mechanical and chemical barrier to prevent delivery and infection.
What is the purpose of the activation stage?
It allows the cervix to ripen and soften, therefore it is more easily dilated for contractions.
What is priming and when does it occur?
Priming is the up-regulation of contractile associated proteins (CAPS). Occurs during the activation stage.
The uterus activates contractions associated proteins. Give some examples.
Prostaglandin receptors, COX-2, oxytocin receptors, gap junctions (better transmission of signals between cells for more powerful contractions), calcium signals, ion channels.
What 3 things does the cervix and fetal membranes produce during the activation stage?
Nitric oxide, COX-2 and Matrix metalloproteinases (MMP2).
What 2 things are released during stimulation?
Oxytocin and local prostaglandin. Triggered by cervical distension and promotes uterine contractions.
Name 5 hormones involved in initiating labour.
Cortico-releasing hormone (CRH) is produced from the fetus hypothalamus. It stimulates adrenocorticotropic hormone (ACTH) release from anterior pituitary. This stimulates cortisol production from adrenals. This stimulates dehydroepiandrosterone (DHEAS) release, which increase estrogen levels to stimulate contractile proteins. There is no drop in progesterone!
What hormone is responsible for lactation?
Prolactin. Suckling ensures prolactin secretion. It relies on progesterone and oestrogen levels decreasing.
What causes oxytocin release?
Suckling stimulates paraventricular and supraoptic nuclei to produce oxytocin, for milk ejection.
Suckling stimulates the production of which peptide?
Vasoactive intestinal peptide.
