Parturition Flashcards
1
Q
FORCES OF RETENTION what do the following do to promote labour? 1. progesterone 2. cervix 3. hypervolaemia 4. adrenaline 5. relaxin 6. Corticotrophin releasing hormone
A
- strengthens muscle in cervix
Dampens down excitability of uterine smooth muscle - softens towards the end of the third trimester
- suppresses the release of hormones
- acts in similar way to progesterone
- acts on chemical transmitters in uterine muscle to reduce its contractibility
- inhibits the release of prostaglandins
2
Q
FORCES OF RELEASE
- oestrogen
- oxytocin
- vasopressin
- cortisol
- prostaglandins
- corticotrophin releasing hormones
- uterine distension
A
- promotes release of prostaglandins
increases the number of oxytocin receptors on uterine myocytes
causes myocytes to form gap junctions - increases contractibility of the uterus
- promotes contraction of uterine muscle
- blocks action of progesterone
- sensitise uterine muscle to oxytocin and act to soften the cervix
used synthetically to induce labour - increase the contractibility of the uterus towards term
- distension promotes reflex contraction
3
Q
- at the pelvic inlet, which diameter is greater?
- at the pelvic outlet, which diameter is greater?
- which pelvic shape is most favourable for giving birth?
A
- tramsverse diameter
- AP diameter
- gynecoid - oval inlet, wide suprapubic arch, generous capacity
4
Q
name the 4 key characteristics of the uterus
A
- tone - constant resting tone
- contractility - increases during later stages of pregnancy due to increase in number of oxytocin receptors
- fundal dominance - contractions start at fundus and move down
- rhythmicity - inherent rhythm of contractions
5
Q
- describe the positive feedback cycle of uterine contractions
- what is the purpose of contractions in the third stage of labour?
A
- contractions of uterine myometrium force baby down on the cervix, causing cervical distension
stretch receptors in cervix send nerve impulses to the neurosecretory cells in the hypothalamus
release of oxytocin from posterior pituitary
oxytocin stimulates the myometrium to contract more forcefully - contract the uterus down and decrease blood flow to prevent haemorrhage
6
Q
Describe the following foetal head presentations
- suboccipito-bregmatic
- suboccipitofrontal
- occipitofrontal
- mentovertical
- submental bregmatic
A
- occiput is the leading part. Chin tucked into chest. Most favourable
- partially deflexed. Wider diameter.
- deflexed vertex. wider diameter
- top of head is leading part. diameter wider than pelvic outlet. Difficult to deliver
- face first.
7
Q
Describe the following cardinal movements of labour:
- engagement
- descent
- flexion
- internal rotation
- extension
- external rotation
- expulsion
A
- entry of head into pelvic inlet
- head moves deep into pelvic cavity
- resistance of head against soft tissues of pelvis causes baby’s chin to meet chest
- foetus moves from transverse to anteroposterior position
- extension of neck to turn corner of pubic arch so that head is born
- rotation so that head is more transverse so that shoulders can be born
- rest of body is born
8
Q
What occurs, and what is the duration of the following stages of labour?
- latent
- first
- second
- third
A
- onset of contractions > regu;ar contractions. Cervix becomes fully effaced
3-4 cm dilation. can take several days - regular contractions. 3-4cm > 10cm
- 25 hrs in primiparous women; 5.5 hours in multiparous
- full dilation > delivery
1 hour in primiparous women; 0.25 hours in multiparous women - delivery of placenta and membranes. Involves contraction of uterus and haemostasis to prevent haemorrhage
- 25 hours.
9
Q
- what does foetal mammary gland development result in?
- what hormone promotes branching of this structure?
- describe breast development during puberty
- describe breast development during pregnancy
- what happens to the breasts following menopause?
A
- rudimentary duct tree
- oestrogen (and inhibited by testosterones)
- High levels of oestrogen promote significant ductal development, plus the growth of stromal and fat tissue
- progesterone and prolactin mediate lobuloalveolar development in oestrogen primed gland tissue
- due to lower levels of oestrogen, mammary gland tissue atrophies and the mammary glands become smaller and replaced with adipose tissue
10
Q
FOETAL BREAST DEVELOPMENT
- what is the name of the primitive structures that give rise to the breasts?
- at what gestational age are the primary milk ducts formed?
- describe breast development at 32-40 weeks
A
- milk streaks
- 32 weeks
- lobular areolar structure containing colostrum develop
ducts open onto the areola
nipple and areola become pigmented
11
Q
- Which hormones strongly affect breast growth in girls at puberty?
Describe the influence of the following hormones on the breast tissue during pregnancy:
- oestrogens
- progesterone
- prolactin
- serum placental lactogen
- ACTH and HG
A
- oestrogen and hGH
- stimulates ductal system proliferation and differentiation
- duct enlargement and widening. growth of lobes, lobules and alveoli
- influences nipple growth.
essential for complete lobular-alveolar development - areolar growth
- combines synergistically with prolactin and progesterone to promote mammary growth
12
Q
describe breast changes in pregnancy at the following stages:
- 6-8 weeks
- 12 weeks
- 12-16 weeks
A
- fullness, tenderness, tingling. increased blood supply leads to more prominent veins
- pigmentation of nipple and areola. Areola becomes enlarged, and nipple becomes more pronounced.
- colostrum begins to be secreted
13
Q
- between which intercostal spaces is breast tissue located?
- what is the name given to the tail of tissue extending towards the axilla?
- what is the areola?
- what are the tubercles of montgomery?
A
- 2nd and 6th
- tail of spence
- circular area of pigmented skin in the centre of the breast, containing sebaceous glands
- sebaceous glands in the areola, surrounding the nipple
14
Q
- what are the basic units of the mature glandular breast tissue?
- what are these structures lined with?
- what are these structures surrounded by? What is the significance of this?
A
- alveoli/acini
- lactocytes - produce milk
- myoepithelial cells - contract to eject milk into the lobules
15
Q
- name the 2 arteries that supply the breast
- what is the venous drainage of the breast?
- which nodes drain the breast?
- what is the innervation of the breast?
A
- internal thoracic artery (branch of subclavian) and lateral thoracic artery (branch of the axillary)
- internal and external mammary veins and axillary veins
- axillary nodes
- 2nd - 6th intercostal nerves