Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Scientific Basis of Midwifery > Physiology of 1st Stage > Flashcards

Physiology of 1st Stage Flashcards

1
Q

Describe the uterus during pregnancy

A
  • Uterus begins to grow by hyperplasia and then after 4 months hypertrophy
  • Myometrium consists of bundles of myometrial cells separated by connective tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is hyperplasia?

A

Increased amount of organ tissue due to cell proliferation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the uterus at term

A
  • Muscle fibre density highest in fundus, reducing until cervix where there is more connective tissue than muscle
  • Uterine muscle consists of longitudinal, circular and spiral muscle fibres (used as ligatures)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the contractile strength of the uterus relate to?

A
  • The proportion of muscle

- Upper segment contracts stronger to push baby down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the 2 segments of the uterus

A
  • Towards the end of pregnancy
  • Upper segment = formed from fundus body
  • Lower segment = formed from isthmus and cervix
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the isthmus?

A

Narrow passage/ organ that connects 2 larger parts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is quiescence?

A

Uterine muscle has spontaneous contractibility and is never completely quiet so low intensity contractions always occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens approximately 6 weeks prior to labour?

A

Intensity of quiescence increases; these are called Braxton-Hicks and are not associated with cervical effacement or dilation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is cervical effacement?

A

Shortening, softening and thinning of the cervix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 2 main functions of the uterus?

A
  • To grow but remain quiescent (inactive)

- To commence powerful contractions at the right time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What might women notice at the end of pregnancy?

A
  • Mood swings/ surges of energy
  • Walking may become more difficult
  • Relief of pressure at fundus
  • Lightening
  • Increased pressure in pelvis
  • Nesting
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is lightening?

A

SFH starts to reduce as baby starts to descend towards the birth canal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why does dilation occur?

A

As a result of uterine action and the counter-pressure applied by the intact bag of membranes or presenting part (or both)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does the cervix change prior to labour?

A
  • Cervix is rigid in pregnancy
  • Connective tissue will soften
  • Partial dilation of external os evident from 24 weeks but individuals vary = cervical assessment unreliable indicator of labour
  • At term, 90% of cervix is water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the 2 elements of cervical softening?

A
  • Increased vascularity and water content

- Structural changes in connective tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe effacement

A
  • If softening has taken place, contractions pull on cervix, stretching it
  • Effacement takes place before regular contractions
  • Shortens and thins cervix so both os disappear
  • Leads to inclusion of cervical canal
  • Operculum (mucous plug) becomes dislodged
  • Longitudinal fibres allow cervical dilation without presenting part pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a ‘show’?

A

Blood-stained mucoid discharge (operculum) seen in early labour and small loss of red blood during transitional stage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What happens if an unripe cervix attempts to dilate?

A

Can cause damage to collagen fibres which can lead to miscarriage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What hormones are involved in the initiation of labour?

A
  • Cortisol
  • Progesterone
  • Oestrogen
  • Prostaglandins
  • CRH
  • Oxytocin
  • Relaxin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is CRH?

A

Corticotrophin Releasing Hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What effect does cortisol have?

A
  • Produced by anterior pituitary of foetus
  • Production increases towards term
  • Affects and reduces maternal progesterone production
22
Q

What effect does progesterone have?

A
  • Inhibits contractions in pregnancy
  • Local changes in concentration not reflected in maternal blood; foetal membranes increase cortisol levels to reduce progesterone
23
Q

What effect does oestrogen have?

A
  • Slight rise in levels makes uterus more sensitive to oxytocin at term (receptors become unblocked and more sensitive)
  • Stimulates oxytocin receptors in myometrium and gap junctions to form
  • Encourages placenta to release prostaglandins to soften and efface cervix
24
Q

Describe the oestrogen:progesterone ratio

A
  • Changing ratio of oestrogen and progesterone is important for effective contractions in labour
  • Increasing oestrogen/ decreasing progesterone leads to release of phospholipase A2 which releases arachidonic acid which stimulates prostaglandin synthesis
25
Q

What effect do prostaglandins have?

A
  • Occur in placenta, foetal membranes, decidua, myometrium and cervix
  • Important in labour progress
  • In late pregnancy, prostaglandin synthesis stimulated by coitus, VE, membrane sweep, amniotomy and labour
  • Exogenous prostaglandins will ripen the cervix and induce labour
26
Q

What is an amniotomy?

A

Artifical rupture of membranes

27
Q

What effect does oxytocin have?

A
  • Used to induce labour
  • Endogenous production by nipple stimulation can initiate labour
  • Receptors in myometrium increase in pregnancy
  • Rapid production in labour
  • Also synthesised by decidua
28
Q

What is the Ferguson reflex?

A

Pressure in the vagina/ cervix increases oxytocin production and causes the uterus to contract/ retract

29
Q

What effect does relaxin have?

A
  • Inhibits myometrial contractility and softens joints
  • Early fall in levels (high in 1st trimester)
  • Associated with preterm labour
  • Promotes cervical ripening towards end of pregnancy
30
Q

What factors may initiate parturition?

A
  • Response to environment
  • Familial (genetic)
  • Time of lunar month/ ovarian cycle
  • Circadian rhythm (sleeping pattern)
  • Mammals labour best at time of day they are usually resting (at night)
31
Q

What is parturition?

A

Childbirth

32
Q

When should the midwife be contacted?

A

When regular, rhythmic uterine contractions are experienced that are uncomfortable and/or painful

33
Q

Describe myometrial contractility

A
  • Myometrial cells packed with long bundles of actin and myosin; slide past each other to enable muscle shortening for contractions
  • Non-pregnant uterus contracts in response to adrenaline/ noreadrenaline
  • Noreadrenaline causes contractions, adrenaline inhibits contractions
  • Paraplegies go into labour so contractions are under hormonal control not nervous
34
Q

What are gap junctions?

A
  • Gaps that pass messages between myometrial fibres
  • Form from bundles of protein called connexions
  • Allow rapid transmission due to reduced electrical resistance = fibres contract together
35
Q

Describe gap junctions

A
  • Number of gap junctions increases throughout pregnancy to 1000/cell
  • Greater density of gap junctions if labour occurs spontaneously at/ before term
  • More gap junctions = larger area of muscle contracting = greater intrauterine pressure changes
36
Q

What pressure changes occur during contractions?

A
  • Increase in pressure of 20mmHg can be felt manually

- Pressures can rise as high as 75mmHg in 2nd stage

37
Q

Describe how contractions occur

A
  • Involuntary
  • Amount of elastin rises throughout pregnancy; this enables contraction and retraction during labour and after birth
  • Upper segment becomes gradually shorter and thicker
  • Contractions strongest at top of fundus
  • Must be rest between contractions to allow myometrium and foetus to be reoxygenated
38
Q

What is retraction?

A

Unique property of uterine muscle, to remain slightly shortened following a contraction

39
Q

Describe the coordination of contractions

A
  • Uterus exhibits pacemaker-like activity
  • Contractions begin from each side of fundus near the cornuae
  • Contractile waves strongest and last longer at fundus where there is highest density of muscle fibres
  • Peak is reached simultaneously all over uterus and then fades together - known as fundal dominance
40
Q

Describe the polarity of the uterus

A
  • 2 segments of uterus work in neuromuscular harmony during contractions
  • Upper pole (segment) contracts strongly and retracts to expel foetus
  • Lower pole (segment) contracts slightly and dilates to allow expulsion
41
Q

What is the retraction ring?

A
  • Ridge formed between upper and lower segments
  • Normal for all labour, but if exaggerated ridge is noted abdominally above symphysis, can be sign of mechanically obstructed labour; known as Bandl’s ring
42
Q

How are the forewaters and hindwaters formed?

A
  • Chorion detaches from uterine wall due to stretching of lower segment and effacement
  • Membranes extruded through cervical opening
  • Head of foetus acts as ‘ball valve’
  • Presenting part separates fore and hind waters
43
Q

What is foetal axis pressure?

A
  • Forewaters spread pressure of contractions over cervix’s aiding dilation
  • Hind waters cushion baby from contractions
  • Force of contractions transmitted through foetal body to cervix is called foetal axis pressure
44
Q

Describe membrane rupture

A
  • Frequently occurs when cervix between 8-10cm as bag of fore waters descends
  • Also associated with collagen degradation of membranes
  • Increases prostaglandin release
  • Associated with onset of stronger, coordinated contractions
45
Q

What must be the situation for labour to progress well?

A
  • Soft cervix
  • Adequate oxytocin receptors
  • Adequate gap junctions
  • Adequate prostaglandin production
  • Mother not stressed
46
Q

What would aid the progress of labour?

A
  • Well-fitting presenting part on cervical os
  • Foetus in optimal position
  • No obstruction to foetal descent
47
Q

Describe effective contractions

A
  • Regular with relaxation inbetween
  • Gradually increasing strength and frequency
  • Frequent but <4 / 10 mins
  • Long-lasting but not over 1 min in 1st stage
48
Q

What is an LSCS?

A

Lower Segment Caesarean Section

49
Q

What is augmentation?

A

Labour starts naturally but help is needed to make labour progress and have stronger contractions

50
Q

What is os short for?

A

Orifice

Scientific Basis of Midwifery (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions