Anatomy and physiology of the breast Flashcards

1
Q

What stimulates myoepithelial cells?

A

Oxytocin

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2
Q

What is the name of the centre of the breast?

A

The lumen

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3
Q

Where is milk released?

A

The milk duct

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4
Q

What stimulates alveolar cells?

A

Prolactin

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5
Q

What are the inner cells of the breast? Which are the outer cells?

A

Inner=alveolar

Outer=myoepithelial

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6
Q

What blood enters the breast? What blood exits the breast?

A

Enters=arterial blood (vessel at the back)

Exits= venous blood (vessel at the front)

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7
Q

What are the 3 phases of lactation?

A

Lactogenesis I
Lactogenesis II
Lactogenesis III

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8
Q

What occurs is lactogenesis I?

A

Initiation of milk secretion

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9
Q

What happens in lactogenesis II?

A

Production of colostrum & transitional milk

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10
Q

What happens in lactogenesis III?

A

The development of milk & maintenance of established lactation

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11
Q

What controls Lactogenesis I & II?

A

The endocrine system hormones

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12
Q

What controls lactogenesis III?

A

Autocrine (local) control

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13
Q

When does lactogenesis I start and finish?

A

Mid pregnancy- Day 2 postnatally

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14
Q

What signifies the start of lactogenesis I?

A

Milk components are first seen in breasts and colostrum can be expressed in pregnancy

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15
Q

What can be found in maternal plasma from mid pregnancy during lactogenesis I?

A

Alpha lactalbumin (protein) that regulates production on lactose

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16
Q

What initiates lactogenesis II?

A

Birth

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17
Q

When does lactogenesis II start and finish?

A

Starts day 2

Finished day 8

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18
Q

What swaps in lactogenesis II?

A

Endocrine control swaps to autocrine control

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19
Q

During which stage of lactogenesis are there rapid cardiovascular changes?

A

Lactogenesis II

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20
Q

What is another term for lactogenesis III?

A

Galactopoiesis

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21
Q

When does lactogenesis III Begin?

A

8/10 days

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22
Q

What gets established in lactogenesis III?

A

Mature milk supply

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23
Q

In lactogenesis III what does the autocrine control allow?

A

Supply and demand of milk

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24
Q

Where is prolactin produced?

A

Anterior pituitary gland

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25
Q

What does progesterone do in the breast tissue?

A

Suppresses the action of prolactin

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26
Q

What does PIF do and where is it secreted?

A

Secreted by the hypothalamus and suppresses the action of prolactin

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27
Q

What drug surpresses lactation?

A

Bromocriptine

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28
Q

What does dopamine do?

A

Suppresses production of prolactin

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29
Q

Which drug is an agonist (encourager) of dopamine?

A

Bromocriptine

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30
Q

What drug encourages milk production?

A

Metoclopramide

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31
Q

How does metoclomapride work!

A

It inihibits the action of dopamine, to prevent inhibition of prolactin and increase milk supply

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32
Q

Which drug is an antagonist of dopamine? Which is an agonist?

A

Bromocriptine is an agonist

Metochlopramide is an antagonist

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33
Q

What three factors increase prolactin levels?

A

Stress, exercise, sex

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34
Q

What is the function of the circadian rhythm in breast feeding?

A

Helps with night feeds

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35
Q

What does nipple stimulation help with?

A

Release of prolactin

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36
Q

When does prolactin level return to baseline?

A

3-4 hrs after feed

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37
Q

Stages of the prolactin reflex?

A

1) Baby suckles
2) Sensory impulses pass from nipple to brain
3) Prolactin is secreted by the anterior gland and goes via the blood stream to the breasts
4) acini/lactocytes produce milk

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38
Q

What cells produce milk?

A

Lactocytes

Acini cells

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39
Q

When are prolactin levels highest?

A

At night

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40
Q

Why does prolactin level peak after a feed?

A

To produce milk for the next feed

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41
Q

What hormone suppresses ovulation?

A

Prolactin

42
Q

How do receptor sites on acini cells become primed?

Prolactin receptor theory

A

Expulsion of placenta opens prolactin receptor sites

Prolactin binds to receptor sites (priming the sites)

43
Q

What happens to unprimed prolactin receptor sites?

Prolactin receptor theory

A

They shut down, reducing their potential for milk production

44
Q

What hormone must be present for milk synthesis?

A

Prolactin

45
Q

What cells of the alveoli are milk producing cells?

A

Lactocytes

46
Q

Where are Prolactin receptor sites?

A

On lactocyte alveolar cells

47
Q

What allows prolactin in the blood to move into the lactocytes and stimulate synthesis of breast milk components?

A

Receptors on lactocytes

48
Q

Hypothesis of feedback system of breast milk

A

When alveolus is full of milk
Walls stretch, altering shape of prolactin receptors
Prolactin cant bind and activate
Rate of milk synthesis slows as milk empties from alveolus
Prolactin receptors return to normal shape

49
Q

Let down reflex

A

Oxytocin cause breasts to expel or ‘let down’ milk

50
Q

What are 2 related aspects of oxytocin in the removal of milk from breast?

A

Let down reflex

Baby sucking role

51
Q

What causes milk ducts to dilate?

A

Oxytocin

52
Q

What hormone causes myoepithelial cells to contract?

A

Oxytocin

53
Q

Oxytocin reflex (4 steps)

A

Baby suckles
Sensory impulses nipple—> brain
Oxytocin secreted by posterior pituitary gland goes via bloodstream to breasts
Myoepithelial cells contract and expel milk

54
Q

Neuro-endocrine mechanism breastmilk

A

Hypothalamus maintaining homeostasis by releasing oxytocin

55
Q

Causes of milk ejection as a Conditioned response?

A

Touch, smell, sound of baby

56
Q

What causes milk ejection as an unconditioned response?

A

Nipple stimulation

57
Q

Three steps of oxytocin and prolactin release from suckling to action?

A

Nipple stimulation by baby suckling sends sensory impulse to hypothalamus
Hypothalamus stimulates posterior pituitary to release oxytocin and anterior pituitary to release prolactin
Oxytocin stimulates milk release from breast, Prolactin stimulates milk production

58
Q

What neuron pathway does nipple stimulation sensory impulse travel down to the hypothalamus?

A

Afferent sensory neurons

59
Q

What nervous system does milk production signals occur in?

A

Central nervous system

60
Q

What receptors in nipple are stimulated my sucking (that send signal to brain)?

A

Sensory proprioreceptors

61
Q

FIL

A

Feedback inhibitor of lactation

62
Q

What causes milk to be produced by prolactin?

A

Removal of milk from breast

63
Q

What is autocrine regulator?

FIL

A

A protein secreted in milk that inhibits synthesis of milk constituents

64
Q

Why does milk in breast inhibit production of milk constituents?

A

The presence of autocrine regulator protein (FIL) in milk inhibits synthesis of milk

65
Q

Why does removal of milk cause production of milk constituents?

A

Because the autocrine regulator protein in the milk is removed to milk synthesis is no longer inhibited and prolactin can produce milk

66
Q

Inhibitor of milk synthesis=?
Milk producer=?
Cause of milk secretion=?

A

FIL Feedback Inhibitor (autocrine regulator protein)
Prolactin
Oxytocin

67
Q

Alveolus

A

Small sac in the mammary gland

68
Q

Where is the lobe? (Breast diagram)

A

From where the breast starts to protrude to the base of the nipple

69
Q

Montgomery tubercles location

A

On the areola (bumps on areola)

70
Q

Lactiferous duct location?

A

Stringlike lines going into nipple have rounded area like balloon that is the duct

71
Q

What are alveolar lactocytes surrounded by?

A

Myoepithelial cells

72
Q

Centre of alveolus?

A

Lumen

73
Q

What surrounds the lumen of the alveolus? (Making up the alveolar wall)

A

Lactocytes

74
Q

How do lactocytes expel milk?

A

When myoepithelial cells contract they contract lactocytes

75
Q

What causes glandular and ductal growth in the breast during puberty?

A

Oestrogen, progesterone and growth hormones

76
Q

What happens to the areola in puberty?

A

They enlarged and darken

77
Q

What causes breasts to enlarge during puberty?

A

Deposition of adipose tissue

78
Q

When do breasts develop and when do they stop?

A

Every menstrual cycle until ages 35

79
Q

What hormones cause breasts to develop in pregnancy?

A

Progesterone, Prolactin, human placental lactogen and growth hormone

80
Q

When in pregnancy can collistrun be secreted?

A

Starting at 16-20 weeks

81
Q

What causes delay in lactogenesis II?

A

Preterm delivery (<28 weeks)

82
Q

Location of the breasts?

A

Anterior chest wall

83
Q

Where do the breasts extend from? (Ribs)

A

2nd to 6th intercostal cartilage (rib)

84
Q

What level is the nipple on the breast in coordinance to the ribs?

A

4th intercostal space

85
Q

What 3 types of tissue are in the breast?

A

Glandular tissue, embedded fatty tissue, fibrous connective tissue

86
Q

What ligaments are in the breast?

A

Suspensory ligaments

87
Q

What are the epithelial cells of the alveoli?

A

Lactocytes

88
Q

What two things surround lactocytes

A

Rich vascular supply

Myosepithelial cells

89
Q

What hormones in high levels suppress milk production during pregnancy?

A

Oestrogen

Progesterone

90
Q

What is the result of large gaps between lactocytes in the first 4 days post partum?

A

Enhanced passage of milk components such as immunoglobulins, lymphocytes and macrophages into the milk (properties of colostrum)

91
Q

What type of cells are myoepithelial cells

A

Smooth muscle, contraction cells

92
Q

What reflex are myoepithelial cells a part of as a result of which hormone?

A

Let down reflex

Oxytocin

93
Q

What part of the breast is made up of 5-10 ducts and smooth muscle fibres with a rich blood supply and sensory nerve endings?

A

Nipple

94
Q

What’s the purpose of Montgomery tubercles on the areola?

A

They produce secretions to lubricate and protect the areola and nipple during pregnancy and lactation also the odour of these is to direct the baby towards the breast

95
Q

What does the lymph supply do in the breast?

A

Collects excess fluid, bacteria and cast off cell parts

96
Q

Where is the lymph drainage channelled to?

A

Axiliary notes

97
Q

What nerves are in the breast?

A

Branches of the 4th, 5th and 6th intercostal nerves

98
Q

When are prolactin levels highest?

A

At night

99
Q

How do Prolactin levels affect lactogenesis at night?

A

More feeds at night to increase production

100
Q

What physiciological affect does oxytocin have?

A

Contraction of the uterus

101
Q

Where is oxytocin secreted from

A

Posterior pituitary gland