12.Physiology of Lactation

8/8/2019 12.Physiology of Lactation

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PHYSIOLOGY OF LACTATION


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- Breast feeding is infants suckling milk at the breast

- Lactation is the maternal process of making milk

- Breast feeding + Lactation Bio - Psycho -socio -cultural Processes

- Multiple sites are involved in process of lactation

i) Breasts

ii) Functioning of endocrine glands

iii) Emotional response of mother

iv) Cultural context


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Anatomy of Mammary Gland

- Breasts are paired mammary gland (modifiedexocrine glands)

- Having a ductule system, secreting outward 14 to

the surface of organ

- Glands are anchored to the overlying skin and to the

pectoral muscles by suspensory ligaments of cooper

- Three major structures of breast are

i) Skin

ii) Subcutaneous tissue

iii) Body of the breast


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i) Skin : General skin, nipple and areola are visible

externally

- Areola or Areola mammae is pigmented areasurrounds the nipple

- Montgomerys glands are present in Areola (raised

projections)-sebaceous glands secretes the areolaand nipple

- The Nipple (papilla mammae)

* Raised projection in the center of areola* External opening where the milk comes out

* Contains smooth muscle fibres and sensory nerve

endings cause it to become erect when stimulated


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ii) Subcutaneous tissue

- Subcutaneous tissue consist of gland, fat, connectivetissue

- Size of a womans breast reflects the amount of fatand connective tissue, not glandular tissue

- Size of the breast nothing to do with functionality


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iii) Body of the Breast (corpus Mammae)

- Corpus mammae is Latin word

Body mamma (breast) glandular organ

- Breast is made up of two parts

a) Glandular tissue b) Supporting tissue

(Parenchyma) (Stroma)


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a) Glandular Tissue

- Consists of lobular, ductular and alveolar structures

- The breast has 15-25 Labi (singular lobus) each

seperated by connective tissue from one another

- The duct from lobus goes to the nipple

- Lobi are subdived into lobuli (20-40 in the breast)and each labuli subdivided in to 10-100 alveoli

contd


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- Ie

10-100 alveoli

forms

Lobi (20-40 in the breast)

forms the duct

Enter into nipple

- The alveolus (plural, alveoli) smallest functioning

unit of the mammary gland


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- Alveolus

Made up of 2 types of cells

Secretary epithelial cells Myoepithelial cells

with

Synthesize fat and Surround the secretary

Protein into milk epithelial cells

responsible for

milk ejection


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b) Stroma

- Contains the connective tissue, fat, blood

vessels, nerves and lymphatics

- Duct system is located with in the

connective tissue and fat


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The process of making human milk

i) Hormones associated with milk production

ii) Stage of mammary function


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i)Hormones associated with milk production

-Hormones govern Birth, pubertal growth, conception,

pregnancy, delivery and also lactation-During pregnancy

Prolactin levelbut

Estrogen and Prolactin inhibiting hormone

Suppress

The activity of Prolactin

contd


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- Sed Estrogen

helps

Progesterone for Proliferation of glandular tissue andductule development during pregnancy

- PCL, HCG, Human Chorionic Somato mammotropin

all contribute for mammary gland growth duringpregnancy

- At birth

Drop in estrogen and progesterone level, oxytocin and

Prolactin associated with lactation

contd


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-Oxytocin

causes

Contraction of myoepithelial cells

Milk-ejection reflex or Let-down reflex

causesSensation of Tingling or Sensual feeling

- Fatigue, stress, fear or shame

inhibits

Milk ejection reflex

contd


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- Prolaction

* Described as Great sensation hormone (relax or

euphoric)* Pro means for

* Lactin means milk

* Prolactin during pregnancyProlactin prior to birth and again few hrs

after birth or neonate suckling

* At term 150-200ng / ml


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ii) Stages of mammary function

- There are 4 basic stages

a) Mammogenesis

b) Lactogenesis

c) Lactation

d) Involution


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b) Lactogenesis

- Gradual process of making milk

- Occur in 3 stages

Lactogenesis I Lactogenesis II Lactogenesis III

- During these stages human milk varies in

components, appearance and volume


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Lactogenesis I:

- Begins around 14-16 wks of gestation

- Ductular and lobular proliferation by the

influence of hormones

- Colostrums like substance is produced but

not secreted

- This stage continues until second trimester


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Lactogenesis II:

- Begins around 28 weeks gestation

- If breast manipulated leaking can occur

- Colostrum the first milk, is a thick

substance that appears yellow (carotene

content)

- Colostrum present in ducts in 2nd trimester and

secreted at first few days of postpartum

- The hormonal changes involve primarily HPL,

progesterone, Estrogen and Prolactin

contd


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After placenta delivered

Estrogen and progesteroneRemains

Prolactin in high level

Colostrum is important, rich in immunoglobulins,has laxative effect on gut aids in passage ofMeconium

It is higher in protein, Lower in fat, and CHO

Lower in energy ie 67Kcal/100ml 20Calories/OunceMature milk has about 75Kcal/100ml,

22.5 Calories/Ounce

contd


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Lactogenesis II continues only when breast is

adequately stimulated

By Adequate stimulation

Lactogenesis II continued

First secretesColostrum

Gradually replaced by

Transitional milk (3-10days)

-Dramatic hormonal changes

-do the tears

contd


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- In core temperature (engorgement)

by 10th day

Transitional milk replaced by Mature milk


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Lactogenesis III:

-Called Galatopoiesis

-Begins 10 days after birth-Mature milk contains about 22.5 calories /Ounce

Fore milk i) Produced and stored

-Mature milk between feedingHind milk ii) Released at the

beginning of next

i) Produced during feeding feeding

ii) Released at the end of iii) Appearance similar

feeding to skimmed milk

iii Much richer iv Characteristics blue


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3) Lactation

- Continued production of milk

- Regulated by oxytocin and Prolactin


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4) Involution

- Lactation continued as long as breast is suckled

- During weaning

Infant suckles less frequently

Prolactin level

Breast is not emptied

Engorged

oxytocin to Myoepithelium

contd


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ACTH (A.P.) -Necessary for maintenance

of Lactation

Thyroxine (Thyroid) -Important in maintaininglactation

-Either by direct effect on

mammary glandsor

By control of metabolism

Thyrotropin releasing - Stimulates release ofHormone Prolactin

(Hypothalamus) - To maintain established

lactation


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Customs and Beliefs in relation toLactation

Customs / cultural Behaviours

Native American -Value the Traditional methods

Asian -Earlier generations breast fed

second generations Not breastfed delay in

Breast feeding or Bottle and breast

African -Bottle feeding-Status symbol

Hispanic -Belief that breast feeding isgood

Americans -Artificial feeding is equalent

to human milk

contd


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Mexican American -Colostrum is dirty or bad

dont begin breast feeding at

birth

Beliefs

- Breast feeding is a learned art, woman must be motivated to

learn it

- 6 factors influence motivation to learn - AttitudeFelt need

Stimulation

Emotion

Competence

Reinforcement

contd


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-Some Erroneous beliefs about breastfeeding

experience

i) Breast feeding hurtsii) Breast feeding will make the breast to sag

iii) I cant breast feed because I didnt prepare my

nipplesiv) I dont want to breast feed because I dont like to

drink milk


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Respons b l ty o a NurseMidwife

- Influence the attitude- Who come with positive attitude requires positive

reinforcement

- Those who cane with negative attitude in need of

motivation

i) Confront wrong beliefs and assumptions attitude

ii) Or remove components of failure or fear


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Birth injuries

Trauma during birth includesi) Trauma to skin and superficial tissues

ii) Muscle Trauma

iii) Nerve Traumaiv) Fractures


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i) Trauma to skin and superficial tissues

a) Skin Trauma

- Cause is iatrogenic ie forceps blades, vacuumextractor cups, scalp electrodes and scalpels

Cause Effect

1) Forceps blades Abrasion, bruising,superficial fat necrosis

2) Vacuum extractor cups Abrasion

3) Scalp electrodes Puncture wounds4) Caesarean section Laceration of the

babys skin

contd


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Nursing management

- Keep clean and dry wound

- If any s/s of infection medical advice is important- Antibiotics

- Deeper lacerations needs closure with dutterflystrips or sutures

b) Superficial tissues

- It involves edematous swellings or drwising or both

- During labour

Part of fetus overlying the cervical cas

Subjected to

contd


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Pressure-girdle of contact

lead to

Obstruction of venous returnResults in

Congestion and edema

Consists

Serum and blood (Serosanguineous

fluid)


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Caput succedaneum:- Occurs in cephalic

presentation the edematous swelling under the scalp

and above the periosteumi) Doesnt enlarge in size

ii) Can pit on pressure

iii) Can cross a suture lineiv) resolves by 36hrs

-Baby may experince little discomfort

-Gentle handling is appropriation


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Other injury

-In face presentation - Congested and bruised eyes

- Edematous lips-In breech presentation - Bruised and edematous

genitalia and buttocks

-Baby may have discomfort and pain

-Proper handling while changing nappies or dressingbaby

-Hygiene in nappy area

-Apply ointment-If skin excoriated infection can occur

-edema / bruising reslove with in few days of life

contd


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ii) Muscle trauma

-injuries to muscle result from tearing or when the

blood supply is disrupted


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Torticollis

-Commonly damaged muscle is stern mastoid


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CompressionofBlood vesselsGradually

Alveoli collapse

Restingstate

-During weaningmilk changes istermsof

a) Its volume

b) Nutritional componentsc) Immunologic properties

contd


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Suckling

Stimulates

Anterior pituitary Posterior Pituitary

To secrete To Secrete

Prolactin Oxytocin

Stimulates Stimulates

Breast alveoli Breast alveoli

To To

Secrete milk Eject milk into duct

Infant can drink it


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Hormonal contribution to lactation

Hormone Function

Prolactin (A.P.) - Stimulates alveolar cells to

produce milk

- Primarily initiating lactation

- Secondary Important

maintaining lactation- Cause lactation infertility

by

contd


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* release of FSH and LH form

pituitary

or* Causing ovaries to be un

responsive to gonadotropins

Prolactin inhibitinghormone

(Hypothalamus) -Suppresses release of Prolactin

from anterior PituitaryOxytocin (P.P.) -Causes myoepithelial cells to

contract

contd


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P (O


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Progesterone (Ovary

and Placenta) At parturition

Blood level drops

aids in

initiating lactation

-Not important for lactationthere after

Growth Hormone

(A.P.) -Act with Prolactin in initiation

- Important in maintainingestablished lactation

contd

12.Physiology of Lactation

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