chapter 19 - birth and development of infant

Question 1

what is parturition

Answer 1

• birth, when the foetus is expelled from mother at the end of gestation

Question 2

what is labour

Answer 2

• sequence of events before birth

Question 3

what are some changes that happen before labour

Answer 3

• hormonal: ligaments of pelvis soften, strengthens contractions of uterus
• foetus: head in mothers pelvis, legs crossed, knees drawn up to its abdomen
• cervix: softens, shortens in length, opens a little

Question 4

what happens during the first stage of labour

Answer 4

• months 7-9: weak irregular contractions, frequent 30min interval contractions (labour pains)
• dilation of cervix: from onset labour to complete dilation (opening) of the cervix
• labour: lasts for ~8-9hours for first child
• wave like contractions: (kinda like peristalsis), causes uterus to shorten, cervix to open, allows foetus to move more freely into pelvis, head is pushed down
• complete dilation: 10cm, occurs at end of 1st stage
• birth canal: curved passage, uterus, cervix and vagina

Question 5

what happens during the second stage of labour

Answer 5

• water breaks: amniotic membrane breaks, triggers stage of expulsion
• stage of expulsion: can last ~20min-2hours, delivery of foetus
• foetus: head stretches the vagina -> contracts abdomen muscles -> contraction of uterus -> push foetus through vagina, head faces towards mothers back
• mother: pulse rate increases, perspiration occurs
• expulsion: foetal head can be pushed out of shape (skull = separated by joints = movement), head delivered first (breathing begins), shoulders turn to fit into bones of pelvis, rotates sideways to face mothers hips

Question 6

what happens during the third stage of labour

Answer 6

• umbilical chord: cut and tied, umbilicus (naval) is all that remains
• vernix: baby is covered with a waxy material, this isn’t entirely removed (decreases occurrence of skin infections)
• afterbirth: placenta, amnion, chorion and umbilical chord are expelled
• blood clots: form to prevent blood leakage

Question 7

what are the characteristics of the new born infant

Answer 7

• full term: ~50cm, ~3.3kg, head is 1/4 of body length, legs are 1/3 of body length
• can breathe, suck, swallow, see, removes wastes, tastes, smell, hear, turn head, cries to signal help
• reflexes: movements occur automatically in response to a particular stimulus
• e.g. placing something (nipple / dummie) in babies mouth stimulates sucking

Question 8

how does the baby rely on the mother during development

Answer 8

• embryo / foetus relies on mother for supply of oxygen and nutrients and removal of wastes and co2, protection against changes in temp, shock and many disease causing organisms
• placenta: lungs, liver and alimentary canal of foetus don’t function, obtain nutrients from placenta

Question 9

exchange and circulation of foetus before birth

Answer 9

• foetus -> umbilical arteries -> placenta -> umbilical vein -> foetus
• foetus -> ductus venousus -> inferior vena cava -> right atrium -> ductus arterialises / Forman ovale

Question 10

what are the three bypasses of the foetus

Answer 10

• DV: blood vessel that bypasses the liver: partial hepatic vein -> inferior vena cava
• DA: blood vessel that bypasses the lungs: pulmonary artery -> aorta
• FO: opening between two chambers of the heart (blood entering RA goes straight into LA), blood from placenta = highly oxygenated, this increases blood flow

Question 11

what happens to the circulation after birth

Answer 11

• new born can no longer rely on mother / placenta for food / oxygen
• DV: closes, allows liver to become a fully functioning organ
• respiratory: stimulated by first breath, lungs begin to function, expansion means blood flow occurs
• DA: decreases due to expansion of lungs, eventually closes
• FO: closes off due to increased blood supply needed for the lungs
• hole in heart: occurs when the FO doesn’t close

Question 12

what happens to the infants heart rate and breathing

Answer 12

• B first 2 weeks: babies lungs undergo 45 breaths / minute, after two weeks breathing slows
• HR: high rate of 125/130 (180 beats / min), because more oxygen is needed for increased muscular activity (keep baby warm)
• RBC: #increases to carry extra oxygen to tissues
• WBC: very high count at birth, decreases rapidly by 7th day

Question 13

what changes to the mother occur after childbirth

Answer 13

• puerperium: 8 weeks post childbirth
• reproductive organs: (especially uterus) continues to contract, organs return to their non-pregnant state
• flattening of abdomen: contractions and gradual shrivelling of muscle fibres brings about shrinking
• discharge of fluid: from shrinking uterus (mixture of blood / breakdown products of tissues)
• blood volume / pulse: gradually returns to normal, pulse is slower
• emotional changes: postnatal depression, mood swings, adjusting to new situation
• menstruation: begins after 6 months (if breast feeding), within 10 weeks (if not)

Question 14

describe the structure of the breasts

Answer 14

• lobes: breast divided into 16-25 sections
• lobules: each lobe is divided into lobules
• alveoli: makes up wall of each lobule, milk secreting region of breast
• fatty tissue: surrounds lobules and lobes
• milk spaces: from lobules, ducts open into wide spaces, spaces serve as reservoirs for milk
• duct: from milk spaces short, straight duct leads to nipple
• nipple: each lobe has its own milk space, 15-25 openings on the nipple

Question 15

what is lactation

Answer 15

• the initiation and maintenance of milk secretion and delivery of milk to infant
• hormones: cause changes in breasts, becoming larger in size and oil secreting glands around nipple change, secretes milk 1-2 days after birth
• colostrum: first secretion, watery yellowish-white, contains little to no fat, high content of antibodies

Question 16

what is the milk let down reflex

Answer 16

• automatic response to trigger milk secretion, milk is stored until suckling begins

Question 17

what are the steps of the milk let down reflex

Answer 17

1. as the baby suckles the nipple, nerves in the nipple are stimulated and messages are sent to the brain
2. pituitary gland releases oxytocin
3. oxytocin triggers contraction small muscles around milk-filled lobules
4. milk is ejected into ducts and out through the nipple
   - mother: needs a well balanced diet with lots of calcium, vit D and phosphate
   - produces up to 1.5 L milk / day

Question 18

what is gestation

Answer 18

• the time the embryo / foetus is carried in the uterus (pregnancy)