Human Growth and Development 2

Question 1

Maternal changes during pregnancy

Answer 1

-must adapt to provide environment, nutrients, waste removal, buoyancy, respiratory gases for the developing embryo/fetus

• metabolic changes
• cardiovascular system (need to increase blood volume by 40%)
• renal system
• respiratory system
• gastrointestinal tract

Question 2

Metabolic changes during pregnancy

Answer 2

• human placental lactogen (hPL) – From Placenta
– Breast maturation
– hPL promotes growth of the fetus – maternal glucose-sparing effect (prevents the mother from using all of her glucose)

Question 3

Physiological changes to: cardiovascular system

Answer 3

• Blood volume increases 25-40%
• Increased cardiac output (SV X HR)
• Decreased total peripheral resistance • Decreased blood pressure

Question 4

Physiological changes to: renal system

Answer 4

• Enlarged kidneys
• Dilated ureters
• Increased bladder capacity
• Increased renal blood flow
• Increased GFR
• Sodium retention
• urine production increases to handle the additional fetal wastes

Question 5

Physiological changes to: respiratory system

Answer 5

• Increased blood flow
• Respiratory system–oedematous and nasal
congestion may occur
• Ribcage relaxation= expansion
• Increased ventilation
• Increased O2 and decreased CO2 in maternal blood
•Dyspnea (difficult breathing)may develop late in pregnancy

Question 6

Physiological changes to: gastrointestinal system

Answer 6

• Decreased motility
• Smooth muscle relaxation –progesterone, relaxin
• morning sickness occurs due to elevated levels of estrogen and progesterone

Question 7

Labour

Answer 7

•Estrogen reaches a peak during the last weeks of pregnancy causing myometrial weakness and irritability
•Weak Braxton Hicks contractions may take place (opening of calcium channels in the muscle causes these)
•As birth nears, oxytocin and prostaglandins cause
uterine contractions
• Emotional and physical stress:
– Activates the hypothalamus
– Sets up a positive feedback mechanism, releasing more oxytocin

Question 8

Development of fetal circulation

Answer 8

• By the end of the 3rd week:
– The embryo has a system of paired vessels
– The vessels forming the heart have fused

Question 9

Fetal circulation

Answer 9

• Umbilical arteries and veins
• Three vascular shunts (occluded at birth)
– Ductus venosus – venous shunt that bypasses the liver
– Foramen ovale – opening in the interatrial septa to bypass pulmonary circulation (don’t need blood to lungs as don’t need to breathe)
– Ductus arteriosus – transfers blood from the right ventricle to the aorta (fetus doesn’t need to oxygenate its own blood)

Question 10

The breathing baby

Answer 10

• Once carbon dioxide is no longer removed by the placenta, central acidosis occurs
• This excites the respiratory centers to trigger the first inspiration
• This requires tremendous effort – airways are tiny and the lungs are collapsed
• Once the lungs inflate, surfactant in alveolar fluid helps reduce surface tension

Question 11

Lactation

Answer 11

• The production of milk by the mammary glands
• Estrogens, progesterone, and lactogen stimulate the hypothalamus to release prolactin-releasing hormone (PRH)
• The anterior pituitary responds by releasing prolactin

Question 12

Advantages of breast milk for the infant

Answer 12

• Advantages of breast milk for the infant
– Fats and iron are better absorbed
– Its amino acids are metabolized more efficiently than those of cow􏰄s milk
– Beneficial chemicals are present – IgA, other immunoglobulins, complement, lysozyme, interferon, and lactoperoxidase
– Interleukins and prostaglandins are present, which prevent overzealous inflammatory responses
– Its natural laxatives help cleanse the bowels of meconium