Human Anatomy and Physiology

1
Human Anatomy and Physiology

• Pregnancy, birth and nutrition of young

2
Pregnancy

• Sperm reach egg (30 min.)
• Sperm highly motile
• Prostaglandin in semen causes uterus and
  fallopian tubes to contract towards egg
• Female aids sperm movement
• Estrogen causes differential fluid pressure in
  reproductive tract
• Estrogen decreases cervical mucus

3
Sperm survival

• Factors decreasing survival
• Leakage from vagina
• Acidity of female tract

4
Fertilization

• Sperm capacitation
• Acrosomal enzymes weaken oocyte membrane
• Sperm nucleus and centriole penetrates into the
  ovum
• Monospermy is assured by
• Entry of extracellular Na reversing oocyte
  membrane polarity
• Ca causes cell to prepare for cell division
• This cortical reaction destroys sperm receptors
  on plasma membrane of the egg

5
Early development

• Fertilized embryo takes 7 days to implant
• Nutrients provided by wall of fallopian tube
• By week 8, placenta is formed and serves as the
  organs

6
Hormones

• Viability of the corpus luteum maintained by hCG
• Levels of estrogen and progesterone rise due to
  secretion by the placenta
• Estrogen and progesterone levels rise in
  anticipationof birthing and lactation

7
Birthing

• Involuntary contractions of uterine smooth muscle
  (positive feedback)

8
Birthing

• Amniotic sac pushes up against cervix wall
  (breaking of water)
• Birth follows
• Further uterine contraction expels the placenta

9
Lactation

• Rising estrogen and progesterone levels stimulate
  release of PRH
• Lactogenesis
• Colostrum is the first milk
• Little fat, mostly protein, vitamins, IgA
  antibodies

10
Milk let down reflex

• Positive feedback (galactopoiesis)

11
Female pill

• Estrogen and progesterone in high doses
• inhibit ovulation because hypothalamus fails to
  secrete luteinizing hormone
• Low doses
• alter egg transport time in fallopian tube
  preventing implantation
• abnormal development of endometrium
• abnormal cervical mucus lethal to or blocks
  entry of sperm
• abnormal contraction of fallopian and uterine
  musculature