Repro System Part 3 - Pregnancy

Why must the sperm do after entering the vagina

• two main things for their last maturation step (what is this process called)

  • Explain how it works

    • Three main things that occur in the sperm

• How long does it take the sperm to reach the gg

• What must it pass through

• How does the vagina help with this (two things)

  • What hormones affect this process (comes from the semen)

• Sperm undergoes capacitation becomes hyperactive

• Albumin, enzymes, lipoproteins bind to sperm:

  • glycoprotein coat removed

  • intracellular changes

  • develop strong whip-like motion

• Sperm must pass through (~30 min) cervical mucous (thin, estrogen)

• Uterine & oviduct contractions aid transport

  • (estrogen, protaglandins - semen helps aid in contractions)

In what part of the female body does the fertilization occur

• how long is the oocyte viable for

• how long is the spermatozoa viable for

• Fertilization happens in the fallopian tubes

• Oocyte viable for 24h

• Spermatozoa viable 4-6 days

Fertilization

• how many sperms reach the oocyte

• What does the progesterone do

  • Produced from what cells

• What does acrosomal enzymes do

• About 100 sperm reach oocyte

• Guided by chemotaxis (progesterone from cumulus cells)

  • It attracts the sperms towards the oocyte

• Sperm tunnel through barriers (acrosomal enzymes will remove the layers of the oocyte at the the head (acrosome) of the sperm)

• First sperm fusing with egg wins

Fertilization - Cortical Reaction

• How does more sperms are prevented from enerting the oocyte after the first binds?

  • how does the sperm bind with the oocyte

  • After binding what does it trigger

  • What does the event cause

• Explain how the nucleus fuses together

  • four steps

Prevent addition sperm binding with oocyte (polysperm)

• Sperm docks with sperm-binding proteins on oocyte membrane

• Triggers depolarization of oocyte

• Fusion of cortical granules (oocyte intracellular vesicles) with outer membrane

• Coat fertilized oocyte and prevent penetration by additional sperm

  • (i.e. prevents polyspermy)

How the nucleus fuse together

• cortical reactions triggered by binding

• sperm nucleus enters the egg

• oocyte completes the meiotic division

• zygote nucleus formed

What happens after fertilization

• 5 steps

• Blastocyte vs trophoblast

• ovulation

• fertilization

• cell division

• blastocyst reaches uterus

• blastocyst implanted and now called trophoblast (with the addition of embryo and other structures)

Fertilization hormone

• what is it called

• what cell secrets it

• What two things does the hormone do

• What hormone is it similar to

• What other application is useful with the help of the hormone

• Human chorionic gonadotropin (hCG) secreted from trophoblast (the fertilized egg)

• Takes over from pituitary to maintain corpus luteum and prevent next menstrual cycle

• Similar in structure to LH

• Basis of pregnancy test

Why does hCG maintain the corpus luteum?

• hormones

• Progesterone keeps endometrium intact

  • We don’t want it to break down during pregnancy

• Progesterone, estrogen, inhibin: feedback suppression of pituitary (Lh and FSH)

  • For the increase of the three hormones

Fetus and placenta

• Placenta Performs role of

• Digestive, respiratory and renal systems for the fetus

• Exchange of:

• nutrients/waste

• oxygen/carbon dioxide

• proteins, chemicals, etc

Placental circulation

• Is there a link between mother and fetal child’s vasculature (blood vessels)

• What transfers nutrients and gases between the two?

• Maternal vasculature not physically linked to fetal vasculature

• Maternal blood forms a lacunae(lake)

  • The space linked the maternal vasculature to the fetal’s vasculature

• Fetal chorionic villi transfer gases & solutes between mother & fetus

Placenta: A Temporary Endocrine Gland

• produces what four things

• Explain why HCG decreases at this point

• + explain the movement

  • More information next flashcard

• HCG decreases because the placenta takes over

• produces human placental lactogen

  • or human chorionic somatomammotropin

• secretes estrogen and progesterone to the mother

Movement of hormones and other things between the mother’s blood placenta, fetal blood and fetal adrenal cortex

• DHEA is a precursor to estrogen

• The fetal adrenal cortex produces it, moves it to the fetal blood and to the placenta where it gets converted into estrogen

• Placenta also produces progesterone

• Therefore the progesterone and the estrogen gets diffused into the mother’s blood to continue supplying nutrients to the fetus

Function of placental hormones

• list the four hormones as well as their main function(s)

Human chorionic gonadotropin

– maintains corpus luteum; stimulates fetal testis

Progesterone

– suppresses uterine contractions, cervical plug, mammary gland development (milk)

Estrogen

– uterine development (growth, blood supply, oxytocin receptors), breast duct development, etc

Human placental lactogen

– Structurally related to growth hormone and prolactin

– High in mother/low in fetus

– Decreases maternal cellular uptake of glucose, enhances maternal lipolysis

Normal terms of pregnancy:

• six - list the weeks

  • First trimester

  • second trimester

  • third trimester

  • normal birth

  • preterm

  • postterm

• First trimester: 0-12 weeks embryo development

• Second trimester: 12-28 weeks fetal development,

• Third trimester: 28 weeks to delivery fetal maturation

  • Lungs fully develops in the child

• Normal birth: 37-42 weeks after last menstrual cycle

• Preterm: fetus born > 28 weeks usually viable without intervention

• Postterm: >42 weeks

  • Force birth

  • e.g. C-section

Maternal adaptations to pregnancy

• renal

• cardiovascular

• immune system

• calcium homeostasis

• Renal:

  • increased vasopressin levels increase blood volume

  • increased activity RAS sodium and fluid retention

• Cardiovascular: increased output

• Immune system: partially suppressed

  • Reason: new growing in the body should not be attack by the immune system

• Calcium homeostasis: pregnancy associated hyperparathyroidism

  • calcium transfer to fetus

  • increased calcitonin to limit mobilization of maternal bone

    • Protecting the maternal bone

How is labour triggered?

• What is the other name for it?

• What does the ovary release?

• What does the placenta do?

• What receptors involved

  • What three hormones released in the body

• Before parturition, relaxin released from ovary and placenta loosens the ligaments in the pelvic bone and cause the cervix to soften

Triggers/Initiation?

• increase Estrogen & oxytocin receptors in uterus increase

• increase Fetal cortisol

• increase Placental corticotropin-releasing hormone (CRH)

• increase Prostaglandins

What hormones are necessary for breast milk?

• Before parturition

  • two hormones

  • what do they do

  • what do they prevent

• After parturition

  • Two hormones involved

  • what does each hormone

  • Where are they produced?

Before parturition

• Estrogens and progesterone needed for the development of mammary glands but inhibit milk production

After partuitition

• Prolactin triggers Epithelial milk producing cells

• Oxytocin triggers Myoepithelial cells to squeeze the milk to the milk duct and out the breast

• Both released from the pituitary gland

Explain the regulation of oxytocin and prolactin (milk control)

• in what pituitary is it secreted from

• Posterior secrets oxytocin

• anterior pituitary triggered by decrease PIH in the hypothalamus

  • Release prolactin

• Positive feedback from mechanoreceptors in the nipples (increased sucking)