Hormones in Early Pregnancy Quiz

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Questions and Answers

Which hormonal change occurs as a result of human chorionic gonadotropin (HCG) secretion during early pregnancy?

Enlargement of the corpus luteum (correct)

Degeneration of the endometrium

Inhibition of corpus luteum activity

Decrease in progesterone production

What is NOT a function of the placenta during pregnancy?

Transfer of gases

Production of insulin (correct)

Excretion of wastes

Hormone production

What is the role of relaxin during pregnancy?

Facilitating uterine contractions

Maintaining pregnancy by inhibiting uterine contractions (correct)

Stimulating fetal growth

Promoting the degeneration of corpus luteum

Which two hormones are primarily secreted by the corpus luteum during the early stages of pregnancy?

Progesterone and estrogen Signup and view all the answers

How does the placenta contribute to the hormonal environment in early pregnancy?

By producing hormones that maintain pregnancy Signup and view all the answers

Which hormone is responsible for the growth of the uterus and breasts during pregnancy?

Oestrogen Signup and view all the answers

What is the primary function of Human chorionic gonadotrophic (HCG) during early pregnancy?

Maintains the corpus luteum Signup and view all the answers

Which hormone's role includes relaxing smooth muscle and inhibiting uterine contractions?

Progesterone Signup and view all the answers

What is the main action of Human placental lactogen during pregnancy?

Alters maternal metabolism Signup and view all the answers

Which hormone is released by the corpus luteum and then the placenta to soften pelvic ligaments?

Relaxin Signup and view all the answers

Which process involves the release of the sperm nucleus into the cytoplasm of the ovum?

Acrosome reaction Signup and view all the answers

What is the role of hyluronidase during fertilization?

To dissolve the external membranes of the ovum Signup and view all the answers

What is the critical physiological change that sperm undergo during capacitation?

Increase in motility Signup and view all the answers

During which phase of the menstrual cycle does implantation occur?

Secretory phase Signup and view all the answers

What happens to the zona pellucida immediately after the penetration of the first sperm?

It undergoes a hardening reaction Signup and view all the answers

What is the initial step in the fertilization process that attracts sperm to the ovum?

Chemoattraction Signup and view all the answers

Which hormone plays a role in the chemoattraction of sperm to the ovum?

Oxytocin Signup and view all the answers

What marks the end of the capacitation period for sperm?

Acrosome reaction takes place Signup and view all the answers

Study Notes

Physiology of Pregnancy

Overview of pregnancy stages: ovulation, fertilization, implantation, embryo, and fetus
Objectives for the lecture include describing sperm transport, physiological sperm changes before ovum penetration, endocrine changes during pregnancy and placental hormones.

Objectives

Students will learn the path sperm takes to the mid-oviduct.
Students will learn about physiological and chemical changes to sperm before penetration of the ovum
Students will learn about endocrine changes during pregnancy
Students will learn about placental hormones and their function.

Fertilization

Sperm chemoattraction to the ovum occurs by signals like oxytocin, prostaglandins and chemotactic factors.
Sperm adheres to the zona pellucida
Sperm penetrates the zona pellucida via the acrosome reaction
Sperm fuses with the egg membrane which leads to the breakdown of the fusion area. Then, the sperm nucleus enters the egg cytoplasm.

Capacitation

Sperm capacitation occurs in the female genital tract fluids, improving motility and preparing for the acrosome reaction
Capacitation takes 2-3 hours
Sperm undergoes physiological and chemical changes.
Only capacitated sperm can penetrate the zona pellucida

Implantation

Implantation occurs on the anterior or posterior wall of the uterine body near the fundus, on or about the 6th day (20th of menstrual cycle)
The endometrium is in the secretory phase.
Stages of implantation include orientation, apposition, attachment, and invasion
Blastocyst moves to the uterus, contacts the endometrium and the trophoblast burrows into the uterine wall

Implantation involves

The blastocyst moves from the fallopian tube to the uterus
The blastocyst contacts the endometrium
The trophoblastic layer erodes the endometrium, and the blastocyst burrows into the endometrium.

Placenta

The placenta forms after implantation
The trophoblast remains associated with it
Placental hormones are secreted to maintain pregnancy
Functions of the placenta include:
- Transfer of gases
- Transport of nutrients
- Excretion of wastes
- Hormone production (estrogen, progesterone)
- Formation of a barrier (incomplete and non-selective)

Endocrine Changes During Pregnancy

After implantation, the syncytiotrophoblast secretes human chorionic gonadotropin (HCG)
Enlargement of the corpus luteum occurs instead of degeneration
Corpus luteum secretes progesterone and relaxin to maintain pregnancy, inhibiting uterine contractions
After the 8th week of pregnancy, HCG levels decrease, but progesterone and estrogen are maintained by the placenta

Hormones

Estrogen:
- Produced in the corpus luteum initially, then by the placenta
- Responsible for uterus and breast growth
Progesterone:
- Produced in the corpus luteum and then by the placenta
- Relaxing smooth muscles
- Inhibits uterine contractions, preparing the uterus for labor
- Regulates body fat storage
Human Chorionic Gonadotropin (HCG):
- Secreted by the trophoblast of the developing embryo
- Keeps the corpus luteum healthy, until the placenta takes over

Human Placental Lactogen

Affects maternal metabolism
Transfers glucose to the fetus
Mobilizes fatty acids from maternal stores

Relaxin

Released by the corpus luteum initially and then by the placenta
Softens pelvic ligaments
Reduces myometrial tone

Fetoplacental Unit

The fetus and placenta work together to produce steroids
Cholesterol is converted into progesterone, androgens, and estrogens
These hormones are then transferred across the placenta to the fetus and maternal blood.

Test your Understanding

The corpus luteum degenerates slower after fertilization/implantation because of HCG.

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Description

Test your knowledge on the hormonal changes and functions related to early pregnancy. This quiz covers critical hormones such as HCG, relaxin, and the role of the placenta. Explore how these hormones contribute to the physiological changes during pregnancy.