Origin and Development of Organ Systems

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Questions and Answers

What is a common emotional response experienced during pregnancy that can involve mixed feelings about the pregnancy?

Indifference

Ambivalence (correct)

Excitement

Joy

Which trimester is primarily focused on accepting the pregnancy?

Postpartum period

3rd trimester

1st trimester (correct)

2nd trimester

What is a common activity associated with the third trimester in preparation for the baby's arrival?

Introversion

Childbirth education classes (correct)

Narcissism

Ambivalence

Which term describes the act of preparing the home and selecting a name for the baby?

Nest-building Signup and view all the answers

Which of the following is NOT typically associated with the emotional responses during pregnancy?

Euphoria Signup and view all the answers

Which germ layer is responsible for forming the linings of the gastrointestinal tract and respiratory tract?

Entoderm Signup and view all the answers

What is the role of the mesoderm during development?

Development of the heart and circulatory system Signup and view all the answers

At what week does the heart begin to beat during fetal development?

24th day Signup and view all the answers

Which fetal circulation shunt directs blood away from the liver?

Ductus Venosus Signup and view all the answers

What structures are responsible for shunting blood to supply important organs in the fetus?

Shunts Signup and view all the answers

What psychological condition is associated with body image and boundary issues related to narcissism and introversion?

Narcissism Signup and view all the answers

What physiological change typically occurs in the uterus during pregnancy regarding its size?

Increases in length, depth, and width Signup and view all the answers

Which of the following describes somatic symptoms that the father may experience due to Couvade syndrome?

Nausea and vomiting Signup and view all the answers

In what way may sexual desire change during pregnancy?

It may either increase or decrease Signup and view all the answers

What are the local changes that occur in the body during pregnancy?

Alterations in uterus, cervix, vagina, ovaries, and breasts Signup and view all the answers

What is the average weight range for a baby at full term (week 40)?

3000-3200g Signup and view all the answers

What major physiological change occurs as a baby takes its first breaths of air?

Blood is forced to travel through the lungs Signup and view all the answers

Which condition does not affect the fetus during pregnancy?

Superstitions about external factors Signup and view all the answers

What is a characteristic of monozygotic twins?

Form from the division of a single zygote Signup and view all the answers

Which statement accurately describes the appearance of a fetus in week 36 of pregnancy?

Fingernails grow to the end of fingertips Signup and view all the answers

What common psychological problem might expectant mothers face?

Feeling of being robbed of leisure time Signup and view all the answers

How many creases are typically found on the soles of a fetus's feet at full term?

One or two Signup and view all the answers

What psychological change relates to the belief that pregnancy will stretch a woman's abdomen and breasts permanently?

Concern about physical appearance Signup and view all the answers

What is the primary reason for the increase in uterine blood flow at the end of pregnancy?

Increase in the size of the placenta Signup and view all the answers

Which sign indicates softening of the cervix during pregnancy?

Goodell's sign Signup and view all the answers

What is a probable sign of pregnancy that is determined through a bimanual examination?

Chadwick's sign Signup and view all the answers

What occurs to the diaphragm as pregnancy progresses?

It is pushed upwards by the enlarging uterus. Signup and view all the answers

Which of the following is true about Braxton Hicks contractions?

They are false labor contractions. Signup and view all the answers

What is the primary purpose of the operculum during pregnancy?

To seal the cervical canal and protect against bacteria Signup and view all the answers

What change in vaginal secretions occurs during pregnancy?

Lower pH due to increased Lactobacillus activity Signup and view all the answers

Which hormonal change is directly linked to the softening of pelvic ligaments and joints during pregnancy?

Increased relaxin and progesterone levels Signup and view all the answers

What is a possible effect of supine hypotension syndrome during pregnancy?

Decreased venous return to the heart Signup and view all the answers

What is the expected increase in blood volume during pregnancy?

30% - 50% increase Signup and view all the answers

Which mouth-related change is a common symptom during pregnancy?

Hyperptyalism leading to excessive saliva Signup and view all the answers

What anatomical change occurs to the umbilicus around the 28th week of pregnancy?

The umbilicus protrudes outward Signup and view all the answers

What percentage of women may experience nausea and vomiting during early pregnancy?

50% of women Signup and view all the answers

What is a psychological change that can be seen during pregnancy?

Increased likelihood of anxiety and worry Signup and view all the answers

Study Notes

Germ Layers

Entoderm: Forms linings of pericardial, pleural, and peritoneal cavities, gastrointestinal tract, respiratory tract, tonsils, thyroid, thymus, parathyroid glands, and lower urinary system.
Mesoderm: Develops supporting structures of the body including dentin of teeth, upper portion of the urinary system, reproductive system, heart, circulatory system, blood cells, and lymph vessels.
Ectoderm: Forms central nervous system (CNS), peripheral nervous system (PNS), skin, hair, nails, sebaceous glands, sense organs, mucous membranes of anus, mouth, nose, tooth enamel, and mammary glands.
Blastocyst: Provides baseline for all organ systems by 8 weeks during organogenesis.
Rubella infection can impact the development of organ systems.

Cardiovascular System Development

Day 16: Formation of a single heart tube.
Day 24: Initiation of heart beating.
Week 6-7: Development of septum and valves.
Week 11: Electrocardiogram (ECG) can be performed; accuracy improves by week 20.
Week 10-12: Doppler ultrasound assessment of heart activity.
Week 20: Stethoscope can be used to listen for fetal heart sounds.

Fetal vs. Extrauterine Circulation

Fetal oxygen exchange occurs via the placenta, not the lungs.
Blood bypasses the lungs in utero, directly supplying lung tissue.
Specialized structures (shunts) direct blood flow to essential organs:
- Ductus venosus: Shunts blood to liver.
- Foramen Ovale: Directs blood from right to left side of the heart.
Survival rate for fetuses is over 95%, with signs of vitality including Moro reflex and fingernail growth.

Fetal Development Milestones

Week 36:
- Length: 42-48 cm; Weight: 1800-2700 g (5-6 lb).
- Body stores of glycogen, iron, carbohydrates, and calcium increase; fat deposition noted; lanugo decreases.
Weeks 38-40:
- Length: 48-52 cm; Weight: approximately 3000 g (7-7.5 lbs).
- Full-term characteristics include mature lungs, absence of lanugo, mature hair, placental detachment, and initiation of breathing.

Twin Development

Monozygotic Twins: Arise from a single fertilized egg; share one placenta and two amnions.
Dizygotic (Fraternal) Twins: Result from two separate fertilized eggs; each has a separate placenta and amniotic sac.

Psychological Changes During Pregnancy

Pregnancy Duration: 9 months allows the fetus and family ample time to prepare.
Superstitions: Common beliefs regarding pregnancy can impact emotional responses, though they do not affect fetal health.
Common Psychological Problems: Concerns about career impact, body changes, financial burdens, and perceived time consumption associated with children.

Nursing Responsibilities

Assist in stress coping mechanisms; ensure women feel secure and supported through prenatal interactions.
Encourage expression of feelings and promote positive beliefs about having a baby.

Psychological Tasks in Trimesters

1st Trimester: Acceptance of pregnancy; dealing with ambivalence.
2nd Trimester: Acceptance of the baby; engaging in anticipatory behaviors like shopping for baby supplies.
3rd Trimester: Preparing for birth and the arrival of the baby.

Emotional Responses to Pregnancy

Possible feelings of ambivalence, grief, and narcissism; mood changes due to hormonal fluctuations.
Consideration of the father’s emotional experience (Couvade syndrome), reflecting pregnancy symptoms.
Sexual desire changes and adjustments to the family dynamic as older siblings prepare for the new baby.

Physiological Changes of Pregnancy

Local Changes: Alterations in uterus, cervix, vagina, ovaries, and breasts.
Systemic Changes: Affect integumentary, respiratory, circulatory, gastrointestinal, urinary, skeletal, endocrine systems, including weight fluctuations and temperature changes.

Uterine Changes

Significant increase in uterine size:
- Length expands from 6.5 to 32 cm.
- Weight increases from 50 to 1000 g.
- Early thickness of the uterine wall is 1-2 cm, thinning to 0.5 cm towards the end of pregnancy.
Uterus can hold over 7 lbs and approximately 1000 ml of amniotic fluid.### Uterine Changes
Vascularity and dilation of blood vessels increase significantly during pregnancy, expanding from 15-20 ml/min to 500-750 ml/min by term.
Decidua development is essential for embryo implantation and support.
Uterine size increases, displacing intestines and elevating the diaphragm and liver, leading to pressure on the stomach and bladder.
"Lightening" refers to the fetus settling lower in the pelvis, typically occurring two weeks before term for primigravidas.
Hegar’s sign presents as softening of the lower uterine segment, detectable at six weeks.
Ballottement, felt between 16-20 weeks, involves the fetus bouncing in amniotic fluid during a bimanual exam.
Braxton Hicks contractions, or "practice" contractions, occur as early as the second trimester, becoming more pronounced in the last month.

Cervical Changes

Cervix exhibits increased vascularity, appearing violet due to blood flow.
Goodell's sign pinpoint's the cervix's softening early in pregnancy.
Operculum, a mucus plug, forms to protect the uterus from infection.

Vaginal Changes

Leukorrhea (white discharge) from increased vaginal epithelial activity is a presumptive sign.
Chadwick’s sign indicates a color change in the vaginal wall, shifting to a deep violet hue due to vascularity.
Vaginal pH decreases from >7 to 4-5, enhancing resistance to bacterial infections, but can predispose to Candida infections.

Ovarian Changes

The placenta becomes the key hormonal organ, halting FSH and LH production, thus preventing ovulation.

Breast Changes

Tenderness and fullness noted by the 6th week due to rising estrogen levels, with breast size increasing from tissue hyperplasia.
Areola darkens, increasing in diameter from 1.5 inches to 2-3 inches.
Montgomery's tubercles secrete lubrication for nipple protection.
Colostrum can be expelled by the 16th week, containing high protein.

Integumentary System

Striae gravidarum appear as pink or reddish streaks that fade to silvery-white.
Linea nigra develops, a brown line extending from umbilicus to pubis.
Melasma (mask of pregnancy) presents as darkened facial regions due to hormonal changes.

Respiratory System

Increased nasal congestion attributed to elevated estrogen levels is common.
Uterine enlargement pushes the diaphragm, potentially causing shortness of breath, especially late in pregnancy.

Temperature Changes

Early pregnancy brings an elevation in body temperature, influenced by progesterone, with a decrease noted around the 16th week as the placenta assumes hormonal duties.

Cardiovascular System

Blood volume increases by 30-50% to ensure adequate placental nutrient exchange.
Cardiac output rises by 25-50%, with a heart rate increase of approximately 10 bpm.
Edema commonly occurs due to pressure on lower extremity veins from the expanding uterus.

Gastrointestinal System

Increased pressure from the growing uterus results in slower gastrointestinal motility, precipitating heartburn and constipation.
Morning sickness affects about 50% of women due to rising hormone levels.
Hemorrhoids and gum hypertrophy can occur due to increased blood flow and pressure.

Urinary System

Fluid retention increases by 7.5L to support blood volume for placental exchange.
Urinary output rises 60-80%, with initial frequency peaking in the first trimester due to pressure but easing in the second.

Skeletal System

Increased calcium and phosphorus demand supports fetal skeletal development.
Softening of pelvic ligaments aids fetal passage while leading to lordosis, which can cause back pain.

Endocrine System

Placenta acts as an endocrine organ, producing estrogen, progesterone, and other hormones to maintain pregnancy.
Thyroid glands enlarge to boost metabolic rates and prevent goiter.

Immune System

Immunologic changes reduce rejection of the fetus while increasing white blood cell count for infection protection.

Weight Changes

Total weight gain throughout pregnancy ranges from 25-35 lbs, from various sources including the fetus, placenta, fluid, and increased blood volume.

Signs of Pregnancy

Presumptive signs include subjective symptoms such as nausea and breast changes, while probable signs are detectable by an examiner (e.g., Hegar's sign).
Positive signs provide definitive evidence of pregnancy, including fetal heart sounds and visualization via ultrasound.

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Description

This quiz explores the origin and development of organ systems, focusing on the three germ layers: entoderm, mesoderm, and ectoderm. Each layer's contributions to various body structures and systems are examined in detail. Test your knowledge on how these layers shape the human body during development.