Dining which prenatal period is the basic body plan established?
To review:
The prenatal period during which the establishment of basic body plan takes place.
Introduction:
The development of a fetus takes 38 weeks from the time of fertilization of an egg. This period is known as a prenatal period that is divided into embryonic, fetal, and germinal period. The germinal period spans from the conception to 2 weeks after the fertilization. Third to eighth week is marked by an embryonic period.
Explanation of Solution
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The body plan is established during an embryonic period of prenatal period. The basic body plan is a tube within a tube structure. The outer tube forms the outer body wall and the inner tubes forms the respiratory and digestive tract. These tubes are separated by a serous cavity. The structures in the basic body plan are skin, outer body wall, body cavity, inner tube, kidney, gonads, and limbs. The skin consists of two layers: outer epidermis and inner dermis. The outer body wall includes the trunk muscles.
The inner body tube in the abdominal and thoracic cavity contains the digestive and respiratory tract, respectively. The pericardial and pleural cavity separates the heart and lungs, in the respiratory tract, from the outer body wall. The peritoneal cavity in the abdomen separates the digestive tract from the outer body wall. These cavities are lined by visceral and parietal serosa. The muscle, bone, and skin constitute the limbs.
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Chapter 3 Solutions
Human Anatomy
- Explain how the three germ layers are involved in forming the extra-embryonic membranes, and discuss the importance of the placenta as an endocrine organ.arrow_forwardName the three primary germ layers and the body systems that are formed by eacharrow_forwardDescribe the three parts of the prenatal period, includingthe length of time for each part.arrow_forward
- Prenatal development is the time from fertilization to birth and includes both embryonic and fetal periods. It is divided into period of three calendar months called trimester. Describe the major events of each trimester.arrow_forwardDefine the normal age range for the onset of puberty.arrow_forwardDoes physical development begin from the top or below? From the side to the center?arrow_forward
- Describe the main physiological events of embryonic and fetal development during each trimester, including major body systems.arrow_forwardThe first outward change of puberty in girls is: Rapid growth to reach the adult height and weight. Enlargement and development of the breasts Increase in clear vaginal secretions. Onset of menstruation .arrow_forwardState the roles of progesterone and estrogen in fetal development.arrow_forward