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By the end of this section, you will be able to:
  • Discuss the importance of an infant’s first breath
  • Explain the closing of the cardiac shunts
  • Describe thermoregulation in the newborn
  • Summarize the importance of intestinal flora in the newborn

From a fetal perspective, the process of birth is a crisis. In the womb, the fetus was snuggled in a soft, warm, dark, and quiet world. The placenta provided nutrition and oxygen continuously. Suddenly, the contractions of labor and vaginal childbirth forcibly squeeze the fetus through the birth canal, limiting oxygenated blood flow during contractions and shifting the skull bones to accommodate the small space. After birth, the newborn’s system must make drastic adjustments to a world that is colder, brighter, and louder, and where he or she will experience hunger and thirst. The neonatal period (neo- = “new”; -natal = “birth”) spans the first to the thirtieth day of life outside of the uterus.

Respiratory adjustments

Although the fetus “practices” breathing by inhaling amniotic fluid in utero, there is no air in the uterus and thus no true opportunity to breathe. (There is also no need to breathe because the placenta supplies the fetus with all the oxygenated blood it needs.) During gestation, the partially collapsed lungs are filled with amniotic fluid and exhibit very little metabolic activity. Several factors stimulate newborns to take their first breath at birth. First, labor contractions temporarily constrict umbilical blood vessels, reducing oxygenated blood flow to the fetus and elevating carbon dioxide levels in the blood. High carbon dioxide levels cause acidosis and stimulate the respiratory center in the brain, triggering the newborn to take a breath.

The first breath typically is taken within 10 seconds of birth, after mucus is aspirated from the infant’s mouth and nose. The first breaths inflate the lungs to nearly full capacity and dramatically decrease lung pressure and resistance to blood flow, causing a major circulatory reconfiguration. Pulmonary alveoli open, and alveolar capillaries fill with blood. Amniotic fluid in the lungs drains or is absorbed, and the lungs immediately take over the task of the placenta, exchanging carbon dioxide for oxygen by the process of respiration.

Circulatory adjustments

The process of clamping and cutting the umbilical cord collapses the umbilical blood vessels. In the absence of medical assistance, this occlusion would occur naturally within 20 minutes of birth because the Wharton’s jelly within the umbilical cord would swell in response to the lower temperature outside of the mother’s body, and the blood vessels would constrict. Natural occlusion has occurred when the umbilical cord is no longer pulsating. For the most part, the collapsed vessels atrophy and become fibrotic remnants, existing in the mature circulatory system as ligaments of the abdominal wall and liver. The ductus venosus degenerates to become the ligamentum venosum beneath the liver. Only the proximal sections of the two umbilical arteries remain functional, taking on the role of supplying blood to the upper part of the bladder ( [link] ).

Questions & Answers

where is heart located
medical Reply
thoracic cavity
Ashley
1
Noor
between which line
medical
where is the thorax located at?
angel
heart located between T5-T8
Biplav
thorax is the area between the base of neck to the diaphragm
Biplav
why does a person's complexion change when he relocates to another cold environment & tends to become more light skinned, does this mean the distribution of melanin to the surface of the skin changes ?
Ferrel Reply
what is Aponeurosis
Komolika Reply
aponerosis is modifications of deep fascia of the skin.. it generally covers the muscles Or tendons within it
niyati
A sheet of parly white fibrous tissue that takes the place of tendon in flat muscles having a wide area of attachment
mishra
what is the difference between sex and gender?
Hridya Reply
Those are synonyms
Ferrel
What is Physiology?
Nancy Reply
The study of functions of the human body.
Evans
study of human body
obaidullah
The biochemical study of any organism (eg. different systems) is called Physiology.
Doctor
which category of bone is among the most numerous in the skeleton?
DAMSON Reply
what is a nutrition ?
Jitu Reply
Nutrition is the process of providing or obtaining the food necessary for health and growth.
Gloria
Nutrition is the process of taking food and using it for growth , repair and metabolism ...
Om
how many parts of bone
Amir Reply
know the meaning of both messages
Amir
what is the name of suture that is present between frontal. parietal. occipetal ...
Amir
what is the name of suture that is present between frontal. parietal. occipetal ...
Amir
Coronal suture present between frontal and parietal bone and lambdoid suture present between parietal and occipital bone ...
Om
Squamous suture
Ferrel
& where is the squamous suture ?
Ferrel
what is meant by synovial joint? and what is this role
Fozia
type of joint that is found between bones that move against each other. it's function is to prevent bone friction
Ferrel
epinephrine is the true meaning of epi
Michele Reply
what does the word 'epi' means
Melex Reply
good evening, my question is what are function of metal in human body like aluminum?
Yosef Reply
please want you to help me in understanding digestive system
Hamidu Reply
this is muscular system?
Patel Reply
bruh moment
Viana
It is an organ system consisting of skeletal ,smooth and cardiac muscles
mishra
im too retarded to be here
Viana
naww Viana, I know it's hard to absorb info, I'm having the same issue, but keep practising, chin up.
Katarina
what is the question
Amir
to have a better understanding as to how our human bodies function. the knowledge we gain can improve our quality of life. Without our study of anatomy how could a doctor know what prescription to give us when our bodies is being attacked by a bacteria? We wouldn't!
Robin Reply
discuss nervers system in human being life.
Allen Reply
neuralgia what is other name of it
Muniba

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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