Parturition and lactation - class-XI

• Mammary glands or breasts are modified sweat glands that lie over the pectoral muscles. Each breast has a broad multiporous tip called nipple for the release of milk. A circular pigmented area called areola lies below it. Each breast contains 15-20 glandular lobes separated from one another by dense connective tissue and adipose tissue. Each lobe is further made of many lobules having glandular or secretory alveoli.

Parturition is the act of expelling the full-term young one from the mother's uterus at the end of gestation. Gestation (pregnancy) is completed in about 266 days from the mother's last menstruation.

The mammary glands of the female undergo differentiation after the pregnancy and starts producing milk towards the end of it, called lactation and the milk produced during these initial few days is referred to as colostrum. This contains many antibodies that is essential for the new born babies to develop resistance against any pathogen attack or disease. During oogenesis the gamete mother cell undergoes meiosis division to form the primary oocyte and this further divides into the secondary oocyte and a polar body by means of an unequal division. 

 Prolactin hormone is secreted by pituitary gland it stimulates the secretion of milk from mammals. It rises only when a baby suckles. Hormone oxytocin cause tiny muscles around the alveoli to squeeze the milk by using small tubes called milk ducts. Oxytocin is also responsible for contraction of uterus muscles, during and after birth. Prolactiiin and Oxytocin help the mother to form an emotional bond with her baby. Progesterone regulates the growth in size of alveoli and lobes. Estrogen stimulates the milk duct system to grow. Follicle stimulating hormone, luteinizing hormone and human chorionic gonadotropin control the level of estrogen and progesterone production.    

Parturition, also called birth or childbirth, process of bringing forth a child from the uterus, or womb. The prior development of the child in the uterus is described in the article human embryology. The process and series of changes that take place in a woman’s organs and tissues as a result of the developing fetus are discussed in the article pregnancy. Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition originate from the fully-developed foetus and the placenta which requires the release of oxytocin from the posterior lobe of the maternal pituitary.

After ovulation the lining of the (graafian) follicles grow inward, forming corpus luteum (yellow body), which temporary function as endocrine tissue. It secrete estrogen and progesterone, which stops additional ovulation, and thickening of uterine wall. If pregnancy does not occur within 14 days corpus luteum degenerates and menstruation follows.

Gestation (pregnancy) is completed in about 266 days from the mother's last menstruation. The gestation period of human beings is 270 days to 280 (approximately). It is usually about 266 days i.e., 36 weeks.

Parturition can be defined as the act of expelling the full term young ones from the mother's uterus at the end of the gestation period. In other words, the process of delivery of the fetus is known as parturition.

The delivery of the developed foetus after 9 months is known as parturition. Ovulation is the release of the secondary oocyte from the ovary. 

The hypothalamus secretes the Gonadotropin-releasing hormone which is responsible for menstruation sequence. The GnrRH repressed by the prolactin hormone, which encourages the production of milk. Without the GnRH release, the menstrual cycle wont begin a new event of pregnancy.

• Parturition is a phenomenon of giving birth. It is a process of delivering a child from the womb to the outside. It is usually initiated by the release of oxytocin hormone. 
• This hormone increases the contraction of uterine muscles. Prostaglandins are synthesized and released in response to the oxytocin hormone. Also, an increase in estrogen and progesterone ratio indicates the initiation of the parturition process. 
• Prolactin hormones are released after the parturition in order to secrete the milk from the mammary gland.

Parturition is the process of giving birth to the child.

The foetal ejection reflex is triggered by the fully developed foetus and placenta, which sends signals to the maternal pituitary gland to release oxytocin. Oxytocin then causes the uterine contractions necessary for childbirth.

Gestation length varies by age of dam, breed, and sex of the calf. Gestation length ranges from 279 to 287 days. For most breeds, 283 days is common. In dogs, the entire gestation period is approximately nine weeks, or 63 days, although it can range from 58 to 68 days. Cat pregnancy normally lasts between 63 to 67 days, but it can be tough to know exactly how long a cat is pregnant for. The cat gestation period can vary from as short as 61 days to as long as 72 days. so, 'the correct option is-Animal - Cow, Gestation period - 330−345 days'

It has been observed that by the end of the second month of pregnancy period, the foetus develops limbs and digits. Also, by the end of the first trimester (12 weeks), most of the major organs are developed, for instance, the limbs and external genital organs. The signals for parturition derives from the fully developed foetus and the placenta that further leads to mild uterine contraction referred to as foetal ejection reflex. By the end of pregnancy, the mammary glands initiate producing milk by the lactation process. 

Lactation is the method of synthesizing and secreting milk from the postpartum female breast mammary glands in reaction to a child sucking in the nipple. Mammary glands, which are enclosed in the breasts, produce the milk. The mammary gland consists of milk-carrying lactiferous ducts that grow and branch widely in reaction to estrogen, growth hormone, cortisol and prolactin during pregnancy.The prolactin of the pituitary hormone is extremely influential in establishing and maintaining the supply of breast milk. It is also essential for mobilizing breast milk maternal micro vitamins and minerals.

• When a woman is in a lithotomy or semi-sitting position, the Foetal Ejection Reflux is impaired and the increased pain caused by the sacrum’s inability to move as the baby descends can be intolerable
  
• Foetal ejection reflex in human female is induced by fully developed foetus and placenta. so, option D is correct

Gestation period is the time taken for embryo development after fertilization of egg in the female animal. 

Gestation period is the time taken for embryo development after fertilization of egg in the female animal. In humans the gestation period is approximately 38 weeks. 

Parturition is the process of expulsion of the child from the uterus or womb. It involves three stages- shortening and the opening of the cervix, descent and birth of the baby, and pushing out of the placenta. It is also known as childbirth. Thus the correct answer is option B.

The gestation period is the time in which the fetus develops, which starts with the fertilization and ends with the birth. The gestation period of brown rat is 21 days.
Thus, the correct answer is option (A), '20-22 days'.

Parturition is the process of childbirth, which is driven by forceful muscular contractions of the uterine wall, stimulated by oxytocin.

The gestation period is calculated from the first day of the last menstrual period. This is used to calculate the expected date of delivery (EDD).

Gestation period is the time period of pregnancy. It is approximately 9 months in humans. So the correct answer is B.

Development of fetus from the time of conception until birth is called as gestation period.

Parturition is an induced Complex neuroendocrine mechanism. In this signals are originated from a fully developed fetus and placenta. This lead to mild uterine contractions and hence fetal ejection reflex. Then oxytocin acts on uterine muscles leading to strong uterine contractions. This further continues to stronger and stronger contractions. As a result, the baby is expelled out of the uterus with placenta through the birth canal. 

Parturition is also called as childbirth. It is the act of delivering baby from uterus. Gestation is a period of developing embryo from conception to birth. It is a duration considered between pregnancy and birth. Ovulation is a process of releasing of egg from the ovary or Graafian follicle. Implantation is the process in which fertilized egg or zygote adheres or attaches to the endometrium wall of the uterus. Conception is the act of conceiving  a baby. In this, zygote is formed from the fusion of egg and sperm.

The release of the hormone oxytocin from maternal pituitary which leads to the milk ejection.  Oxytocin stimulates the muscle contraction surrounding the breast to squeeze out the milk. 

Parturition is an induced Complex neuroendocrine mechanism. In this signals are originated from a fully developed fetus and placenta. This lead to mild uterine contractions and hence fetal ejection reflex. Then oxytocin is released from maternal pituitary and it acts on uterine muscles leading to strong uterine contractions. This further continues to stronger and stronger contractions. As a result, the baby is expelled out of the uterus with placenta through the birth canal. 

Parturition is an induced Complex neuroendocrine mechanism. In this signals are originated from a fully developed fetus and placenta. This lead to mild uterine contractions and hence fetal ejection reflex. Then oxytocin acts on uterine muscles leading to strong uterine contractions. This further continues to stronger and stronger contractions. As a result, the baby is expelled out of the uterus with placenta through the birth canal. 

Parturition is the process in which a mother gives birth to its young one. It initiates when the message initiating parturition starts with the fetal brain, its control of ACTH release from the pituitary, and increased cortisol production by the fetal adrenal. The cortisol stimulates placental enzymes which cause placental progesterone to be made into estrogen. Oxytocin leads to the contraction of smooth muscles of myometrium of the uterus, which directs the full term foetus towards the birth canal.

Parturition
or childbirth is the event of bringing a child into the world from the uterus
of the mother. It is the apotheosis of pregnancy. It involves forceful muscle contractions
of the uterine wall which push the child out of the womb through the vaginal
canal.

Parturition is the process of giving birth or delivery. The signals for parturition originate from the placenta as well as fully developed foetus. Both these induces uterine contractions. These uterine contractions are called as foetal ejection reflex. This then stimulates the release of oxytocin hormone from the maternal pituitary gland. 

• Gestation length of a cow ranges from 279-287 days and is usually 283 days. 
• The gestation period of a dog usually ranges from 58-68 days. 
• The camel has a gestation period of 13-14 months or 410 days approximately. 
• The gestation period of a rat varies from 21-23 days (rarely 26 days). 

Colostrum is the name given to the first milk produced by the mammary glands of mammals. It consists of various antibodies that provide natural passive immunity to the newborns. This immunity is transient and does not have a latent period or a negative phase.

Foetal ejection reflex in human female is induced by fully developed foetus and placeta which causes mild contraction. This induces the release of oxytocin from maternal posterior pituitary ultimately leading to parturation due to strong contractions.

Relaxin is a hormone secreted by the ovary and placenta during pregnancy that relaxes the pelvic ligaments and softens the cervix to facilitate child birth.

• Relaxin is a hormone secreted by the placenta that causes the cervix to dilate and prepares the uterus for the action of oxytocin during labour.
  
• Relaxin is a protein hormone of about 6000 Da.
• Relaxin is produced by the ovary and the placenta.

Colostrum is the form of milk produced by the mother, after the birth of the baby. This is the first milk and is known to contain nutrients, proteins, antibodies and many growth factors essential for the growth and development of immunity in the baby. This milk contains high amounts of IgA. This antibody is required to protect the mucous membranes present in the throat, lungs and intestine of the baby from infection. 

Whole cow's milk also contains too much protein, sodium, potassium, phosphorus and chloride which may put a strain on an infant's immature kidneys. In addition, the proteins, fats and calcium in whole cow's milk are more difficult for an infant to digest and absorb than the ones in breast milk.
So, the correct option is "D" (Less fats and less lipids).

The duration of pregnancy from conception till birth is known as gestation. It occurs for a duration of 40 weeks. The release of eggs from the ovaries (or the mature graafian follicle) is known as ovulation. Implantation is the process in which the embryo in the blastocyst stage is implanted in the uterus. When the egg fuss with the sperm resulting in the formation of zygote it is known as conception. Parturition is the act of childbirth in which the baby is delivered from the uterus. So, the correct option is 'A - 3, B - 4, C - 2, D - 1, E - 5'.

Oxytocin i a hormone released by the posterior pituitary that helps the muscles of the uterus to contract during parturition (child birth). It also stimulates the release of prostaglandins that help cause further contraction. So, the correct option is 'child birth'.

• The increased levels of oxytocin at the time of parturition are responsible for vigorous uterine contractions and the dilation of the uterus. 
• The estrogen-progesterone ratio increases during the end of the 3rd trimester which results in the increased ability of the mammary glands for lactation.

Oxytocin is the hormone that stimulates powerful uterine contractions, and its concentration increases significantly to determine the onset and progression of labor (childbirth).

Birth occurs when foetal development is complete, typically around 38-40 weeks of gestation. The zygote is the initial single-cell stage formed at fertilization, not the developed stage ready for birth. The uterus is the organ, not the developing organism. At birth, the foetus has developed all major organ systems and is ready to survive outside the womb. Thus, completion of foetal development is the prerequisite for birth.

The process of delivery of foetus is called as parturition. Parturition is the act of expelling the full-term foetus from the mother's uterus at the end of gestation. In this process fully developed foetus produces foetal ejection reflex which stimulates pituitary to release oxytocin hormone. This hormone causes vigorous uterine contraction that leads to the delivery of feotus. This process is also known as the delivery of the foetus when the pregnancy period gets over. The importance of parturition is that the event results in the foetus to come out of the womb. The process is accompanied with the onset of lactation.

Salmonella atra is an amphibian having one of the longest gestation periods among animals existing on this earth. They have a gestation period between 36-48 weeks.

The horse has a gestation period of around 342 days whereas it is around 289 days for the cow.

Oxytocin is a hormone which is released from the pituitary gland. It is responsible for the muscular contraction which occurs during the parturition. The fully developed baby exerts a pressure on the walls of the uterus and as a result, it signals the pituitary gland to release oxytocin. The muscular contractions are responsible for the expulsion of the baby out of the uterus.

Parturition or childbirth is the event of bringing a child into the world from the uterus of the mother. It involves forceful muscle contractions of the uterine wall which push the child out of the womb through the vaginal canal. Several events take place after the birth of the child, including expulsion of the placenta, umbilical cord, and fetal membrane.

Foetal ejection reflex occurs at the time of parturition and are gentle uterine contactions produced by the placenta. This may occur due to extremely high levels of adrenaline during childbirth. Since parturition is a neuro-endocrine process, oxytocin is released by the neurohypophysis of maternal pituitary which stimulates stronger contractions of the uterus and induces labour pain, with decreasing progesterone levels and marks the end of the gestation period. Hence, the correct answer is 'Release of oxytocin from maternal pituitary'.

The amniotic fluid is the protective liquid contained by the amniotic sac of a gravid amniote. This fluid serves as a cushion for the growing fetus but also serves to facilitate the exchange of nutrients, water, and biochemical products between mother and fetus. Amniotic fluid is present from the formation of the gestational sac. The forewaters are released when the amnion ruptures prior to childbirth.

During pregnancy in the human, hormones such as relaxin allows the pelvic bones to be more flexible for delivery. The gap of the symphysis pubis, normally is 4–5 mm but during pregnancy there is an increase by at least 2–3 mm. The symphysis pubis separates to some degree during childbirth hence pubic symphysis is an amphiarthrodial joint.

Oxytocin is a peptide hormone secreted by the posterior pituitary. It is also a neuropeptide, used for inter-neuron communication. This hormone is responsible for secretion or ejection of milk. PRH or prolactin releasing hormone is responsible for the release of Prolactin or PRL, which is a hormone responsible for milk production. Progesterone inhibits lactation during pregnancy.

In medical terms, the third stage of labor is known as the afterbirth. This stage involves the expulsion of the placenta, umbilical cord, and fetal membranes after the baby has been delivered.