Biol 121 Genetics, Evolution And Answers


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  • Subject Code : BIOL 121
  • University : Australian Catholic University
  • Subject Name : Biology

Introduction

Pregnancy is a normal physiological process which requires the synchronisation of multiple organs of our body. For meeting the needs of the developing foetus, a pregnant woman undergoes many anatomical changes in the breast tissues and physiological changes in the circulatory system, cardiovascular system and the kidney. Such changes are based on ovary endocrine secretions, and possibly placenta and decidua. In maintaining maternal and foetal homeostasis, there are lot of changes happens in the body at endocrine level also where different hormones are secreted to take over their specialised functions. Dysregulation of these homeostatic controls causes serious disorders at the time pregnancy (Soma-Pillay et al., 2016). In this essay the case study of teenage female named Nevaeh is pregnant. She is undergoing through physical and physiological changes which have been discussed in the essay.

Physiological and Cardiovascular Changes in Pregnancy

Breast tissue contains mammary gland that is the glandular structure of the apocrine glands. Human breast production is distinctive on many grounds. These gland produces milk and delivers it through a large network of branched ducts to the nipple. During pregnancy for the lactation, the hormone prolactin stimulates the growth and development of these branched ducts and alveoli lined with lactocytes that secrete milk, and by creating colostrum. (Javed & Lteif, 2013). Another hormone, oxytocin is also released in large amounts. This is a fertility facilitator and breastfeeder. Oxytocin helps in contraction of uterus during childbirth and lactation after child birth. Oxytocin facilitates the flow of milk through the breast during breastfeeding, so that it can be excreted by the breasts (Magon, & Kalra, 2011).

The cardiovascular system also gets effected by the physiological changes. MAP is the mean blood pressure in the blood vessels of a person over a single cardiac cycle. Mean arterial pressure is the pressure needed to adequately perfuse the body's organs (Walsh, & Baxi, 2008). The cardiovascular system experiences many rapid, gradual, and significant changes during the pregncny. The high blood pressure over time causes narrowing, weakening or hardening of arteries around the kidneys. These weak arteries will not be able to supply blood efficiently to the kidney and eventually they will lose their ability to purify blood and control the body's fluid, and electrolytes. The high blood pressure also disrupts the arteries thereby hindering the excretion process (Zhang et al., 2013).

The changes in GIT have been observed during pregnancy. Good motility is the muscle stretching and contractions in the gastrointestinal (GI) tract. The muscles rhythmic contraction is called peristalsis. These movements allow the movement of food in digestive tract, also ensures the nutrient absorption. In pregnancy the changes in peristalsis gets effected. There will be decreased esophageal sphincter pressure which results in the gastroesophageal reflux and also aspiration risk increases. The change in motor function of gastric causes nausea and vomiting in pregnant women. Also, there is a decrease in the rate of bowel movement causing abdominal bloating and constipation (Baron, Ramirez, & Richter, 1993).

The dietary nutrients like proteins have to be taken care during pregnancy. Protein is an important component of diet which promote growth and development. There is deposition of proteins in maternal and foetal tissues during pregnancy. The recommendations for dietary protein intake are 75 to 100 grams of protein per day. This also helps to preserve maternal homeostasis, to prepare for lactation and to expand uterine tissues during pregnancy. It has a positive effect on foetal tissue growth and brain development (Elango, & Ball, 2016).

Renal Physiology in Pregnancy

Anti-diuretic hormone (ADH) is responsible for controlling blood pressure. It maintains the volume of fluid in the body by lowering the amount of water that is excreted out in the urine. The kidney helps to take back water from the urine into the body. Therefore, the concentration of urine increases, and the loss of water is lessened. The high ADH concentrations cause the blood vessels to undergo constriction (become smaller), this raises the blood pressure (Brian Cuzzo; Sandeep A. Padala; Sarah L. Lappin). The fluid deficiency can ultimately be replenished by increasing the intake of water.

During pregnancy, the flow of blood in the vascular system increases and peripheral vascular resistance decreases, and the cardiac output is also high. The dilution of the vessels of mother makes the blood pressure go low and this allows for the expansion of the fluid of mother occurs, which helps in the prevention of placental hypoperfusion in Nevaeh case she is out of risk from these factors (Junji et al., 2011).

The changes happen in RAAS system as well during the pregnancy. The renin–angiotensin–aldosterone system (RAAS) helps in regulating the blood pressure, electrolyte and fluid balance . When the blood flow is less, kidneys converts the prorenin to renin. The renin further forms Angiotensin I which is obtained by convertion of angiotensinogen. The angiotensin-converting enzyme (ACE) then further converts Angiotensin I to Angiotensin II . Angiotensin II function is to narrow the blood vessels or helps in vasoconstrictions.

This will result in increasing the BP. Angiotensin II is responsible for secretion of aldosterone. This hormone will increase the absorption of the sodium by renal tubule and results in absorption of the water (Lumbers, & Pringle, 2014). The changes in RAAS occurs in pregnancy. The ovary and the placenta help in endocrine secretions. In pregnancy the Angiotensin II levels rises which helps in maintaining the BP and the blood volume and flow of blood in placenta. The role of maternal RAAS system helps in endocrine secretion in pregnancy and the positive outcome of pregnancy (Lumbers, & Pringle, 2014).

During pregnancy one has to take care of medications they are taking as it have serious effect on the body physiology. Neveah has taken Paracetamol in high dose. Paracetamol can be taken as a rectal, oral, or intravenous. Paracetamol is absorbed in GIT which is antipyretic and analgesic agent. The oral availability in the body depends on the dose taken, in this case Nevaeh has taken higher dose, so the hepatic first pass effect is decreased and the bioavailability is increased. It is metabolized in the liver by conjugation with glucuronic acid (55%) and sulfuric acid (35%). the metabolite detoxification occurs by conjugation with glutathione (Raffa et al., 2018).

The half-life of a drug is the time taken by the drug in the plasma of the body to get reduced to 50% of its concentration. The half-life of a drug helps to know the accumulation of drug with drug concentrations. Our kidneys help in excretion of the metabolites through urine. The half-life of paracetamol is 6 h so after 24 hours 98% of the dose of paracetamol is eliminated from the body.

A urinalysis is a urine test that involves testing the urine 's composition, concentration and content. A hormone called human chorionic gonadotropin is assessed by urinalysis during pregnancy. Nevaeh urinalysis showed greater protein amounts which can suggest a kidney problem. And follow-up checks for diabetes and kidney function should be performed for elevated blood glucose and ketones. Abnormal pH levels indicate a disorder in the kidney or urinary tract. Specific gravity and bilirubin are within the range. Lack of nitrites and leukocyte esterase does not suggest a symptom of urinary tract infection (Mayo clinic, 2020).

Conclusion

The human body experiences many rapid, gradual, and significant changes during the pregnancy. A pregnant woman undergoes various physical changes in the vascular system, GIT and the kidney to meet the needs of the developing foetus. As the foetus grows and evolves, a variety of anatomical changes may occur in the female body to accommodate the growing foetus, including placental growth, weight gain, abdominal expansion, breast enlargement, glandular growth and changes in posture. Many changes occur in the body at the endocrine stage in preserving maternal and foetal homeostasis, even where various hormones are secreted to take over their specific functions. These changes in body help to meet the need of the growing demand of the foetus.

References

Baron, T. H., Ramirez, B., Richter, J. E. (1993). Gastrointestinal motility disorders during pregnancy. Ann Intern Med. 118(5), 366‐375. doi:10.7326/0003-4819-118-5-199303010-00008

Brian Cuzzo; Sandeep A. Padala; Sarah L. Lappin. Vasopressin (Antidiuretic Hormone, ADH) Treasure Island (FL): StatPearls Publishing

Elango, R., & Ball, R. O. (2016). Protein and Amino Acid Requirements during Pregnancy. Advances in nutrition (Bethesda, Md.), 7(4), 839S–44S. https://doi.org/10.3945/an.115.011817

Javed, A., & Lteif, A. (2013). Development of the human breast. Seminars In Plastic Surgery, 27(1), 5–12. https://doi.org/10.1055/s-0033-1343989 Junji, I., Toshiki, M., Tomoko, S., Saki, I., Satoshi, K., Fumihiro, S., Ken-ichi, Y., Akiyoshi, F. (2011). Pregnancy-associated homeostasis and dysregulation: lessons from genetically modified animal models. The Journal of Biochemistry, 150(1),5–14. https://doi.org/10.1093/jb/mvr069 Lumbers, E. R., & Pringle, K. G. (2014). Roles of the circulating renin-angiotensin-aldosterone system in human pregnancy. Am J Physiol Regul Integr Comp Physiol. 306(2), R91-101. doi: 10.1152/ajpregu.00034.2013. Epub 2013 Oct 2.

Magon, N., & Kalra, S. (2011). The orgasmic history of oxytocin: Love, lust, and labor. Indian Journal of Endocrinology and Metabolism, 15 (3), S156–S161. https://doi.org/10.4103/2230-8210.84851 Mayo clinic. (2020). Urinalysis. Retrieved from https://www.mayoclinic.org/tests-procedures/urinalysis/about/pac-20384907

Raffa, R. B., Pawasauskas, J., Pergolizzi, J. V., Jr, Lu, L., Chen, Y., Wu, S., Jarrett, B., Fain, R., Hill, L., & Devarakonda, K. (2018). Pharmacokinetics of oral and intravenous paracetamol (acetaminophen) when co-administered with intravenous morphine in healthy adult subjects. Clinical drug investigation, 38(3), 259–268. https://doi.org/10.1007/s40261-017-0610-4

Soma-Pillay, P., Nelson-Piercy, C., Tolppanen, H., & Mebazaa, A. (2016). Physiological changes in pregnancy. Cardiovascular Journal of Africa, 27(2), 89–94. https://doi.org/10.5830/CVJA-2016-021

Walsh, C. A., & Baxi, L. V. (2008). Mean arterial pressure and prediction of pre-eclampsia. BMJ (Clinical research ed.), 336(7653), 1079–1080. https://doi.org/10.1136/bmj.39555.518750.80

Zhang, Y. P., Zuo, X. C., Huang, Z. J., Kuang, Z. M., Lu, M. G., Duan, D. D., & Yuan, H. (2013). The impact of blood pressure on kidney function in the elderly: a cross-sectional study. Kidney & blood pressure research, 38(2-3), 205–216. https://doi.org/10.1159/000355769

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