Heart Conduction System and Vitamin B12

This document provides information about the heart conduction system and the role of vitamin B12 in protein metabolism. It includes answers to questions about food sources of vitamin B12, deficiency symptoms, and the risks faced by individuals following a vegan diet. References are also provided.

BIOSCIENCE
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Author’s Note:

Answer to the question number 2:
The heart conduction system is made up of a band of specialist cardiac muscle cells
throughout the walls of the heart which transmit signals to the cardiac muscle to contract. The
primary constituents of this heart conduction mechanism are the AV node, SA node, Purkinje
fibers, His bundle, and left and right bundle branches. The SA node begins by triggering the
atrial muscles to contract. The SA node is also known as anatomic pacemaker (van Weerd &
Christoffels, 2016). After that a signal is transmits through the AV node, further through the
bundle of his branches and the ventricles via the Purkinje fibers. This signal generates a current
on a graph called an Electrocardiogram (EKG or ECG) which is visible in the EKG or ECG
machine (Sebastian et al., 2013). The valves among the atria and ventricles are closed when the
atria are void of blood. At that same point the atria commences to recharge and the electrical
signal passes the AV and His bundles to the branches of the Bundle and Purkinje fibers. This
system delivers an instantaneous rhythmic beat in the heart (Sebastian et al., 2013). The activities
in the cardiac process should be harmonized in order to effectively pump the heart and to ensure
the systematic and respiratory circulations operate synchronously.
Impulse generation is the first step in cardiac conduction system. The Sino- Atrial or
SA node contracts and creates nerve signals which travel across the cardiac wall. This leads to
contracts between both atrias. The Sino- Atrial node lies in the right atrium's upper wall. The
nodal tissue has both of nervous and muscle tissue attributes (van Weerd & Christoffels, 2016).
When the Sino- Atrial node pulse reaches the AV node, it takes around ten times fraction of a
second. This pause enables the atria to contract before the ventricle contraction and to
release their contents in the ventricles. The electrical signals are then continued down the atrio-
ventricular bundle. This fiber bundle sections out in to 2 bundles and pulses are traveled in to

the right and left ventricles in the center of the heart (Sebastian et al., 2013). The
atrio- ventricular bundles are divided into Purkinje fibers at the foundation of the heart. As the
signals meet these fibers, the muscle fibers are activated in the ventricles which signal to
contract. Blood passes from the right ventricle through the pulmonary artery to the lungs. Blood
pumps to the aorta from the left ventricle (Sebastian et al., 2013).
Answer to the question number 3 (a):
Two food sources with high vitamin B12 content are:
1. Organ meats such as beef liver.
2. Clams or Shellfish (Medlineplus.gov, 2019).
Answer to the question number 3 (b):
For protein metabolism, vitamin B12 is essential in the body. It helps to develop red blood cells
and keep the central nervous system intact. Vitamin B12 aids to generate and preserve the myelin
around nerve cells, the formation of red blood cells, the mental capacity, and the break down in
energy production of certain fatty acids and amino acids (Betterhealth.vic.gov.au, 2019).
Answer to the question number 3 (c):
Deficiency of vitamin B12 causes weakness, fatigue, appetite loss, constipation, loss of weight
and anemia (Ods.od.nih.gov, 2019). There may also be nerve problems, including numbness in
the feet and hands and tingling. Other side effects involve depression, balance
issues, confusion, poor memory, dementia, and tongue or mouth soreness (Ods.od.nih.gov,
2019).

A recent investigation suggests that early pregnancy females experiencing from vitamin B12
deficiency were up to five times as probable in regard to women with high levels of vitamin B12
to have a child with neural tube defects, such as spina bifida (Pelizzo et al., 2014)
Answer to the question number 3 (d):
Group of people with vegan diet face the risk of deficiency in vitamin B-12, which excludes
animal protein products from their diet. The deficiency of vegan diet can be worsened
by lactation and pregnancy. Plant foods lack sufficient cobalamin to ensure long- term health
(Betterhealth.vic.gov.au, 2019).

References:
Betterhealth.vic.gov.au. (2019). Vitamin B. Retrieved from
https://www.betterhealth.vic.gov.au/health/healthyliving/vitamin-b
Medlineplus.gov, V. (2019). Vitamin B12: MedlinePlus Medical Encyclopedia. Retrieved from
https://medlineplus.gov/ency/article/002403.htm
Ods.od.nih.gov. (2019). Office of Dietary Supplements - Vitamin B12. Retrieved from
https://ods.od.nih.gov/factsheets/VitaminB12-Consumer/
Pelizzo, G., Calcaterra, V., Fusillo, M., Nakib, G., Ierullo, A. M., Alfei, A., ... & Cena, H.
(2014). Malnutrition in pregnancy following bariatric surgery: three clinical cases of fetal
neural defects. Nutrition journal, 13(1), 59.
Sebastian, R., Zimmerman, V., Romero, D., Sanchez-Quintana, D., & Frangi, A. F. (2013).
Characterization and modeling of the peripheral cardiac conduction system. IEEE
transactions on medical imaging, 32(1), 45-55.
van Weerd, J. H., & Christoffels, V. M. (2016). The formation and function of the cardiac
conduction system. Development, 143(2), 197-210.