| Unit Code: | 401002 |
| Unit Name: | Bioscience 1 |
| Credit Points: | 10 |
| Unit Level: | 1 |
| Assumed Knowledge: | None |
This assessment task will develop your knowledge of the function and importance of healthy body systems in an individual. It focuses on homeostasis and importance of nutrition in maintaining a healthy body. Skills being developed include researching, writing, referencing and presenting information in a clear and concise written format. This task aims to develop an understanding of homeostatic processes that take place within the body and the importance of maintaining a healthy body. This assessment meets Learning Outcomes 1, 3 and 5.
All information obtained from books, journal articles or websites must be appropriately referenced both in-text and in the reference list. You must follow the American Psychological Association (APA) (6th ed) referencing style which is available from the Western Sydney University Library website and the Bioscience 1 vUWS site.
Q2. Describe the components and conduction pathway of the cardiac conduction system of the heart. Relate the conduction system to the corresponding sequence of heart chamber contractions. (400 words, 10 marks)
Q3. Vitamin B12 is an essential nutrient that is important for normal development and health. Please answer the following: (200 words, 5 marks)
a. Name 2 food sources high in vitamin B12.
b. Describe the functions of vitamin B12 in the body.
c. Describe the possible consequences to the body if there is a deficiency in vitamin B12 in pregnant and non-pregnant individuals.
d.Name one group of people that is more likely to be at risk of becoming deficient in vitamin B12 and why.
Short answer questions
Q2.
The cardiac conduction system is composed of nodes and different conduction cells. The nodes and cells are initiated and co-ordinated the conduction of heart muscles and cardiac cycle.
SA node is composed of specialised cells known as pacemaker cells and it is situated in the upper wall of the right atrium. SA node is found in the junction of the right atrium and superior vena cave (Bailey, 2018). The impulses created by the SA node can be influenced by the sympathetic nervous system and parasympathetic nervous system.
Electrical impulses from SA node can spread across the atria and reach the AV node which is situated within the atrioventricular septum. It is also located near to the coronary sinus (Human Cardiac Anatomy, 2019).
It is a continuation of specific tissues of the AV node and helps in the transmission of electrical impulses from the AV node to the Purkinje fibres of the ventricles. The purkinje fibres descend down into the interventricular septum before dividing into right bundle branch and left bundle branch.
The network of specialised cells creates purkinje fibres which are abundant with glycogen and have gap junction. The Purkinje fibres situated in the subendocardial surface of the ventricular walls can help in the transmission of cardiac impulses to the myocardium of the ventricles from the bundle of atrio-ventricular (White, 2017).
Heart chamber contractions
Cardiac conduction is considered as rate of electrical impulses which cause the heart to contract and relax. It has been isolated that specialised cells in the SA node can instinctively produce electrical impulses which spread to both atria via gap junction. The incident is responsible for contraction of atria, as a result, the blood moves from atria to the ventricles (Bailey, 2018). SA node causes contraction of both atria. Consequently, the AV node is delaying the impulse and ensuring that the atria have sufficient time before the ventricular systole to eject the blood into ventricles. Thus the valve between the atria and ventricles close when the atria are empty. In addition, the right bundle branch can help in conducting the impulses to the Purkinje fibres situate in the right ventricles (Bailey, 2018) and the left bundle branch can conduct the electrical impulses to the purkinje of the left ventricle. Thus, the rapid conduction of Purkinje fibres can allow the contraction of ventricular and blood is moved in the pulmonary artery and aorta from both ventricles. Hence, the right ventricle uses pulmonary artery to send blood to the lungs and left ventricle send blood to the aorta.
Q3.
Sources of vitamin B12
The richest sources of vitamin B12 are clams (3 ounces contains 84 mcg) and liver (3 ounces contains 70.7 mcg).
Function
Deficiency
Deficiency of vitamin B12 can cause weight loss, constipation, diarrhoea, menstrual disturbance, nerve and brain damage, dementia, irregular heartbeat, fatigue and shortness of breath along with sore mouth and anaemia (Carter, 2017).
Lack of vitamin B12 during pregnancy can increase the risk of premature delivery, anaemia, neural defects in newborn, and spina bifida (Carter, 2017).
At risk
It has been isolated that vegetarian people have the maximum chance of B12 deficiency compared to others. Vegan diet during pregnancy and lactation can increase the risk of deficiency as it is deficient in vitamin B12. In addition, people with diabetes, alcoholic, Crohn’s disease, and celiac disease are vulnerable to develop vitamin B12 deficiency as such condition can interfere with vitamin B12 adsorption (Carter, 2017).
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