Homeostasis Of Calcium Ion, Adaptive Immunity, Neuromuscular Junction, Renin-Angiotensin-Aldosterone System, Blood Clotting, And Wigger’s Diagram

Parathyroid hormone’s role in calcium homeostasis

The homeostasis of calcium ion within the blood occurs due to parathyroid hormone (PTH), calcitonin, and alpha hormone. The parathyroid hormone (PTH) impacts the bone cells in three forms. Firstly, it directly affects the stimulation of the reabsorption of the bone. Secondly, it stimulates the production of alpha, dihydroxy-Vitamin D production, and thirdly, it initiates the recovery of calcium from the kidneys. After calcium is recovery, it is important to note that its flow from and to the bones is initiated by the calcium homeostasis process. Vitamin D is responsible for bone strength, which is converted into calcifediol inside the liver and into calcitriol inside the kidneys.  Osteoclasts are responsible for the reabsorption in the bones and it releases calcium in the blood to regulate the process and maintain bone strength.

Choose ONE of the below scenarios and highlight this row bold.  State which general property of adaptive immunity the scenario illustrates in the second column. Select ONE phrase (from the list below) that BEST describes what is happening at a cellular level to result in this property of adaptive immunity. Write the letter corresponding to this phrase in the third column.  An example is included in italics.  (1 mark)

Possible phrases are listed below. Not all phrases will need to be used and only ONE phrase is required per row. If you record more than one, you will not be awarded any marks for your explanation.  

Using the patellar reflex as an example, explain the purpose of a neural reflex.

The main purpose of neural reflexes is to detect dysfunctionality in the central nervous system (CNS). When an individual is able to respond to any stimulus physically imposed to him or her then he or she can be considered sound in terms of neural functionality. As such, neural reflexes help in detecting the health of the CNS. The neural reflex is a whole pathway which is initiated at the receptor cells, tissue as well as muscles, and it progresses to spinal cord without reaching the brain through a path referred to as the reflex arc. The reflex arc consists of the sensory or afferent organ and muscle or cell. Therefore, citing the example of patella reflex, it can be said that the functionality of the neurons is checked using a reflex hammer which hits the patella tendon below the patella so that it can be affirmed that the muscles are reactive to the neural reflex imparted on them through the hit.

Adaptive immunity and its general properties

The patella reflex occurs when one is hit with a reflex hammer below the patella to check whether his or her neural functionality is proper or not. Therefore, when the strike is received at the area below the patella muscle, the leg muscles receive a reflex from the spinal cord, which makes it kick in a forward direction. However, when the person hit tightly clasp his or her hands, the kick may fail to occur. Additionally, this may also happen when the reflex arc is not facilitated due to a modified and turned reflex pathway. Therefore, in such a bent, the impulse fails to travel to the spinal cord leading to no production of reflex action which in turn makes the kick not to occur.  

The following are the four major events that take place when a neuromuscular junction (NMJ) occurs for muscular contraction:

1. Release of Acetylcholine (ACH)): The release of the Ach takes place when a nerve impulse reaches the end bulb of the synapse. It is a neurotransmitter that is released from the synaptic vesicle, which contains the Ach. The diffusion of the Ach takes place across the synaptic cleft that is present between the efferent neuron and its end plate.
2. Activation of the Ach receptors: This is followed by the second step where the end plate of the efferent neuron serves as the binding site for the free Ach, which leads to the opening of the ion channels. Therefore, the passage of sodium ions is facilitated across the muscular cell membrane.
3. Generating the action potential of the muscles: The third step involves the passage of the sodium ions cross the muscular cell membrane where the muscle action potential is developed.
4. Breaking of the Ach: The last step to take place involves the breakdown of the Ach. The Acetylcholine breakdown particularly takes place at the synaptic cleft where acetylcholinesterase (AChE) enzyme is formed. The formation of the acetylcholinesterase (AChE) enzyme ends the entire process of the neuromuscular junction, therefore, leading to the occurrence of the muscular contraction.

Think about how the renin-angiotensin-aldosterone system acts to maintain normal blood pressure. Susan has sustained damage to her adrenal glands.  Consequently, her circulating levels of aldosterone are abnormally low.  

1. Where are the target cells for aldosterone located in the body?  

The target cells for aldosterone are located at the distal part of the nephron in the body. Therefore, it is in the kidneys.

1. What do you expect the lack of aldosterone to do to Susan’s blood pressure? Explain your answer. 

The key role of aldosterone is to stabilise the functions of the body. It mainly conserves sodium, retains water, stabilises the blood pressure, and secretes potassium. It is important to note that lack of aldosterone in the body mans the aforementioned actions are disrupted or become dysfunctional. The lack of aldosterone could cause high blood pressure in Susan, and the elevation can result in low flight and fight power. Additionally, lack of aldosterone may lead to a disrupted sodium potassium level in Susan’s body resulting in a collapse. Besides, lack of aldosterone could lead to frequent urination, extreme tension, anxiety, stress as well as nervousness. All these issues can also restrict normalization of Susan’s blood pressure and disrupt the entire process of her body. Hence the level of aldosterone must be controlled.

The normal sinus rhythm is the default rhythm of the heart which occurs at the rate of 60 to 100 beats per minute (bpm). This rhythm occurs from the Sino-atrial node also known as the SA node or the pacemaker and reaches the ventricular chambers of the heart through the artio=ventricular (AV) node as well as the His-Purkinge system. However, it is to be noted that the level of rhythm is not always constant as it is directly dependent upon the body activities. For example, when the sinus rhythm is high, for instance, about 100 bmp, in adults, then it is referred to as sinus tachycardia whereas when it is lower than 60 bmp in adults it is referred to as sinus bradycardia. On the other hand, when the rhyme varies at every beat with a series of irregular beats it is referred to as sinus arrhythmia.

Neuromuscular junction and reflex pathway

For each of the scenarios below, indicate whether you would you expect resting heart rate to be greater or less than that associated with normal sinus rhythm.  Explain the cardiac physiology underlying the identified change.   

Baroreceptors are specific receptors which are used to identify transitions in the blood pressure of an individual. The Baroreceptors help to detect the changes in the blood pressure, and this is the reason why when the blood pressure reaches a point below the normal, it is immediately controlled back to normal through the help of suitable interventions. In case of wide spread vasodilation, the blood pressure abruptly decrease for a prolonged period. Therefore, during these periods, the baroreceptor in the carotid sinus and aorta immediately act to increase the width of the lacuna of aorta blood vessel by stretching the arterial walls.

Parents, a father who is heterozygous for blood group A and a mother who is heterozygous for blood group B, are wondering what, if any, are their chances of producing a child with blood group O.

The chance of the parents producing or giving birth to a blood group O child will be one-fourth (1/4) of their total outcome. This is because the parents are naturally heterozygous. Therefore, the geneotype of the father is a combination of A and O alleles. In spite of the father having blood group A and the mother having a geneotype which is acombination of B and O alleles and despite her blood group being B, there can be an occurrence of monohybid cross  between the parents. This could in turn lead to a generation of 4 different types of genetypes for the children including AB,AO,BO and OO blood groups. Henceforward,out of the four geneotypes, the occurrence of O blood group can only happen once and that is the reason why the probabilty the parents   giving birth to blood group O children is ¼.

The intrinsic pathway in blood clotting occurs when the fibrin proteins join to form a clot at the site of injury. On the other hand, the extrinsic pathway of blood clotting happens when protein which is not contained in the blood stream forms the clot.  The second difference is that in the case of intrinsic pathway in blood clotting, the clot occurs due to the fibrin protein, which is a protein contained inside the blood stream. However, in the case of the extrinsic pathway of blood clotting, the protein is activated by a tissue factor that causes coagulation.

Renin-angiotensin-aldosterone system

The Wigger’s diagram (below) represents pressure and volume relationships in the left side of the heart during one cardiac cycle.  To answer this question, you should focus on the changes in pressure in different chambers of, or vessels leading from, the left side of the heart.

For ONE of the labelled points, state which valve is open/closed at that time.  Highlight your chosen point in bold.  You must also explain WHY that valve opened/closed and where the blood is flowing immediately after this point in time, due to the change in position of the valve.  An example is provided in italics.  (2 marks)

Consider the events occurring after you have eaten a high carbohydrate meal.  For each of the organs listed in the table below, describe ONE mechanical and ONE chemical digestion event that will contribute to the digestion of carbohydrates.

Continue to consider the events occurring after you have eaten a high carbohydrate meal.  In the table below explain how the listed organs are involved in the absorption and metabolism events (specific to carbohydrates) that occur after this meal.

Since the partial pressure has got low amount of oxygen during inspiration the level of carbon dioxide elevates the expiration volume of the lungs making the carbon dioxide to move out of the lungs however retaining the oxygen inside. Nonetheless, the oxygen molecules on the tissues exert more pressure leading to the diffusion of oxygen into the blood stream thus forcing the carbon dioxide to remain in the lungs before their expulsion.

The epithelial lining in the trachea or windpipe is made up of respiratory epithelium tissues. The respiratory epithelium tissues are types of tissues that contain cilia lining inside the tract of the respiratory system. Therefore, the trachea is also lined with this type of tissue. The layer is ciliated inside and there is presence of outside the trachea that prevents the trachea from collapsing. The presence of the cilia makes the area moistened; therefore, safeguarding the passage of the air through the nose to the lungs beyond the larynx.

The structure of the epithelium at the respiratory tract is columnar that is, rectangular in three dimensions. Therefore, this peculiar shape helps in forming the cilia which are hair-like growth on the inner lining of the trachea. The cilia keeps the trachea moistened leading to a smooth passage of air through the pipe without dehydration hindrance.  

While handling someone else’s urine, it is important that the person handles it without getting infection to own self. This is so because the urine sample might contain a lot of pathogenic microorganism which the person might not be aware of. Therefore, the person needs to wear all the concerned protective equipment that can protect him or her from being infected by the germs in the urine. These protective equipment include a laboratory coat, disposable gloves, masks, shower cap, and a proper uniform of the designation. The laboratory coat should not be worn outside the laboratory and the collection room. The gloves should also be for only one-time use. The hand hygiene should be strictly considered.

The results of dipstick urinalysis of two urine samples are listed below.

Sample 1 belongs to a 16-year-old male ‘gamer’ who has locked himself in his room all weekend to play computer games (he didn’t really even come out to eat or drink). 

Sample 2 belongs to a 22-year-old female triathlete who is careful with her diet, hydration, and almost exercises to excess.

For each parameter, fill in the normal values. (Hint: Refer to the Week 10 laboratory activity to get you started).

Choose ONE of the samples described above and answer the following questions in the space provided.

1. Compare the normal and sample values. List any abnormalities you observe in the section below. Are they higher or lower than normal?  (1 mark)
2. Give a situation in which you might expect to see these changes in an otherwise healthy  (1 mark)
3. What might have been happening in the nephron to cause these abnormal results? Explain your observed abnormalities by linking them with the part of the nephron involved and the process involved (i.e. filtration, secretion or reabsorption).  Ensure that any relationships between the abnormal readings are made clear in your response.  (2 marks)

A higher level of specific gravity might be due to the partial or failed reabsorption of the fluid from the Glomerulus Filtrate. The nephron might not be able to do so due to a short interval of time between which the urine formation is taking place. The short interval can be due to excess urination. The increased urination can be attributed to the fact that the parasympathetic nervous system which is responsible for preparing the body for the emergency situations might have not functioned properly. The malfunction might have caused the adrenaline to secrete more, therefore, causing flight and fight disruption. As a result, the urination increased and caused partial filtration, thus, keeping the presence of the particles in the urine which increased its specific gravity.

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