Question 1
The cerebellum is an essential part of the neuromuscular system in that it plays major roles in the timing of muscular activities and the smooth progression of one muscular movement to the next. The summary of how this is done is that it sequences all the muscular activities necessary for a particular movement, and then makes corrective adjustments as necessary when the movement is being executed so that they conform to the motor impulses being generated by the cerebral cortex and other significant parts of the central nervous system (Ganong, 2005).
For instance, for an individual holding a cup and wants to lift that cup from off the table, the cerebellum is very important so as not to experience awkward movements or even spill the contents of the cup. The cerebellum receives information about what the individual intends to do from the cerebral cortex, that is, lift the cup from the table. The cerebrum generates the actual motor signals to the biceps group of muscles and other flexors to lift the cup. However, as this is being done, the cerebellum continues to receive sensory information from particular receptors (proprioceptors) located around the moving joint, the elbow. Specifically, the proprioceptors in this joint inform the cerebellum about the position of the elbow, the forces acting on the joint, the rate of movement, etc. As this happens, the cerebellum then compares the sensory information with the intended movement as sent from the cerebral cortex. If these two does not match favourably, subconscious corrective impulses are then sent from the cerebellum to the motor system to modulate the intended action and either increase or decrease the level of stimulation of the flexors and extensors as necessary.
Also, the cerebellum assists the cerebral cortex in planning ahead what sequential movement is needed in advance, even while the current motor action is still being executed, making progress from one movement to the next smooth and easy.
Question 2:
The cerebellum is one organ that has been found to ‘learn’ from mistakes. It is important for the regulation of muscle movements, making voluntary muscular action easy and smooth. However, when a particular muscle movement does not conform exactly to what was intended, the wiring of the cerebellum takes note of this, adapts and adjust the movement, increasing or decreasing the level of stimulation of involved muscles next time.
The cerebellum is composed of different types of cells and neurons, however, the Purkinje cells are very important to this learning process (Hall, 2005). Typically, for a new movement, the degree to which the cerebellum modulates the level of stimulation or inhibition of motor groups both at the beginning and end of contraction, and the timing of these actions are usually incorrect. For instance, an individual who closes his eyes and intend to bring his finger to the tip of his nose would most likely get this wrong at first try. However, as he continues this process his cerebellum ‘learns’ the process and makes corrections as necessary. How this happens is not known exactly, but the Purkinje cells of the cerebellum have been said to play a large role.
When a new movement occurs such as moving the finger to the tip of the nose with the eyes closed, there are feedback impulses to the cerebellum from proprioceptors in the muscles and joints involved. These inform the cerebellum how much the actual movement deviates from the intended movement. It has been said that these impulses cause a change in the sensitivity of the Purkinje cells and a resulting alteration in the timing and other aspects of control of muscle movements to achieve perfection (Ganong, 2005).
Question 3:
The perception of body speed is a complex process, requiring the combination of sensory information from different receptors and organs, and the analysis of this information by the cerebellum. The cerebellum analyses these signals and determines whether there is need to make adjustments or not (Ganong, 2005). Mainly, the body’s perception of speed is informed by signals from the visual system, vestibular system and proprioceptors.
For an individual running on a straight track with the eyes wide open, the rapidly changing visual scenes relative to his own position informs the brain how fast he or she is approaching a position or object. In other cases, the sight of moving objects in the individual’s field of vision can also inform the brain how fast he or she is travelling. Similarly, as he or she runs, the vestibular system in the inner ear and the vestibule-cerebellum functions together to maintain balance as well as determine the rate of movement of body parts. What the proprioceptors do is to relay information back to the brain about the relative positions of body parts to each other. The cerebellum functions significantly in interpreting this rapidly changing spatiotemporal information and makes adjustments as necessary.
Question 4:
Tendons are known to attach muscles to bone. They make it possible for a large bulk muscle to converge on a single uniform point of insertion, making the actions of muscles easy and efficient. The body possesses various forms of lever systems, to which the tendons are vital for their function. For instance, flexion movement occurring at the elbow involves the biceps muscle applying tension by contracting against its point of insertion in the proximal part of the radial bone. However, this is made efficient by the operation of tendons at the distal end of the biceps muscle. In this case, as in most cases, the tendon puts the point of insertion in front of the joint, making its operation much efficient than if the point of insertion were too close to the fulcrum. It is important to note that tendons do not contract, but make it easy for contracting muscles to function efficiently.
Question 5:
Nerves in humans are classified into three groups – A, B and C – with the A group further subdivided into α, β, γ, and δ nerve fibres on the basis of their diameters, conduction velocity and absolute refractory period (Hall, 2005). The A group of nerves have the largest diameters and includes somatic motor nerves (suppling muscles) and nerves subserving proprioception, touch and pressure. The C group are the smallest in diameter and mainly subserve sensory functions.
Motor nerve fibres supplying muscles, as explained, are larger in diameter than sensory nerve supply to the same muscle. Also, they have greater conduction velocities than sensory nerve fibres, making rapid reflex actions possible.
Question 6:
The whole body is composed of two types of skeletal muscle fibres namely white (fast) or red (slow) muscle fibres (Ganong, 2005). There are some differences between these two types of muscle fibres, however, what gives the slow fibres their reddish appearance is the abundance of myoglobin in them while the white fibres have a deficit of myoglobin.
The red muscles are of the slow variety and commonly consist of smaller fibres and usually supplied by smaller nerve fibres unlike the white muscle fibres that are fast and consist of large fibres for maximum contraction strength.
Red muscle fibres are commonly supplied by vast numbers of blood vessels for rapid oxygen and nutrient delivery as they depend mainly on oxidative metabolism, while the white muscle fibres are sparsely supplied by blood vessels and have to depend on anaerobic glycolytic enzymes for energy release.
Examples of red muscle fibres include ocular muscles while examples of white muscle fibres include the soleus and gastrocnemius.
Question 7:
The process of contraction occurs as a result of the shortening of the contractile elements of muscle, at the level of the basic functional unit of the muscle. This process occurs via the sliding filament mechanism (Ganong, 2005).
When a motor impulse is generated and sent across to the neuromuscular junction, there is release of acetylcholine at the end-plate. This results in the binding of acetylcholine to its receptors on the muscle side of the junction, leading to an increase in the conductance of sodium and potassium ions at the end-plate membrane (Hall, 2005). An end-plate potential is then generated which leads to an action potential across the muscle fibres. The generated action potential causes depolarization which then spreads inwardly along the T-tubules. Meanwhile, there is a simultaneous release of calcium ions from the sarcoplasmic reticulum, diffusing among the thick (myosin) and thin (actin) filaments, and causing them to slide alongside each other. The formation of cross-linkages between these filaments and the sliding action causes the shortening seen in contracting muscles. Within the fraction of a second, the outbound calcium ions are then pumped back into the sarcoplasmic reticulum for storage until a new action potential comes along. The absence of calcium ions causes a cessation of the interaction between the filaments, and subsequent relaxation.
Question 8:
- Deltoid muscle: This muscle is very important to the abduction of the upper limbs. A major injury to this muscle would make it difficult to raise the hand up (abduct) from the side. It would also weaken flexion and extension of the shoulder joint.
- Iliopsoas muscles: This combination of two important muscles constitutes the chief flexors of the thing at the hip joint. A major injury to this muscle group would cause inability to flex the thigh on the hip.
- Stapedius muscle: This is a fast twitch muscle composed mainly of white fibres and is responsible for the dampening of sound waves hitting the ear drum. A major injury to this muscle would cause hyperacussis, that is, exaggeration of sound impulses and increased sensitivity to sound.
Question 9:
The energy pathways of skeletal and smooth muscle cells are very much similar with both relying on ATP for the contraction processes. Usually, this ATP is split to form ADP and the energy liberated by this process is used to push the contractile machinery of the muscle fibres. The ADP is then re-phosphorylated, usually within the fraction of a second, to form ATP which is then broken down again, to supply energy and keep the process running (Ganong, 2005). However, there are different ways by which the energy required for re-phosphorylation is generated.
The first source is the breakdown of phosphocreatine which possesses a high-energy phosphate bond that can be used to re-synthesize ATP. When a molecule of phosphocreatine is cleaved, it instantly releases a great amount of energy which causes a new phosphate ion to bind to a molecule of ADP and forming ATP. The only drawback to this is the relatively low amounts of phosphocreatine in muscle tissue.
Secondly, the process of glycolysis which also occurs frequently in muscle tissue also liberates energy, after the anaerobic breakdown of glycogen to pyruvate and lactate, which is then used to convert ADP to ATP.
Lastly, oxidative metabolism is another source of energy. Here, the end products of glycolysis are used to synthesize ATP in the presence of oxygen. Particularly, pyruvic or lactic acid, combined with other carbohydrates and fats lead to the formation of ATP which is essential for muscle contraction.
Question 10:
Muscle contraction occurs at the level of the muscle fibre which consists of the sarcolemma (the fibre’s cellular membrane), and more importantly, the myofibrils – the muscle filaments (Ganong, 2005). There are two major types of muscle filaments in skeletal muscles which are actin and myosin. Each muscle fibre contains hundreds to thousands of myofibrils with each myosin filament related to two actin filaments. On cross-section, the myosin filaments are the thick filaments, while the actin filaments are the thin filaments. These filaments interdigitate to cause the alternate dark and light bands seen grossly on skeletal muscles as striations (Hall, 2005).
Contraction is caused by the interaction between one myosin filament, two actin filaments and calcium ions. There are binding forces which holds the actin and myosin filaments together and release them as necessary. The exact mechanism by which the interaction between the filaments causes contraction is not known, but has however been explained using the ratchet theory.
The myosin filaments possess cross-bridges whose heads attach directly with the actin filaments. When the heads of the cross-bridges bind profoundly to active sites on the actin filaments, it has been postulated that some changes occur in the intramolecular forces between the cross-bridge’s arm and its head. These changes cause the head to tilt towards the arm and dragging the attached filament along with it. This head tilt is called the power stroke, and immediately after this, there is a disengagement of the head from the active site and it extends forwards to bind to another active site farther down the line on the actin filament. Again, there is a change and a tilt which pulls the actin filament closer. This process is repeated several times, all within the fraction of a second, pulling the actin filaments towards the middle of the myosin filament, and eventual muscle shortening or contraction.
Question 11:
Question 12:
When the right ventricle enlarges as it does in congestive heart disease, there is a loss of its effectiveness in pumping blood into the pulmonary circulation. As a result of this, blood coming in from the rest of the body (systemic circulation) starts pooling up, and there may be a back-flow effect. When this happens, there is a build-up of pressure in the superior vena cavae, leading to an increase jugular venous pressure; and in the inferior vena cavae, leading to liver enlargement, pedal swelling and ascites.
Question 13:
Every day, the work environment keeps changing constantly, becoming more unpredictable and complicated than ever. The pharmacy environment is fraught with several risks, depending on the chosen viewpoint. Considering the increase in regulatory requirements and scrutiny on workplace environments, it has become imperative to develop risk management policies even in a pharmacy. More so, it provides an avenue to isolate risks and determine which ones are opportunities or potential disadvantages.
Question 14:
Risk management and assessment are concepts that address the inherent potentials for dangers in any environment and the need for possible preventive or containment measures when they occur. Risk assessment simply has to do with identifying what dangers can occur in a particular organization. Risk management refers to the handling of unplanned events, i.e. existing policies put in place to contain an unexpected but well-thought out situation when it occurs.
Question 15:
Developing risk management policies is very important and the first thing is to identify what the hazards are. Then, it is important to identify who is at risk of being harmed and how. With the knowledge of the risk, next is to agree on precautions. This should then be put in practice and followed up with appropriate records. It is necessary to review these risk policies regularly.
Question 16:
A pharmacy assistant has vital roles to play in risk management activities as he/she is an important stakeholder and has first-hand exposure to organization responsibilities and roles in the organization. The assistant is in a vital position to advice the management on what to do and can fill in key information gaps.
Question 17:
With the recent evidences from the developments and advancements in technology that we have globally, I see pharmacy growing exponentially and going forward to cross new frontiers. The study of pharmacy has been revolutionized, and with innovations in biotechnology and genomics, care for patients would be individualised. Also, with the growing demand for pharmacists to be more involved in patient care, there would be better outcomes for all.
Question 18:
Pharmacy is has dramatically emerged and changed over time right from the Ayurvedic era up till now. Some of the things that have been responsible for the developments include separation from the physician as an independent profession, establishment of regulatory bodies that ensured compliance with standards, founding of pharmaceutical associations and schools, and technological advancements. More so, the importance of pharmacy within healthcare has helped to solidify its role.
References
Ganong, W. F. (2005). Review of medical physiology (21st ed.). United States: McGraw-Hill Medical
Hall, J. E. (2005). Guyton and Hall textbook of medical physiology (11th ed.). Philadelphia, PA: Elsevier Saunders
