Posts

Influenza A

Explain how mutation and reassortment can result in the emergence of Influenza A viruses. Describe and discuss the role of the Haemagglutinin in host adaptation, providing examples of host and virus determinants that are important in influenza host-switching.  Essay Plan: Influenza A: The virus itneslt is a negative sense ssRNA with 8 segments: PB1, PB2, PA, HA, NP, HA, M, NS, translating to more than 14 proteins. With a viral coat having 2 major glycoprotiens the haemagglutinin (HA) - mediates cell entry through binding to sialic acid and is a host-range determinant, and is also the main target of neutralising antibodies neuraminidase (NA), there are currently known to be 18HA subtypes and 11NA subtypes. Context of Influenza - Influenza A: It was the cause of the great Spanish Flu pandemic of 1918 causing the death of around 50 million individuals. The virus and its subtype H1N1 was established using reverse genetics using viral particles found from preserved samples from infe
Post a Comment
Read more

Heart Failure and the Ryanodine Receptor

Define the syndrome heart failure and discuss the cellular and molecular basis of poorly contracting hypertrophic myocardium . Secondly discuss the potential role of the ryanodine receptor in the pro-arrhythmic status of failing heart. Heart failure (HF) has several aetiologies however it most commonly occurs due Artherosclerotic cardiovascular ischaemia, in an acute case following a myocardial infarction (MI) or more chronically due to coronary artery disease. It can be broadly described by the haemodynamic model as to be when the metabolic requirement of the body is not met due to decreased cardiac contractility and output ( Braunwald, 2013 ). It may arise at any age but statistically it is more prevalent in the elderly.  Epidemiologically it is of great concern, as even though overall there is a decrease in cardiovascular disease-related mortality HF is a noticeable exception in this encouraging trend.  In HF due to the loss of healthy myocardium there is a compensator
Post a Comment
Read more

Spinal Cord Injury and the Autonomic Nervous System

Image
Provide a detailed diagram of the autonomic nervous system and discuss the effects a spinal cord injury (complete section) at T4 would have on autonomic function upstream and downstream of the injury? Though Spinal cord injuries in popular culture connected to paralysis and loss of motor function, in fact, spinal cord injury leads to a loss of sensory, motor and autonomic functions and maladapative changes below the level of the injury. The spinal cord is a highly organised segmented structure, essential for the conveyance of neural connection from the central nervous system to be communicated to the periphery. There are 8 Cervical, 17 Thoracic, 5 Lumbar and 5 Sacral segments, each uniquely corresponding to outflow to specific organ systems (See Figure 1). In current clinical practice spinal cord injuries are classified via the loss of motor and sensory function , with only the lower limbs being affected termed paraplegia, while movement lost in both limb is termed quadripleg
Post a Comment
Read more

ANS Control of the Gastrointestinal Tract vs Vasculature

Image
Compare and contrast the autonomic control of the intestine and the  syst emic vascular system . Your answer should be weighted equally (50%) between each system. The enteric nervous system is often refered to the 'small brain' in popular culture, due to the presence of around 100-500 million intrinsically active neurones in the gastrointestinal area. However the ENS is also well connected to the autonomic nervous system, with parasympathetic and sympathetic input. The descending vagus is the main conveyor of the parasympathetic signal (with output at the sacral level of the spinal cord) with stimulatory in both sensory and motor functions. With stretch, osmolarity and temperature conveyed to the CNS along the vagus, allowing for motor output of gastrointestinal secretion an motility from the vagus; termed the vago-vagal reflex. Sympathetic preganlionic innervation arises from the T8-L2 region synapsing at the coeliac, the superior and inferior mesenteric gang
Post a Comment
Read more

Essential Hypertension

Hypertension is the largest single contributor to global mortality, with approximately 25% of the population suffering from increased blood pressure. Hypertension is also a great economical burden with around 10% economic spent on therapies. However, though there are currently a myriad of potential therapeutics available around only half of current patients respond to the traditionally available treatment. This can be attributed to the complex presentation of the illness, with a combination of epigentics and environments resulting in a non-specific cause of hypertension in over 90% patients. Though the risk factors arising from hypertension are widely known, such as stroke, kidney failure and hear disease, the underlying mechanism of the pathophysiology is still not fully understood. Increased sympathetic nerve activity is widely recognised as a contributor to the increased blood pressure, however the precise cause of this is not known. In animal models of hypertension and in
Post a Comment
Read more

Automatic Respiration and Ondine's Curse

Image
The act of breathing is often automatic and unforced. However, the respiratory physiology that underpins automatic, unconscious breathing is complex, with scientific consensus yet to be reached regarding many of its aspects. In 1873 Legallois identified the kernel of breathing control to be at the level of brainstem, breathing continued even with the removal of the cerebrum. In the 1980s, the repiratory area was narrowed to the Pons and Medulla of the brainstem, this was discovered following in vivo experimentation in cats, as surgical removal of the brain below this level was followed by a cessation of the automatic respiratory rhythm. This subsequently led to the discovery of the pontine, ventral and dorsal respiratory groups (the PRG, VRG and respectively). Withing these respiratory groups clusters of respiratory neurons are found, so-called due to firing at a distinctive point of the respiratory cycle. Respiratory are key in modulating the respiratory cycle, while some
Post a Comment
Read more