Voltage-gated ion channel Essays

PERMEATION MACHINERY OF GATED ION CHANNELS Introduction: Permeation means to pass through a pore, channel or a tube like structure and permeation machinery, a term attributed to overall structure of apparatus that is responsible for ion movement across plasma membrane. This apparatus involves channels that are commonly known as ion channels. Ion channels are pore-forming membrane proteins whose functions include establishing a resting membrane potential, shaping action potentials and other electrical

potentials in these neurons, it was impossible that the motor neurons could be activated. So, the result was presented as the emergence of paralysis in the affected areas. Initial blockage of sodium ion channel totally deactivated an entire process in the neuromuscular junction. In other words, sodium ions mainly influence to the action potential generated in muscle cells, so TTX may inhibit muscle activity

start off Ions can not pass the bilayer of a cell they may only pass through the semipermeable membrane through Ion channels found in proteins with in the cell membrane. These Ion channels are semipermeable because they only allow certain Ions to pass through them. There are 2 different types of Ion channels there are gated and nongated channels. There are also two types of gated channels the first is a voltage gated channel will open depending on the charge of the Ion. The second type of gated channel

2013M007 1. Define ion channels. Ion channels are proteins present on the cell membrane. They are pore forming and they facilitate the movement of selective or non-selective ions across the cell membrane. 2. Classify ion channels. TYPE DESCRIPTION Voltage gated ion channels They can be opened or closed according to the changes in the membrane potential. Ex: Activation gate of Na+ channel is opened during the upstroke of action potential in depolarization. Ligand gated ion channels They can be opened

does not possess Na/K channels. Instead, it is equipped with voltage-gated calcium channels and small vesicles that contain a neurotransmitter. The membrane of the postsynaptic neuron contains receptors that enable the neurotransmitter to dock (lock & key principle). These receptors are directly connected to an ion channel. In the case of an excitatory chemical synapse, this postsynaptic ion channel will be a Na/K ion channel. In the absence of the neurotransmitter, these channels are closed. When an

becomes more positive. The threshold of neurons are held at -55 mV. During graded potentials, the neurotransmitters are released from the presynaptic terminal and binds onto a chemically gated channels on the postsynaptic neuron which causes the gate channels to open causing leakage to happen which, in turn, permits ions to flow out of the cell. When the charge meets the threshold, the neuron is then excited enough to cause an action

Voltage gated channels open and close in response to an electrical voltage, so they are affected by changes in electrical change around them. When a neuron is “at rest” a charge difference is maintained between the inside and the outside of the cell. This charge difference is produced and maintained largely by active transport using sodium-potassium pumps. The pumps send ions out of the cells and bring potassium ions in. While other channels allow some flow of potassium ions back out of

sodium (Na+) ions, which in turn result from concentrated changes in functional activity of ion channels. Cell membranes are made up of a phospholipid bilayer- consisting of two layers of linked fatty molecule. Various specialized proteins, such as ion channels, float in this bilayer. Ion channel are membrane-spanning proteins that allows the passage of certain ions through the membrane. The cell membrane of a neuron is selectively permeable to potassium ions, meaning that ion channels that will only

Discuss the role of proteins in cell membrane transport Cell membranes are the barriers and gatekeepers of the cell; they provide overall structure, control the exchange of molecules between the extra and intercellular environments and are the site for many important processes. Cell membranes consist of a phospholipid bilayer where each repeating unit is comprised of two fatty acid tails bound to a phosphate head including a polar group attached to the glycerol region. Due to the amphipathic nature

INTRODUCTION Approximately 36 million individuals have Alzheimer’s disease (AD) worldwide which is the common cause of dementia in the range of higher ages (Alzheimers.net, 2014). About 5% to 8% of people aged above 65, 15% to 20% of people aged above 75 and 25% to 50% of those aged above 85 are affected by Alzheimer’s disease (Duthey, 2013). Alzheimer’s disease is an irreversibly progressive disease of the brain characterised by gradual loss of memory, change in personality and a decline in cognitive

Introduction The Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disease. It is characterised by muscle weakness of the proximal lower limbs as a result of auto-antibodies produced against the voltage-gated calcium channels (VGCC) found on the presynaptic membrane of the neuromuscular junction(1). Most of the time, LEMS is classified as a paraneoplastic syndrome as it is often associated with cancer (small cell lung cancer in particular) (2, 3). One of the earliest descriptions of this

proteins that aid in the transfer of water across membranes via a channel. Since they only allow water to pass through, this does

transmitting information. To understand the action potential, which is essentially the flow of ions in and out of the neuron that differ from the normal flow, one must understand the relation of ions, especially sodium and potassium, with the neuron. Neurons are covered by membranes that regulate the inflow and outflow of chemicals, and certain chemicals, like sodium and potassium can only flow in and out via channels along the membrane. At rest, the membrane maintains a certain polarization between the

neurotoxin plays its role by inhibiting the action of the Ca2+ activated voltage gated K+ Channels found in aortic smooth muscle cells and GH3 anterior pituitary cells. Hence, it is an high-affinity inhibitor of high-conductance due to its three disulphide bonds and conformational stability. By binding to the exterior interface of the channel protein, the positively charged residues of the toxin enables reversible blockage of the channel, which results in the hyper-excitability of the nervous system (Massefski

pathway, opioid drug or also called opiates. Opioids are agonists that act on opioid receptors coupled to Gi/Go-protein-coupled receptors and exert powerful effects on ion channels on neuronal membranes. Opioids helps opening of potassium channel to cause hyperpolarization of the cell and inhibit the opening of voltage-gated calcium channels. This decreases neuronal excitability and reduce transmitter release due to inhibition of Ca2+ influx. Mostly morphine is distributed in the brain and spinal cord

impulses away from the brain and spinal cord to voluntary muscle. Neurons communicate via an electrochemical signal called an action potential that sends information down an axon and away from the cell body. They are based on the movements of ions through channels in the membrane of an axon. A molecular message is sent to neighboring neurons when an action potential is reached. This is an all or nothing process. Triggering Action Potential: At rest, a neuron holds a balance of excitatory and inhibitory

(iii) Non-Associative Procedural Learning in the Aplysia (a) Habituation Invertebrates can be particularly useful for the analysis of the neuronal basis of behaviour. The sea slug, Aplysia californica has a nervous system comprising about 20 000 neurones, has been used by Eric Kandel and his colleagues to study learning and memory. Non-associative learning in Aplypia involves habituation and sensitisation in the gill-withdrawal reflex. A jet of water squirted on the siphon causes the gill to retract

2. Blood glucose concentrations are around 4.5mmol/L due to homeostasis’ negative feedback loop. When 75g glucose is ingested, the glucose concentration in extra-cellular fluid(ECF) increases. Glucose sensing occurs at β-cells on the pancreas, which have GLUT2 insulin independent transport proteins on their cell membrane. Glucose enters the β-cell down a concentration gradient from the ECF to the intra-cellular fluid(ICF), through the GLUT2 proteins. This glucose is completely oxidised in mitochondria

calcium ions (Ca2+) and lengthen in the absence of calcium ions . The interaction of the thin and thick filaments can occur through the sliding filament theory or the cross bridge theory. The contraction and relaxation of the cardiac fibers is a complex process involving influx and outflow of Ca2+ in the myocyte. Contraction and Relaxation of Cardiac Fibers A cell membrane

the different ions endeavor to balance out on both sides of the membrane, they cannot because the cell membrane sanctions only some ions to pass through channels (ion channels). At rest, potassium ions (K+) can cross through the membrane facilely. Additionally at rest, chloride ions (Cl-) and sodium ions (Na+) have a more arduous time crossing. The negatively charged protein molecules (A-) inside the neuron cannot cross the membrane. In integration to these selective ion channels, there is a pump