NEUROLOGY 2 MARKS : PART 12

NEURON:

  • A nerve cell that receives and sends electrical signals over long distances within the body.
  • neuron receives electrical input signals from sensory cells (called sensory neurons) and from other neurons.
  • A neuron that simply signals another neuron is called an interneuron.
  • Neurons are divided into four major types: unipolar, bipolar, multipolar, and pseudounipolar. Unipolar neurons have only one structure extending from the soma.
  • Bipolar neurons have one axon and one dendrite extending from the soma.
  • Neurons (also known as neurones, nerve cells and nerve fibers) are electrically excitable cells in the nervous system that function to process and transmit information

REFLEX:

  • Reflexes, or reflex actions, are involuntary, almost instantaneous movements in response to a specific stimulus.
  •  Reflex arcs that contain only two neurons, a sensory and a motor neuron, are considered monosynaptic. 
  • Examples of monosynaptic reflex arcs in humans include the patellar reflex and the Achillesreflex.
  • Reflex tests are performed as part of a neurological exam, either a mini-exam done to quickly confirm integrity of the spinal cord or a more complete exam performed to diagnose the presence and location of spinal cord injury or neuromusculardisease. Deep tendon reflexes are responses to muscle stretch.

AFFERENT AND EFFERENT:

  • Neurons that receive information from our sensory organs (e.g. eye, skin) and transmit this input to the central nervous system are called afferent neurons.
  • Neurons that send impulses from the central nervous system to your limbs and organs are called efferent neurons.
  • Afferent” and “efferent” are not different types of neurons, they are terms for pathways that connect a neuron or brain area with other brain areas. 
  • Afferent to a given brain area are connections that bring signals into it, efferent are connections that carry signals out of it.

DOPAMINE:

  • Dopamine is a neurotransmitter, a chemical responsible for sending messages between the brain and different nerve cells of the body.
  • In the brain, dopamine functions as a neurotransmitter, a chemical released by neurons (nerve cells) to send signals to other nerve cells.
  • The brain includes several distinct dopamine pathways, one of which plays a major role in the motivational component of reward-motivated behavior.
  • Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement .

ATP:

  • ATP stands for adenosine triphosphate.
  • ATP is the principal molecule for storing and transferring energy in cells. ATPs are used as the main energy source for metabolic functions.
  • ATP is an adenine nucleotide bound to three phosphates.
  • There is a lot of energy stored in the bond between the second and third phosphate groups that can be used to fuel chemical reactions.
  • The process of phosphorylating ADP to form ATP and removing a phosphate fromATP to form ADP in order to store and release energy respectively is known as the ATP cycle.

SEROTONIN :

  • Serotonin is a neurotransmitter. Its chemical name is 5-Hydroxytryptamine or 5-HT.
  • It is derived from tryptophan. 
  • Serotonin is found in all vertebrates, mainly in the gastrointestinal tract, blood platelets and central nervous system.
  • As a neurotransmitter, serotonin helps to relay messages from one area of the brain to another.
  • This includes brain cells related to mood, sexual desire and function, appetite, sleep, memory and learning, temperature regulation, and some social behavior.
  • There may be a link between serotonin and depression.
  • If so, it is unclear whether low serotonin levels contribute to depression, or if depression causes a fall in serotonin levels.

SYNAPSE:

  • The function of the synapse is to transfer electric activity (information) from one cell to another.
  • The transfer can be from nerve to nerve (neuro-neuro), or nerve to muscle (neuro-myo).
  • The region between the pre- and postsynaptic membrane is very narrow.

THERE ARE TWO TYPES OF SYNAPSES:

  • Electrical synapses.
  • Chemical synapses.

NEUROMUSCULAR JUNCTION  :

  • A neuromuscular junction (or myoneural junction) is a chemical synapse formed by the contact between a motor neuron and a muscle fiber.
  • It is at the neuromuscular junction that a motor neuron is able to transmit a signal to the muscle fiber, causing muscle contraction.
  • The neuromuscular junction is a type of synapse where neuronal signals from the brain or spinal cord interact with skeletal muscle fibers, causing them to contract.
  • It is at the neuromuscular junction that a motor neuron is able to transmit a signal to the muscle fiber, causing muscle contraction.
  • Muscles require innervation to function and to maintain muscle tone, avoiding atrophy.

NEUROMUSCULAR JUNCTION  :

  • A neuromuscular junction (or myoneural junction) is a chemical synapse formed by the contact between a motor neuron and a muscle fiber.
  • It is at the neuromuscular junction that a motor neuron is able to transmit a signal to the muscle fiber, causing muscle contraction.
  • The neuromuscular junction is a type of synapse where neuronal signals from the brain or spinal cord interact with skeletal muscle fibers, causing them to contract.
  • It is at the neuromuscular junction that a motor neuron is able to transmit a signal to the muscle fiber, causing muscle contraction.
  • Muscles require innervation to function—and even just to maintain muscle tone, avoiding atrophy.

CATHERINE SHALINI RAJA
M.P.T.,MIAP.,PGDYN
CARDIO RESPIRATORY PHYSICAL THERAPIST
FITNESS & SPORTS REHABILITATION SPECIALIST.

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