The Nervous system | Questions and Answers

Compare the sympathetic and the parasympathetic nervous system

  • The sympathetic nervous system primary process is to stimulate the flight or fight response. It is consistent at the basic levels to maintain homeostasis; it is thought to be complementary to the parasympathetic nervous system.  There are two types of neurons that are responsible for the sympathetic nervous system we have the preganglionic and postganglionic. The shorter preganglionic neurons originate from the thoracolumbar region of the spinal cord T1-T4,  at the synapsis within the ganglia the presynaptic neurons release acetylcholine which activates nicotic acetylcholine receptors on the postganglionic neurons which extend across most of the body.
  • With the With the exception, the postganglionic neurons of the sweat glands cause activate the muscarinic receptor but the receptors that are found in the thick skin. On the other hand, the parasympathetic nervous system is responsible for resting and digestive proses, and general activities that happen when an individual is on rest these include sexual arousal, eating and salivating. The fibres arise from the central nervous system. The specific nerves are the cranial nerves, we have the ocular nerves facial nerves and the verges nerves. The ocular motor nerves of the parasympathetic nervous system invert the smooth muscles in the eyes that cause the pupils to contract and the lens to the building. The facial nerves innervate many glands of the head. Including the fibres that activate the nasal glands and lacrimal glands of the eye originate in the lacrimal glands of the pons. The vagus nerve prive fibres to the neck and nerve plexus that virtually serve every organ in the thoracic and abdominal cavity.

  1. How the tension generated by skeletal muscle can be altered?
  • On the whole, the muscle is either contracted or relaxed. This is dependant on the number of cross ridges that are pivoting, the fibres resting right at the time of stimulation. And the frequency of the stimulus. The types of contraction are CONCENTRIC – the tension of the muscle was altered by attaching the muscle to less than its peak tension on stimulation it creates enough pressure to lift the load. Tension will remain constant although the length of the muscle changes. This is an isotonic contraction.
  • In eccentric contraction, the muscle elongates as tension is generated, when the eccentric contraction is ended the unopposed load stretches the muscle until the muscle tears or then tendon is pulled elastic recoil is needed to oppose the load. The third is isometric contraction, the same muscle is attached to a load that exceeds its peak. On stimulation, the tension will rise to a peak, but the muscle as a whole cannot shorten.

  1. Outline the use of nerve conduction studies?
  • This is the measurement of the speed of the electrical impulses through the nerve to determine destruction, during this test the nerve is stimulated using surface electrodes. Two electrical rods placed over the nerve and electricity is applied. It is then calculated by calculating between the electrodes and the time it takes for the impulse to reach the nerve.
  • EMG measures the electrical activities of the muscles. The speed of the nerve conduction is directly related to the diameter and degree of myelination.a normally functioning never we transmit stronger and faster nerve conduction. Nerve conduction is often done with EMG to establish whether the issue is nerve related or muscle. A disease that nerve conduction can be made for are Guilian Barr syndrome- a condition in which the bodies nervous system attacks the peripheral nervous system. Carpel tunnel syndrome pinched a nerve and chronic inflammatory polyneuropathy.

  1. Use of EMG studies
  • This is a diagnostic procedure that accesses how health the muscles are, and the nerves that control them. Motor neuron transmits electrical signals that muscles to contract and EMG translates these signals into a graph. It uses electrodes to transmit or detect electrical signals attached to the surface of the skin to measure the speed and string of the electrical impulses travelling between or more points. Can review muscle dysfunction or nerve and can determine if there defects in the nerve to muscle transmission. This test when the doctor or heath provider notices signs of muscle or nerve damage like tingling, numbness and weak muscle. EMG is also helpful in ruling out disorders like muscular dystrophy and disorders that affect the motor neuron.
  1. Functions of the limbic system?
  • The limbic system is complex sets of brain structure that are located on both sides of the thalamus. Right under the cerebrum. It is not a separate system but a collection of structures, from the telencephalon, diencephalon and mesencephalon. It includes the olfactory bulb, hippocampus, the amygdala and the anterior thalamic nuclei.
  • Supports some functions this includes epinephrine flow, emotion behaviour and long-term memory. Operates by influencing the endocrine system and the and the autonomic nervous system. Its is high. It is highly interconnected with the nuclear accumbens which is the brain pleasure centre which plays a role in sexual arousal, and the high people get from taking drugs. These responses are regulated by dopaminergic projections from the limbic system. It is also interconnected with the prefrontal cortex.
  • Two parts seem especially important in emotion the amygdala and the anterior parts of the cingulate gyrus. The amygdala recognises angry or fearfully expressions asses danger and it’s the fear response. The cingulate gyrus plays a role in expressing our emotions, through gestures and resolving mental conflicts.
  • There is an extensive connection between the lower brain, the higher brain which allows for integration and response to a variety if stimuli. Most of the limbic system input is relayed through the hypothalamus which the neural clearing house for both autonomic and emotional response.

  1. What are differences between the somatosensory and autonomic nervous system?
  • The somatosensory is made of some sensory which is made of some receptors. Sensory receptors, mechanoreceptors, photoreceptors, and thermo receptors and chemoreceptors. It comprises important processing centres for proprioception, mechanoreception, nociception and thermoception. The sensory receptors over the skin and epithelial tissue, skeletal muscle and bone
  • Processing happens in the primary somatosensory regions of the parietal lobs of the cerebral cortex, information is sent from the receptors via the sensory nerves which pass through the spinal cord and reaches the brain. The system works when the activity in the sensory neurons is triggered by a stimulus and the information passes to another area that is related to where the stimulus is coming from. For example pain. The first neuron always its cell body in the dorsal root ganglia of the spinal nerve. The second nerve has its cell body in the spinal cord or the blood stream. This nerves ascending neuron will cross to the opposite side of the spinal cord, or the blood and the axons terminate in the thalamus.
  • Finally in the case for the third neuron as its cell body in the  VPN of the thalamus and ends in the postcentral gyrus of the parietal lob.  This is the primary somatosensory area. It relates the concourse and subclause commands,  concourse commands are controlled by the corticobulbar tracts.  it is controlled through the corticospinal pathway. Medial and lateral pathway.
  • The cortical spinal pathway is generally a direct pathway, direct synapses between the higher and lower neurons. The medial and lateral are indirect.
  • The medial pathway regulates ton and gross movement, of the neck and the truck, vestibular spinal tracts maintain posture and balance, tectospinal tracts are the reflex centres, and reticular tracts have a wide range effect.
  • The autonomic nervous system controls cardiac and smooth muscle tissue. Homeostatic regulation autonomic reflexes and has 2 division para and sympathetic division. Sensory impute integration in the hypothalamus. Has three sets of ganglia the sympathetic chain ganglia, collateral ganglia suprarenal medullae.

  1. Description of flaccid paralysis
  • Weakness or paralysis and reduced muscle tone with no known cause may be caused by disease or trauma that affects the nerves associated with the involved muscle. For example, the serving of the somatic nerves to the muscle will suffer flaccid paralysis. When the muscle enters this stage, they become wimp and cannot contract. It can be fatal if it affects the respiratory muscles.
  • A common cause of flaccid paralysis is the anterior spinal artery syndrome in which the anterior artery is blocked. This can be caused by spinal cord trauma or thrombosis or artery disease, also hyperkalemia, which is the excess amount of potassium, hypokalemic periodic paralysis. Treatment is usually through physiotherapy and reinforming of correct movement patterns.

  1. Spastic paralysis
  • A feature of altered skeletal muscle performance, with a combination of paralysis, increased tendon activity and hypertonia, results from the loss of inhibition of the motor neurons. Causing excessive muscle contraction, this eventually leads to hyperreflexia. It is often treated with a drug called baclofen which acts on the agonist at GABA. Which is inhibitory. Happens in the disorder of the CNS affecting the upper motors neuron in the form of a lesion
  • Happens when there is an imbalance in the excitatory and inhibitory inputs of the motor neurons caused by damage to the spinal cord. This damage causes a change in the balance between the nervous system and the muscles. Found in conditions where there is damage to the brain or the brain has not formed properly. We see it in congestive spastic paralysis and cerebral palsy.

  1. How each muscle fibre type affects the performance capabilities of the muscles?
  • Slow fibres – contract slowly and release energy slowly, as required by the body during the steady state exercise they efficient in using oxygen to generate ATP making them resistant to fatigue but are unable to produce the power of fast twitch fibres. During endurance activity, the slow fibres are preferably recruited for the movement because they are more efficient in meeting the demands
  • Intermediate fibres – these are muscle fibres that have been converted to insurance training, these muscles are slightly larger and have more mitochondria. As well as a greater blood supply.
  • Fast fibres –  contract fast and release the energy fast, they fatigue fast due to the anaerobic respiration providing energy. The body recruits these muscle to when you are about to explosive activities like explosive runs.

 

 

Sources

Budnik, V., & Wendler, F. (2016). Extracellular vesicles round off communication in the nervous system. Nature Reviews Neuroscience17(3), 160.

Budnik, V., & Wendler, F. (2016). Extracellular vesicles round off communication in the nervous system. Nature Reviews Neuroscience17(3), 160.

 

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s