Anderson Logic: The relationship between CNS and PNS.
Across such disparate methods and topics, all these studies share the goal of better understanding the relationships among the brain. The nervous system is divided into two main parts: the central nervous system ( CNS) and the peripheral nervous system (PNS). The CNS is. The peripheral nervous system (PNS) includes all the nerves that lie outside of the central nervous system. Learn more about how the PNS.
It is connected to the peripheral nervous system PNS which includes the nerves in our extremities. But, there are big differences between the two. And, there are more cell types in the nervous system than just neurons. Without glia, growing neuronal processes rarely find their target. And, if they do, they will fail to form a functioning contact synapse.
- Human Physiology/The Nervous System
- Understanding the Central & Peripheral Nervous Systems
The glue is the true The differences in healing abilities of CNS and PNS injuries become clearer when we focus on the regional differences, which, to a large extent, depend on glial cells.
In the CNS there are three main types of glial cells: But in the PNS, there are neither astrocytes nor microglia and so-called Schwann cells do the isolation. What does that mean for an injured neuron? The basic problem An injury to nervous tissue always leads to the same basic problem. A given signal originating from the cell body can't reach its destination any more: If the process of a neuron is severed, the part without the cell body will degrade. If the process of a neuron is not severed but loses its insolation because oligodendrocytes in the CNS or Schwann cells in the PNS are damaged and die then the signal will stop and attempts to regenerate the isolation sheet will start.
The situation in the PNS Sending out new processes and re-establishing the right contacts works relatively well in the PNS, for example after a deep cut into or through a finger. This is because regenerating neurons receive considerable support. Scavenger cells from the immune system hurry to remove the debris of the old isolation material, while they excrete molecules, which encourage Schwann cells to participate.
It is responsible for regulating all of our conscious and unconscious movements, memories, and more. It is one system; however, in order for scientists and wellness experts to discuss it clearly, the nervous system is divided into several subsystems according to their respective functions. A critical piece of the puzzle is understanding the two main structural components of the nervous system and how they relate to each other.
Structure The nervous system is divided into two main parts: The CNS is made up of the brain and spinal cord. The brain is an organ that weighs about three pounds and lives in the skull.
We do know that the brain is made up of two types of tissue: The spinal cord starts at the brain stem and extends down the back through the center of the spine. It ends in the lumbar region of the spine low back. So, the CNS covers the area starting at the brain and running all the way down the spine—quite a large region of the body. There are 12 cranial nerves meaning they start at the head and about 31 pairs about spinal nerves nerves that originate from various parts of the spine.
It gathers information from the internal and external environments of the body and sends that information to the CNS for processing. The grey matter in the brain is primarily responsible for this processing, while the white matter helps send information to different areas of grey matter. The brain makes a decision on how to respond to the information it is given, and sends out signals to the rest of the body by way of the PNS.
The spinal cord helps to connect the brain to the PNS, and is also responsible for carrying out reflexes. The other part comes from the medial cord.
See below for details. Posterior cord[ edit ] diagram showing human dermatoms, i. The posterior cord gives rise to the following nerves: The upper subscapular nerve, C7 and C8, to the subscapularis muscle, or musculus supca of the rotator cuff. The lower subscapular nerve, C5 and C6, to the teres major muscle, or the musculus teres major, also of the rotator cuff. The thoracodorsal nerve, C6, C7 and C8, to the latissimus dorsi muscle, or musculus latissimus dorsi.
The axillary nerve, which supplies sensation to the shoulder and motor to the deltoid muscle or musculus deltoideus, and the teres minor muscle, or musculus teres minor. The radial nerve, or nervus radialis, which innervates the triceps brachii muscle, the brachioradialis muscle, or musculus brachioradialis, the extensor muscles of the fingers and wrist extensor carpi radialis muscleand the extensor and abductor muscles of the thumb.
The difference between centre and periphery
See radial nerve injuries. The medial cord gives rise to the following nerves: The median pectoral nerve, C8 and T1, to the pectoralis muscle The medial brachial cutaneous nerve, T1 The medial antebrachial cutaneous nerve, C8 and T1 The median nerve, partly. The other part comes from the lateral cord. C7, C8 and T1 nerve roots. The first branch of the median nerve is to the pronator teres muscle, then the flexor carpi radialis, the palmaris longus and the flexor digitorum superficialis.
Brain CNS and PNS
The median nerve provides sensation to the anterior palm, the anterior thumb, index finger and middle finger. It is the nerve compressed in carpal tunnel syndrome. The ulnar nerve originates in nerve roots C7, C8 and T1. It provides sensation to the ring and pinky fingers. It innervates the flexor carpi ulnaris muscle, the flexor digitorum profundus muscle to the ring and pinky fingers, and the intrinsic muscles of the hand the interosseous muscle, the lumbrical muscles and the flexor pollicus brevis muscle.
This nerve traverses a groove on the elbow called the cubital tunnel, also known as the funny bone. Striking the nerve at this point produces an unpleasant sensation in the ring and little fingers. Other thoracic spinal nerves T3-T12 [ edit ] The remainder of the thoracic spinal nerves, T3 through T12, do little recombining. They form the intercostal nerves, so named because they run between the ribs. For points of reference, the 7th intercostal nerve terminates at the lower end of the sternum, also known as the xyphoid process.
The 10th intercostal nerve terminates at the umbilicus, or the belly button. The somatic nervous system is that part of the peripheral nervous system associated with the voluntary control of body movements through the action of skeletal muscles, and also reception of external stimuli. The somatic nervous system consists of afferent fibers that receive information from external sources, and efferent fibers that are responsible for muscle contraction.
The somatic system includes the pathways from the skin and skeletal muscles to the Central Nervous System. It is also described as involved with activities that involve consciousness. The basic route of the efferent somatic nervous system includes a two neuron sequence.
The first is the upper motor neuron, whose cell body is located in the precentral gyrus Brodman Area 4 of the brain. It receives stimuli from this area to control skeletal voluntary muscle. The upper motor neuron carries this stimulus down the corticospinal tract and synapses in the ventral horn of the spinal cord with the alpha motor neuron, a lower motor neuron. The upper motor neuron releases acetylcholine from its axon terminal knobs and these are received by nicotinic receptors on the alpha motor neuron.
The alpha motor neurons cell body sends the stimulus down its axon via the ventral root of the spinal cord and proceeds to its neuromuscular junction of its skeletal muscle. There, it releases acetylcholine from its axon terminal knobs to the muscles nicotinic receptors, resulting in stimulus to contract the muscle.
The somatic system includes all the neurons connected with the muscles, sense organs and skin. It deals with sensory information and controls the movement of the body. The Autonomic System[ edit ] The Autonomic system deals with the visceral organs, like the heart, stomach, gland, and the intestines.Central Nervous System vs. Peripheral Nervous System
It regulates systems that are unconsciously carried out to keep our body alive and well, such as breathing, digestion peristalsisand regulation of the heartbeat. The Autonomic system consists of the sympathetic and the parasympathetic divisions.
Human Physiology/The Nervous System - Wikibooks, open books for an open world
Both divisions work without conscious effort, and they have similar nerve pathways, but the sympathetic and parasympathetic systems generally have opposite effects on target tissues they are antagonistic. By controlling the relative input from each division, the autonomic system regulates many aspects of homeostasis. One of the main nerves for the parasympathetic autonomic system is Cranial Nerve X, the Vagus nerve.
The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses. The Sympathetic and Parasympathetic Systems[ edit ] The sympathetic nervous system activates what is often termed the fight or flight response, as it is most active under sudden stressful circumstances such as being attacked.
This response is also known as sympathetico-adrenal response of the body, as the pre-ganglionic sympathetic fibers that end in the adrenal medulla but also all other sympathetic fibers secrete acetylcholine, which activates the secretion of adrenaline epinephrine and to a lesser extent noradrenaline norepinephrine from it. Therefore, this response that acts primarily on the cardiovascular system is mediated directly via impulses transmitted through the sympathetic nervous system and indirectly via catecholamines secreted from the adrenal medulla.
Western science typically looks at the SNS as an automatic regulation system, that is, one that operates without the intervention of conscious thought. Some evolutionary theorists suggest that the sympathetic nervous system operated in early organisms to maintain survival Origins of Consciousness, Robert Ornstein; et al.
One example of this priming is in the moments before waking, in which sympathetic outflow spontaneously increases in preparation for action.