(855) 4-ESSAYS

Type a new keyword(s) and press Enter to search

Nervous impulses

            
             Inside the cytoplasm of a neurone, there are large negatively charged organic particles, which are too big to cross the membrane. Ordinarily there are a large number of potassium ions (K+) inside the cell, which diffuse across the selectively permeable membrane. Eventually equilibrium is reached where the net movement of K+ ions into and out of the cell is equal. This is due to the attractive forces of the negatively charge organic molecules. This point is known as the resting potential and is generally said to be around -70mv. When a stimulus stimulates a receptor, a potential difference is created across the cell. This is detected by the electrosensitive Sodium (Na +) channels closest to the stimuli, which consequently open allowing sodium ions to diffuse in as a result. A local current is produced that causes the next sodium channel to open and so on, consequently the impulse travels along the nerve. This is known as an action potential. The inside gradually becomes more positive compared to the outside and generally the potential difference is said to climax to around +30mv. This process is known as depolarisation and only last a few milliseconds. As the cell is now highly positive it is very desirable for it to return back to the resting potential. Sodium channels then close and will not reopen for a short period of time known as the absolute refractory period. At this time Na+ ions are actively pumped out of the cell and the membrane becomes more permeable to K+. Additional channels open and potassium diffuses down a concentration gradient into the cell. This restores the negative charge of the axon.
             Myelinated Neurone.
             In a myelinated neurones a nervous impulse travels down the neurone by a mechanism known as saltatory conduction. But how does this work? As before when a stimulus stimulates a receptor, a potential difference is created across the cell. Electrosensitive Sodium (Na +) channels closest to the stimuli, open and sodium ions diffuse in.


Essays Related to Nervous impulses

1. Neurons and the Central Nervous System

... part of the body to another. There are three types of neurons, each having a different function; Sensory, transmit impulses received by the nerve endings to the central nervous system. Motor, carry outgoing signals from the brain or spinal cord to other areas of the body and inter-neurons, ... receive signals from the sensory and send impulses to the motor. They act as 'basic building blocks' (Toates, 2007) for emotions, communications and behavior ... charge, the neurotransmitter is either inactivated by enzymes or by returning it to the pre-synaptic neuron through re-uptake. The ...

  • Word Count: 1030
  • Approx Pages: 4
  • Has Bibliography
  • Grade Level: Undergraduate

2. Comparison of nervous system and the endocrine system

... affects behavior through hormones secretion. Example: sexual behavior is affected by hormone release from the gonads and depression is due to reduced activity of the norepinephrine synapses found in the nervous system. The differences out weigh the similarities. The endocrine system is made up of a complex array of very different glands, with the main component being the Pituitary gland. On ... endocrine system hormones are secreted into the blood stream and diffused. They then bind to special receptors on distant target cells. Due to the fact that neurons communicate through electrical...

  • Word Count: 880
  • Approx Pages: 4
  • Grade Level: Undergraduate

3. The Human Nervous System

... is broken down into two major divisions, the central nervous system and the peripheral nervous system. The central nervous system consists of the brain and spinal cord. The brain serves as regulatory center through which the activities of the whole body are integrated and controlled. The brain receives sensory impulses that provide information about the body's internal and external state. In ... rage, and all other emotions that affect our behavior. • The brain is the source of higher mental process including thought, reasoning, judgment, memory and learning. (Caroline 300) The nervou...

  • Word Count: 686
  • Approx Pages: 3
  • Grade Level: High School

4. Nervous System

The nervous system is a wonder of the human body; it is the main control of most of the bodies systems, directly, or indirectly. The brain, and its peripheral components, are composed of ... of neurons, each with a specific job. The Motor neuron is a neuron developed specifically for handling the high voltage used for your muscles; its entire structure is hardened against damage, erratic impulses, etc. Te inter-neuron is just that, an Intermediary Neuron, this type of neuron sits between 2 neurons, and either passes the message, or blocks it, sort of like a referee. This ... ...

  • Word Count: 284
  • Approx Pages: 1
  • Grade Level: High School

5. Locomotion and Digestion

... the same time under normal conditions. If they are to contract, they must be stimulated by the nervous system. There are several steps involved in the initiation of contraction in a skeletal muscle fiber by the nervous system. First, the motor neuron produced electrical impulses that are conducted to the ends of its axons, where the neuron forms synapses (neuromuscular junctions) ... with one or more muscle fibers. At these synapses, the neuron releases acetylcholine as a chemical neurotransmitter. Acetylcholine excites each muscle fiber, stimulating it to produce impulses that are simil...

  • Word Count: 9019
  • Approx Pages: 36
  • Has Bibliography
  • Grade Level: Undergraduate

6. Body Systems

... a muscle, and extension, the stretching of a muscle. Muscle contraction is triggered by nerve impulses. Some nerves provide impulses for many muscle fibers, especially to large muscles such as your eyes, a single nerve may provide impulses to only two or three muscle fibers. There are three types of muscle tissues, smooth muscles ... a person's overall health and lifestyle. The recovery time for injury-related muscle problems varies with the type and severity of the injury. Your nervous system coordinates all of the activities in your body-from breathing or digesting food to sensing pain...

  • Word Count: 1261
  • Approx Pages: 5
  • Grade Level: High School

7. ADD

... brain, which regulates arousal and screens incoming messages from within and outside of the body. The limbic system, which is a group of related nervous system structures, located in the midbrain and linked to emotions and feelings then sends the messages to the frontal lobes. Finally, the frontal lobes ... ADD have the same goal, to provide the brain with the raw materials it needs to concentrate over a sustained period of time, control impulses, and regulate motor activity. The drug or combination of drugs that work best for the patient depends on the individual's brain chemistry and c...

  • Word Count: 12292
  • Approx Pages: 49
  • Has Bibliography

8. System Aspect

... skeletal muscle, and the autonomic, which is involuntary and controls cardiac and smooth muscle and glands. The autonomic nervous system has two divisions: the sympathetic and the parasympathetic. Many, but not all, of the muscles and glands that distribute nerve impulses to the larger interior organs possess a double nerve supply; in such cases the two divisions may exert ... opposing effects. Thus, the sympathetic system increases heartbeat, and the parasympathetic system decreases heartbeat. The two nervous systems are not always antagonistic, however. For example, both nerve supplies...

  • Word Count: 1025
  • Approx Pages: 4
  • Grade Level: Undergraduate

9. Hearing Losses

... a mechanical system (the levers of the middle ear) to motion in non-compressible fluid (the fluids of the inner ear) to electrochemical impulses in the nervous system. The outer ear carries the oscillations to the eardrum via the ear canal, a passive acoustic filter which imparts a pre-emphasis between ... below about 1KHz is sampled by cilia in the cochlea in the fashion of simple A/D conversion systems, mapping amplitude to strength of periodic nerve impulses. The multi-channel high-frequency subsystem consists of a series of thousands of filters of narrow bandwidth, a mechanical/hydr...

  • Word Count: 2665
  • Approx Pages: 11

Got a writing question? Ask our professional writer!
Submit My Question