central nervous system

Examples of central nervous system in the following topics:

• The Nervous System

  • The nervous system is composed of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves).
  • Two major divisions of the nervous system are the central nervous system (CNS) and the peripheral nervous system (PNS).
  • The vertebrate central nervous system (CNS) contains the brain and the spinal cord .
  • The main function of the PNS is to connect the central nervous system (CNS) to the limbs and organs, essentially serving as a communication relay between the brain and the extremities.
  • The central nervous system (2) is a combination of the brain (1) and the spinal cord (3).

• Neurons and Glial Cells

  • In most types of vertebrate animals, it consists of two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS).
  • Flatworms of the phylum Platyhelminthes have both a central nervous system, made up of a small "brain" and two nerve cords, and a peripheral nervous system containing a system of nerves that extend throughout the body.
  • Compared to invertebrates, vertebrate nervous systems are more complex, centralized, and specialized.
  • In (f) vertebrates, the brain and spinal cord comprise the central nervous system, while neurons extending into the rest of the body comprise the peripheral nervous system.
  • Recall the differences in structure and function between the central and peripheral nervous systems

• Glia

  • While glia (or glial cells) are often thought of as the supporting cast of the nervous system, the number of glial cells in the brain actually outnumbers the number of neurons by a factor of ten.
  • Glial cells of the (a) central nervous system include oligodendrocytes, astrocytes, ependymal cells, and microglial cells.
  • Glial cells of the (b) peripheral nervous system include Schwann cells, which form the myelin sheath, and satellite cells, which provide nutrients and structural support to neurons.
  • (a) Astrocytes and (b) oligodendrocytes are glial cells of the central nervous system.
  • Describe the specific roles that the seven types of glia play in the nervous systems

• Transduction and Perception

  • The most fundamental function of a sensory system is the translation of a sensory signal to an electrical signal in the nervous system.
  • In the nervous system, a positive change of a neuron's electrical potential (also called the membrane potential), depolarizes the neuron.
  • Integration of sensory information begins as soon as the information is received in the central nervous system.
  • All sensory signals, except those from the olfactory system, are transmitted though the central nervous system: they are routed to the thalamus and to the appropriate region of the cortex.
  • Explain how stimuli are converted to signals that are carried to the central nervous system

• Epinephrine and Norepinephrine

  • An increase in norepinephrine from the sympathetic nervous system increases the rate of contractions in the heart.
  • It is also a neurotransmitter in the central nervous system and sympathetic nervous system, where it is released from noradrenergic neurons in the locus coeruleus.
  • Epinephrine and norepinephrine are released by the adrenal medulla and nervous system respectively.
  • These hormones go one step further and trigger the renin-angiotensin-aldosterone system, the hormone system that regulates blood pressure and water (fluid) imbalance.

• Sensory-Somatic Nervous System

  • The sensory-somatic nervous system transmits sensory information from the body to the brain and motor movements from the brain to the body.
  • The sensory-somatic nervous system is composed of cranial and spinal nerves and contains both sensory and motor neurons.
  • Sensory neurons transmit sensory information from the skin, skeletal muscle, and sensory organs to the central nervous system (CNS).
  • Without its sensory-somatic nervous system, an animal would be unable to process any information about its environment (what it sees, feels, hears, etc. ) and could not control motor movements.
  • Explain the role of the cranial and spinal nerves in the sensory-somatic nervous system

• Reception

  • All bilaterally symmetric animals have a sensory system.
  • The development of any species' sensory system has been driven by natural selection; thus, sensory systems differ among species according to the demands of their environments.
  • Although the sensory systems associated with these senses are very different, all share a common function: to convert a stimulus (light, sound, or the position of the body) into an electrical signal in the nervous system.
  • Stimulation of the sensory receptor activates the associated afferent neuron, which carries information about the stimulus to the central nervous system.
  • This scheme shows the flow of information from the eyes to the central connections of the optic nerves and optic tracts, to the visual cortex.

• Autonomic Nervous System

  • The autonomic nervous system, the relay between the CNS and internal organs, is divided into the sympathetic and parasympathetic systems.
  • The autonomic nervous system (ANS) serves as the relay between the central nervous system (CNS) and the internal organs.
  • There are two divisions of the autonomic nervous system that often have opposing effects: the sympathetic nervous system and the parasympathetic nervous system .
  • While the sympathetic nervous system is activated in stressful situations, the parasympathetic nervous system allows an animal to "rest and digest."
  • In the autonomic nervous system, a preganglionic neuron of the CNS synapses with a postganglionic neuron of the parasympathetic nervous system.

• Muscle Tissues and Nervous Tissues

  • Smooth muscle cells have a single, centrally-located nucleus and are spindle shaped.
  • The walls of blood vessels, the tubes of the digestive system, and the tubes of the reproductive systems are composed primarily of smooth muscle.
  • Skeletal muscle is under voluntary, somatic nervous system control and is found in the muscles that move bones.
  • Cardiac muscle is not under voluntary control, but is influenced by the autonomic nervous system to speed up or slow down the heart beat.
  • The main cell of the nervous system is the neuron.

• Structure and Function of the Muscular System

  • The muscular system is closely associated with the skeletal system in facilitating movement.
  • Both voluntary and involuntary muscular system functions are controlled by the nervous system.
  • Cardiac myocytes are shorter than skeletal equivalents and contain only one or two centrally located nuclei.
  • Smooth muscle tissue is associated with numerous organs and tissue systems, such as the digestive system and respiratory system.
  • Smooth muscle myocytes are spindle shaped with a single centrally located nucleus.