sympathetic nervous system

Examples of sympathetic nervous system in the following topics:

• Autonomic Nervous System

  • The autonomic nervous system, the relay between the CNS and internal organs, is divided into the sympathetic and parasympathetic systems.
  • There are two divisions of the autonomic nervous system that often have opposing effects: the sympathetic nervous system and the parasympathetic nervous system .
  • Most preganglionic neurons in the sympathetic nervous system originate in the spinal cord.
  • While the sympathetic nervous system is activated in stressful situations, the parasympathetic nervous system allows an animal to "rest and digest."
  • The sympathetic and parasympathetic nervous systems often have opposing effects on target organs.

• Epinephrine and Norepinephrine

  • One of the most important functions of norepinephrine is its role as the neurotransmitter released from the sympathetic neurons to affect the heart.
  • 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.

• Humoral, Hormonal, and Neural Stimuli

  • In some cases, the nervous system directly stimulates endocrine glands to release hormones, which is referred to as neural stimuli.
  • Here, neuronal signaling from the sympathetic nervous system directly stimulates the adrenal medulla to release the hormones epinephrine and norepinephrine in response to stress.

• Hormonal Regulation of Stress

  • The sympathetic nervous system regulates the stress response via the hypothalamus.
  • The sympathetic division of the vertebrate autonomic nervous system has evolved the fight-or-flight response to counter stress-induced disruptions of homeostasis.
  • In the initial alarm phase, the sympathetic nervous system stimulates an increase in energy levels through increased blood glucose levels.
  • If glycogen reserves were the only energy source available, neural functioning could not be maintained once the reserves became depleted due to the nervous system's high requirement for glucose.
  • Glucocorticoids also have anti-inflammatory properties through inhibition of the immune system.

• 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).
  • The PNS includes motor neurons (mediating voluntary movement), the autonomic nervous system (comprising the sympathetic nervous system and the parasympathetic nervous system, which regulate involuntary functions), and the enteric nervous system (a semi-independent part of the nervous system whose function is to control the gastrointestinal system).
  • The nervous system performs several functions simultaneously.
  • Some organisms, such as sea sponges, lack a true nervous system.
  • Octopi may have the most complicated of invertebrate nervous systems.

• Adrenal Glands

  • These cells are innervated by pre-ganglionic autonomic nerve fibers from the central nervous system.
  • The release of epinephrine and norepinephrine is stimulated by neural impulses from the sympathetic nervous system.
  • Secretion of these hormones is stimulated by acetylcholine release from pre-ganglionic sympathetic fibers innervating the adrenal medulla.

• Mammalian Systems and Protective Mechanisms

  • The mammalian respiratory system equilibrates air to the body, protects against foreign materials, and allows for gas exchange.
  • Bronchi are innervated by nerves of both the parasympathetic and sympathetic nervous systems that control muscle contraction or relaxation, respectively.
  • Alveoli are made of thin-walled, parenchymal cells that are in direct contact with capillaries of the circulatory system.
  • The respiratory system has protective mechanisms to avoid damage.
  • Air enters the respiratory system through the nasal cavity and pharynx.

• The Nervous System

  • The nervous system is composed of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves).
  • A classification of the nervous system can be performed under different aspects.
  • 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 autonomic nervous system, also part of the peripheral nervous system, controls internal body functions that are not under conscious control.

• 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

• Muscle Tissues and Nervous Tissues

  • 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.
  • Describe the structure and function of nervous tissue; differentiate among the types of muscle tissue