Nervous System

• nervous system is the command center of the body
• the nervous system is composed of the brain, spinal cord, and nerves
• the primary functions of the nervous system are:

  • sensory - detects external and internal stimuli through sensory receptors
  • integrative - processing, analyzing, and responding to sensory information
  • motor - comes after integration of information; reaction to stimuli
• central nervous system contains the brain and the spinal cord.

  • the key decision maker; processes sensory information
• peripheral nervous system includes cranial and spinal nerves.

  • also includes ganglia, sensory receptors
  • divided into sensory and motor division
• under pns - sensory division

  • afferent (towards) division
• under pns - motor division

  • efferent (away) division
  • it is divided into somatic and autonomic division
• under the pns - somatic division (sns)

  • regulates voluntary functions
  • conveys output from cns to skeletal muscles
• under pns - autonomic nervous system (ans)

  • regulates involuntary functions
  • it is divided into sympathetic, parasympathetic, and enteric
• Sympathetic Nervous System

  • Fight or flight.
• Parasympathetic Nervous System

  • Rest and digest.
• Enteric Nervous System

  • intrinsic control of the digestive system.
• parasympathetic

  • pupil - constricted
  • heart - decreased heart rate and contractility
  • airways - bronchoconstriction
  • blood vessel - vasodilation
  • sweat glands - decreased sweat production
  • liver - glycogenesis
  • digestive system - increased peristalsis
  • adrenal glands -
  • uterus - relaxed
  • urinary system - decreased urination
• sympathetic

  • pupil - dilated
  • heart - increased heart rate and contractility
  • airways - bronchodilation
  • blood vessel - vasoconstriction (inhibited from pns)
  • sweat glands - increased sweat production
  • liver - glycogenolysis
  • digestive system - decreased peristalsis
  • adrenal glands - increased production of catecholamines
  • uterus - contracted
  • urinary system - increased urination
• Catecholamines has an effect on the body’s heart rate, heart contractility, and airways.
• Epinephrine from the adrenal gland will make your heart beat faster and contract faster and stronger.
• Norepinephrine from the adrenal gland will make your blood vessel vasoconstrict.
• Sympathetic nervous system has no primary effect on our blood vessel. The cause of vasoconstriction is the inhibition of parasympathetic nervous system.
• What causes penis erection?

  • Parasympathetic
• Point and shoot 

  • P (Erection) - parasympathetic nervous system
  • S (Ejaculation) - sympathetic nervous system
• External control of the digestive system can be controlled by sympathetic and parasymphatetic nervous system.
• Ascending sensory tracts (sends senses or stimuli / carries sensory information to to the brain)

  • Spinothalamic Tract (most common)
  • Dorsal Column-Medial Lemniscal Pathway (DMCL)
  • Spinocerebellar Tract
  • Trigeminal Pathway
• Descending motor tracts (sends signal / response to the tissues, muscles, organs, etc.)

  • Corticospinal Tract (most common)
  • Extrapyramidal Tract (more on psychiatric nursing)
  • Rubrospinal Tract
  • Reticulospinal Tract
• The patient cannot perceive pain 

  • Ascending
• The patient cannot move their left arm

  • Descending
• Soma (cell body) — houses the nucleus and some organelles.

  • Responsible for the metabolic activities of the neurons.
• Dendrites — receives signal from other neurons

  • Transmits the signal to the cell body
• Axon — transmits electrical impulses (action potential)
• Axon hillock is the part between the soma and the axon. This is the region where the axon meets the soma and where action potentials are initiated.
• Myelin sheath — it insulates the axon. Increases speed of action potential.
• Axon terminal — the one attached to the dendrites
• Neurons and glial cells are both in neural cells.
• Neurons primarily transmit nerve impulses.
• Cells under CNS

  • Astrocytes
  • Oligodendrocytes
  • Microglia
  • Ependymal cell
• Astrocytes

  • Star-shaped.

  Supports neurons and blood brain barrier (BBB) — BBB is the barrier between the blood vessel and the brain.
• Why is BBB important?

  • Protects brain from pathogens and regulates nutrient and ion balance.
  • With the BBB, we can easily filter out the substances that goes in and out.
• Oligodendrocytes

  • Main function is to form myelin sheath (insulates the axon of CNS and speeds up the axon potential)
  • Beside the neurons in our brain.
• Microglia

  Very important for immunity. It secretes macrophages so it will undergo phagocytosis incase a pathogen enters your brain
• Ependymal cells

  • Lines the ventricles (produces cerebrospinal fluid)
• Cells under PNS

  • Schwann cells
  • satellite cells