Divisions of the Nervous System

• ganglia are clusters of neuron cell bodies
• Organization of the Nervous System

  A) brain

  B) spinal cord

  C) nerves

  D) ganglia

  E) input

  F) sensory nervous system

  G) somatic sensory

  H) visceral sensory

  I) motor nervous system

  J) somatic motor

  K) autonomic motor

  
• Sensory nervous system detects stimuli and transmits information from receptors to the CNS.
• Somatic sensory

  Sensory input that is consciously perceived from receptors (e.g., eyes, ears, and skin)
• Visceral sensory

  Sensory input that is not consciously perceived from receptors of blood vessels and internal organs (e.g., heart)
• Motor nervous system initiates and transmits information from the CNS

  to effectors.
• Somatic motor

  Motor output that is consciously or voluntarily controlled;

  effector is skeletal muscle
• Autonomic motor

  Motor output that is not consciously or is involuntarily controlled; effectors are cardiac muscle, smooth muscle, and glands
• The autonomic nervous system (ANS) is a nervous system component responsible for regulating involuntary bodily functions, such as:

  ○heart rate,

  ○digestion,

  ○respiratory rate,

  ○Micturition and

  ○pupillary response.

  2 divisions – parasympathetic(comes from midbrain and sacral) and sympathetic(comes from thoracic and lumber regions) nervous systems

  
• Somatic Nervous System

  Somatic motor neuron transmits nerve signals to skeletal muscle.

  Somatic sensory neuron detects stimuli and transmits nerve signals from the special senses (i.e., vision, hearing, equilibrium, smell, taste), the skin, and proprioreceptors in joints and muscles.

  
• Autonomic Nervous System

  Preganglionic autonomic motor neuron transmits nerve signals to a ganglionic autonomic motor neuron

  Ganglionic autonomic motor neuron transmits nerve signals to smooth muscle, cardiac muscle, and glands.

  Visceral sensory neuron detects stimuli associated with blood vessels and the viscera.

  
• ●The ANS is important for regulating the bodily functions, and essential for maintaining homeostasis.

  ●This means balancing the body’s conditions and functions necessary for living.

  ●Also involves fight or flight or rest and digest.

  ●Examples of the functions controlled by the ANS are salivating, sweating, changing pupil size, managing heart rate, respiration, and secreting hormones.

  
• Functions Of The ANS

  A) Constricts pupil

  B) Stimulates saliva production

  C) Constricts bronchi

  D) slows heart rate

  E) Stimulates stomach, pancreas, and intestines

  F) Stimulates urination

  G) Promotes erection of genitals

  H) Dilates pupil

  I) Inhibits saliva production

  J) Dilates bronchi

  K) Accelerates heart

  L) Stimulates epinephrine and norepinephrine release

  M) Stimulates glucose release

  N) Inhibits stomach, pancreas, and intestines

  O) Inhibits urination

  P) Promotes ejaculation and vaginal contractions

  
• What Controls The Autonomic Nervous System?

  ●The ANS works by receiving information from either external stimuli or the body.

  ●The hypothalamus receives autonomic regulatory input from the limbic system (a group of structures deep in the brain which is associated with functions such as memory, emotion, and fear).

  ●The hypothalamus uses this input to control much of the activity of the ANS.

  
• Hypothalamus

  Integration and command center for autonomic functions; involved in emotions

  
• Brainstem

  Contains major ANS reflex centers

  
• Spinal cord

  Contains ANS reflex centers for defecation and urination

  
• What Controls The Autonomic Nervous System?

  ●Acetylcholine – is primarily found within the parasympathetic nervous system, which has an inhibiting effect.

  ●Epinephrine – also known as adrenaline, is primarily found within the sympathetic nervous system, which has a stimulating effect.

  ●Norepinephrine – also known as noradrenaline, is primarily found within the sympathetic nervous system and has a stimulating effect.

  
• Parasympathetic Division (craniosacral division)

  Origin:

  Preganglionic neurons located in brainstem nuclei and S2-S4

  segments of spinal cord (craniosacral)

  CN Ill (oculomotor), CN VII (facial), CN IX (glossopharyngeal), CN X (vagus) , S2-S4 segments of spinal cord , Pelvic splanchnic nerves

  
• Parasympathetic Division (craniosacral division)

  Functions:

  • Brings body to homeostasis in conditions of "rest-and-digest"
  • Conserves energy and replenishes nutrient stores
• Parasympathetic Division

  A) Preganglionic neuron

  B) Long preganglionic axon

  C) Ganglionic - neuron

  D) Short postganglionic axon

  E) Autonomic ganglion

  F) terminal ganglia

  G) intramural ganglia

  
• Parasympathetic Division

  both the preganglionic neuron and short postganglionic neuron release acetylcholine

  
• Sympathetic Division (thoracolumbar division)

  Origin:

  Preganglionic neurons located in lateral horns of

  T1-L2 segments of spinal cord

  
• Sympathetic Division (thoracolumbar division)

  Functions:

  • Brings body to homeostasis in conditions of "fight-or-flight"

  • Increases alertness and metabolic activities

  
• Sympathetic Division

  A) Short, branching preganglionic axon

  B) Preganglionic neuron

  C) Long postganglionic axon

  D) Ganglionic neuron

  E) Autonomic ganglion

  
• Sympathetic Division

  The preganglionic neuron releases acetylcholine whereas

  the postganglionic neuron releases adrenaline/noradrenaline

  
• Sympathetic Nervous System

  ●The sympathetic division is primarily concerned with preparing the body for exercise and emergencies.

  ●It is functionally considered the fight-or-flight division.

  ●It slows bodily processes that are less important in emergencies, such as digestion.

  
• Sympathetic Nervous System

  A) Dilates pupils

  B) Inhibits salivation

  C) Relaxes bronchi

  D) Accelerates heartbeat

  E) Inhibits peristalsis and secretion

  F) Stimulates glucose production and release

  G) Secretion of adrenaline and noradrenaline

  H) Inhibits bladder contraction

  I) Stimulates orgasm

  
• Sympathetic 4 Pathways

  A) Spinal nerve

  B) Integumentary structures

  C) Via cervical gray rami to all spinal nerves

  D) Postganglionic sympathetic nerve

  E) Head and neck viscera

  F) superior cervical ganglion

  G) Thoracic organs

  H) cervical and thoracic ganglia

  I) Splanchnic nerve

  J) Most abdominal organs

  K) thoracic splanchnic nerves

  L) prevertebral ganglia

  M) Pelvic organs

  N) lumbar and sacral splanchnic nerves

  O) Adrenal medulla

  P) Adrenal gland

  Q) No ganglionic neuron;

  R) thoracic splanchnic

  S) adrenal medulla

  
• Types of Sympathetic Pathways.

  A) spinal nerve pathway

  B) Postganglionic sympathetic nerve

  
• Types of Sympathetic Pathways.

  A) Splanchnic nerve pathway

  B) Adrenal medulla pathway

  
• Sympathetic Stress Response

  A) Pituitary Gland

  B) Adrenocorticotropic Hormone (ACTH)

  C) Adrenal Glands

  D) cortisol

  E) ADRENALINE

  
• Sympathetic Stress Response

  A) HYPOTHALAMUS

  B) Activates Sympathetic Nervous System

  C) Activates Adrenal Medulla

  D) Releases Epinephrine

  E) Releases Norepinephrine

  F) ACTH

  G) cortisol

  
• Parasympathetic Nervous System

  ●The parasympathetic division is primarily concerned with maintaining homeostasis at rest and is functionally considered the rest-and-digest division.

  ●It relaxes the individual once the emergency has passed (e.g., slows the heart rate down and reduces blood pressure) and conserves the body’s natural activity by decreasing activity/maintaining it.

  if not controlled can lead to chronic stress

  
• Parasympathetic Nervous System

  A) constrics pupils

  B) stimulates flow of saliva

  C) Constricts bronchi

  D) slows heart rate

  E) stimulates peristalsis and secretions

  F) bile release

  G) contracts bladder

  
• Parasympathetic Pathways

  The cranial nerves from the parasympathetic division are the oculomotor (CN III), facial (CN VII), glossopharyngeal (CN IX), and vagus (CN X) nerves.

  The remaining parasympathetic preganglionic axons originate from S2–S4 spinal cord segments to form the pelvic splanchnic nerve

  
• Comparison of Neurotransmitters and Receptors of the Two Divisions

  A) Ach

  B) nicotinic receptors

  C) ACh

  D) muscarinic receptor

  E) ACh

  F) nicotinic receptors

  G) ACh

  H) muscarinic receptor

  I) sweat glands

  J) ACh

  K) nicotinic receptors

  L) NE

  M) adrenergic receptors

  N) most other body structures

  O) ACh

  P) adrenal medulla cells

  Q) ACh

  R) nicotinic receptors

  S) adrenal medulla cells

  
• Cholinergic Receptors - Nicotinic

  All postganglionic neurons in the ANS (both parasympathetic division and sympathetic division)

  Adrenal medulla (gland innervated by preganglionic neuron of sympathetic division)

  Neuromuscular junction of skeletal muscle

  Some neurons of central nervous system (neurons involved in learning and memory)

  Always excitatory

  
• Cholinergic Receptors - Muscarinic

  All effectors of parasympathetic target organs

  limited sympathetic target organs that have muscarinic receptors i.e sweat glands

  Generally excitatory (except for selected structures, such as:

  cardiac muscle pacemaker cells)

  
• Adrenergic Receptors - Alpha Receptors - alpha 1

  Almost all effectors of sympathetic division (exceptions include cardiac muscle and bronchioles)

  Causes contraction of most smooth muscle, including blood vessels of the skin, blood vessels of GI tract, blood vessels of kidneys, arrector pili, uterus, ureters, internal urethral sphincter, dilator pupillae muscle of eye