autonomous nervous system

What does the ANS control?

controls glands, cardiac, and smooth muscles (mostly viscera) usually involuntarily

Functions of Somatic Nervous System

(receptor and what it affects)

Somatic nervous system (SNS)

• Conscious control

• Somatic sensory receptor detects stimulus

• Somatic motor neuron affects skeletal muscles

  • One motor neuron

Functions of Autonomic Nervous System

(receptor and what if affects)

Autonomic nervous system (ANS)

• Unconscious control

• Visceral sensory neurons detects stimulus

• Autonomic motor neurons innervate smooth muscle, cardiac muscles, glands

What is a visceral reflex? Name an example of it with its components of a reflex arc.

Visceral reflexes: unconscious, automatic, stereotypical response to some stimulus

• Example: Baroreflex for blood pressure

  • Stimulus: High blood pressure

  • Receptor: stretch on baroreceptors on carotid sinuses and aorta

  • Afferent neuron: Glossopharyngeal nerve

  • Integrating center: medulla oblongata cardiac center and vasomotor center

  • Efferent neuron: Vagus nerve

  • Effector: SA node of the heart

  • Response: decrease heart rate which lowers blood pressure

Functions of Sympathetic Nervous System?

(Local or Systemic? Branches?)

Sympathetic nervous system: “fight or flight” response which

• Increase alertness, heart rate, blood pressure, pulmonary airflow, blood glucose concentration, blood flow to cardiac and skeletal muscles, but…

• Decrease blood flow to skin and GI tract

• Systemic

• Highly branched to innervate several viscera

Functions of Parasympathetic Nervous System?

(Local or Sympathetic? Branches?)

Parasympathetic Nervous System: “rest and digest” response

• Decrease energy use, starts maintenance such as digestion and elimination of waste, to maintain homeostasis

• Local & Systemic

• Postganglionic neuron releases ACh 

• Not as branched

What is preganglionic neuron vs postganglionic neuron? What are their differences?

(location of soma, hormones, myelination)

Preganglionic neuron: has their soma at the brainstem or spinal cord and terminates at a ganglion

• myelinated

• Releases ACh

Postganglionic neuron/ganglionic neuron: has their soma at a ganglia and then goes to their target cell

• unmyelinated

• Releases norepinephrine (sympathetic) or ACh (few sympathetic)

• Releases ACh (parasympathetic)

Continuous with one-another

Name all the structures that the sympathetic preganglionic neuron passes through starting with its cell body.

myelinated preganglionic axons from lateral horn of the spinal cord (T1-L2) → anterior rootlets → anterior root → spinal nerve → anterior ramus → white communicating ramus → sympathetic chain ganglia / paravertebral ganglia

same level (sweat glands, piloerector, blood vessels)
synapse at sympathetic chain ganglion → gray communicating ramus → spinal nerve → target cell

different height (freaking everything else)
sympathetic chain ganglion → synapse at diff level chain ganglion → gray communicating ramus → target cell

abdominal organs
sympathetic chain ganglion → synapse at splanchnic nerve → prevertebral ganglion → target cell

The length of the sympathetic postganglionic neuron and where its cell body is located at? Which structures will this neuron pass through?

long with soma residing in the

• Sympathetic chain ganglia/paravertebral ganglia

• Cervical ganglia (ganglia in the cervical area)

• Prevertebral/collateral ganglia

ganglion to target cell

Where are the adrenal glands located?

Adrenal/suprarenal glands: superior to kidneys

What are the two main parts of the adrenal glands?

• Adrenal cortex: outer part that secretes steroid hormones

• Adrenal medulla : inner part that secretes

  • catecholamines: mostly epinephrine but also norepinephrine and a little bit of dopamine

The length of the parasympathetic preganglionic neuron and post ganglionic neuron and where their soma are located at.

• Preganglionic neuron: long and contain soma located at midbrain, pons, medulla oblongata and S2-S4 of spinal cord’s lateral gray horn

• Postganglionic neuron: short and contain soma in terminal ganglia near the target organs

Sympathetic Nervous Effects on Organs

• Heart: increase heart rate and stroke volume (how much blood gets pumped in a single pump)

• Blood vessels:

  • Cutaneous and gastrointestinal blood vessels vasoconstrict

  • Brain, heart, skeletal muscles vasodilate

• Iris: contract dilator muscles; dilate eye pupils for more light

• Bronchioles: bronchodilate for more air flow

• Digestive and urinary functions: decrease motility and functions

• Clitoris contraction and ejaculation in males

Parasympathetic Nervous Effects on Organs

• Heart: decrease heart rate

• Blood vessels:

  • No effect

• Iris: contract constrictor muscles; constrict eye pupils for less light

• Bronchioles: bronchoconstriction for less air flow

• Digestive and urinary functions: increase motility and functions

• Clitoris / Penis erection

What is the enteric nervous system?

Enteric nervous system: digestive tract’s own nervous system innervating smooth muscles and glands regulating motility of esophagus, stomach, intestines and secretion of digestive enzymes and acid

What is dual innervation? Name a few antagonistic effects on certain organs. Name a couple of cooperative effects.

most viscera contain nerve fibers from both sympathetic and parasympathetic divisions causing either antagonistic or cooperative effects

• Antagonistic effects: sympathetic effects opposes parasympathetic effects

  • Sympathetic: increases heart rate vs Parasympathetic: decreases heart rate

  • Sympathetic: inhibits digestion vs parasympathetic: stimulates digestion

• Cooperative effects: sympathetic and parasympathetic affects an overall effect
  
  

• Saliva:

  • Sympathetic: increase mucus production in salivary glands

  • Parasympathetic: increase serous production in salivary glands

• Sexual intercourse:

  • Parasympathetic: erection of penis/clitoris

  • Sympathetic: orgasm

Name the organs that do NOT have dual innervation.

innervated by sympathetic fibers only

• adrenal medulla

• piloerector muscles

• sweat glands

• blood vessels

ANS can be controlled by what other locations in which ways?

– Cerebral cortex: conscious activities affect hypothalamus which affect ANS

– Hypothalamus: integration center for many autonomic function and is also involved with emotions affecting ANS

– Brainstem: contains many visceral reflex centers that affect the ANS (ie: bp, lens, heart rate, pupil size)

– Spinal Cord: affects ANS for defecation and urination