The Autonomic Nervous System and Higher-Order Functions Flashcards
Autonomic nervous system
Adjusts our basic life support systems without conscious control
ANS
Coordinates cardiovascular, respiratory, digestive, urinary, and reproductive functions
Preganglionic neurons
- CNS
- Send axons to synapse on ganglionic neurons in autonomic ganglia outside the CNS
Sympathetic division
- Fight or flight
- Made of preganglionic fibres from T1-L2, ganglionic neurons in ganglia near vertebral column and neurons in adrenal glands
Parasympathetic division
- Rest and digest
- Made of preganglionic fibres leaving the brain and sacral segments
2 types of sympathetic ganglia
Sympathetic chain ganglia and collateral ganglia
Sympathetic chain ganglia
Anterior roots in spinal segments in T1-L2 give rise to myelinated white ramus communicans which in turn leads to the sympathetic chain ganglia
Postganglionic fibres
Target structures in the body wall and limbs rejoin the spinal nerves and reach their destinations by way of the posterior and anterior rami
Splanchnic nerves
Formed from preganglionic fibres that innervate the collateral ganglia
Celiac ganglion
Innervates the stomach, liver, gallblader, pancreas, and spleen
Superior mesenteric ganglion
Innervates small intenstine and initial segments of the large intestine
Inferior mesenteric ganglion
Innervates the kidneys, urinary bladder, terminal portions of the large intestine and the sex organs
Adrenal medulla
Preganglionic fibres entering the adrenal gland synapse within the adrenal medulla
Sympathetic activation
- In crisis, the entire sympathetic division responds
- Increased alertness, energy and euphoria, increased cardiovascular and respiratory activites, elevation in muscle tone, mobilisation of energy reserves
Stimulation of sympathetic division
Secretion of:
- ACH or norepinephrine (NE) at specific locations
OR
- Epinephrine (E) and NE into the general circulation
Varicosities
Sympathetic ganglionic neurons end in telodendria studded with varicositites containing neurotransmitters
2 types of sympathetic receptors
Alpha and beta receptors
Types of postganlgionic fibres
Adrenergic, cholinergic, nitroxidergic
Sympathetic division
2 sympathetic chain ganglia
3 collateral ganglia
2 adrenal medullae
Parasympathetic division
Preganglionic neurons in the brainstem and sacral segments of the spinal cord, and ganglionic neurons in peripheral ganglia located within or next to target organs
Intramural
Within
Terminal
Next to
What do preganglionic fibres leave the brain as?
Components of cranial nerves III, VII, IX, and X
Pelvic nerves
Preganglionic fibres leaving sacral segments form pelvic nerves
Parasympathetic division
Relaxation, food processing, and energy absorption
What do all parasympathetic preganglionic and postganglionic fibres release?
ACh
2 types of postsynaptic membranes ACh receptors
Muscarinic receptors: produces longer lasting effect
Nicotinic receptors: less long lasting
Parasympathetic division
Innervates areas serviced by cranial nerves and organs in the thoracic and abdominopelvic cavities
Dual innervation
Receive input from both divisions
Autonomic plexuses
Cardiac, pulmonary, esophageal, celiac, inferior mesenteric, and hypogastric plexuses
Autonomic tone
Even when stimuli are absent, autonomic motor neurons show a resting level of action
Visceral reflex arcs
Perform the simplest function of the ANS
2 types of visceral reflex arcs
Long reflexes: with interneurons
Short reflexes: bypassing the CNS
Parasympathetic reflexes
Govern respiration, cardiovascular functions, and other visceral activities
What performs higher-order functions?
- Performed by the cerebral cortex and involve complex interactions among areas of the cerebral cortex and between the cortex and other areas of the brain
- Involve conscious and unconscious information processing
- Subject to modification and adjustment over time
Memory consolidation
Conversion from short-term to long-term memory
Amnesia
Loss of memory as a result of disease or trauma
Deep sleep
- Slow wave, non-REM sleep
- Body relaxes and cerebral cortex activity is low
REM sleep
Active dreaming occurs
Reticular activating system (RAS)
- Network in the reticular formation
- Most important to arousal and the maintenance of consciousness
Age related changes
- Reduction in brain size and weight
- Reduction in neuron numbers
- Decrease in blood flow to the brain
- Changes in the synaptic organisation of the brain
- Intracellular and extracellular changes in CNS neurons
