Autonomic and Central Nervous System Overview

Difference between autonomic and somatic nervous systems

The autonomic system controls involuntary actions (smooth muscle, cardiac muscle, glands), while the somatic system controls voluntary skeletal muscle movements.

Divisions of the autonomic nervous system

Sympathetic, parasympathetic, and enteric.

Primary function of the sympathetic division

Prepares the body for 'fight or flight' responses, increasing heart rate, dilating pupils, and redirecting blood flow.

Primary function of the parasympathetic division

Promotes 'rest and digest' activities such as digestion, urination, and slowing the heart rate.

Function of the enteric nervous system

Regulates the digestive tract independently of CNS input, though it can be influenced by sympathetic and parasympathetic divisions.

How the three divisions of the ANS work together

They maintain homeostasis by balancing stimulation and inhibition of target organs.

Types of sympathetic ganglionic neurons

Sympathetic chain ganglia, collateral ganglia, and adrenal medullae.

Location of sympathetic chain ganglia

On both sides of the vertebral column.

Location of collateral ganglia

Anterior to the vertebral bodies, near major arteries.

Function of adrenal medullae ganglia

Release epinephrine and norepinephrine into the bloodstream.

Control of sympathetic activation

By centers in the hypothalamus and brainstem.

Effects of sympathetic activation

Increased alertness, metabolic rate, heart rate, and respiratory rate.

Neurotransmitters released by the sympathetic system

Acetylcholine (ACh) and norepinephrine (NE), and epinephrine from the adrenal medulla.

Types of adrenergic receptors

Alpha and beta receptors.

Function of alpha-1 receptors

Cause vasoconstriction and increase blood pressure.

Function of alpha-2 receptors

Inhibit NE release and reduce sympathetic outflow.

Function of beta-1 receptors

Increase heart rate and force of contraction.

Function of beta-2 receptors

Cause bronchodilation and vasodilation in skeletal muscle.

Reason neurotransmitter can have opposite effects

Different receptors (alpha vs. beta) can mediate different responses.

Acetylcholine (ACh)

Neurotransmitter released by parasympathetic neurons.

Cholinergic receptors

Two types are nicotinic and muscarinic.

Nicotinic receptors

Found on postganglionic neurons and adrenal medulla.

Muscarinic receptors

Found on parasympathetic target organs.

Dual innervation

Most organs receive input from both sympathetic and parasympathetic divisions.

Autonomic tone

The continuous, spontaneous activity of autonomic neurons that maintains baseline levels of activity.

Sympathetic division structure

Has short preganglionic and long postganglionic neurons.

Parasympathetic division structure

Has long preganglionic and short postganglionic neurons.

ANS control by the brain

The brainstem executes reflex control, influenced by hypothalamus and modulated by cerebral cortex.

Visceral reflexes

Automatic, involuntary responses to stimuli involving internal organs.

Short-term memory

Holds limited data briefly.

Long-term memory

Stores data more permanently.

Brain regions involved in memory

Hippocampus (formation), amygdala (emotional memory), cerebral cortex (storage), and prefrontal cortex (recall).

Cellular mechanisms of memory formation

Synaptic plasticity, long-term potentiation (LTP), and neurotransmitter regulation.

Consciousness control in the brain

The cerebral cortex and reticular activating system (RAS).

Deep sleep

Body functions slow, energy is restored, growth hormone is released.

REM sleep

Dreaming occurs, brain activity increases, but muscle activity is inhibited.

Dopamine role in the brain

Regulates movement, motivation, and reward.

Dopamine and Parkinson's disease

Parkinson's results from the degeneration of dopamine-producing neurons in the substantia nigra.

Age-related CNS changes

Neuron loss, slower synaptic transmission, reduced brain mass.

Neurofibrillary tangles and plaques

Protein accumulations seen in Alzheimer's disease that disrupt neuron function.

Lifestyle factors reducing Alzheimer's risk

Regular exercise, cognitive activity, healthy diet, and social engagement.