Introduction to the Central and Peripheral Nervous Systems

Practice fill-in-the-blank flashcards covering the anatomical divisions of the CNS and PNS, cranial and spinal nerves, the reflex arc, somatic vs. autonomic signaling, and the neurotransmitters and receptor profiles of the ANS.

The Central Nervous System (CNS) is comprised of the __________ and the spinal cord.

brain

The three main divisions of the Peripheral Nervous System (PNS) are the somatic nervous system, autonomic nervous system, and __________ nervous system.

enteric

The brain and spinal cord are covered and protected by connective tissue coverings known as the __________.

meninges

The seat of higher functions, such as thought, is located in the __________ of the brain.

forebrain

Essential vegetative functions, such as breathing, are controlled by the __________ of the brain.

hindbrain

In the CNS, the primary excitatory neurotransmitter is glutamate, whereas the primary inhibitory neurotransmitter is __________.

GABA

There are __________ pairs of cranial nerves, which are numbered from the front to the back of the brain using Roman numerals.

$$12$$

The cranial nerve responsible for regulating internal organs and carrying nearly $80\%$ of total parasympathetic flow is the __________ nerve (CN X).

vagus

The spinal cord begins rostrally as a continuation of the __________ oblongata.

medulla

Spinal nerves are classified as mixed nerves because they contain both sensory and __________ axons.

motor

In the spinal cord, motor neuron axons conduct impulses to effectors via the __________ roots.

ventral

The cell bodies of sensory axons entering the spinal cord are clustered within the __________ root ganglion.

dorsal

In the peripheral nervous system, a collection of neuronal cell bodies is defined as a __________.

ganglion

In the somatic sensory system, sensory receptors that detect pain are called nociceptors, while those that detect body position are called __________.

proprioceptors

Somatic sensory neurons transmit information regarding the external environment to the CNS using the neurotransmitter __________.

glutamate

Somatic motor neurons release acetylcholine to trigger rapid contraction by activating __________ cholinergic receptors on skeletal muscle cells.

nicotinic

Unlike the somatic motor system, motor output of the autonomic nervous system is involuntary and innervates cardiac muscle, smooth muscle, and __________.

glands

Autonomic motor pathways characteristically use __________ motor neurons in series between the CNS and the effector organ.

two

The cell body of an autonomic postganglionic neuron is located in an autonomic __________.

ganglion

The sympathetic division initiates the 'fight or flight' response, whereas the parasympathetic division promotes the '__________ and digest' response.

rest

Because dual innervation involves opposing effects between the sympathetic and parasympathetic divisions, this dynamic is known as physiological __________.

antagonism

Sympathetic ganglia are positioned close to the vertebral column, creating a __________ anatomical distance between preganglionic and postganglionic connections.

short

Parasympathetic preganglionic motor neurons originate in nuclei of four brainstem cranial nerves and in the lateral gray matter of the __________ spinal cord (S2–S4).

sacral

Preganglionic neurons in both the sympathetic and parasympathetic divisions release the neurotransmitter __________.

acetylcholine

Postganglionic sympathetic neurons typically release __________ to bind alpha and beta adrenergic receptors on target effectors.

noradrenaline

Postganglionic parasympathetic neurons release acetylcholine onto __________ cholinergic receptors on target tissues.

muscarinic

Sympathetic preganglionic axons diverge widely to stimulate widespread responses, while parasympathetic preganglionic pathways produce relatively __________ effects.

localised

In a spinal stretch reflex arc, activation of the motor neuron contracts the effector muscle while motor output to the __________ muscle is inhibited.

antagonistic

Sensory information conveyed from the body via somatic sensory pathways ascends to the __________ cortex for conscious perception.

somatosensory