Quiz 6 15 Organization of the NS, Basic fxns of Synapses, Neurotransmitters

A set of flashcards covering the organization of the nervous system, neuron structure, central and peripheral divisions, autonomic functions, and synaptic physiology.

How many neurons are contained in the central nervous system?

More than 100 billion neurons.

What is the basic functional unit of the central nervous system?

The neuron.

What are the two major components of the central nervous system (CNS)?

The brain and the spinal cord.

Which division of the nervous system carries information from receptors to the central nervous system?

Sensory (Afferent) Division.

What does the somatic sensory division specifically monitor?

The skin, muscles, and joints.

What does the visceral sensory division monitor?

Internal organs.

Which division of the nervous system carries commands away from the central nervous system?

Motor (Efferent) Division.

Which system provides voluntary control over skeletal muscles?

Somatic Nervous System.

What neurotransmitter is used by the single motor neuron in the somatic nervous system?

Acetylcholine (ACh).

What is the function of the autonomic nervous system?

Involuntary control of cardiac muscle, smooth muscle, and glands.

What type of pathway characterizes the autonomic nervous system?

A two-neuron pathway consisting of preganglionic and postganglionic neurons.

What is the common nickname for the sympathetic division?

"Fight or Flight".

What is the common nickname for the parasympathetic division?

"Rest and Digest".

Which system is responsible for controlling gastrointestinal function?

Enteric Nervous System.

Through which structures do incoming signals mostly enter a brain motor cortex neuron?

Synapses located on the neuronal dendrites and the cell body.

What is the maximum number of synaptic connections an input fiber might make with a single neuron?

Up to $200,000$ synaptic connections.

Through what single structure does an output signal leave a neuron?

A single axon.

What is the function of motor neurons?

They take nerve impulses from the CNS to muscles or glands.

What structural type characterizes motor neurons in the transcript?

Multipolar.

What is the function of sensory neurons?

They take nerve impulses from sensory receptors to the CNS.

What structural type characterizes sensory neurons in the transcript?

Unipolar.

Where are interneurons (association neurons) located?

Entirely within the CNS.

What is the function of dendrites?

To receive stimuli and carry it to the cell body.

What is the function of the cell body (soma)?

It is the site of cellular activity.

What is the primary function of the myelin sheath?

To increase the speed of action potential conduction.

What are the gaps between Schwann cells along an axon called?

Nodes of Ranvier.

What is saltatory conduction?

The process where a nerve impulse jumps from node to node along an axon.

On which side do sensory nerves enter the spinal cord?

The dorsal side.

Where are the cell bodies of sensory nerves located?

Outside the spinal cord in the Dorsal Root Ganglia.

Where do motor nerves exit the spinal cord?

The ventral side.

Where are the cell bodies of motor nerves located?

Within the gray matter of the spinal cord.

What are the four components of the brain as listed in the CNS organization?

Cerebrum, Cerebellum, Brainstem (midbrain, pons, medulla), and Spinal cord.

What tissues are included in the Peripheral Nervous System (PNS)?

All nervous tissue outside the CNS, including cranial nerves, spinal nerves, peripheral nerves, sensory receptors, and ganglia.

How many pairs of spinal nerves are there?

$31$ pairs.

How many pairs of cranial nerves are there?

$12$ pairs.

What are the two main functions of the PNS?

Carrying sensory information to the CNS and conducting motor commands from the CNS to muscles and glands.

What does proprioception refer to in the sensory division?

The sense of body position and movement.

Which system can generate coordinated gastrointestinal tract activity without direct input from the CNS?

The Enteric nervous system.

What are the two components of the cerebrum mentioned in the transcript?

The telencephalon and the diencephalon.

What is the largest part of the brain?

The cerebrum.

What structure connects the two hemispheres of the cerebrum?

The corpus callosum.

Which lobe of the cerebral cortex controls decision-making, personality, and voluntary movement?

The Frontal Lobe.

Which lobe processes sensory information like touch, temperature, and spatial awareness?

The Parietal Lobe.

Which lobe handles hearing, language comprehension, and memory storage?

The Temporal Lobe.

Which lobe is primarily responsible for visual processing and recognition?

The Occipital Lobe.

What brain region surrounds the third ventricle?

The diencephalon.

What is the function of the thalamus?

It serves as a sensory relay station.

What are the functions of the hypothalamus?

Homeostasis and endocrine control.

What is the role of the epithalamus?

It contains the pineal gland and regulates sleep.

What is the function of the subthalamus?

Motor control.

Where is the cerebellum located?

Behind the brainstem.

What are the primary functions of the cerebellum?

To monitor and regulate movement, integrate postural adjustments, maintain equilibrium, and perceive speed.

What three structures compose the brainstem?

The midbrain, pons, and medulla oblongata.

What is the primary role of the brainstem?

Maintaining vegetative functioning.

Where is the core gray matter located in the spinal cord and what is its shape?

It is in the core of the cord and is H-shaped.

Into what are the white matter regions of the spinal cord separated?

Columns.

What do ascending tracts in the spinal cord columns carry?

Sensory information up to the brain.

What do descending tracts in the spinal cord carry?

Motor commands from the brain.

What is gray matter primarily made of?

Cell bodies and dendrites of nerve cells, interneurons, and terminal portions of axons.

What does white matter contain?

Tracts or pathways made of bundles of myelinated nerves.

Which tract transmits impulses downward to excite motoneurons that control muscles?

The Pyramidal tract.

Where do extrapyramidal tracts originate and what is their function?

They originate in the brain stem and control posture.

What sensory information is carried by the dorsal column–medial lemniscus pathway?

Fine touch, vibration, and proprioception.

What information is carried by the spinothalamic tract?

Pain, temperature, and crude touch.

What is the function of spinocerebellar tracts?

Unconscious proprioception.

What is the function of the corticospinal tract?

Voluntary movement.

What is the purpose of the reticulospinal tract?

Posture and locomotion.

What movements are controlled by the tectospinal tract?

Reflex head and neck movements.

In neuroanatomy, what is the definition of a 'tract'?

A bundle of axons located within the brain or spinal cord.

In neuroanatomy, what is the definition of a 'nerve'?

A bundle of axons located outside the central nervous system.

Which glial cell is associated with tracts in the CNS?

Oligodendrocytes.

Which glial cell is associated with nerves in the PNS?

Schwann cells.

What structure serves as the CNS-PNS interface for cranial nerves?

The brainstem.

What structure is considered the 'bridge' that functionally links the CNS and PNS?

The spinal nerve.

Define the nerve property of 'Irritability'.

The ability to respond to stimuli.

Define the nerve property of 'Conductivity'.

The ability to transmit electrical potential along the axon.

What activates most activities of the nervous system?

Sensory experiences that excite sensory receptors.

Where does somatic sensory information enter the CNS?

Through peripheral nerves.

What comprises the 'Skeletal motor nerve axis' levels of control?

The spinal cord, reticular substance, basal ganglia, cerebellum, and motor cortex.

What type of fiber leaves the CNS in an autonomic motor pathway?

A preganglionic fiber.

What type of fiber innervates the effector in an autonomic motor pathway?

A postganglionic fiber.

What neurotransmitter do sympathetic adrenergic fibers release?

Epinephrine.

What is the origin of the sympathetic nervous system in the spinal cord?

Thoracolumbar (segments $T1-L2$).

What is the origin of the parasympathetic nervous system?

Craniosacral (Brainstem: $CN III$, $VII$, $IX$, $X$; Sacral: $S2-S4$).

Compare the preganglionic fiber lengths of the Sympathetic and Parasympathetic systems.

Sympathetic preganglionic fibers are short; Parasympathetic preganglionic fibers are long.

Compare the postganglionic fiber lengths of the Sympathetic and Parasympathetic systems.

Sympathetic postganglionic fibers are long; Parasympathetic postganglionic fibers are short.

Where are sympathetic ganglia located?

Near the spinal cord (sympathetic chain and collateral ganglia).

Where are parasympathetic ganglia located?

Near or within the target organ.

What is the neurotransmitter for preganglionic neurons in both ANS divisions?

Acetylcholine (ACh).

What is the primary postganglionic neurotransmitter for the sympathetic nervous system?

Norepinephrine (NE).

What is the postganglionic neurotransmitter for the parasympathetic nervous system?

Acetylcholine (ACh).

What percentage of all parasympathetic nerve fibers are found in the Vagus nerves ($CN X$)?

About $75\%$.

What is the effect of the sympathetic division on the pupil?

It dilates the pupil.

What is the effect of the parasympathetic division on the heart?

It slows the heartbeat (decreases cardiovascular activity).

What is the effect of sympathetic activation on the airways?

Bronchodilation (relaxes airways/increases diameter).

What is the effect of the sympathetic division on digestion?

It inhibits digestion.

What is the effect of sympathetic activation on blood glucose?

It increases blood glucose levels.

Contrast the functional units of the somatic and autonomic motor systems.

Somatic: Motor unit; Autonomic: Autonomic reflex arc.

What is an example of a monosynaptic reflex arc?

The knee jerk response (Patella Tendon Reflex).

What is an example of a complex reflex involving multiple synapses?

The crossed extensor reflex.