Central Nervous System (CNS)

Flashcards about the Central Nervous System (CNS), including cell types, organization, protective elements, brain structures, functions, sensory systems, motor systems, states of consciousness, and neurodegenerative diseases.

What are the two basic cell types of the nervous system?

Neurons and glial cells (glia)

What is the function of axons of afferent neurons?

Carry sensory information from peripheral receptors to the CNS

What is the function of axons of efferent neurons?

Carry motor information to the periphery

What is a ganglion?

A collection of cell bodies located outside the CNS

In the spinal cord, what does 'dorsal' refer to?

Sensory

In the spinal cord, what does 'ventral' refer to?

Motor

What are astrocytes?

Star-like cells that physically support neurons, form the blood-brain barrier, and maintain electrolyte balance

What are oligodendrocytes?

Cells that form the myelin sheath around neuronal axons

What are ependymal cells?

Cells that produce cerebrospinal fluid

What are microglia?

Scavengers that ingest bacteria and cellular debris in the CNS

What does gray matter consist of?

Unmyelinated nerve cell bodies, dendrites, and axon terminals

What are nuclei in the context of the CNS?

Clusters of cell bodies in the brain and spinal cord

What does white matter consist of?

Mostly myelinated axons

What are tracts?

Bundles of axons that connect different regions of the CNS

What is the role of cerebrospinal fluid (CSF)?

Provides physical and chemical protection to the CNS

What bone structures protect the brain and spinal cord?

Cranium and vertebral column

What are the three layers of the meninges?

Dura mater, arachnoid mater, and pia mater

What happens in hydrocephalus?

Cerebrospinal fluid accumulates and increases pressure in the CNS

What is the coronal or frontal plane?

Vertical plane that splits the brain into front and back sections

What is the sagittal plane?

Vertical plane that splits the brain into left and right sections

What is the horizontal or transverse plane?

Horizontal plane which splits the brain into upper and lower sections

What are the three main parts of the brain?

Cerebrum, cerebellum, and brainstem

What two major subdivisions does the forebrain develop into?

Cerebrum and diencephalon

What three parts does the hindbrain develop into?

Cerebellum, pons, and medulla oblongata

What is the function of the corpus callosum?

Connects left and right hemispheres of the cerebrum

What are the four major subdivisions of the diencephalon?

Thalamus, epithalamus, hypothalamus, and subthalamus

What is the function of the thalamus?

Integrating center and relay station for sensory and motor information

What is the function of the pineal gland within the epithalamus?

Responsible for melatonin secretion

What is the function of the hypothalamus?

Plays an important role in homeostasis and behavioral drives

What are the functions of the frontal lobe?

Personality, emotions, and control of movement

What is the function of the parietal lobe?

Skin and muscle sensation

What is the function of the occipital lobe?

Vision

What is the function of the temporal lobe?

Hearing and memory functions

What is a primary function of the brainstem?

Connects the cerebrum with the spinal cord

What are key functions of the midbrain?

Eye movements, auditory and visual processing

What are key functions of the cerebellum?

Control of movements and processes sensory inputs to coordinate execution of movement

What are key functions of the limbic system?

Learning, emotion, visceral functions, and integration of endocrine function

What is a dermatome?

Area of skin supplied by a pair of spinal nerves

What is a primary function of the spinal cord?

Conveys signals from sensory receptors to the brain and signals from the brain to effector organs

What is the function of dorsal roots?

Carry incoming sensory information to spinal cord

What is the function of ventral roots?

Carry motor information away from spinal cord

What are the three functionally divided areas of the cerebral cortex?

Sensory, motor, and associative areas

What is a key function of the sensory cortex?

Receiving and interpreting sensory information from different parts of the body

What is a key function of the motor cortex?

Planning, controlling, and executing voluntary movements

What is a key function of the associative cortex?

Integrates generated visual, auditory, gustatory and other general sensory signals

What sensations are part of the somatosensory system?

Touch, pressure, pain, temperature, position, movement, and vibration

What is the sensory pathway?

Stimulus to CNS integration

What do chemoreceptors respond to?

Respond to chemical ligands

What do mechanoreceptors respond to?

Respond to mechanical energy

What do thermoreceptors respond to?

Respond to temperature

What do photoreceptors respond to?

Respond to lights

What do nociceptors respond to?

Respond to noxious stimuli

What is sensory coding?

Coding sensory information for processing

What does the modality of a sensory input refer to?

Type of sensory information transmitted

What are the four distinct somatic modalities?

Touch, proprioception, pain, and thermal sensation

List the receptors for somatic sensation.

Tactile (Meissner's) corpuscle, Tactile (Merkel's) corpuscle, Free nerve ending, Lamellated (Pacinian) corpuscle, and Ruffini corpuscle

Define adaptation in the context of sensory receptors.

Reduction in response in the continuous presence of a stimulus

What are tonic receptors?

Adapt slowly to stimuli and generate action potentials throughout the duration of the stimulus

What are phasic receptors?

Adapt rapidly to stimuli or respond only briefly each time the stimulus changes

What are receptive fields, two-point discrimination, and lateral inhibition?

Mechanisms of localizing a stimulus

What are ascending pathways?

The neural pathways by which sensory information from the peripheral nerves is transmitted to the cerebral cortex

What do motor systems control?

Motor systems control our movements.

List examples of what our movements allow us to do.

Maintain balance and posture, move our eyes, body and limbs and communicate.

What must motor systems do to control behavior?

Convey accurately timed commands to many different muscles, adjust posture, and consider the mechanical arrangement of muscles, bones, and joints

What are the three interrelated organizational principles that motor systems rely on to create movement?

Receive a continuous flow of sensory information, are organized as a hierarchy of control levels(spinal cord, brainstem and cortical motor areas) and are organized in parallel(e.g., multiple parallel systems each involved in a slightly different aspect of control, all contribute to produce smooth coordinated movements)

Motor systems rely on 3 interrelated organizational principles to create movement including what?

Accurately timed commands

What are the 5 brain areas involved in the middle level of motor control?

Sensorimotor cortex, brainstem, cerebellum, thalamus, and basal nuclei (basal ganglia)

What are key brain motor centers?

Cerebral cortex, sensorimotor cortex, and basal nuclei (basal ganglia)

What is the main function of the cerebral cortex in motor control?

Planning and ongoing control of voluntary movements

What is the function of the primary motor cortex?

Executing voluntary movements

What is the function of the premotor area?

Involved in planning and coordinating movements.

What is the function of the somatosensory cortex?

Processes sensory input like touch and proprioception

A somatotopic representation similar to that of the somatosensory cortex exists in the primary motor cortex, the largest amount of neurons are dedicated to what?

The largest proportional dedication of neurons dedicated to their motor control

What are the two main functions of basal nuclei?

Initiate movement and suppress the activity of muscles that would resist the intended movement

What is the role of extrapyramidal system?

Modulate and refine movement, particularly involuntary motor control, posture, and coordination

What are the key functions of the cerebellum in motor control?

Provide timing signals to the cerebral cortex and spinal cord, coordinate movements that involve several joints, and store memories of movements

What is the primary function of descending (motor) pathways?

Carry motor signals from the brain or brainstem to muscles via the spinal cord

What does the pyramidal system consist of?

Consists of the corticospinal and corticobulbar tracts

What do Medullary pyramids contain?

Contains motor fibers from the pyramidal system

What does the two neuron chain - upper motor and lower motor neuron consist of?

Upper motor neuron: originates in brain and Lower motor neuron: leaves spinal cord and travels to skeletal muscle to cause muscle contraction

What is the primary function of the corticospinal tract (CST)?

The transmission of signals for voluntary or willed and skilled movements

What is the primary function of the Corticobulbar Tract (CBT)?

Voluntary control of movements of muscles of the head, face, tongue, neck(pharynx and larynx)

What is coordinated by Axons from neurons in the brainstem?

Used to coordinate the large muscle groups of the trunk and proximal portions of the limbs, in the maintenance of upright posture in locomotion and in head and body movements when turning toward a specific stimulus(involuntary and automatic muscle control[muscle tone, balance, posture, reflexes and locomotion])

What is an EEG?

Measuring of the electrical activity on the scalp using electrodes

What varies with attention, arousal, sleep and dreaming in the context of EEGs?

Wave forms vary with behavioural states, specifically in terms of attention, arousal, sleep and dreaming.

What are the two main phases of sleep?

NREM(non-rapid eye movement) sleep and REM(rapid eye movement)

What does the activation an inhibition control in RAS neurons?

Neurons of the RAS project widely across the cortex and thalamus, influencing EEG patterns. Activation and inhibition of RAS neurons mediate transitions between wakefulness and sleep

What does the Suprachiasmatic nucleus do in the morning and evening?

Activates Orexin -Producing neurons, Regulates Melatonin secretion

What is the function of Orexins?

Maintain the awake state

What part of the brain are Orexins produced?

Brainstem and hypothalamus

Learning and memory

Learning-Acquisition of info. as a consequence of experience. Memory-The relatively permanent storage form of learned info.

What are the durations of short and long term memories?

Short term memory lasts from seconds to minutes and long-term memory can persist for days to years

Key functions of short term memory

Requires ongoing neural activity(graded/action potentials) and is often referred to as working memory when used in cognitive tasks

Memory storage involves __, differing for declaratory memory (facts, events) and procedural memory(skills, habits)

Distinct brain regions

LTP at glutaminergic synapses

Glutamate -Glutamate receptors on the postsynaptic neuron include: AMPA receptors and NMDA receptors

Language as a complex code is

Listening ,seeing ,reading, and speaking involved

What does the left hemisphere specialize in when regarding langauage

conceptualizing and producing speech/writing, neural control of speaking/writing, recent verbal memory

Broca's area is associated with

Motor aspects of speech

Wernicke's area is associated with

Comprehension of language; association of visual, auditory and tactile input with words

Dementia is associated with

Underlying mechanism may be related to a build-up of proteins in the brain that interferes with how the brain functions or works. Different protein build-ups are seen in different types of dementia.