A&P 1 Final Exam Review: Neurons and Sense

Afferent Function

Receive and transmit information

Integrative Function

Process information

Efferent Function

Respond to information

Central Nervous System (CNS)

• Processing and Integration of Information

• brain and spinal cord

Peripheral Nervous System (PNS)

• other branches from CNS

Somatic

• skeletal

• voluntary

Visceral

• internal organs

• involuntary

Neuron

• primary cell of nervous system

• receive, process, respond, and transmit information

Neuroglia

• provide support to neurons

Only neurons in the CNS are

Interneurons

Interneurons role

process and integrate information from afferent neurons

CNS Glial Cells

• Astrocytes

• Oligodendrocytes

• Ependymal Cells

• Microglia

PNS Glial Cells

• Satellite Cells

• Schwann Cells

Astrocytes

• create blood brain barrier

• regulate contents of the ECF/white space

• connect blood vessels and neurons

• most abundant

Oliogodendrocytes

• form myelin sheath in CNS

• myelinate many nerve fibers

Ependymal Cells

• produce cerebrospinal fluid

• have cilia to help circulate CSF

Microglia

• immune defense

• migratory

Satellite Cells

• Surround Soma of PNS neurons

• reset chemical/ion levels in soma

Schwann Cells

• form myelin sheath in PNS

• 1 cell body per axon

Myelin Sheath

• layers of plasma membrane

• insulate axons and increase transmission speeds

Nodes of Ranvier

gaps in the myelin sheath

Myelination

production of myelin sheath

Myelin sheath works by

preventing Na+ leakage between nodes

Saltatory Conduction

signal jumps from node to node only occurring in myelinated axons

Continuous Condutionc

signal must go step-by-step along the axon occurring in unmyelinated axons

fibers that usually do not regenerate

CNS

PNS fiber regenerate under these conditions

• soma intact

• myelin remains

Neurogenesis

development of new neurons from neuronal stem cells

Neurogenesis mostly occurs during

fetal development

Neurogenesis is mostly the development, change, building, and breakdown of

synapses

Chemotaxis

axons and dendrites grow in response to molecular cues, either attractive or repulsive

Examples of an excitatory neurotransmitter

• Acetylcholine

• Epinephrine

• Norepinephrine

Parkinsons Disease

• neurodegenerative disease

• causes dopamine deficiency

Alzheimer’s Disease

• neurodegenerative disease

• associated with ACh deficiencies and nerve growth factor

Neural integration

ability of neurons to process information, store it, and make decisions

Neural Coding

Signals that translate into sensations

Memories

Physical pathways through neurons in the brain

Neurons are organized into

neural circuits

Synaptic Plasticity

ability of synapses to change in response to use/disuse

Synaptic Potentiation

ability to make transmission across synapse easier

Short term memories are essentially due to

elevated Ca2+ levels

short term memories vanish due to

lack of use of synapse

Gray Matter in the brain consist of

• cell bodies

• dendrites

• unmyelinated axons

Gray Matter in the brain is ______

superficial

White matter in the brain consist of

• myelinated bundles of axons

• connects regions of the brain

tracts

myelinated bundles of axons

White matter in the brain is _____

deep

Association Tracts

connects regions of cerebral cortex within a hemisphere

Commissural Tracts

connect one cerebral hemisphere to another

Projection Tracts

connect cerebrum to other parts of the brain and spinal cord

Anterior of the Central Sulcus Function

• motor/executive function

• thinking

Posterior of the Central Sulcus Function

• mostly sensory

Cerebral Cortex Function

higher level processing (thinking + reasoning)

Broca’s Area Function

motor and language

Wernicke’s Area Function

recognition of language

The Diencephalon consist of

Thalamus and Hypothalamus

Thalamus Function

filter information on its way to the cerebral cortex, except for smell, while processing sensory input

Hypothalamus Function

• autonomic and endocrine control center

• hormone secretion

• unconscious, automatic systems, and visceral organs

Ventricles

4 internal chambers within the brain

CSF is produced in

ventricles

CSF

clear liquid that fills ventricles and canals of CNS

CSF Functions

• Buoyancy

• Protection

• Chemical Stability

CSF is derived from

blood plasma

Choroid Plexus

spongy mass of capillaries on floor of each ventricle, blood

Cells that line ventricles and cover choroid plexus

ependymal cells

Role of Ependymal cells and CSF

filter blood to help produce CSF

Blood Brain Barrier

regulates what substances move from blood stream to brain tissue

Neuron need alot of ATP for

Na/K Pumps

Spinal Cord

information highway that connects brain with lower body

Spinal Cord Basic Functions

1. Conduction

2. Neural Integration

3. Locomotion

4. Reflexes

Conduction

 sensory and motor information move up and down the spinal cord

Neural Integration

spinal neurons receive input from multiple sources, integrate it, and execute appropriate output

Locomotion

Spinal cord coordinates repetitive sequences of contractions for walking

Reflexes

involuntary responses to stimuli that are vital to posture, coordination, and protection

In spinal cord gray matter is ____ to white matter

deep

Posterior Horn of Spinal Cord

receives sensory information

Anterior Horn of Spinal Cord

sends information via motor neurons (efferent)

Funiculi

Columns of white matter arranged in the spinal cord

Ascending Tracts usually involve

3 neurons from receptors

Descending tracts usually involve

2 motor neurons

Decussation

crossing of the midline of tracts

Spinothalamic Tract

• Ascending Tract

• receptors → thalamus

Spinothalamic tract is responsible for

pain and temperature signals

Corticospinal Tract

• Descending Tract

• pathway for voluntary motor control

Somatic Reflexes

quick involuntary reactions of skeletal muscle to stimulation

Characteristics of Somatic Reflexes

1. Stimulation required

2. Quick

3. Involuntary

4. Stereotyped

Somatic Reflex Arc

1. Receptor

2. Sensory (afferent) Neuron

3. Integration Center

4. Motor (efferent) Neuron

5. Effector Muscle

The Stretch Reflex

when a muscle is stretched, it fights back and contracts

The stretch reflex is

monosynaptic

Reciprocal Inhibition

prevents muscles from working against each other by inhibiting antagonist when agonist is excited

Flexor (Withdrawal) Reflex

quick contraction of flexor muscle resulting in the withdrawal of a limb from an injurious stimulus

Flexor (Withdrawal Reflex) is

polysynaptic

General Sensations

sensations we feel due to presence of receptors all over the body

Specialized Sensations

sensation due to specialized receptors in the head

Sensation

the activation of sensory receptors and transmission of that information to the CNS via electrical signals

Perception

when the cerebral cortex receives information and assigns meaning to it requiring selective attention

Selective Attention

brain decides what information is of use and what to ignore

Exteroceptors

receptors that respond to stimuli in external environment (somatic)

Internoceptors

receptors that respond to changes in body’s internal environment (visceral)

Chemoreceptors

receptors that respond to chemicals