Neuro Lecture 1

Thalamus - a part of the Diencephalon

relay center

Hypothalamus- a part of the Diencephalon

homeostasis

Epithalamus- a part of the Diencephalon

endocrine glands

Subthalamus- a part of the Diencephalon

movement

Gray Matter

made up of neuron cell bodies, it is the surface of the brain (it is ganglia, nuclei, cortex)

White Matter

made up of axons *wiring of the brain (it is the tract, lemniscus, fasciculus, column, peduncle, capsule

Brainstem

 medulla, pons, midbrain- conveys information between the cerebrum and the spinal cord, integrates information, regulates vital functions such as respiration, heartrate, temperature

• Connects brain to spinal cord

• Coordinates involuntary movements

Cerebellum (back of brain)

two hemisphere connected to each other by a vermis - connected to the brainstem by peduncles - coordinates movements

• Maintains posture, balance, and muscle tone

• Coordinates muscle movement

Cerebrum (front of brain)

 - makes up 85% of the brain

• controls voluntary movement

• Processing center for thought, language, memory, sensory information

• Consist of 2 hemispheres and 4 lobes

Cerebrum lobes

• Frontal

• Parietal

• Temporal

• Occupital

• Limbic

• Insular

Cerebral cortex

gray matter covering the surface of the hemispheres

Corpus collosum

 connects the cerebrum hemispheres

Circle of Willis

•  ring of 9 arteries, main blood supply

Soma - Components of Neurons

• cell body the produces the neurotransmitters

Dendrites - Components of Neurons

• small, short fibers that conduct impulses to the cell body from other neurons - input unit

Axon - Components of Neurons

long single nerve fiber that conducts information/impulses away from the cell body to other neurons

Presynaptic terminals - Components of Neurons

the fingerlike projections that transmit the info

Synaptic cleft - Components of Neurons

• space between neuron where the interneuron communication takes place

Axon hillock - Components of Neurons

•  area in the soma that gives rise to the axon

Myelin sheath - Components of Neurons

•  fatty covering that insulates the fibers to help the impulses flow smoothly

Nodes of ranvier - Components of Neurons

• the breaks in the myelin sheath, exposing the axon, that contain a high density of Na+ channels that contribute to the generation of action potentials

Axoplasmic Transport

the mechanism for transporting neurotransmitters & other substances to and front the soma through the axon to and from the presynaptic terminal

*occurs at various speeds - slows with aging

Anterograde transport

• from the soma to the presynaptic terminal

Retrograde transport

•  from the synapse to the soma

Membrane Channels (4 types)

 channels allows ions (Na+, K+, Cl-, Ca++) to cross the membrane making the electrical potential possible

Leak channels

• allows slow continuous diffusion

Modality-gated channels

open in response to mechanical forces such as stretch, touch, pressure, or thermal or chemical changes - specific to sensory neurons

Ligand-gated channels

 open in response to the binding of a chemical neurotransmitter

Voltage-gated channels

• open in response to changes in electrical potential - important in release of neurotransmitter & formation of action potentials

Depolarization

• the neurons cell membrane potential becomes less negative than its resting potential - increases the possibility that the neuron will generate a transmittable signal - excitatory

Hyperpolarization

•  the neurons cell membrane potential becomes more negative than its resting potential - decreases the possibility that the neuron will generate a transmittable signal - inhibitory

Modulation

• long-lasting changes in the neuron’s electrical potential - causes small changes that alter the flow of ions

Action potential

a large change in the electrical potential of a neuron’s membrane, resulting in rapid spread of an electrical potential 

*transmits info over longer distances

*the meaning of the signal is determined by the neural pathway along which it is conducted

Afferent (sensory) neurons - Categories of Neurons based on information flow

• receive information from inside and outside the body and send impulses to the spinal cord and brain

Interneurons - Categories of Neurons based on information flow

• found throughout the brain and spinal cord - relay impulses from sensory to motor neurons - outnumber all other neurons in the body

Efferent (motor) neurons - Categories of Neurons based on information flow

• conduct impulses from the brain and spinal cord to muscles or glands throughout the body

Convergence - Interactions between Neurons

• the process by which multiple inputs from the variety of cells terminate on a single neuron

Divergence - Interactions between Neurons

• the process by which a single neuron branches out to many cells

*both contribute to the distribution of information throughout the nervous system

Astrocytes - type of Glia cell

•  star-shaped provide physical & nutritional support to neurons by cleaning up, transporting nutrients, holding neurons in place, regulating the extracellular space

Oligodendrocytes - type of Glia cell

 from the myelin for the CNS neurons

Schwann Cells - type of Glia cell

form the myelin for the PNS neurons

Microglia Cells - type of Glia cell

• the immune system for neurons, digesting dead neuron parts

Neuroinflammation

CNS response to infection, disease, and injury

Beneficial glia roles

remove debris, support regeneration/myelination, reseal blood brain barrier, provide trophic support

Harmful glia roles

• overactivity releases toxic compounds, stimulate cellular breakdown

Neutral Stem Cells

Neural stem cells give rise tot he different types of cells in the CNS - neurons, astrocytes, & oligodendrocytes

*Stem cells give the ability to:

• Self-renew

• Differentiate into most types of neurons & glial cells

• Populate developing & degenerating regions of the central nervous system

Synapse

• Electrical impulse passes through the cell body down through the axon which releases neurotransmitter from its tip across the synapse and is picked up by the dendrites of the next neuron

Excitatory(EPSP) - Postsynaptic Potentials

•  electrical depolarization of a neurons cell membrane initiated by the binding of a neurotransmitter to receptors & produced by the instantaneous flow of Na+, K+, or Ca++ into the cell

Inhibitory(IPSP) - Postsynaptic Potentials

• electrical hyperpolarization of a cell membrane initiated by the binding of a neurotransmitter to receptors & produced by the instantaneous flow of Cl into the cell and/or K+ out of the cell

Presynaptic Facilitation

• the excitatory process by which transmitter released by one axon terminal causes the second axon to release a greater than normal amount of neurotransmitter

Presynaptic Inhibition

•  the inhibitory process by which transmitter released by one axon terminal causes the second terminal to release a lower than normal amount of neurotransmitter

Acetylcholine - type of neurotransmitter

• skeletal muscle contraction, pleasure/reward cognition

Glutamate - type of neurotransmitter

learning/memory

Glycine - type of neurotransmitter

CNS inhibitory, calming, muscle and brain support

GABA - type of neurotransmitter

inhibition, sedation, antianxiety, antiseizure, sleep inducing

Dopamine - type of neurotransmitter

motor activity, cognition, behavior, reward

Norepinephrine - type of neurotransmitter

•  sympathetic ANS, vigilance, mood

Serotonin - type of neurotransmitter

sleep, mood, appetite, arousal levels

Histamine - type of neurotransmitter

wakefulness, attention

Opioid peptides - type of neurotransmitter

pain modulation

Substance P - type of neurotransmitter

pain alert, mood regulation

Nitric Oxide - type of neurotransmitter

vascular regulation