Cheat Sheet 16: Nervous System

Nervous System

The highly complex system that is responsible for coordinating our sensory and motor functions by transmitting signals around our body.

Glial Cells

Capable of dividing.

Neuron

Consists of several dendrites, single branched axon, and cell body (soma) - cannot divide.

Oligodendrocytes

Produce myelin in CNS.

Sensory (Afferent)

Receive initial stimulus from environment.

Schwann Cells

Produce myelin in PNS.

Microglia

CNS phagocytes.

Association (Interneuron)

Receive input from sensory and send to motor neuron -- Make up 99% of the body's neurons.

Ependymal Cells

Circulate CSF with cilia.

Satellite Cells

Support cells in PNS.

Motor (Efferent)

From brain, stimulate target cells (effectors) to elicit response.

Dendrites

Receive information to transfer to cell body.

Axon Hillock

Site of action potential generation.

Axon

Transfer impulses away from cell body.

Astrocytes

Physically support CNS neurons; maintain nutrient and mineral balance.

Peripheral Nervous System (PNS)

Utilizes preganglionic/postganglionic axons, various neurotransmitters, and differing receptors to act on the effector organs (targets).

Central Nervous System (CNS)

Contains the brain, spinal cord, and interneurons.

Blood-Brain Barrier

A blockade of cells that prevents or slows the passage of drugs, ions, and pathogens into the CNS; permeable to O2, CO2, glucose, and small non-polar molecules.

Somatic Nervous System

Innervates skeletal muscle.

Forebrain

Largest part of the brain.

Autonomic Nervous System

Controls involuntary bodily functions.

Sympathetic Branch

Involved in fight or flight responses, increasing blood pressure & heart rate, ejaculation, and generation of energy.

Limbic System

Includes hippocampus, amygdala, and hypothalamus; responsible for behavioral and emotional responses.

Cerebrum

Contains cerebral cortex; divided by lobes (telencephalon subdivision).

Diencephalon

Subdivision including thalamus, hypothalamus, and pineal gland.

Frontal Lobe

Responsible for conscious thought (attention).

Parietal Lobe

Responsible for sensory functions; somatosensation, proprioception.

Temporal Lobe

Responsible for sound processing/interpretation.

Occipital Lobe

Responsible for visual input.

Hindbrain

Posterior part of the brain.

Cerebellum

Balance and coordination.

Parasympathetic Branch

Rest and digest functions.

Brainstem

Connects cerebrum to spinal cord.

Pons

Relay center between cortex and cerebellum.

Medulla oblongata

Controls breathing, heart rates, and gastrointestinal activity.

Na+/K+ Pump

Maintains resting potential of -70 mV using ATP.

Resting Potential

-70 mV with K+ higher inside the cell; Na+ higher outside.

Depolarization

Stimulus increases neuron's potential with the opening of gated ion channels.

Repolarization

Polarization is restored with K+ moving out of gated ion channels.

Hyperpolarization

Excess K+ leaving neuron before channels fully close.

Refractory Period

Neuron unresponsive to new stimulus until the Na+/K+ pump returns ions to resting potential locations.

Mechanoreceptors

Respond strongly to their own stimuli and weakly to others; for touch.

Thermoreceptors

Respond to temperature changes.

Nociceptors

Respond to pain.

Electromagnetic Receptors

Respond to light.

Chemoreceptors

Respond to taste, smell, and blood chemistry.

Neurotransmitters

Chemical messengers that transmit signals across a synapse.

Acetylcholine (ACh)

Binds to ACh receptors on post-synaptic membrane for nerve transmission.

Glutamate

Most common CNS neurotransmitter in vertebrates; excitatory.

GABA

Found in brain; inhibitory neurotransmitter.

Glycine

Found in CNS outside brain; inhibitory neurotransmitter.

Epinephrine (E)

Acts in sympathetic nervous system; causes bronchodilation and vasodilation to lungs and skeletal muscles.

Norepinephrine (NE)

Acts in sympathetic nervous system; causes vasoconstriction to the digestive system and kidneys.

Action Potential

All-or-nothing response of a neuron to a stimulus.

Sensory Receptors

Specialized cells that detect and respond to sensory stimuli.

Increased digestion, relaxation, and sexual arousal

Effects of the parasympathetic nervous system.

Voltage-gated Ca2+ channels

Activated by action potential for calcium to enter the neuron.