Nervous System and Higher Brain Functions

Vocabulary flashcards covering the Autonomic Nervous System, Membrane Potentials, Action Potentials, Synaptic Transmission, Brain Anatomy, and Sensory Systems based on lecture notes.

Homeostasis

The maintenance of a stable internal environment to which the autonomic nervous system plays a critical role.

Gap junction

A method of direct communication between cells.

Indirect cell communication

Communication occurring via paracrine signaling, neurotransmitter secretion, hormone selection, and neurohormone secretion.

Endocrine signaling

Acts via hormones and neurohormones secreted into the blood to control processes relying on duration rather than speed.

Central nervous system (CNS)

The division of the nervous system consisting of the brain and spinal cord.

Enteric nervous system (ENS)

The nerve network specifically of the digestive tract.

Somatic nervous system

Fibers of the motor neurons that supply the skeletal muscles.

Autonomic nervous system

Fibers that innervate smooth muscle, cardiac muscle, and glands; regulates internal processes outside of conscious awareness.

Autonomic nerve pathway

Consists of a two-neuron chain including a preganglionic fiber and a postganglionic fiber.

Sympathetic pathway

A pathway utilizing $ACh$ (Acethylcholine) followed by $NE$ (Norepinephrine) or $E$ (Epinephrine).

Parasympathetic pathway

A pathway utilizing $ACh$ followed by $ACh$.

HPA axis

The axis involving the release of cortisol to help the body resist stress.

Diffusion

The process of movement of molecules under a concentration gradient due to random collisions.

Electrochemical gradient

The combined force of concentration (chemical) gradients and electrical gradients (electrostatic force).

Membrane potential

A separation of opposite charges across the plasma membrane.

Equilibrium potential for K+

$$-90\,mV$$

Equilibrium potential for Na+

$$+60\,mV$$

Resting membrane potential

$$-70\,mV$$

Leak channels

Channels that permit ions to diffuse down concentration gradients.

Na/K ATPase

Pumps $3\,Na^{+}$ out of the cell for every $2\,K^{+}$ pumped into the cell.

Depolarization

A change in membrane polarization to more positive values than rest.

Repolarization

Return to resting membrane potential after depolarization.

Hyperpolarization

A change in membrane polarization to more negative values than rest.

Action Potential

A brief all-or-nothing reversal in membrane potential lasting approximately $1\,ms$ brought about by rapid changes in permeability to $Na^{+}$ and $K^{+}$ ions.

Voltage-gated Na+ channel

Opens quickly in less than $0.5\,ms$ in response to depolarization; responsible for the rising phase of the Action Potential.

Voltage-gated K+ channel

Opens more slowly in response to depolarization allowing $K^{+}$ to flow out; responsible for the falling phase and after hyperpolarization.

Contiguous conduction

Propagation of action potentials in unmyelinated fibers by the spread of locally generated current to adjacent regions.

Saltatory conduction

Propagation of action potentials in myelinated axons by jumping from node to node.

Multiple sclerosis

An autoimmune disease where the defense system attacks the myelin sheath, slowing impulse transmission.

Graded potential

Potentials that occur in varying degrees of magnitude, die out over short distances, and correlate with stimulus size.

Electrical synapses

Neurons connected directly by gap junctions.

Chemical synapses

Uses a chemical messenger to transmit information one way across a space separating two neurons.

Convergence

The synaptic input of many neurons onto one neuron.

Divergence

The synaptic output of one neuron onto many neurons.

Temporal summation

The additive effect of Postsynaptic Potentials (PSPs) occurring close together in time.

Spatial summation

The additive effect of PSPs occurring together on nearby parts of the same cell.

Presynaptic inhibition

Synaptic inhibition of a synaptic terminal causing a decrease in transmitter release.

Cerebral cortex: Frontal lobe

Contains the Primary motor cortex.

Cerebral cortex: Parietal Lobe

Contains the Somatosensory cortex.

Cerebral cortex: Occipital Lobe

Contains the Primary Visual cortex.

Cerebral cortex: Temporal Lobe

Contains the Primary Auditory cortex.

Thalamus

A sensory relay station important in motor control.

Hypothalamus

Regulates many homeostatic functions and contains pre-sympathetic neurons activated by stress.

Brain stem

Link between spinal cord and higher regions; controls cardiovascular, respiratory, and digestive function.

Optic disc

The area where no image can be detected because it lacks photoreceptors.

Fovea

Area of high acuity and most distinct vision.

Rhodopsin

Found in photoreceptors; consists of Opsin + Retinal.

Rods

Photoreceptors sensitive to low light (scotopic) that serve low acuity and peripheral vision.

Cones

Photoreceptors sensitive to bright light (photopic) that distinguish wavelengths and serve high acuity central vision.

Cochlea

Location of auditory receptors (hair cells).

Pitch

Auditory discrimination depending on the region of the basilar membrane that vibrates.

Loudness

Auditory discrimination depending on the amplitude of vibration of the basilar membrane.

Nociceptors

Somatosensory receptors for pain.

Proprioception

Sense of body position mediated by mechanoreceptors.

Receptive field

A restrictive area where a specific sensory neuron responds to stimulus information.

Lateral Inhibition

Inhibition of adjacent neurons in a map to facilitate localization of stimuli and sharpen contrast.

Acetylcholinesterase (AChE)

Enzyme localized in the synaptic cleft that degrades $ACh$.

Cerebellum

Controls motor coordination by comparing intended movement with actual movement and making adjustments.

Basal Ganglia

Large nuclei involved in motor planning and the initiation of motor sequences.

Parkinson’s Disease

Disease destroying dopaminergic neurons in the basal ganglia, causing difficulty initiating movements and resting tremors.

Wernicke's Area

Cerebral cortex area responsible for language comprehension.

Broca's Area

Cerebral cortex area responsible for speech production.

Hippocampus

Part of the limbic system involved in memory formation and spatial guidance of behavior.