PHYS335: Lab 3

Neuron

functional unit of nervous system

Nerve

group of neurons bound together by connective tissue within PNS

CNS

brain and spinal cord

PNS

everything else in nervous system beyond CNS; contains an afferent and efferent division

Afferent division

 part of PNS moving at/towards CNS (somatic sensory, visceral sensory, special sensory)

Efferent division

part of PNS moving away from CNS (somatic motor, autonomic motor)

Dendrite

many extensions from cell body of neuron dedicated to receiving info

Axon hillock

where axon begins to branch from cell body

Axon

part of neuron that sends signal to neighboring cells

Axonal transport

moves things like neurotransmitter vesicles from cell body to axon terminals

Afferent neuron

sensory neuron; begins in PNS, ends at CNS

most rare!

Interneuron

neurons all contained within CNS

most common!

Efferent neuron

motor neuron; begins in CNS, ends at PNS

Presynaptic neuron

neuron that SENDS signal at synapse

Postsynaptic neuron

neuron that RECEIVES signal at synapse

Glial cells

constitute ½ cells in nervous system

Oligodendrocyte

glial cell that creates and maintains myelin wrappings around axons in CNS (1 cell = 40 myelin wrappings)

Astrocyte

glial cell that regulates extracellular fluid conditions; important in forming blood/brain barrier

Microglia

glial cell that is protector! Removes potentially deleterious invaders (modified immune cells)

Ependymal cells

glial cell that lines fluid filled cavities and manufactures/regulates cerebrospinal fluid

Schwann cell

makes myelin wrapping in PNS (1 cell = 1 wrapping)

Forebrain

 part of brain containing cerebrum (4 lobes), diencephalon (thalamus/hypothalamus)

Thalamus

relay station contained in brain’s diencephalon

Hypothalamus

master regulator of homeostasis contained in brain’s diencephalon

Brainstem

midbrain, pons, and medulla oblongata

contribute to basic life support

Cerebellum

part of brain responsible for maintenance/regulation of ongoing motor programs; important for posture

White matter

myelinated axons that, IN THE BRAIN, are on the inside

Gray matter

cell bodies that, IN THE BRAIN, are on the outside; component that is 6 cell layers thick!

Cerebral cortex

contains gyri and sulci to increase surface area

Basal nuclei

deep cluster of cell bodies that affect input and output to and from cortex

Pituitary gland

master gland of endocrine system located in brain

Limbic system

collection of connected structures associated with learning, emotion, behavior, and other visceral/endocrine functions

Hippocampus

part of the limbic system responsible for learning and memory

Dorsal root

part of spinal cord responsible for afferent input

Dorsal root ganglion

cell bodies of sensory afferent neurons are located here

Ganglion

cluster of neuronal cell bodies outside of CNS

Gray matter

WITHIN SPINAL CORD, containing interneuron and efferent neuron cell bodies

White matter

LINING OUTSIDE OF SPINAL CORD, containing myelinated axons arranged in tracts

Ventral root

part of spinal cord responsible for efferent output

Ascending tract

overall path of sensory information from periphery to brain (through spinal cord)

Descending tract

overall path of motor information from brain to effector organs (through spinal cord)

43

___ paired nerves carry info to and from CNS.

Spinal nerves

contain both afferent and efferent axons

all have somatic components, some have visceral components; 31 total

8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal

List the regional breakdown of spinal nerves.

Electrical potential

when electrical charges of opposite sign are separated, they have potential to do work

High; ion channels are low resistance pathways

Phospholipid bilayer has (high/low) electrical resistance.

Ohm’s law

voltage = current * resistance

PHYSIOLOGY: I = g x (vm – eion)

Current (ion) = (conductance) x (voltage membrane – equilibrium potential of ion)

-70mV

typical resting membrane potential of neuron

Electrochemical gradient

describes both how membrane potential (electro) and concentration (chemical) gradients affect ion movement

Equilibrium potential

the membrane potential at which chemical concentration flux and electrical flux are equal in magnitude but opposite in direction

NO NET FLUX

Nernst equation

61/2 log [concentration(out)/concentration(in)]

Current

WRT Ohm’s law, an example of this concept is the movement of positive ions across cell membrane into cell

Resistance

WRT Ohm’s law, an example of this concept is if all anion channels in a cell were to close, preventing anions from crossing cell membrane

Membrane potential; concentration

When ions flow across the cell membrane, the ___  may change, even though relative __ may not change as much.

CN II

cranial nerve that carries input from receptors in eye

CN IX

cranial nerve that innervates skeletal muscles involved in swallowing and parotid salivary gland

transmits information from taste buds at back of tongue and receptors in auditory-tube skin; also transmits information from carotid artery baroreceptors and chemoreceptors that detect changes in blood gas levels

CN X

cranial nerve that innervates skeletal muscles of pharynx/larynx and smooth muscle/glands of thorax/abdomen

transmits information from receptors in thorax/abdomen

CN XI

cranial nerve that innervates sternocleidomastoid and trapezius muscles in neck