HSCI 210: Nervous System

nervous system

send electrical signals between brain & rest of body to regulate bodily functions, brain + spinal cords + nerves, organ system, maintains constant optimal conditions to ensure enzymes/cells work properly (homeostasis), controls electrical & chemical signals

neuron (nerve cell)

transmit electrical impulses around body, unable to be replaced

• types: sensory/motor/relay

• group of neurons = 1 nerve

soma/cell body

contains nucleus & organelles for neuron to process information

axon

long fiber/tail like portion of neuron, transmits electrical signal away to another neuron/target tissue

dendrites

branches of neuron coming off soma, receive impulses from other neurons,

myelin sheath

fatty sheath to insulate axon, speed up message transmission, takes long to carry messages around body, only some neurons have, in both CNS/PNS

multiple sclerosis

auto-immune disorder, body attacks own myelin sheath, muscles dont receive messages

• symptoms: numbness, difficulty walking, vision problems

• treatment: slow progression & manage symptoms, medication, stem cell transplantation, plasmaphoresis (clean own plasma), no known cure

relapsing/remitting multiple sclerosis stage

bad & good peaks

secondary progressive multiple sclerosis stage

bad & good peaks but quicker rate of disability

primary progressive multiple sclerosis stage

constantly gets worse

progressive relapsing multiple sclerosis stage

steeper & even worse peaks

unipolar

neuron where cell body attached to axon (1 pole), mostly sensory neurons, touch/temperature/pain

bipolar (sensory)

neuron where cell body attached to dendrite above & axon below (2 poles), vision/hearing/smell/taste/equilibrium

multipolar

neuron where cell body attached to multiple dendrites above & axon below (multiple poles), receive/integrate/transmit info, sensory/perception/motor control, found in CNS & some in PNS

glial cells

structural & metabolic support for neurons in CNS + PNS

oligodendrocytes

cells that make myelin sheath in central nerves

schwann cells

cells that make myelin sheath in peripheral nerves

synapses

regions where nerves communicate with each other & other receptors, axon terminal + dendrite

chemical synapse

neurotransmitters (chemicals) cross synaptic cleft to pass message to another neuron, found in CNS/PNS neuromuscular junctions (neuron + muscle) & glands

electrical synapse

action potential (electrical signals) pass through gap junctions to pass message to another neuron, found in CNS & smooth/cardiac muscle

continuous action potential propagation

slow signal sent through neuron, dont have myelin sheath

saltatory action potential propagation

fast signal sent through neuron, have myelin sheath (jumps between myelin in nodes of ranvier)

receptor

specialized cells that detect stimulus (change in environment), stimulate chemical impulses in response, sense organs respond to stimuli, ex: skin/tongue/nose

effector

muscles/glands that produce targeted response to stimulus, ex: gland release hormone to blood/muscle contract to move leg/secretion of saliva from salivary gland

stimulus pathway

1. stimulus to receptor

2. sensory/afferent neuron

3. interneuron

4. motor/efferent neuron

5. response from effector

sensory/afferent neuron

sends message in toward body, feeling

motor/efferent neuron

sends message out away from body, doing

reflex

different types of neurons create autonomic/rapid response to stimulus to immediately reduce risk of danger, doesnt involve conscious part of brain

reflex arc

receptor sends signal to spinal cords & goes directly to effector, monosynaptic (sensory neuron directly connects to motor neuron), involuntary, creates immediate response, involves CNS & PNS (never travels to brain)

central nervous system (CNS)

brain + spinal cord, receives & sends messages to/from body via spinal cord

white matter

mostly myelinated axons (sends quick message), connects brain regions to help learning/attention/motor control, peaks in middle age

gray matter

mostly neuronal cell bodies (soma), unmyelinated, transfer & process info, controls movement/memory/emotion, fully developed in 20s

meninges

connective tissue covering brain & spinal cord

dura mater

outermost protective connective tissue layer, between skull & brain/spinal cord & vertebrae

arachnoid mater

thin middle layer, resembles spider web, loose & acts as cushion

subarachnoid space

area between arachnoid & pia mater, contains large amount of cerebrospinal fluid

cerebrospinal fluid (CSF)

water cushion, consistent circulation bewteen brain & spinal cord

pia mater

inner most layer, tightly bound/continuous to brain & spinal cord (unremoveable)

meningitis

inflammation of meninges

spinal tap

draw out cerebrospinal fluid from subarachnoid space to look for meningitis

epidural injection

pain relief for labor, needle inserted between vertebral bones & above dura mater, steroid placed in epidural space

epidural space

fatty layer above dura mater

brain

controls thought/learning/movement/feeling, frontal/parietal/temporal/occipital lobe

cerebrum

superficial part of brain (hills & valleys)

sulcus/sulci

valley/fold on cerebrum

gyrus/gyri

hill/ridge on cerebrum

central gyrus

transverse valley that divides cerebrum into anterior/posterior halves

homunculus

maps of sensory/processing area on cerebral cortex (outer layer of cerebrum)

primary motor cortex

in precentral gyrus (ventral), muscle motions based off senses

primary sensory cortex

in postcentral gyrus (dorsal), senses feelings

corpus callosum

connects 2 hemispheres of brain to integrate information, white matter nerve tracks (myelinated)

damaged corpus callosum

impulses cant cross brain, developmental delays, seizures, challenges with hand-eye coordination/balance/problem solving

• caused by: aging, strokes, infections, infant seizures, fetal alcohol syndrome

diencephalon

deeper brain structures that manage bodily functions without thinking, balance homeostasis, “primary brain”, thalamus + hypothalamus

hypophysis

pituitary gland

basal ganglia

collection of nuclei deep/central of brain, regulates voluntary movement/habit formation/emotions/learning/eye movement

parkinsons disease

progressive loss of cells in substantia nigra, motor & non-motor impairments

substantia nigra

in basal ganglia, provides dopamine to basal ganglia

brain stem

control involuntary systemic processes that sustain life, has gray matter (nuclei of cranial nerves & reticular formation) & white matter (afferent/sensory tracts & efferent/motor tracts)

peripheral nervous system

nerves carry info to/from CNS, sends messages from nervous system to where it is needed

• autonomic nervous system

  • sympathetic nervous system

  • parasympathetic nervous system

• somatic nervous system

  • sensory/afferent input

  • motor/efferent output

autonomic nervous system

involuntary control

sympathetic nervous system

fight or flight

parasympathetic nervous system

rest & digest

somatic nervous system

voluntary control