by Isabella R 4 years ago
345
The Nervous System
by Isabella R 4 years ago
345
caused by large deposits of beta amyloid proteins
starts off slowly + progressively gets worse
general term for memory loss + other intellectual abilities
common cause of dementia
caused by degeneration of dopamine-releasing neurons in area of midbrain that coordinates muscle movement
affects primarily physical activity
progressive degenerative disorder
appears during childhood or adolescence
fatigue, stress or flashing lights may trigger seizures
characterized by transient, recurring bouts of abnormal brain cell activity
symptoms include swollen lymph glands, painful swallowing, vomiting, choking, fever + mental derrangement
goes from sensory neurons to brain where it multiplies + kills cells
transmitted by direct contact
infections viral brain disease in mammals
inflammation of meninges b/c of viral or bacterial infection
symptoms include headache, fever, fatigue, hallucination, confusion, trouble speaking + remembering, + seizures
caused by herpes + HIV
inflammation of brain
injuries to neck cause quadraplegia (legs, arms, trunk)
injuries below neck cause paraplegia (legs + trunk)
impairs sensation + body function below injured area
biggest danger is subdural hematoma or hemorrhage
bleeding increases pressure within skull + disrupts function
brief period of unconsciousness where electrical activity of neurons is disrupted
violent blow to head or neck
Ventral Root
motor neurons carry AP away from spinal cord to rest of body
Dorsal Root
sensory neurons transmit incoming AP
Hypoglossal
speech + swallowing (tongue muscles)
Accessory
swallowing + movement of head + shoulders
Glossopharyngeal
taste, swallowing, speech + salivation
Vagus
taste, sensations from pharynx, swallowing, coughing, voice, GI tract smooth muscle contraction, heart rate reduction, digestive secretion
Vestibulocochlear
equilibrium + hearing
Facial
taste, facial expressions, tears, salivation + facial sensations
Abducens
Trigeminal
sensations in head, face + jaw, motor control of chewing
Trochlear
movement of eyeball
Oculomotor
movement of eyelid, eyeball, lens, pupil constriction
Optic
vision
Olfactory
sense of smell
Presynaptic membrane is the cell membrane of a neuron that is sending info
Postsynaptic membrane is the cell membrane of a neuron that receives info
muscle cells do not process + integrate info like postsynaptic neurons
too big
muscle cells receive input from 1 neuron (no converging inputs)
whether synaptic connections are excitatory or inhibitory
how many neurons form synapses
stimulus intensity
ready for another action potential
potassium channels close
K moves out
makes interior of axon negative again
K channels open
Na channels close
triggered by influx of Na
inside membrane becomes (+) inside
moves voltage closer to 0
Na goes into axon
Na channels open
threshold is exceeded
neurons that have axons wrapped in myelin sheaths
uninsulated gaps b/w schwann cells (surface of the axon is exposed)
produce myelin sheaths around axons
helps regenerate damaged or severed axons in PNS
speeds up transmission of impulses
causes action potentials to jump from node to node fast
saltatory conduction
saves neuron energy
prevents inward leak of Na + outward leak of K
carries signals from CNS to PNS that control internal organs
contains motor neurons carrying info to smooth or cardiac muscle + all other tissue organs EXCEPT skeletal muscle
controls smooth muscle, cardiac muscle + glands
Sympathetic
prepares body for emergencies
releases norepinephrine
provide unified responses
originate in thoracic + lumbar regions of spinal cord
innervate smooth + cardiac muscle, glands, epithelial cells of kidneys + every organ
regulate body functions
function automatically
Parasympathetic
lets your body relax
releases acetylcholine
becomes part of outflow of cranial nerves
originate in brain
Somatic Division
controls voluntary + involuntary skeletal muscle movements
Spinal Reflexes
involuntary responses that are mediated by spinal cord + nerves
4. causes flex of appropriate muscles + lift your foot
called flexor (withdrawal) reflex
3. sensory neurons stimulate interneurons within spinal cord + signals brain + then motor neurons in leg
2. produces action potentials in sensory neurons travelling to spinal cord
1. person steps on sharp objects + activates pain receptors
signals from internal organs
signals from skin, tendons + muscles
signals from external environment
users begin to crave feelings associated with drug or alter their behaviour to obtain it
either bind or affect their release action or reuptake in some way
cocaine blocks reuptake of dopamine
left + right brains connected by corpus callosum
allows hemispheres to share sensory + motor info
inner portion mostly white matter that connects to lower brain areas
Cerebral Cortex
Frontal Lobe
initiates motor activity, speech + thought
most developed lobe
Occipital Lobe
processes visual info
Temporal Lobe
interprets info comprehends written + spoken language + responsible for judgement
Parietal Lobe
primary somatosensory area
primary motor areas initiates motor activity
less sensitive body parts (thigh)
involve fewer neurons + smaller portions
sensitive body parts (lips + genitals)
involve more neurons + larger portions
receives sensory input from skin
gray matter consisting of neurons w/ unmyelinated axons + their associated neuroglial cells
responsible for memory storage, though, conscious awareness + conscious control of muscles
receives, integrates + interprets sensory info from all organs
outer layer of the cerebrum
associated with language, decisions making + conscious thought
most highly developed region of the brain
when different areas are over stimulated we experience strong feelings + emotions
feelings + emotions influence behaviour
describes all neuronal structures that control emotional behaviour + motivational drives
sends signals to the cerebrum
integrates + relays some outgoing motor activity
receives, processes + transfers info
regulates homeostasis by monitoring sensory signals
lets us know when we are hungry or thirsty
coordinates functions for pituitary gland
Sleep Center
Stages of Sleep
3. Rapid Eye Movement (REM)
when we dream, eyes move rapidly, heart rate, respiration + blood flow to brain increases, + most skeletal muscles go limp to prevent us from responding to our dreams
2. Deep Sleep
muscles relax, heart rate + respiration slow + body temperature falls
1. Wakefulness
steady stream of action potentials get transmitted to cerebrum
group of neurons comprise it + release serotonin that induces sleep by inhibiting neurons that arouse the brain
aids medulla oblongata in regulating respiration
important in coordinating flow of info b/w cerebellum + high brain
contains group of axons that extend from cerebellum to rest of CNS
connects higher brain to spine
excessive amounts of alcohol disrupts function
receives input from joint + muscle receptors, balance + position receptors in ear + visual receptors
stores + replicates sequences of skilled events
muscle memories
coordinates basic body movements that are below level of conscious control
all info going b/w higher areas of brain must go through here
motor nerves from one side of forebrain crosses over to other side of body
right brain controls left body
left brain controls right body
controls coughing, sneezing, vomiting + swallowing
Cardiovascular Center
Respiratory Center
integrates info about blood levels of oxygen + CO2 + adjusts respiration
regulates heart rate + blood pressure
controls vital automatic functions of interval organs
makes interior more negative
Somatostatin
inhibits pancreatic release of growth hormone
released in areas of brain + pancreas
Gamma-Aminobutyric Acid
principal inhibitory neurotransmitter in brain
Endorphins
natural opiates that inhibit pain
released in many areas in brain + spinal cord
Dopamine
excitatory or inhibitory depending on the receptors
released in areas of brian + parts of PNS
Serotonin
involved in moods, sleep cycle + appetite
Norepinephrine
plays role in emotions
depedning on receptors can be excitatory or inhibitory
released in areas of the brain, spinal cord + autonomic nervous system
Glutamate
major excitatory neurotransmitter in the brain
released in areas of brain + spinal cord
Acetylcholine
can be either excitatory or inhibitory on other sites
excitatory on skeletal muscles
released in neuromuscular junctions, autonomic nervous systems + brain
action potential from convergence goes to many other neurons
neuron receives input from many neurons
Axon Terminals
ends in an axon bulb
specialized to conduct electrical impulses
slender tube of cell membrane containing a small amount of cytoplasm
sensory neurons connect directly to an axon
axon originates from a dendrite
motor + interneurons have numerous ones that are short + extend in many directions
receive impulses here
axons originate from point of union with cell body
slender extensions that receive info from receptors or incoming impulses from other neurons
prevents charged molecules + large objects (proteins, viruses + bacteria) from entering cerebrospinal fluid
DOES NOT exchange substances
isolates nervous system from infections
fills space b/w arachnoid + pia mater
arachnoid (medium)
pia mater (inner)
dura mater (outer)
brain enclosed by skull + spinal cord enclosed by hollow channel
Preganglionic Cells
cell bodies of first neurons within CNS
Ganglia
lie outside CNS
Postganglionic Neurons
axons extend far reaches of body to communicate w/ internal glads + organs
Amyotrophic Lateral Sclerosis
begins in spinal cord in areas involved in motor control of skeletal muscle
Multiple Sclerosis
myelin sheaths in CNS become damaged + form hard scar tissue that cannot allow neuron to transmit impulses
Grey Matter
sensory + motor neurons synapse w/ CNS
non-myelinated structures near centre of spinal cord
White Matter
myelinated axons on outer portions of spinal cord
serves as superhighway for action potentials traveling b/w brain + rest of body
