Notes

sensory input
- gathering information
- monitors inside & outside the body
integration
- process and interpret sensory input and decide whether action is needed
motor output
- a response to integrated stimuli
- activates muscles or glands

central nervous system (cns)
- brain
- spinal cord
- develops from the embryonic neural tube

neural tube
- opening of neural tube -> ventricles
- four chambers within the brain
- filled with cerebrospinal fluid

peripheral nervous system (pns)
- nerve outside the brain and spinal cord

pns:
sensory division
- nerve fibers that carry info to the cns
motor division
- conducts action potential away from the cns
- somatic nervous system = voluntary
- autonomic nervous system = involuntary;
consists of only motor nerves

divided into two divisions
- sympathetic division "fight-or-flight"
response to unusual stimulus
response to E divisions (exercise, excitement, emergency, and embarrassment)
to increase of heart rate
- parasympathetic division
conserves energy
relaxation
response to D division (digestion, defecation, and diuresis)

astrocytes
- star-shaped abundant cells
- forms barrier
- controls the chemical environment of the brain
- braces neurons
microglia - disposes of debris
ependymal - circulates cerebrospinal fluid
oligodendrocytes - produces myelin sheath around the nerve fibers in the CNS
axon terminal
- little transmitters at the end of the nerve cell that help transmit signals
- contains vesicles with transmitters
neuroglia
- it can divide
- most found in brain tumors
neurons = nerve cells
- to transmit messages
- found in the cns
cell body
- nucleus & metabolic center of the cell
processes
- fibers that extend from the cell body
synaptic cleft
- gap between adj neurons
synapses
- the junction between nerves
satellite cells
- provides nutrients & structure of the cell
- protects neuron cell bodies
schwann cells
- forms myelin sheath in the PNS
- wraps myelin into a jelly-like fashion
myelin sheath
- protective layer of lipids & proteins
- can be destroyed
autoimmune disease - hardened myelin sheaths into a tissue
nodes of ranvier
- gaps of the myelin sheath along the axon

dendrites
- conduct impulses toward the cell body
axon
- conduct impulses away from the cell body (only 1)

neurons
gray matter
- cell bodies and unmyelinated fibers
- outer layer
- processes the signals & information
white matter
- transmits the information between diff regions of the brain

nuclei
- clusters of cell bodies WITHIN the white matter of the cns
ganglia
- collections of cell bodies outside the cns

sensory neurons
- carry impulses from the sensory receptors
- photoreceptors (respond to light)
- proprioceptors (respond to stretches or tension)
- chemoreceptors (respond to chemicals)
- thermoreceptors (respond to changes in temperature)
- mechanoreceptors (respond to mechanical functions, like touch, pressure, etc)

motor neurons
- carry motor impulses from the cns

multipolar neuron
- a neuron with a single axon and multiple dendrites
bipolar neuron
- one axon & one dendrites
unipolar
- one singular process extending from its cell body
divergent neurons
- single neuron sending information to many others
convergent neurons
- several neurons to one cell

interneurons
- found in neural pathways in the cns
- connects sensory & motor

functions of neurons (physiology)
irritability
- to respond to the stimuli
conductivity
- to transmit an impulse
the plasma membrane at rest is polarized.
fewer positive ions are inside the cell than outside

depolarization
- allows sodium inside
- activates the action potential
- depolarizes the neuron membrane
the action potential
- whilst sodium ions rush in, potassium ions rush out right after.
- an electrical spike that helps transmit messages faster
- requires atp
new impulse propagation
- zips through the body in a fast, lightning pace as it sends messages throughout the body
continuation of the nerve impulse between neurons
- when the impulse reaches the end of a neuron, it sends a chemical transmitter to the next neuron
communication of neurons at synapses
- by exchanging messages through a mixed combo of electrical signals and chemical neurotransmitters

reflex
- involuntarily fast responses to stimuli
reflex arc
- direct route from a sensory neuron, to an interneuron, to an effector
- the process

types
autonomic reflex
- smooth muscle regulation
- heart and blood pressure regulation
- regulation of glands
- digestive system regulation
somatic reflex
- activation of skeletal muscles

regions of the brain
- cerebral hemispheres, diencephalon, brain stem, cerebellum

lobes of the cerebral hemisphere (cerebrum)
fissures
- divides the cerebrum into lobes

- frontal lobe
- parietal lobe
- occipital lobe
- temporal lobe

cerebrum specialized area
somatic sensory area
- receives impulses from the body sensory receptors
primary motor area
- sends impulses to skeletal muscles
broca's area
- involved in our ability to speak

cerebral areas involved in special senses
- gustatory area (taste)
- visual area (sight)
- auditory area (hearing)
- olfactory area (smell)

interpretation areas of the cerebrum
- language region
- language comprehension region
- general interpretation area

basal nuclei
- internal islands of gray matter

regulates voluntary motor activities by modifying info sent to the motor cortex

diencephalon
- sits on top of the brain stem
- enclosed by the cerebral hemisphere
- thalamus, hypothalamus, epithalamus

thalamus
- relay station where they process and transmit sensory info to diff parts of the brain
hypothalamus
- small
- controls on the essential functions, in the focus of regulation
- controls water balance; regulates metabolism; regulates body temperature
epithalamus
- houses the pineal gland that regulates sleep and produces melatonin
- helps to sleep
- roof of the third ventricle
- forms cerebrospinal fluid

brain stem
- attaches to the spinal cord
- midbrain, pons, medulla oblongata

midbrain
- relays sensory and motor info
- keeps us in sync and coordinated
- sits in the middle of the brain

pons
- a bridge for transmitting messages between the cerebrum and cerebellum
- communication
- composed of fiber tracts

medulla oblongata
- the body control center
- regulation in breathing, heart rate, and blood pressure

cerebellum
- involuntary coordination of body movements

protection of the cns
- scalp & skin
- skull and vertebral column
- meninges
- cerebrospinal fluid
- blood brain barrier

meninges
- protects the brain from harm like an umbrella
- folds inward in several areas

dura mater
-protects the brain from bumps and jolts
- double-layered external cover

periosteum
- attached to the surface of the skull
- protection but still allows movement

meningeal layer
- outer cover of the brain

arachnoid layer
- middle layer
- web-like

pia meter
- internal layer
- clings to the surface of the brain

cerebrospinal fluid
- liquid that surrounds & cushions the brain and spinal cord
- acts as a shock absorber, protecting the nervous tissues from sudden impacts or movements
- helps transport nutrients

blood brain barrier
- prevents unwanted substances to enter
- keeps it under control

traumatic brain injuries
concussion
- slight injury
- no permanent brain damage
contusion
- a little brain bruise, but can be treated with the right care and rest needed
cerebral edema
- causes swelling from the inflammatory response; puts pressure on itself

cerebrovascular accident (cva)
- stroke
-the brain tissue supplied with oxygen from the blood source dies
- result of a ruptured blood vessel supplying a region of the brain
- when a sudden traffic jam of the blood vessels occurs, which causes disruption in the functions; need medical attention

spinal cord
- nerves running through the backbone
- helps the brain communicate with the rest of the body
exterior white mater
- conduction tracts
internal gray matter
- mostly cell bodies
- dorsal (posterior) horns
- anterior (ventral) horns
central canal filled with cerebrospinal fluid
meninges cover the spinal cord
nerves leave at the level of each vertebrae
- dorsal root
- ventral root

peripheral nervous system
- nerves and ganglia outside the cns
- nerves = bundles of neuron fibers = bundled by connective tissue

structure of a nerve
- endoneurium
- fascicles are bound together by epinerium

classification of nerves
mixed nerves
- both sensory & motor fibers
afferent nerves
- carry impulses toward cns
efferent nerves
- carry impulses away from cns

spinal nerves
- pair at each vertebrae = 31 pairs