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Nervous System Annabel Quintero Period 7 (Drugs that affect the brain…
Nervous System Annabel Quintero Period 7
Major functions
sensory function
detects changes (stimuli) within and outside the body
motor function
it may respond to stimuli by initiating muscular contractions or glandular secretions
integrative function
it analyzes sensory information, stores some aspects, and makes decisions regarding appropriate behavior
Major divisions and subdivisions
central nervous system (CNS)
consist of the brain and spinal cord
functions
integration of information
thoughts and emotions generated
memories formed and stored
issue instructions
most nerve impulses that influence effector organs begin in the CNS
receive incoming sensory information
peripheral nervous system (PNS)
all nerves that extend from brain and spinal cord
functions
spinal nerves carry impulses to and from spinal cord
cranial nerves carry impulses to and from the cranium
Major part of the brain and
their functions
cerebrum
largest portion and associated with higher mental functions
diencephalon
contains two main parts
thalamus: relays sensory information, recognizes good vs bad sensation
hypothalamus: controls body temperature, water balance metabolism and endocrine function
brain stem
coordinates and regulates visceral activités
midbrain
reflex center for vision and hearing
pons
regulates breathing
medulla oblongata
reflex center for heart rate, BP breathing, vomiting, coughing, sneezing and swallowing
cerebellum
coordinates muscular activity
Names of all the lobes and their functions
parietal lobe
size, shape, color, pain, temperature and speech
frontal lobe
personality/emotions/intelligence, attention/concentration, logic/problem solving
temporal lobe
hearing, speech, memory, sequencing and organization
occipital lobe
processes vision (visual cortex)
the layers of the meninges
dura mater (outer)
tough, white dense connective tissue, contains many blood vessels
arachnoid mater (middle)
very thin, lacks blood vessels
pia mater (inner)
attached to surface of the brain, thin, contains many blood vessels and nerves
Spaces & ventricles
Lateral Ventricles
The left and right lateral ventricles are located within their respective hemispheres of the cerebrum. They have ‘horns’ which project into the frontal, occipital and temporal lobes
Third Ventricle
situated in between the right and the left thalamus
Supra-optic recess – located above the optic chiasm
Infundibular recess – located above the optic stalk
Fourth Ventricle
receives CSF from the third ventricle via the cerebral aqueduct
lies within the brainstem, at the junction between the pons and medulla oblongata
Tissues (structure & function of a neuron)
axon and collaterals end in axon terminals which end in synaptic end bulbs
end bulbs contain synaptic vesicles that contain neurotransmitters
axon
the portion that conducts signal away from the cell body
myelin
fatty substance that surrounds axon, insulates signal
cell body
contains nucleus and other organelles, is the metabolic center
node of ranvier
spaces between myelin/Schwann cells
dendrite
portion if neuron that receives impulse and sends signal to the cell body
Classification of neurons
unipolar
fused axon and dendrite (sensory)
bipolar
one dendrite, one axon (sensory)
multipolar
many dendrites, one axon
Major parts and
functions of the spinal cord
located in the vertebral foramen and is made up of 31 segments
8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal
transmits impulses to and from the brain
gray matter (unmyelinated)
receives and integrate information, especially for spinal reflexes
white matter (myelinated)
serve as information highways to and from the brain
house spinal reflexes
Action potential
step 1
hypo polarization
the initial increase of the membrane potential to the value of the threshold potential and Na+ channels open and Na+ ions flood in
step 0
resting membrane potential
the nerve is at rest/inactive
step 2
depolarization
the membrane potential becomes less negative and Na+ ions enter
step 3
action potential at peak
the voltage becomes positive, Na+ channels close, and the K+ channels open
step 5
hyper polarization
is more negative than the resting potential and K+ channels close and the K+ ions diffuse back into the cell to recreate the resting potential
step 4
repolarization
change in membrane potential that returns it to a negative value and the K+ ions continue to leave the cell
Drugs that affect the brain
dissociative drug
effects
hallucinations, distortion in perception, detachment from the body, fever, seizures, death
marijuana
effects
relaxation, anxiety/paranoia, slow reactions
opioids
effects
drowsiness, confusion, nausea, constipation, slowed breathing
cociane
effects
energy, confidence, appetite, heartbeat
alcohol
effects
reasoning, balance, speech, reaction time, judgment, memory loss
GHB & Rohypnol
effects
comas, hallucinations, nausea, slowed breathing, death, memory loss
nicotine
effects
intense cravings, difficulty concentrating, irritability, sleep disturbances, etc
psychedelics
effects
hallucinations, increased body temperature, heart rate, blood pressure, appetite, nausea
inhalents
effects
coordination, speech, judgement
methamphetamine
effects
increases alertness, appetite, anxiety/paranoia, heart damage, etc
MDMA
effects
energy, muscle cramping, chills, sweat, panic attacks, temperature regulation
Diseases associated with the brain
Meningitis
Infection in the meninges that can spread to the CNS
Dementia
Loss of brain function that occurs with certain diseases
Parkinson’s disease, multiple sclerosis, or Huntington’s diseases are a few other that can lead to dementia
Most common type is Alzheimer’s
stroke
blood flow to brain tissue is blocked causing cell death
Divisions of the PNS
sensory (afferent) nerves
relay information from skin, muscles and glands to CNS
affected by the environment or sense the environment
interneuron
nerves that connect sensory nerves to motor nerves
motor (efferent) nerves
two types
somatic motor neurons (SNS)
conscious voluntary control part of the PNS
sense and responds to external environment
autonomic motor neurons (ANS)
automatic, unconscious, involuntary control
responds to internal environment
sympathetic nervous system
"fight or flight"
parasympathetic nervous system
"feed and breed"
Carry impulses from CNS to organs, muscles
cause an effect or response
Anatomy of the spinal cord
two deep longitudinal grooves (anterior median fissure and posterior median sulcus) divide the cord into right and left halves
white matter, made up of bundles of myelinated nerve fibers (nerve tracts), surrounds a butterfly-shaped core of gray matter housing interneurons and cell bodies
the gray matter divides the white matter into three regions (shaped like an "H")- anterior, lateral, and posterior funiculi (columns), each consisting of longitudinal bundles called tracts
a central canal contains cerebrospinal fluid (CSF)
two spinal nerves extend out from the spinal cord (dorsal and ventral roots)
two nerve roots join to become 31 pairs of spinal nerves
Coverings
made of fibrous connective tissue
perineurium
surrounds a group of nerve fibers (fascicles)
endoneurium
surrounds individual fibers within a nerve
epineurium
surrounds the entire nerve
Neurotransmitters
at least 30-50 different neurotransmitters identified
synaptic end bulbs may contain 2 or 3 different neurotransmitters
needs to be removed or will influence nerve indefinitely
some degraded by enzymes
some reuptake into cells
Compare & contrast the
autonomic nervous system
sympathetic nervous system
"fight or flight"
parasympathetic nervous system
"feed and breed"
Reflex arc
nerve pathway of a reflex response
five parts
sensory receptor
afferent nerve ending detects stimulus
synapse/interneuron integration center
connection between sensory neuron and motor (efferent) neuron
effector
target organ responds to signal
motor/efferent neuron
delivers response to target organ
sensory/afferent neuron
sends signal to CNS (reflex center)