lecture 8: nervous system Flashcards
name the 2 parts of the nervous system
central nervous system (CNS)
peripheral nervous system (PNS)
briefly describe CNS
brain
spinal cord
briefly describe PNS
nerves (cranial and spinal)
ganglia (cluster of neuron cell bodies)
cluster of cell bodies in CNS
nuclei
name the 3 functions of nervous system
sensory input (PNS)
integration (CNS)
motor output (PNS)
describe sensory input (PNS)
response to external and internal stimuli
describe integration (CNS)
interpretation of sensory input
decides appropriate response
describe motor output (PNS)
conduction of signals from the CNS to effector cells
what are neurons
cells specialized for transmitting electrical and chemical signals
name parts of a neuron
cell body
fiber like extensions
what do the fiber like extensions of a neuron consist of
dendrites
axons
describe dendrites
convey signals towards cell body
short and numerous
describe axons
conduct impulses away from cell body
long single processes
some are insulated by myelin sheath
ends in axon terminal
what do axon terminals do
relay signals to other cells by releasing neurotransmitters
form synapses (junctions) between pre-synaptic and post-synaptic neurons
describe synapses
nerves communicate via synapses
neurotransmitter are release from pre-synaptic neuron and act on a post-synaptic neuron
describe pathway (through neuron)
stimuli
dendrites
cell body
axon hillock
axon
axon terminal
synapse
dendrites
cell body
axon hillock
axon
axon terminals
synapse
effector
describe synapse (channels)
neurotransmitters bind to ion channels on post synaptic dendrites and causes hyper (inhibitory) or de (excitatory) polarization
inhibitory - K+ moves out
excitatory - Na+ moves in
(2 separate ion channels)
the time of response is dependent on what
speed of info transmission is dependent on number of synapses (number of neurons) in pathway
describe nerves
PNS
nerve = many axons bundled together
what is ganglion
PNS
all the axons synapsing
name the 3 types of neurons
sensory
motor
interneuron (association neuron)
describe sensory neurons
carry impulses from sensory receptors towards CNS
(afferent - towards)
cell bodies in PNS ganglia
describe motor neurons
carry impulses from CNS to effectors
(efferent - leading away)
most cell bodies in CNS (except for some autonomic neurons)
describe interneuron (association neuron)
connect sensory and motor neuron
shuttle signals through CNS pathways
99% of neurons
describe optice nerve/tract
optic nerve - pns
optic tract - cns
describe structure of spinal cord
bundles of axons emerge from the back (dorsal root) and front (ventral root) of the spinal
cord on either side and finger to form the spinal nerves
dorsal root contains
sensory neurons
ventral root contains
motor neurons
dorsal root ganglion contains
cell bodies of sensory neurons
name difference between brain and spinal cord (organization of matter)
spinal cord has grey matter in center
brain has grey matter as outer layer
describe flow of information through the nervous system
(ex withdrawal reflex)
receptor
sensory neuron
integration center (spinal cord)
motor neuron
effector
describe reflexes
involuntary response to stimuli (without conscious input)
what is a reflex arc
simple nerve circuit
why does doctor check your reflexes
gives info about health of nervous system
describe patellar reflex steps
receptor
sensory neuron
integration (spinal cord, few neurons, not complex)
motor neuron
effector
describe patellar reflex (generally)
2 neuron pathway BUT
also hamstrings must be relaxed for quads to contract
where are reflexes integrated
spinal cord and brain
name reflexes integrated in spinal cord
patellar reflex
withdraw reflex
name reflexes integrated in brain
involuntary
pupillary
swallowing
vomiting
breathing
blinking
sneezing
eyes tearing up
what are meninges
layers of connective tissues that cover the brain and spinal cord
name the 3 layers of meninges (and correct order outer to inner)
dura mater
arachnoid mater
pia mater
what is cerebral spinal fluid (CSF)
clear colourless fluid that surrounds brain and spinal cord
what contains CSF
ventricles - network of cavities within brain and spinal cord
name the functions of CSF
protection
buoyancy (1400g—>50g)
excretion of waste products
transport of hormones
what are glia
supporting cells
name the glial in CNS
astrocytes
oligodendrocytes
ependymal cells
microglial cells
describe astrocytes
provide structure and metabolic support
mediate exchange between capillaries and neurons and help form the blood brain barrier
describe oligodendrocytes
form myelin sheath around axons
describe ependymal cells
have cilia that beat to circulate CSF
line ventricles of brain and central canal of spinal cord
describe microglial cell
immune cell
name glia in PNS
schwann cells
describe schwann cells
form myelin sheath around axons
describe myelin sheath
formed by oligodendrocytes (CNS) or schwann cells (PNS)
waxy coating around axon of neuron
insulates axons
neurons can be…
myelinated
unmyelinated
what are nodes of ranvier
regions of axons without myelin
describe saltatory conduction
nerve impulse (action potential) jumps from
node of ranvier to node of ranvier so impulse moves faster
jumping from node to node in myelinated neurons = saltatory conduction
what is white matter
myelinated axons
what is grey matter
unmyelinated axons
cell bodies
dendrites
axon terminals
ALL synapsing
name effectors (pathway through neuron)
skeletal muscle
sweat glands
heart muscle
digestive smooth muscle
where are neurotransmitters released from (synapse)
axon terminal of presynaptic cell and act on postsynaptic cell
name organization of PNS anatomical (4)
cranial nerves
spinal nerves
ganglia
sensory receptors
describe cranial nerves
paired
info to and from brain
describe spinal nerves
paired
info to and from spinal cord
describe ganglia
cluster of neuronal cell bodies
describe sensory receptors
formed by dendrites of sensory neurons
name and describe (briefly) organization of PNS physiological
afferent (sensory) = towards CNS
efferent (motor) = away from CNS
describe efferent (motor) - organization of PNS (physiological)
somatic = skeletal muscle, voluntary (usually)
autonomic = smooth muscle, cardiac muscle, glands, involuntary
name and briefly describe divisions of autonomic nervous system
sympathetic = fight or flight
parasympathetic = rest and digest
describe ANS (autonomic nervous system)
parasympathetic and sympathetic divisions act on same targets but have opposing effects
which type of nerves is parasympathetic associated with (mostly involves)
cranial nerves
which type of nerves is sympathetic associated with (mostly involves)
spinal nerves
describe vagus nerve
cranial nerve in parasympathetic divining that does many things
what effects of parasympathetic nervous system is vagus nerve associated with
constricts bronchi in lungs
slows heart
stimulates activity of stomach and intestines
stimulates activity of pancreas
stimulates gallbladder
name all effects of parasympathetic division (9)
constricts pupil of eye
stimulates salivary gland secretion
constricts bronchi in lungs
slows heart
stimulates activity of stomach and intestines
stimulates activity of pancreas
stimulates gallbladder
promotes emptying of bladder
promotes erection of genitalia
name all effects of sympathetic division (10)
dilates pupil of eye
inhibits salivary gland secretion
relaxes bronchi in lungs
accelerates heart
inhibits activity of stomach and intestines
inhibits activity of pancreas
stimulates glucose release from liver; inhibits gallbladder
stimulates adrenal medulla
inhibits emptying of bladder
promotes ejaculation and vaginal contractions
TRUE OR FALSE: parasympathetic and sympathetic divisions ALWAYS have opposing effects
FALSEEEEE
they have a complementary effect =
para promotes erection of genitalia AND sym promotes ejaculation and vaginal contractions
where is body of post ganglionic neuron
in PNS ganglia
describe organization of somatic motor neurons in PNS
single motor neuron
releases acetylcholine (stimulates skeletal muscle to contract)
describe organization of sympathetic motor neurons in PNS
pre ganglionic neuron - releases acetylcholine
stimulates adrenal medulla to release epinephrine/norepinephrine into blood (acts as hormone)
OR
acts on post ganglionic neuron - releases norepinephrine (acts on effectors)
describe organization of parasympathetic motor neurons in PNS
pre ganglionic neuron - release acetylcholine (acts on post ganglionic neuron)
post ganglionic neuron - releases acetylcholine (acts on effectors)
name all neurotransmitters (5)
acetylcholine
norepinephrine
dopamine
serotonin
nitric oxide
describe acetylcholine (neurotransmitters)
skeletal muscle contraction
parasympathetic effects
describe norepinephrine (neurotransmitters)
sympathetic effects
describe dopamine (neurotransmitters)
affects sleep, mood, attention and learning
lack of dopamine in brain associated with
parkinson’s disease
excessive dopamine in brain associated with
schizophrenia
describe serotonin (neurotransmitters)
affects sleep, mood, attention and learning
describe nitric oxide (neurotransmitter)
acts as local regulator (ex: vasodilation by acting on smooth muscle)
what is brainstem and what’s it do
hindbrain + mid brain
relays info to and from higher brain centres
name the 3 parts of brainstem
medulla oblongata
pons
midbrain
describe medulla oblongata
contains nuclei that controls visceral functions (autonomic)
describe functions associated with medulla oblongata
breathing
heart rate
vasoconstriction and vasodilation
swallowing
vomiting
digestion
describe pons
contains nuclei that control visceral functions
ex = breathing
describe midbrain
contains nuclei for integration of sensory info
name 2 parts of midbrain and describe
superior colliculi = regulation of visual reflexes
inferior colliculi = regulation of auditory reflexes
name the main parts of brain
brainstem
reticular system
cerebellum
(epithalamus, thalamus and hypothalamus)
cerebrum
limbic system
describe reticular formation
diffuse set of neurons in brainstem
act as sensory filter to decide which info reaches cerebrum
what is RAS
reticular activating system (of reticular formation)
describe RAS
regulates sleeps and arousal
acts as sensory filter (important for sleep)
what does cerebellum do
coordinates motor activities with perpetual and cognitive factors
relays sensory info about joints, muscles, sight and sound to cerebrum
involved in coordination and balance
describe epithalamus
pineal gland - synthesizes melatonin
cluster of capillaries - produce CSF
describe thalamus
relays all sensory info (EXCEPT SMELL) to cerebrum
relays motor info from cerebrum
describe hypothalamus
regulates autonomic activity
regulates pituitary gland
thermoregulation, hunger, thirst, sexual and mating behaviour
what acts as biological clock for humans
suprachiasmatic nuclei (SCN) in hypothalamus
internal time keeper (circadian rhythm)
ex - controls release of melatonin from
pineal gland
describe cerebrum and name parts
most highly evolved structure of
mammalian brain
left hemisphere and right hemisphere
corpus callosum
basal nuclei
cerebrum is involved in
conscious thought
all voluntary actions
personality
describe left hemisphere (cerebrum)
responsible for right side of body
describe right hemisphere (cerebrum)
responsible for left side of body
describe corpus callosum (cerebrum)
major connection between left and right hemispheres
describe basal nuclei (cerebrum)
involve in major brain functions
ex = voluntary movement, cognition, emotions, habits, learning of procedures
describe cerebral cortex
outer covering of gray matter
consists of specialized regions with different functions
name the 4 lobes of cerebrum and their brief functions
frontal lobe = primary motor cortex
parietal lobe = primary somatosensory cortex
occipital lobe = vision
temporal lobe = hearing
what is broca’s area
speech production
left hemisphere
frontal lobe
what is wernickes area
speech comprehension
left hemisphere
temporal lobe
what is limbic system
mediates basic emotions like fear and anger
establishes emotional memory
what does limbic system consist of (6)
hippocampus
olfactory cortex
inner portions of cerebral cortex
thalamus
hypothalamus
amygdala
name the 2 types of memory
short term
long term
describe short term memory
stored in frontal lobes
describe long term memory
stored in different regions of brain depending on type
name and describe the 2 types of long term memory
explicit = memorization of facts that can be recounted
implicit = procedural, remembering how to do something, like riding bike
which type of long term memory takes longer to form
implicit
describe moving information from short term to long term memory
involves hippocampus
enhanced by repetition
influenced by emotional states mediated by amygdala (limbic system)
influenced by association with previously stored info
