Week 5 Science and Scholarship : Nervous system Flashcards
identify the two major anatomical divisions of the nervous system
CNS and PNS
what makes up the CNS
- Brain
- Spinal cord
what makes up the PNS
- Nerves
- 12 pairs of cranial nerves
- 31 pairs of spinal nerves
- Ganglia (collection of neuronal cell bodies)
- Nerve endings
identify the functional divisions of the NS
a) Somatic,Autonomic,Enteric
b) Sensory,Motor,Integrated
what is the function of the somatic NS
VOLUNTARY control of body movements via skeletal muscles
- special senses: vision, hearing, taste, smell, touch etc.
what is the function of the autonomic NS
innervation of INVOLUNTARY STRUCTURES to maintain homeostasis e.g. HR,BP,RR,digestion and arousal
what is the function of enteric NS
- involuntary nervous system of digestive tract
- controls digestion, movement of contents
what is the motor (efferent) NS
-regulates both involuntary and voluntary responses
* innervation of PNS effectors (skeletal, smooth, cardiac muscle, glands)
what is the sensory (afferent) NS
- PNS nerve endings (sensory receptors) process input from environment eg via eyes, ears,skin etc
what is the integrated NS
- Integration of sensory & motor information in the CNS.
- Nerve cells are called interneurons.
identify the characteristics of a neurone
excitable
conductive
secretory
what is meant by the neurone being excitable
Respond to changes in environment/stimuli
what is meant by the neurone being conductive
Transmit electrical signals as action potentials (AP)
what is meant by the neurone being secretory
Transmit messages to other cells via the release of chemical messengers called “neurotransmitters”.
What are dendrites and what is their function
- Receive neural stimuli from other neurons.
- Excitatory/inhibitory in nature.
-branch like extensions
What is the soma and what is their function
- Houses nucleus & organelles.
- Metabolic centre which processes/interprets stimuli
What is the axon and what is their function
*long, slender Cytoplasmic extension
*Conducts nerve impulse to axon terminals so the message can be relayed to effector cell
What is the axon hillock and what is their function
- Site of Action Potential initiation
What is the myelin sheath and what is their function
- Insulates axon & increases speed and efficiency of AP conduction
What are axon terminals and what is their function
- end of axon that forms synapse with other neurons
- To communicate with other cells/neurons
What is the node of ranvier and what is their function
- Unmyelinated segments of the axon
- Impulse “jumps” along these down the axon
what structures are housed in the soma
-nucleus
-mitochondria
-rough ER
-golgi
-cytoskeleton
dendritic tree vs dendritic branch
- Dendritic tree = ALL of the dendrites belonging to one neuron
- Dendritic branch = a single branch of the dendritic tree
where are dendritic receptors found
on the dendritic membrane
there is a ___ amount of mitochondria in neutrons
high
what are nissl bodies
accumulation of ribosomes in neurons
what is axoplasmic transport
transport of material between axon terminal and soma
describe the difference between two movements of axoplasmic transport
- Anterograde = towards the axon terminal (Kinesin)
- Retrograde = towards the soma (Dynein)
what is the synapse
-specialised junction between (1) Neuron-Neuron; (2) Neuron-Effector cell
eg of pseudo unipolar/ uni polar neurons
sensory neurons
what are bipolar neurons
→one main dendrite
→one main axon
eg of bipolar neurons
Rare and found in “special sense”
identify the ways neurons can be classified
-By Shape
- By Function
what are multipolar neurons
→ Two or more dendrites surrounding cell body →One main axon
what’s the Most common neuron in the CNS
multipolar neurons
what are Unipolar/Pseudo-unipolar
- Only one axon from cell body
- Looks like there is only one axon from cell body but branches in two different directions
what are the two overarching steps in neural communication
action potential and synapse
what type of impulse is the action potential
electrical
what type of impulse is the synapse
chemical
define the membrane potential
difference in charge between the (electrical potential) extracellular and intracellular environment
identify the resting membrane potential
-70 mv
SOAPI PONI
identify the types of gated ion channels
voltage gated
chemically/ligand gated
mechanically gated
leakage gated
how do voltage gated ion channels work
respond to changes in charge
how do chemically gated ion channels work
respond to changes in chemical concentration
how do mechanically gated ion channels work
repsond to a mechanical stimulus
how do leakage gated ion channels work
-always open
OR
-randomly alternate between open and closed
identify some key characteristics of the Na/K pump
-continuously working
-requires ATP
-transports 3 sodium ions and 2 potassium ions against concentration gradient
identify steps of action potential
reaching threshold (initiation), depolarisation, repolarisation, hyperpolarisation, and returning to resting
what’s initiation (AP)
-all or nothing event
-stimulus reaches threshold at -55mv
-
what’s depolarisation (AP)
-influx of +ve ions into cell
-voltage gated Na+ channels open
-Na+ into cell
-cell is more positive inside
-voltage increases to +40mv
what’s repolarisation (AP)
-voltage gated Na+ channels close
-volatge gated K+ Chanels open
-K+ moves out of cell
-cell becomes more -ve
-resting membrane potential restored (-70mv)
what’s hyperpolarisation (AP)
-excess K+ pumped out of cell
-some K+ reenters the cell
-channels recalibrate in the refractory period
-
what’s happening when neurons at rest
-Na+ and K+ gated channels closed
-sodium potassium pump maintains voltage at -70 mv
-potassium outside and sodium inside
function of myelin sheath
-speed up action potential
-prevents external stimuli entering cell
-prevents axon damage
myelin sheath coat ___ axons
longer
node of ranvier function
increases rate of action potential conduction
-allows for chain reaction movement (saltatory conduction)
saltatory conduction is ___ than continuous conduction
much faster
purpose of an EMG
measure electrical activity in resting and contracting muscles
describe surface EMG
-non invasive, time efficient but less accurate
-electrodes placed on skin over muscle
describe Intramuscular EMG
-thin wires inserted into muscle
-invasive, time consuming but more accurate
structure of synapse
space between two neurons or a neuron and muscle gland
function of synapse
allows for chemical communication between two neurons or neuron and muscle
Define the sequence of events of synaptic transmission
-neurotransmitters packaged into vesciles at pre synaptic neuron
-vesicles mobilise and dock at presynaptic cell membrane
-action potential reaches the terminal end of the pre synaptic neuron
-volted gated Ca++ channels open, depolarising membrane
-neurotransmitters in vesicles exit axon terminal via exocytosis
-neurotransmitters diffuse across synaptic cleft
-neurotransmitters bind to receptors on post synaptic neuron
-post synaptic potential is stimulated
-another action potential generated
when are electrical synapses present
-when cells utilise gap junctions
what is the role of neurotransmitters
chemical messenger molecules that transmits signals from a neuron to target cell across a synapse. by binding to receptors on post synaptic cell
-can cause excitatory or inhibitory message
synapse vs neuromuscular junction
synapse b/w two neurons vs neuromuscular junction between a neuron and muscle
eg of excitatory neurotransmitter
glutamate
eg of inhibitory neurotransmitter
GABA
what do excitatory neurotransmitters do
make the AP on PSN more likely to fire
-promotes depolarisation
what kind of channels are found on PSN
chemically/ligand gated
what do inhibitory neurotransmitters do
make the AP on PSN less likely to fire
-promotes hyperpolarisation
Ach can be _ or _
excitatory or inhibitory depending on whether it binds to skeletal or cardiac muscle respectively
what happens to unbound neurotransmitters
-removed or recycled by ezynmes, glial cells, pre synaptic cell
identify two ways the neurotransmitters transmit their signals in the PSN
ionotropic or metabotropic
what’s ionotropic neurotransmission
Express post
-ligand gated channels
-open and close in response to neurotransmitters binding
what’s metabotropic neurotransmission
AUS post
-Senses ligand-binding & activates secondary messengers
→ activates other effector proteins:
→ causes signalling cascades within the cell
-Impacts metabolic pathways, membrane permeability etc
-G coupled receptors
identify the two categories of neurotransmitters
-amino acid (fast)
-classical amine (slower)
neurons that utilise amino acid neurotransmitters are called
amino acidergic
identify the 3 categories of neurons that use classical amine neurotransmitters
“catecholaminergic”
“serotonergic”
“cholinergic”
key features of glutamate
(+)
-amino acid class
-memory and learning
key features GABA
(-)
-amino acid
-reduce neuronal excitabiltiy
outline the main precursor for classical amine neurotransmitters
Tyrosine → L-Dopa → Dopamine → Norepinephrine → Epinephrine
features of dopamine
+/-
-classical amine
-euphoria and reward
function of noradrenaline
+
-Concentration, consciousness
features of adrenaline
+
-classical amine
-mood and behaviour
function of serotonin
(-)
-classical amine
-mood, behaviour
serotonin is derived from
trp
function of Ach
+/-
classical amine
regulates physiological functions
describe two main receptor families for Ach
-Nicotinic (ionotropic)
-Muscarinic (metabotropic)
what are excitatory post synaptic potential (EPSP)
EPSPs can add together/summate for a larger “net” effect to make the post-synaptic neuron even more likely to produce an action potential
describe two ways of EPSP summation
-Spatial summation = when there are enough synapses close together
* Temporal summation = when the post-synaptic membrane is depolarized in rapid succession
what are inhibitory post synaptic potentials (IPSP)
Local changes in the membrane
potential that makes a post-synaptic
neuron less likely to generate an action
potential
distinguish between graded vs action potentials
-GP is a graded response vs AP is all or nothing
-GP generated by ligand gated ion channels vs AP is generated by voltage gated ion channel
-GP is transmitted over short distance vs AP transmitted over longer distance (axon)
-GP may lose its signal (‘fizzle out’) vs AP that remains as strong starting from axon hillock
-GP can summate vs AP can not summate
identify 5 divisions of brain
telencephalon
diencephalon
mesencephalon
metencephalon
myelencephalon
(td sty)
white matter =
inner brain (myelinated axons )
grey matter =
outer brain ( dendrites, glial cells, and capillaries + cell body)
why is white matter white
White matter is white due to the myelin sheath surrounding the axon
what are gyri and sulci
gyri (folds) and sulci (grooves)
what is a fissure
deep sulci
what structure protects the Brain
meninges
term used to describe top of brain
dorsal
term used to describe bottom of brain
ventral
what’s a nerve
a set of axons in the periphery
what’s a nucleus
cluster of neuronal cell bodies within the CNS
what’s a ganglion
cluster of neuronal cell bodies usually outside of CNS
where is the medulla found
hindrbain : myelencephalon
function of medulla oblongata
- Functionally & anatomically similar to the spinal cord
- Responsible for vital reflexes eg breathing
-heart rate , salivation ,coughing, sneezing
where are the pons and cerebellum found
in the hindbrain: metencephalon
function of the pons
- Pathway for information flow to- and
from- the cerebellum - Works with the medulla and other parts of the brain to increase arousal
function of cerebellum
- Regulates motor movement, balance & coordination
- Vital for shifting attention between auditory & visual stimuli
identify the structures of the midbrain / mesencephalon
-tectum ‘roof’
-tegmentum ‘floor’
-crus cerebri /Cerebral Peduncles
function of the tectum
- superior colliculus: visual
- inferior colliculus: auditory
how many coliculi in the tectum
4 (A/P + L/R)
function of tegmentum
- substantia nigra: dopamine production
- periaqueductal grey (PAG): pain suppression
function of crus cerebri
- large collection of fibre bundles
connecting - cortex and pons > cerebellum * cortex and spinal cord
identify structures of diencephalon
thalamus and hypothalamus
function of thalamus
Relay station for sensory & motor information
function of hypothalamus
- Regulates the internal environment of the body
- Controls the release of specific hormones (from pituitary gland)
- Affects “drive states”: hunger, thirst, sexual behaviour
- Regulate emotional states: fear, anger
- Important for regulating body temperature & blood chemistry
outer region of telencephalon is
the cerebral cortex
identify the 2 main subcortical structures of the telencephalon
the limbic system and basal ganglia
Outline the functions of the limbic system
- Hippocampus: memory
- Amygdala: emotion
outline the functions of basal ganglia
-Planning and coordinating of movement
* Other cognitive functions (attention, language planning)
describe the structure of cerebral cortex
-divided into L/R hemispheres
-contralaterally organised
what does it mean if the brain is gyrencephalic
- brain is folded into a series of “hills”/gyri
- increase surface area
- enable complex functions
function of frontal lobe
motor, planning, reasoning, judgment
primary motor cortex is in which lobe
frontal (pre-central gyrus)
what separates. the frontal and parietal lobe
central sulcus
function of parietal lobe
Somatosensation
primary somatosensory cortex is in which lobe
parietal (post-central grus)
function of temporal lobe
language, hearing, memory
Primary auditory area (auditory cortex) is in which lobe
temporal lobe
what separates the temporal lobe from frontal and parietal lobes
Sylvian fissure/lateral sulcus
function of the occipital lobe
vision
primary visual cortex is in which lobe
the occipital
what separates the parietal and occipital lobe
parieto-occipital sulcus
what separates the occipital lobe into U/L
calacrine sulcus
what’s the 5th lobe
insular lobe/ insula
function of insula
motor control, decision-making, sensory
what separates L and R hemisphere of the brain
longitudinal fissure
how many layers in neocortex
6 layers
identify the main cortical cell
pyramid cell
identify the cortical fibre types
-commissural fibres
-association fibres
-projection fibres
what do commissural fibres do
connect two cerebral hemispheres
eg of commissural fibres
corpus callosum
identify the parts of corpus callosum
-rostrum
-genu (knee bend)
-body
-splenium
function of association fibres
connect various parts within the same hemisphere
-gyrus to grus
-lobe to lobe
eg of association fibres
cingulum
function of projection fibres
connects cerebral cortex with subcortical regions (brain stem or SC)
eg of projection fibres
corona radiata
internal capsule
what is BA 1,2,3
primary sensory cortex
what is BA 4
primary motor cortex
what does BA mean
Brodmanns area
what is BA 22
Wernickes area
what is BA 44
brocas area
what is BA 17
primary visual cortex
what is BA 41
primary auditory cortex
what things protect the brain
skeleton (skull and vertebra)
meninges
CSF
identify the layers of the meninges from outer to inner
dura mater
arachnoid mater
pia mater
features of the dura mater
-outermost layer
-support and protection
features of the arachnoid mater
-filament projections/spiderlike
-enables CSF flow
features of Pia mater
-innermost layer, lies flush within surface of brain
-very thin
where is the subdural space
between the dura mater and the arachnoid mater
where is the subarachnoid space
between the arachnoid mater and the Pia mater
what is CSF
cerebrospinal fluid
briefly describe structure of CSF
clear and colourless fluid
functions of the CSF
-buoyancy and shock absorption/ cushioning
-nourishment (glucose, oxygen…)
-communication, removal of wastes and exchange nutrients
how many ventricles in brain
4
name the ventricles in the brain
2 x lateral ventricles
-third and fourth ventricle
what produces CSF
ependymal cells
what is the choroid plexus
section of ependymal cells
describe the formation of CSF
-plasma filtered and tissue fluid forms in thalamus
-this ISF is filtered through the epyndmal cells and CSF forms in the 3rd ventricle
describe the movement of CSF
-from the choroid plexus of the lateral ventricles
-into the interventricular foramen
-into 3rd ventricle
-into cerebral aqueduct
-into choroid plexus of 4th ventricle
THEN
*-into medial aperture –> subarachnoid space, brain and SC
OR
*into lateral aperture–> subarachnoid space, brain and SC
how does CSF exit the subarachnoid space
via arachnoid granulations into the subdural space (blood vessels of systemic circulation)
why is so much blood supply needed for the brain
-anaerobic respiration produces lactic acid, highly destructive to cerebral tissue
-anaerobic respiration produces much less ATP
what is ischaemia
decreased oxygen/ blood supply to brain
what is infarction
region of cell death due to ischaemia
what is penumbra
region of cells that are functionally compromised but can be salvages with blood flow
why is arterial blood important for brain
allows delivery of O2 and essential hormones
why’s venous blood return important for the brain
allows for removal of wastes eg CO2 and lactate
identify the 3 branches of the aorta
1.Braciocephalic artery
-Right subclavian
-Right common carotid
2.Left common carotid
3.Left subclavian
anterior circulation consist of
right and left common carotid artery that make up right and left ICA (internal carotid artery)
posterior circulation consist of
right and left subclavian artery that makes up right and left vertebral artery
how much blood supply to the brain is posterior vs anterior
anterior 80% vs posterior 20%
what links anterior and posterior circulation
circle of willis
what do the subclavian arteries branch into
vertebral Arteies (VA)
the VA divide into ____
3 arteries
-anterior spinal artery
-posterior inferior cerebellar artery (PICA)
-posterior spinal arteries
function of anterior spinal artery
-single artery
-supplies anterior 2/3 of cord and medial medulla
function of posterior spinal arteries
supplies posterior and lateral spinal chord (1/3)
function of PICA
-supplies inferior/posterior surface of the medulla
-lateral medulla
-choroid plexus of 4th ventricle
basilar artery forms when ___
L and R vertebral arteries fuse
basilar artery divides into ___
posterior cerebral arteries (PCA)
superior cerebellar arteries (SCA)
pontine arteries
anterior inferior cerebellar arteries (AICA)
function of AICA
-supplies inferolateral pons
-supplies anterolateral surface of cerebellum
function of pontine Arteries
3-5 small arteries supply pons
function of SCA
-supplies superior part of cerebellum
-and midbrain
function of PCA
-supply posterior parts of brain and the basilar artery terminates here
what structures makes up the circle of willis
– Posterior cerebral arteries
– Posterior communicating arteries – Internal carotid arteries
– Anterior cerebral arteries
– Anterior communicating artery
identify the two main branches of the ICA
anterior cerebral artery and middle cerebral artery
function of ACA
Supplies most of the cortex on the superior and anterior medial surface of the brain
function of MCA
-largest
-supplies 80% of brain
what’s a haemmmorhage
a burstage
what’s a embolism
thrombus migrates
identify the functions of the limbic system
Homeostasis Olfaction Memory Emotion
function of the amygdala
Emotional response and emotional tagging
structure of amygdala
almond shaped structure
describe location of the parahippocampal gyrus
located in the ventromedial temporal lobe
structure of hippocampus
sea horse shaped
function of hippocampus
memory maintenance and formation
what is explicit memory
episodic and semantic memory
structure of hypothalamus
sits under thalamus
function of hypothalamus
regulates various physiological response eg thirst, hunger, thermoregulation and hormone secretion
function of olfactory cortex
-region of brain responsible for interpreting olfactory information (smell)
what 3 horizontal structures make up brain stem
spinal cord
cerebellum
extended forebrain
what 3 longitudinal structures make up brain stem
tectum
tegmentum
basal portion
how many cranial nerves
12 pairs
how many nuclei of cranial nerves are in brain stem
10 (number 2-12)
function of cerebellar peduncles
(3 peduncles) connect brain stem to cerebellum allowing information to travel
function of reticular formation
-Produce neurotransmitters
-Modulation of motor and sensory pathways
-Arousal and consciousness
-Regulate sleep-wake cycles
-Cardiovascular and respiratory control
where is the reticular formation
Set of interconnected nuclei located throughout the brainstem within the tegmentum
function of superior colliculi
visual reflexes
function of inferior colliculi
auditory reflexes
identify anterior structures of brain stem
-crus cerebri
-pyramidsx2
-olivesx2
function of crus cerebi
motor pathway
function of pyramids
motor pathway
black structure in midbrain
substantia nigra
function of the cerebellum
coordinate smooth movements, balance and posture, muscle tone
what fossa does the cerebellum sit in
posterior cranial fossa
what layer covers the cerebellum
dura- tentorium cerebelli
what is the cerebellum divided into
two hemispheres
what connects the two cerebral hemispheres
the vermis
gyri of the cerebellum are called
folia
what separates gyri in the cerebellum
fissures
grey matter in the cerebellum is called
cerebellar cortex
white matter in the cerebellum is called
arbor vitae
(tree of life)
what separates the anterior and posterior lobes of the cerebellum
primary fissure
function of the posterolateral fissure of the cerebellum
separates the flocculonodular node which lies anterior and inferior to the cerebellar hemispheres.
function of horizontal fissure of the cerebellum
separates posterior lobe into superior and inferior portions
how many cerebellar peduncles
3
name the cerebellar peduncles
1.Superior: midbrain (efferent)
2.Middle: pons (afferent)
3.Inferior: medulla (afferent)
identify the functional divisions of the cerebellum
Vestibulocerebellum
Spinocerebellum
Cerebrocerebellum
function of Vestibulocerebellum
eye control and balance
function of Spinocerebellum
muscle tone and skilled movement
-proprioception
describe the structure of the spinal chord
-Column of nervous tissue
-ascending (sensory/afferent) and descending (motor/efferent) tract
where is white matter in the spinal chord
on the periphery
where is grey matter in the spinal chord
more central
what is the dorsal (posterior) root
carries afferent (sensory) nerves from PNS to CNS
what is the ventral (anterior) root
carries efferent (motor) nerves from CNS to PNS
when sensory and motor nerves meets it is called
spinal nerve
what is the dorsal horn
collection of nerve cells, houses somatic and visceral sensory nuclei
what is the ventral horn
collection of nerve cells, houses somatic motor nuclei
what is the lateral horn
collection of nerve cells, houses visceral motor nuclei
function of the grey commissure
connects left and right region of SC
function of somatic motor neurons
somatic motor innervate the skeletal muscles
function of visceral motor neurons
visceral motor neurons are a part of the autonomic nervous system and innervate glands, cardiac muscle, smooth muscle
white matter of spinal chord is divided into
dorsal , lateral and ventral column
dorsal column is involved with
sensory info ONLY
ventral column is involved with
sensory and motor info ONLY
lateral column is involved with
sensory and motor info ONLY
identify two types of motor function
somatic and visceral
what are upper motor neurons
-begin motor cortex and extend in superior regions off CNS
-synapse with LMN
what are lower motor neurons
-Originate in brainstem & spinal cord
- Make up descending tracts that innervate muscles & cause contraction
where are lower motor neurons most abundant
cervical enlargement (supplies upper limbs) and lumbar enlargement (supplies lower limbs)
identify the types of lower motor neurones
alpha and gamma lower motor neurones
function of alpha motor neurons
-supply extrafusal muscle fibres (main muscle mass)
-receive input from spinal interneurons, muscle spindles and UMN
function of gamma motor neurones
-supply intrafusal muscle fibres (proprioceptors)
-detect position sense of muscles and feed it to SC
what proprioceptive information does the motor unit receive
- Muscle Spindles
*encodes muscle length
*synapses on αMN - Golgi Tendon organs
*encodes muscle tension
*synapses on inhibitory interneurons
how is the motor homunculus oriented
akin to a man lying down across the longitudinal fissure with feet hanging off
function of the pyramidal motor system
- Motor Planning & initiation
function of basal ganglia
- modulates movements
- selects & initiates willed
movements - major input to motor cortex
define reflex
A reflex is a rapid, subconscious sequence of actions in response to a stimulus which can be either:
(1) unlearned or inborn
(2) learned or acquired
outline the mechanism of a reflex
Receptor – site of stimulus transduction
Sensory neuron – transmits afferent impulses to CNS
Integration centre – in the CNS
Motor neuron – conducts efferent impulses from integration centre to the effector
Effector – muscle fibre/glandular cell that produces response (muscle contraction/glandular secretion)
what are the ways that reflexes can be classified
by system or by number of synapses
identify how reflexes are classified by system
Spinal
Cranial
Visceral
Somatic
Superficial
Deep tendon
difference between a spinal and cranial reflex
spinal– integration happens in the spinal cord eg patellar
Cranial – integration happens in the brainstem eg moving eyes
superficial vs deep tendon reflex
Superficial – involves stimulation of sensory afferents in the skin;
Deep tendon – involves stimulation of sensory afferents within muscle such as tendons
difference between mono and polysynaptic reflex
-Monosynaptic – involves only one synapse in the CNS. This synapse is between a single sensory neuron
Polysynaptic – involves two or more synapses in the CNS between sensory neurons, motor neurons and interneurons
identify the grading system for reflex
0 Absent
+ present but reduced
++ Normal
+++ Increased, possibly normal
++++ Greatly increased, often associated with clonus
what are the categories of sensation
exteroception/superficial
proprioception/deep
interoception/visceral
special senses
define somatosensation
The ability to perceive touch, temperature, pain and body position through action potentials.
what makes up exteroception(superficial)
- Pain
- Temperature
- Touch
pain receptor =
nocioreceptor
temp receptor =
thermoreceptor
how is temp and pressure detected
temperature-dendrites of unipolar neuron detect temperature
pressure-encapsulated nerve ending of unipolar neuron detects pressure
how is gustation detected
gustatory receptor detects then releases neurotransmitters which triggers dendrites of the unipolar neuron
pain vs nociception
Nociception: sensory transduction of signals that triggers pain
Pain: unpleasant sensory & emotional experience associated with actual or potential tissue damage.
identify two ways pain is specialised
-types of axons;
-responsiveness to stimuli
A delta pain =
fast pain
C fibre pain =
slow pain
what two factors effect axon function
diameter and myelination
identify the three main somatosensory pathways
Dorsal Column Medial-Lemniscus Pathway
Anterior Spinothalamic Tract
Lateral Spinothalamic Tract
what does DCML pathway regulate
Fine Touch & Proprioception
* Two-point discrimination
* Vibration
what are the components of DCML
1st order neurons
2nd order neruons
3rd order neurons
what are 1st order neurons in DCML
axons ascend in dorsal columns and synapse at medulla
what are 2nd order neurons in DCML
axons CROSS IN medulla and head up to thalamus
what are 3rd order neurons in DCML
neurons in thalamus that project to somatosensory Cortex
what does anterior spinothalamic tract regulate
crude touch and pressure sensation
what does lateral spinothalamic tract regulate
pain, temperature sensations
what are 1st order neurons in anterior spinothalamic tract
-Axons synapse in dorsal horn
what are 2nd order neurons in anterior spinothalamic tract
- Axons immediately CROSS IN SPINAL
CORD & head to thalamus
what are 3rd order neurons in anterior spinothalamic tract
Neurons in thalamus project to
Somatosensory cortex
what are 1st order neurons in lateral spinothalamic tract
- Aδ fibres (fast pain) + C fibres (slow
dull pain) - Axons synapse in dorsal horn
what are 2nd order neurons in lateral spinothalamic tract
- Axons IMMEDIATELY CROSS IN SPINAL
CORD & head to thalamus
what are 3rd order neurons in lateral spinothalamic tract
- Neurons in thalamus project to
Somatosensory cortex
what adds emotional context to lateral spinothalamic tract
cingulate gyrus
what are the two physiological ways pain can be regulated
afferent regulation
descending regulation
how does descending regulation work (pain)
-Periaqueductal gray matter (PAG) neurons play role in modulating pain
-Influences raphe nucleus in the medulla
-secrete endogenous opioids that bind to 2nd order neuron and relay the pain to higher centres
how does afferent regulation work (pain)
Pain evoked by activity in nociceptors
can be reduced by simultaneous activity in mechanoreceptors
what things do the autonomic NS regulate
Blood pressure
Heart and breathing rates
Body temperature
Digestion
Metabolism (thus affecting body weight)
The balance of water and electrolytes
The production of body fluids
Urination
Defecation
Sexual response
identify the divisions of the autonomic NS
sympathetic and parasympathetic NS
how many neurons involved in autonomic response
2 neurons sytem
-pre ganglion (in CNS) and post ganglion (outside CNS) neuron
contrast somatic and autonomic NS
-one neuron response vs two neuron chain
-voluntary vs involuntary
-originates in spinal column (CNS) vs originates in pre-ganglionic nuron (CNS)
-stimulatory vs stimulatory or inhibitory
function of sympathetic NS and what does it supply
-Prepares body for physical activity/fight or flight
-Visceral organs, adrenal gland (medulla), vascular smooth muscle, sweat glands and arrector pili muscles in hair
function of parasympathetic NS and what does it supply
-Rest and digest
-Organs of head, neck, trunk and external genitalia
contrast neurotransmitters in Autonomic vs Somatic NS
-Somatic always involves Ach
-Sympathetic uses NE and epinephrine (only Ach for sweat gland)
-Parasympathetic uses Ach
what do alpha receptors induce when undergoing sympathetic response
(1 or 2) smooth muscle contraction
what do beta receptors induce when undergoing sympathetic response
(2 or 3) smooth muscle relaxation
(1) cardiac muscle contraction
what do muscarinic receptors induce and detect when undergoing sympathetic response
detect Ach, produce sweat
is the pre or post ganglionic fibre longer (sympathetic)
post (more nerves in PNS allow for widespread, generalized responses)
where are pre ganglionic fibres found in sympathetic NS
T1-T12
L1-L2
which forms lateral horn
are post ganglionic fibres myelinated
no (slow means more control,more flexible and energy saving)
what are the types of post ganglionic fibres for sympathetic NS
paravertebral and pre vertebral
what is the sympathetic chain
Comprised of paired, longitudinally arranged, paravertebral sympathetic ganglia linked together.
what’s a splanchnic nerve
nerve on the post-ganglionic nerve that innervates visceral targets (contain visceral sensory fibres and autonomic fibres)
what things can a pre ganglionic fibre do
-can synapse directly onto adrenal medulla (chromaffin cells)
-can synapse on a paravertebral ganglia within the sympathetic chain
-can synapse on a prevertebral ganglia past the trunk
is the pre or post ganglionic fibre longer (parasympathetic)
pre (more complex and fine tuned functions need more time in CNS)
contrast where terminal ganglia lie in sympathetic vs parasympathetic NS
terminal ganglia lie closer to target cell in parasympathetic NS compared to further away from target cell in sympathetic NS
what is an autonomic plexus
collection of sympathetic and parasympathetic fibres
define transmission
Transmission carries the signal from site of transduction to the cortex through a pathway involving multiple neurons
what sense is not relayed to the thalamus
olfaction (smell)
what’s labelled line principle
sensory information from different modalities (like taste, smell, and touch) is sent to the brain through distinct, dedicated pathways called “labeled lines.”
Outline steps in visual pathway
- Light waves pass through the cornea, enter pupil(iris), lens, retina
- rods and cones are stimulated
3.impulses pass via optic nerve
4.impulses reach optic chiasm
5.impulses reach optic tract
6.relay in lateral geniculate body (thalamus)
7.projection to super colliculus
8.optic radiation
9.fibres terminate in VA 17 (formation of image)
10.fibres travel to VA 18 for interpretation in detail
“Curious Explorers Like Really Nice Chisels To Gauge Super Rocks For image interpretation”
describe transduction in eye
Light (electromagnetic energy) activates photoreceptors located within the retina of the eye
identify the two types of photoreceptors
rods and cones
features of rods
are monochromatic (no colour information) and have low visual acuity, but excel at detecting dim lights and peripheral vision
features of cones
mediate colour vision and have high visual acuity in bright light
centre of retina =
macula (fovea is the pit in macula)
periphery of retina has ____
more rods than cones
optic disc aka
blind spot (no photoreceptors)
what does the image in the retina look like
Image on the retina is inverted and reversed
after retina the info goes to
optic nerve
optic nerves cross at
optic chiasm
what’s the optic tract
Axons extending from the optic chiasm
where does the optic tract terminate
thalamus and superior colliculus
where in the thalamus does the optic tract terminate
lateral geniculate nucleus
what splits the occipital lobe
calcarine sulcus
identify two streams of visual processing
what (naming) and where (motion) stream
function of external ear
collection of sound
function of middle ear
impedance matching:match relatively low-impedance airborne sounds to the higher-impedance fluid of the inner ear
Outline auditory pathway
-sound waves enter ear
-vibration of tympanic membrane
-vibration travel to ossicle in mid ear
-transmission to ova window of cochlea
-movement of fluid in cochlea
-stimulation of hair cells along basilar membrane
-hair cells convert mechanical vibrations into neural signals
-neural signals travel along auditory nerve
-neural signals reach brainstem
-signals extend to thalamus
-signals extend to auditory cortex
-processing occurs
“Sound Vibrations Travel Over Oceans, Making Silly Hairy Noodles Not So Tall After Processing”
function of inner ear
analysis and transduction of of signals
Outline pathway for balance
-hair cells
-nerve fibres
-vestibular ganglion cells
-vestibular nuclei (4)
-cerebellum/eye movement/muscle tone/head position/thalamus/emesis centres/
“Happy Nervous Vessels Visit Calm Centers”
brocas aphasia
“telegraphic speech” or you know what to say but you can’t.
wernickes aphasia
fluent speech but the words lack meaning and the patient is not aware of it.
-Inability to comprehend spoken words.
outline pathway for speech production (including understanding)
-Hearing (Inner ear, CN VIII etc)
-Area 41 (PAC of temporal lobe)
-Wernickes area (sensory matching)
-Hear and comprehend words
-Wernickes area (word storage)
-Brocas area (motor program)
-Motor cortex (motor execution)
-Cranial nerves
-speech
“I Always Wonder How We Begin Making Clear Speech”
outline olfactory pathway
-odourant Molecule
-olfactory Receptor
-Olfactory area
-olfactory Bulb
-olfactory Tract
-primary olfactory Area
THEN
Other areas: either to amygdala/hippocampus or orbitofrontal cortex
“MROBTAO - My Red Orange Balloon Takes Afloat Overhead”
outline process of gustation
-particles dissolved in salvia and to be tasted
-detected by taste receptors
-tranmission to thalamus VPM(ventral posteromedial nucleus)
-gustatory cortex
“PTTG - Particles To Taste Great”
identify different tastes
sweet
salty
sour
umami
bitter
flavour =
taste + smell+ texture+ temperature+ appearance
what makes up the neocortex
conical ribbon, longitudinal fissure and subcortical ganglia
semantic vs episodic memory
s=facts and general knowledge, factual
e=life events/experiences, non factual
function of cerebrocerebellum
planning and execution of skilled voluntary movements
name the sequence of events in transmission of nervous response
sensory receptor
sensory neuron
dorsal root ganglion
dorsal root
dorsal horn
dorsal column
interneuron
ventral column
ventral horn
ventral root
motor neuron
effector
outline components of corticospinal pathway
cell body
corona radiata
internal capsule
midbrain
pons
medulla
pyramidal decussation
spinal chord
innervated pathway
visceral vs somatic reflex
visceral=involves smooth muscle, cardiac muscle, glands eg.decrease in HR in response to carotid sinus
somatic = involves skeletal muscle contraction eg patellar reflex
describe two layers of retina
vertical-contains photoreceptors, bipolar cells and ganglion cells
horizontal-contains interneurons, horizontal cells and amacrine cells
ageusia
Ageusia is the loss of taste functions of the tongue
difference between spinothalamic and corticospinal tract
The spinothalamic tract is a somatosensory tract and the corticospinal tract is a motor tract
why is there no ventral root ganglion
because of the inexistence of the peripheral synapse
