Physiology Flashcards
define the CNS
brain + spinal cord
what are the components of the PNS
12 CN
31 SN
+ branches
what percentage of cardiac output does the brain recieve
15%
what percentage of oxygen usage does the brain take?
20%
What are gyri, sulci and fissures?
gyrus = outward projection sulcus = inward projection fissure = deep sulcus
what is the other name for the Sylvian fissure
lateral fissure
what is the name of the fissure separating the 2 cortexes
cerebral interhemispheric
what is the function of the corpus callosum
communication between hemispheres
name the components of the brainstem in order from superior to inferior
midbrain, pons, medulla
what is the main function of the thalamus
relay centre
the LGN is part of what brain structure
thalamus
the thalamus, hypothalamus, subthalamus and epithalamus are collectively known as what?
diencephalon
what hormones does the hypothalamus synthesise
ADH, oxytocin
the hypothalamus has a role in hormone release from the _____
anterior pituitary
name the meninges from superficial to deep
dura mater
arachnoid
(subarachnoid space +CSF)
pia
what arteries does the anterior circulation arise from
internal carotid
what arteries does the posterior circulation arise from
vertebral arteries
the IC bifurcates into the ….
MCA and ACA
the ophthalmic artery is a branch of the ____
IC
the anterior choroidal artery is a branch of the ___
IC
what artery connects the right and left anterior cerebral arteries
anterior connecting artery
what artery supplies the medial cerebral hemispheres
anterior cerebral arteries
what artery supplies the lateral hemispheres, basal ganglia and the internal capsule?
middle cerebral artery
what artery runs in the sylvian lateral fissure
middle cerebral artery
the vertebral arteries are a branch of the _____
subclavian arteries
the vertebral arteries pass through the _____ of C_ to _
through transverse foramen of C6-C2
the vertebral arteries join to form the ____ at the _____
join forming basilar at pons
the posterior inferior cerebellar arteries are branches of the _____
vertebral arteries
what artery terminates at the interpeduncular cistern?
basilar artery
the superior and anterior inferior cerebellar arteries are branches of the _____
basilar artery
what artery supplies the thalamus and occipital lobe
posterior cerebral arteries
the pontine arteries are branches of the _____
basilar artery
what structure does the dural venous sinuses drain to
internal jugular vein
is the superior sagittal sinus is paired or unpaired?
unpaired
the superior sagittal sinus goes from the anterior falx cerebri to the _____
confluence of the sinuses
is the calcarine sulcus is on the anterior or posterior aspect of the brain?
posterior
the cingulate sulcus is in the midline or lateral brain surface?
midline
During foetus development, there are 3 primary vesicles which give rise to the brain, what are their names?
prosencephalon
mesencephalon
rhombencephalon
ROMan PRO MESsage
Name the lobes of the brain
parietal frontal occipital temporal insular limbic
What is the function of the insular lobe?
has a role in pain
the precentral gyrus of the frontal lobe contains the _____
motor cortex
the calcarine fissure of the occipital lobe contains the ____
visual cortex
the postcentral gyrus of the parietal lobe contains the _____
somatosensory cortex
the superior temporal gyrus of the temporal lobe contains the ____ and _____ on the dominant side
auditory cortex and wernicke’s area
what is the function of wernicke’s area
speech comprehesion
the inferior frontal gyrus of the frontal lobe on the dominant side contains _____
broca’s area
what is the function of broca’s area?
speech production
the micturition inhibition centre is part of which lobe?
frontal lobe
which lobe is responsible for executive function?
frontal lobe
which lobe contains the hippocampus
temporal lobe
what is the main function of the hippocampus
memory
which lobe contains the frontal eye feilds
frontal lobe
the amygdala is a part of the ____ system
limbic system
is the cerebellum directly above or below the tentorium cerebelli
below
does the cerebellum control ipsilaterally or contralaterally?
ipsilaterally
Name the structures that attach the cerebellum to the brainstem
superior, middle and inferior peduncles
Name the tree of white matter in the cerebellum
arbor vitae
Name the layers of the cerebellum from superficial to deep
outer molecular layer
middle Purkinje cell layer
inner granule cell layer
What is the name to the midline portion of the cerebellum?
vermis
What cell type sends efferents from the cerebellum
purkinje cells
Where to afferent inputs to the cerebellum arrive?
peduncles
What is the commonest cause of bilateral cerebellar disturbance?
Acute alcohol exposure
What type of information does the cerebellum receive and where doe sit send it?
receives sensory info for movement and sends it to thalamus
also sends intented motor
the cerebellum receives sensory info for movement, where does it send it?
thalamus
where does the cerebellum send intended motor information?
corticospinal tract
Is the basal ganglia a grey or white matter structure?
grey
Name the 5 components of the basal ganglia
caudate nucleus putamen globus pallidus subthalamic nucleus substantia nigra
Name the components of the striatum
caudate nucleus, putamen
Name the components of the corpus striatum
caudate nucleus, putamen, globus pallidus
Name the components of the lenticular nucleus
putamen, globus pallidus
Is the internal capsule a grey or white matter structure?
white
What is the function of the internal capsule?
Connects cerebellar hemispheres
What is the function of the direct pathway of the basal ganglia?
increases thalamus outflow to enhance movement
What is the function of the indirect pathway of the basal ganglia?
inhibits thalamus outflow to stop unwanted movement
Describe the main function and appearance of the substantia nigra?
dark streak in brainstem
produces dopamine
does the basal ganglia control ipsilaterally or contralaterally?
contralaterally
changed muscle tone, dyskinesia, tremor, chorea and myoclonus could all arise due to a lesion in the ______
basal ganglia
what structure produces CSF
choroid plexus of the ventricles
how much CSF is produced/absorbed a day
a pint
what structures does the cerebral aqueduct connect?
3rd and 4th ventricle
what structures does the interventricular foraminae of Monroe connect
3rd to lateral ventricles
dendrites convey graded electrical signals ____ to the neuron soma
passively
what part of a neuron contains the nucleus
body aka soma
neurons coma in different shapes; unipolar, pseudounipolar, bipolar and multipolar. what shape is a retinal neuron?
bipolar
neurons coma in different shapes; unipolar, pseudounipolar, bipolar and multipolar. what shape is a DRG?
pseudounipolar
neurons coma in different shapes; unipolar, pseudounipolar, bipolar and multipolar. what shape is a LMN?
multipolar
What is the most numerous cell type in the CNS?
glial cells
Name the 4 major types of glial cell
astrocytes
oligodendrocytes/Schwann cells
microglia
ependymal cells
There is no connective tissue in the CNS, what cell type instead takes on this role?
astrocytes
What is the shape of an astrocyte
a star
Name 3 of the roles of an astrocyte
blood brain barrier
homeostasis
support
Name the cells that produce myelin
oligodendrocyte in CNS
Schwann cell in PNS
Describe how the appearance of schwann cells and oligodendrocytes differs
oligodendrocytes have multiple branches attaching to multiple axons, whereas there is only 1 schwann cell for every segment of each axon
Name the gap in the myelin sheath of a nerve, between adjacent schwann cells
node of ranvier
What is the function of myelin sheaths and rodes of ranvier?
increase conduction velocity
What cell type are microglia derivates of?
macrophages
What is the function of microglia?
immune monitoring, antigen presentation
What is the function of ependymal cells
form the epithelium lining the ventricles
Ependymal cells are ciliated. true or false?
true
Where is white matter found in the brain?
deep to the layer of outer grey matter
____ matter is composed of cells processes, synapses, glial cells, neuron soma and blood vessels
Grey matter
____ matter is composed of myelinated axons + glial cells + blood vessels
white matter
what level does the spinal cord end
L1/2
name the structure in the spinal cord that contains CSF
central canal
what is the function of the lumbar enlargement of the spinal cord at L1-3?
lower limb innervation
what is the function of the cervical enlargement of the spinal cord at C3-T1?
upper limb innervation
what is the name of the additional grey matter structure in the spinal cord present at T1-L2 and what is its function
lateral horn
contains preganglionic sympathetic neurons
name the grey matter horns of the spinal cord, and what is their basic function
dorsal sensory horn
ventral motor horns
what is the other name for the white matter columns of the spinal cord
fasciculi
what are the names of the white matter columns of the spinal cord
dorsal
lateral
ventral
what is the name of the structure that contains the epidural venous plexuses + adipose and is found between dura and vertebrae
epidural space
the spinal nerves commence the start of the ___
PNS
the posterior rami of spinal nerves supply the _____
back of neck/trunk
the anterior rami of spinal nerves supply the _____
limbs, anterior/lateral trunk
what is the name of the thin piece of connective tissue that is a continuation of the conus medullaris ?
filum terminale
what is the name of the structure that attaches the lateral SC to the dura to suspect the SC with the spinal canal
denticulate ligament
how many neurons are there in the somatosensory pathway
3
where is the cell body of the 1st neuron (the primary sensory afferent) in the somatosensory pathway
in dorsal root ganglia or cranial ganglia
where is the cell body of the 2nd neuron in the somatosensory pathway
dorsal horn of spinal cord or in brainstem
where is the cell body of the 3rd neuron in the somatosensory pathway
thalamus
is a stretch receptor a slow or fast sensory unit?
slow
is a muscle spinal a slow or fast sensory unit
fast
is a Pacinian corpuscle a slow or fast sensory unit?
very fast
‘the site innervated by 1 sensory unit’ is the definition of ____??
receptive field
what can be used to measure receptive field
2 point discrimination
‘the afferent ending of 1 sensory axon’ is the definition of ____???
sensory unit
itch, pain, temp, proprioception and pressure are examples of sensory ____
itch, pain, temp, proprioception and pressure are examples of sensory modalities
____ stimuli have a low threshold for sending a signal in the somatosensory pathway
innocuous
nociceptors are ___ threshold receptors for initiating a signal
high threshold
receptive field size varies with body part. true or false
true
pacinian and meissner’s corpuscles are found on hairy skin. true or false
false
pacinian corpuscles are found on hairy skin, meissner’s corpusclesare found on hairless skin
the dorsal column medial lemniscus pathway innervates the whole body. true or false
false, doesn’t innervate anterior head
what sensory modalities does the dorsal column medial lemniscus pathway deal with
fine touch and conscious proprioception
where does the dorsal column medial lemniscus pathway synapse and decussate
medulla
the fasciculus cuneatus of the DCML pathway innervates _____
everything above T6 (except anterior face)
the fasciculus gracilis of the DCML pathway innervates _____
below T6
what modalities does the spinothalamic tract deal with
pain and temperature
where does the spinothalamic tract decussate and synapse?
at level they enter dorsal horn of the spinal cord
the ____ tract conveys unconscious proprioceptive info to the cerebellum to guide posture and limb movements
spinocerebellar tract
the trigeminal system is responsible for sensory innervation of the anterior head, where are the soma of the trigeminal system located?
trigeminal sensory ganglion
in somatosensation, lateral inhibition modifies information via _____ on the way to the primary somatosensory cortex
inhibitory interneurons
“an alpha motor neuron and all the fibres it innervates” is the definition of _____?
motor unit
name the two types of LMNs
α alpha motor neuron
γ gamma motor neuron
what do alpha motor neurons innervate?
extrafusal fibres of skeletal muscle
what to gamma motor neurons innervate?
muscle spindle intrafusal fibres
type I skeletal muscle fibres get ATP from ______ and are fatigue ____
ATP from oxidative phosphorylation, fatigue resistant
type ____ skeletal muscle fibres get ATP from glycolysis, not fatigue resistant
IIb fast
are muscle spindles in extensors or flexors?
extensors
muscle spindles are monosynpatic. true or false
true
“the αMNs that innervate a single muscle” is the definition of the ______??
motor neuron pool
the _____ regulate muscle tension to prevent overload
golgi tendon organs
the ____ reflex is where a muscle spindle registers a change in the length of skeletal muscle & opposes it
myotatic
the corticospinal CST tract is also know as the ____ tract
pyramidal
85% of fibres in the corticospinal tract cross at the _____ and the other 15% of fibres cross at the ____
85% of fibres in the corticospinal tract cross at the decussation of the pyramids and the other 15% of fibres remain uncrossed
the crossed ____ fibres in the CST are responsible for _____
the crossed lateral fibres in the CST are responsible for fine movements of the distal limb
the uncrossed ___ fibres in the CST are responsible for movements of ____ body parts
the uncrossed ventral fibres in the CST are responsible for movements of proximal/axial body parts
the corticobulbar pyramidal tract contains the CN UMNs for motor innervation to the ______
face, head and neck
motor system outside the pyramidal tract are referred to as the ______ system
extrapyramidal system
name the 4 tracts that make up the extrapyramidal system
rubrospinal
vestibulospinal
reticulospinal
tectospinal
which extrapyramidal tract originates the red nucleus of the midbrain
rubrospinal
what is the function of the rubrospinal tract
excite flexors & inhibit extensors of the upper body
what is the function of the vestibulospinal tract?
posture/antigravity muscles; leg extensors/arm flexors
what is the function of the tectospinal tract?
reflex head movement to visual/auditory stimuli
the reticulospinal tract has two divisions, what are their names
lateral medullary and medial pontine
what is the name of the nerve involved and the spinal cord level of the biceps reflex?
C5/6 musculocutaneous
what is the name of the nerve involved and the spinal cord level of the triceps reflex?
C7/8 radial
what is the name of the nerve involved and the spinal cord level of the knee jerk reflex?
L3/4 femoral
what is the name of the nerve involved and the spinal cord level of the ankle jerk reflex?
S1/2 tibial
the ____ separates scala media and the scala tympani
basilar membrane
in the auditory pathway, where do the hair cells synapse
spiral ganglion
go and learn the auditory pathway.
spiral ganglion> cochlear nerve> ventral cochlear nucleus> dorsal cochlear nucleus> project bilaterally> superior olivary nucleus> lateral lemniscus> inferior colliculus> medial geniculate body> primary auditory cortex in superior temporal gyrus
in the vestibular system, what is are the semicircular canals responsible for
rotational movement
name the otolith organs
urticle and saccule
in the vestibular system, what are the otolith organs responsible for
tilt, acceleration, gravity
in the vestibular system, the cupula is displaced by _____ movement
endolymph
in the vestibular system, the ___ contains the crista, hair cells and cupula
ampulla
the ____ reflex keeps the eyes fixed when the head moves
vestibulocular
the ___ hair cells are afferent CN VII
inner
the ___ hair cells are efferents from the superior olivary nucleus
outer
in the visual system, what is the function of lateral inhibition
aids localization and contrast
in the visual pathway, after fibres cross at the optic pathway where do they go next
optic tract
in the visual pathway, where do fibres go after the optic tract
optic radiation
where is the optic radiation located
superior in parietal lobe, inferior in temporal lobe
in the visual pathway, where do fibres go after the optic radiation
visual cortex
meyer’s loop is part of the ______ that loops around the temporal lobe, it contains _____ visual field fibres
meyer’s loop is part of the inferior optic radiation that loops around the temporal lobe, it contains upper visual field fibres
what is the resting membrane potential of a neuron
-70
what is the threshold membrane potential for an action potential in a neuron
-60
in a neuron action potential, what happens on the upstroke
depolarisation: voltage gated Na channels open
in a neuron action potential, what happens on the downstroke
hyperpolarisation: voltage activated K channels open
the ______ separates the pre and post-synaptic membrane
synaptic cleft
at the termination of a synapse ______ enzyme degrades ACH to ____ and _____
at the termination of a synapse acetylcholinesterase enzyme degrades ACH to acetate and choline
does excitation happen during depolarisation or hyperpolarisation?
depolarisation
ionotropic receptors are rapid and metabotropic receptors are slow at signalling. true or false
true
give an example of an ionotropic receptor
ACh nicotinic receptor
give an example of a metabotropic receptor
ACh muscarinic GPCR
what is the main excitatory transmitter
glutamate
what receptors does glutamate act on
ionotropic NMDA glutamate receptors and ionotropic non-NMDA glutamate receptors
glutamate binding to its receptor triggers a depolarising ____
EPSP excitatory postsynaptic potential
glutamate binding to its receptor triggers a depolarising EPSP, does this always result in an action potential?
no, only if the depolarisation reaches the threshold
what is the main inhibitory transmitter
GABA
what receptors does GABA act on
ionotropic GABA-A or metabotropic GABA-B receptor
what ion is involved ionotropic GABA-A receptors?
Cl
what ion is involved metabotropic GABA-B receptors?
K
GABA binding to its receptor triggers a hyperpolarising ____
IPSP inhibitory post synaptic potential
what is the function of a IPSP
inhibits action potentials
is glycine an inhibitory or excitatory transmitter?
inhibitory
GABA and glycine are both widespread inhibitory neurotransmitters. true or false
false. GABA is widespread but glycine is only found in the brainstem and spinal cord
what type of neuron is glycine involved iwth in the spinal cord?
inhibitory internuerons
what type of neurotransmitter are GABA, glycine and glutamate?
amino acid transmitter
what type of neurotransmitter are dopamine, histamine, NA and serotonin?
amine transmitters
______ type of pain is adaptive and immediate
nociceptive
______ type of pain is adaptive and functions for healing
inflammatory
_____ type of pain is a maladaptive
pathological
what type of stimuli activate nociceptor Aδ fibres
mechanical and thermal
what type of stimuli activate nociceptor C-fibres
all
how is pain from nociceptor Aδ fibres experienced?
first quick stabbing / pricking feeling
how is pain from nociceptor C fibres experienced?
2nd slow burn, throb, cramp, ache
are nociceptor Aδ fibres myelinated?
thinly melinated
are nociceptor C fibres myelinated?
unmyelinated
name the subset of nociceptive C fibres that release pro-neurogenic-inflammation mediators
peptidergic polymodal
where are the soma of neurons in the nociceptive pathway located
trigeminal ganglion or dorsal root ganglion
what horn of the spinal cord contains nociceptive fibres
dorsal horn
name the tract that carries fast Aδ nociceptive fibres to the thalamus
spinothalamic
name the tract that carries slow C nociceptive fibres to the brainstem
spinoreticular
[somatic/visceral] pain is from body wall structures eg. the peritoneum
somatic
is somatic or visceral pain well localised
somatic
is somatic or visceral pain experienced as a dull ache / throbbing sensation
visceral
What word is used to describe the organisation of the primary somatosensory cortex and primary motor cortex
somatotopic
What part of the body makes up the biggest portion of the sensory cortical homunculus and the motor cortical homunculus
hands
How do you recognise the pons on histology sections?
horizontal bands
How do you recognise the midbrain on histology sections?
contains the cerebral aqueduct
In the corticospinal tract, where do fibres go after the medulla?
through pons, then midbrain, then internal capsule, then to primary motor cortex
except reverse?
The prosencephalon (one of the primary vesicles of the brain in development) splits to give rise to 2 secondary vesicles, what are their names?
telencephalon
diencephalon
What structure in the mature brain does the telencephalon become?
the cerebral hemispheres
What structure in the mature brain does the mesencephalon become?
midbrain
The rhombencephalon (one of the primary vesicles of the brain in development) splits to give rise to 2 secondary vesicles, what are their names?
metencephalon
mylencephalon
What structure in the mature brain does the metencephalon become?
pons, cerebellum
What structure in the mature brain does the mylencephalon become?
medulla
Which primary vesicles form the forebrain, midbrain and hindbrain?
forebrain = prosencephalon midbrain = mesencephalon hindbrain = rhombencephalon
