A+P Flashcards
what is a sympathetic chain?
Sympathetic chain: ganglionated chain present bilaterally extending from base of skull to coccyx
what does the sympathetic chain divide into?
cervical, thoracic, lumbar and sacral segments
what do preganglionic sympathetic neurones release?
ACh
what do postganglionic neurones release?
noradrenaline
what is the function of postganglionic sympathetic neurones?
: vasoconstricting blood vessels, regulation of glandular secretion, inhibiting smooth muscle contraction in the GI system
where is visceral pain felt?
visceral pain is felt near viscera or in a cutaneous area or other tissue whose somatic afferents enter spinal segments that receive visceral afferent form viscera
where does the anterior and middle cerebral artery arise from?
internal carotid
where does vertebral artery arise from?
subclavian
on CT you can see sylvan fissure, what is located underneath?
temporal lobe
what is the refractory period?
when na channels are closed and inactivated, no new AP can be generated absolute refractory period
what is the relative refractory period?
some Na channels are in resting state and new AP can be initiated if stimulus are strong enough
why are the refractory periods?
- These mechanisms help limit rate of firing
- Prevent antidromic conduction (helps AP can go in correct directional – unidirectional)
how does BOTOX work?
toxins that cleave snare proteins and prevent NT release
- no action at NMJ
what is neuromytonia?
chronic muscle stiffness and hypertonia
what is the pathology of neuro myotonia?
- AB created against presynaptic potassium channel
- Nerve is then in constant state of depolarisation and transmitter release
what is the pathology of myasthenia gravis?
- AB targeting nicotinic AChR
- Muscle weakness and fatigability that worsens on exercise
what is recuronium?
acting on NMJ
- Competitive muscle relaxants eg rocuronium antagonise the action of Ach on nACHRs
used in anaesthetics
what is the MOA of suxamethonium?
- Depolarising muscle relaxants eg suxamethonium activate nAChRs
anaesthetics
how does anticholinesterases eg neostigmine work?
reverse effects of competitive muscle relaxants by increasing amount of Ach present of synapse
what does the central sulcus separate?
frontal and parietal lobe
what sits behind the lateral sulcus?
temporal lobe
what are the functions of the frontal lobe?
- Higher intellect
- Personality
- Mood
- Social conduct
- Language dominant hemisphere only
what are the functions of the parietal lobe?
- Language
- Visuospatial functions eg 2 point discrimination on non dominant side
what is seen within frontal lobe pathology?
personality/ behavioural changes, inability to solve problems
what is seen within parietal lobe pathology?
attention deficits eg contralateral hemispatial neglect syndrome patint does not pay attention to side of body opposite to lesion
what is seen within temporal lobe pathology?
recognition deficits
not understanding basic sounds
failure to recognise faces
what is agnosia?
recognition deficits
what is auditory agnosia?
inability to comprehend basic sounds
what is prosopagnosia?
inability to recognise faces
what would be seen within occipital lobe pathology?
visual field defects
contralateral hemianopia
what would occur within global lesions?
: severe cognitive defects eg dementia patients can not answer simple questions like their name, date, location
what is aphasia?
acquired loss of language and ability to verbally communicate language
what is the function of brocas area?
associated with speech production and articulation
- Articulate ideas and use words correctly
- Spoken or written language
how would pathology of Broca’s area present?
can understand but can not find correct words
will be irritated
what is the function of wernickes area?
involved in comprehension
- Language processing
- Written or spoken
how would wernickes area pathology present?
can find words but can not understand and then reply with fluent nonsense
will be okay - they do not relaise they are talking nonsense
what is global aphasia?
damage in both brocas and wernickes area
what occurs in the angular gyrus?
multiple types of language related info whether auditory, visual or sensory
- Allows us to associate a perceived word with different images, sensations and ideas
- Close to parietal lobe which processes tactile sensation
describe features of global aphasia
- All aspects and speech and language are affected
- Can only understand a few phrases and words
- Can not read or write or repeat words said to them
- Can not carry out commands or name objects
what structures is the angular gyrus close to?
occipital - visual analysis
temporal lobe - processing sounds
what is the function of the cerebellum?
motor control
active in coordination, precision, timing of movement s
what does the hindbrain consist of?
lower brainstem - cerebellum, pons and medulla
what is the function of the hindbrain?
fundamental to survival
- Respiratory rhythm
- Motor activity
- Sleep
- Wakefulness
what is the function of spinocerebellum?
- Regulating body movements by allowing for error correction
- Proprioceptive movements
what is the function of vestibulocerebellum?
- Controlling balance and ocular reflexes
- Fixation on targets
- Inputs from vestibular and sends outputs back
what does the pyramidal descending tract do?
voluntary control of musculature of body and face
where do the extrapyramidal tracts run within descending tracts?
originate in brainstem and carry info to spinal cord
what is the function of extrapyramidal tracts?
- Involuntary and automatic control of musculature eg muscle tone, balance, posture and locomotion
what are the meninges?
membranous covering of brain and spinal cord
what are the three layers of the meninges?
DAP
dura mater
arachnoid mater
pia mater
what are the functions of meninges?
- Supportive framework for cerebral and cranial vasculature
- Acting with cerebrospinal fluid to protect CNS from mechanical damage
describe the dura mater layer?
outermost layer and located underneath bones of skull and vertebral column
- Thick, tough and inextensible
- Has two layers of connective sheets: periosteal layer and meningeal layer
where are the Dural venous sinuses located?
venous drainage of cranium and empty into jugular vein
describe arachnoid layer
middle layer
- Consists of connective tissue, avascular and has no innervation
- Underneath is sub-arachnoid space
what is located underneath sub-arachnoid space?
CSF
what does pia mater cover?
very thin
follows contours of brain - gyri and fissures
what does the basal ganglia do?
- Acts to modulate and refine cortical activity eg controlling descending motor pathways
reduces a lot of excitatory input
what is white matter?
axons
what is grey matter?
cell bodies
why is it important that the basal ganglia reduces excitatory input?
to prevent excessive/ exaggerated movements
