W8: NS cells & Tissues; Topography; Vestibular Flashcards
Describe the main components of the nervous system
Neurons: ↑metab.; excitable
Glial: non-excitable; smaller; purple staining
MULTIPOLAR: motor neurones; interneurones
BIPOLAR: olfactory; retinal nerve fibre
PSEUDOUNIPOLAR: sensory
Describe the different cell types found in the nervous tissues
ASTROCYTES: BBB - maintain stable environment, K+ buffering
MICROGLIA: phagocytosis
EPENDYMAL CELLS: line cavities: ventircles and central canal
OLIGODENDROCYTE: myelination
SCHWANN CELL (pns): myelination
SATELLITE CELLS: surround cell bodies; protect
Compare grey and white matter
WM: myelinated axons (fat); AXONS
GM: cell bodies: glial, large cell bodies, Nissl bodies, Neutrophil
Explain how cerebrospinal fluid is produced and circulated
CSF (choroid plexus) and circualte and contained within the VENTRICLES and SUBARACHNOID.
=> abs by arachnoid villi (pia+arachnoid projections) => sagittal sinus
=> roof of 4th ventricle
=> enter into subarachnoid via LEUSCHKA & MAGENDIE FORAMINA
Describe how the blood-brain barrier works, and what it implies for drug therapy
BBB prevents wbc from moving into the brain and ensures stable environment of the brain.
Lined with the foot processes of astrocytes, therefore tightjunctions in between can allow passage of LIPID SOLUBLE DRUGS only
Describe how the different topographical features of the brain arise developmentally from different parts of the neural tube
Forebrain
=> DIENCEPHALON = 3rd Ventricle
=> CEREBRAL HEMISPHERES = Lateral Ventricle
Midbrain
=> cerebral aqueduct
Hindbrain
=> Pons; medulla; cerebellum => 4th Ventricle
Spinal Cord
Describe the structures that protect the brain including the dural folds, the scalp, the skull bones and meninges
FALX CEREBRI
FALX CEREBELLI
TENTORIUM CEREBELLI
DIAPHGRAGMA SELLAE
D
A
- CSF & vascular -
P
Understand the components of the diencephalon, where they lie and their function
Contains Th, HypoTh, Pituitary Stalk, Pineal Gland
Primary relay and processing center for sensory information and autonomic control
Describe the blood circulation in the brain including the Circle of Willis and the venous sinuses.
ACA = ANT. MEDIAL SUPERFICIAL - frontal; pre-frontal; motor cortex, anterior parietal
MCA (ICA) = LATERAL BRAIN PARTS - frontal; temporal; parietal
PCA = POSTERIOR INFERIOR PARTS - post. med. parietal, splenium of corpus callosum, inf. medial temporal + hippocampal, medial inferior occipital
Outline briefly the way in which the hair cells in the cupula organs of the semi-circular canals detect rotation
Endolymph found within Hair cells @ ampulla becomes distorted as a result of rotational acceleration which sends AP in vestibular nerve.
- upon rot., ampulla moves d/t attached tO temporal bone
- endolymph stationary d/t inertia
- CUPULA moves around endolymph and becomes distorted
- hair cells move= AP
Outline briefly the way in which hair cells in the macula organs detect body movement
OTOLITH ORGANS:
• Kinocillum & stereocillium protrude into OTOLITH MEMBRANE.
• Otolith calcium crystals embedded and move in response to gravity d/t weight of crystal
• move in direction of kinocillium = AP discharge (vertical forces)
UTRICLE - horizontal: front + back tilt + horizontal acceleration
SACCULE - vertical: vertical acceleration
List the major sensory inputs which contribute to the perception of our body space
1) Tonic labyrinthine reflex - maculae + neck proprioreceptors = maintain head + body relationship
2) Dynamic righting reflex
postural adjustments preventing falling
3) KINETOSIS
Sickness reflex d/t conflicting vestib inputs
4) Vestibuoccular Reflex
Medulllary vestib. nuclei -> extraocular nuclei
influence eye movement
=> occulomotor + trochlear nuclei (sup colliculus)
=> abducens nucleus (pontomedullary.)
=> vestibular nystagmus (COWS)
Explain how vestibular nystagmus can be used to test vestibular function
Test vestibular nystagmus reflex presence by caloric induction
= COWS, if not followed = abnormality present preventing transmission of AP
as medullary vestib nucei influences eye movement
Describe the common diseases and damaging factors that affect vestibular function
LABRYNTHITIS: inflamm, URI association
= CONT. VERTIGO +/- nystagmus + ANS symptoms
*hearing loss vs nil loss in BPPV
= MENIERES DISEASE: endolymph overproduction: nil URI
↑pressure; EPISODIC vertigo, nausea, nystagmus, tinnitus
ANS Summary
Sympathetic: thoracolumbar,
short-pre (cholinergi + nicotinic)
long-post (adrenergic) | alpha beta receptors
Parasymp.: craniosacral
long-pre (Cholinergic + nicotinic ion channel)
short-post (cholinergic + muscarinic G protein)
parasymp: CN III CN VII CN IX CN X
