NAS W5 - BRAIN Flashcards
(24 cards)
BRAIN EMBRYOLOGY
- neural tube differentiates to 3 distinct primary vesicles (forebrain, midbrain & hindbrain)
- forebrain & hindbrain each differentiate to 2 further secondary vesicles, but midbrain remains unchanged (leads to 5 secondary vesicles of brain)
BRAIN DIVISIONS
- divided to sensory brain (to perceive senses) & motor brain (purposeful movements)
- frontal lobe - intellect, language, personality
- parietal lobe receives & processes somaesthetic sensory (useful for senses/perceptions of body surface & internal organs)
- temporal lobe used for hearing
- occipital lobe used for visual information
NEURONE TYPES
multipolar, bipolar, pseudounipolar
GREY/WHITE MATTER
- in brain, outside is grey (cell bodies) & inside is white (myelin)
- in spinal cord, outside is grey (myelin) & inside is white (cell bodies)
GYRUS
the ridges in the brain (gaps between gyrus are sulcus)
FISSURES (MAJOR SULCI)
- central sulcus separates frontal & parietal lobes
- lateral fissure separates temporal lobe from parietal & frontal
- parieto-occipital sulcus separates occipital lobe from parietal lobe
DIENCEPHALON (THALAMIC MASSES)
- part of forebrain
- divided into thalamus & hypothalamus
THALAMUS
- sits on either side of 3rd ventricle
- has thalamic nuclei (group of neurones) which act as switchboards to control what sensory info reaches cerebrum & how motor commands from frontal lobes are distributed downstream
HYPOTHALAMUS
- controls homeostasis
- below thalamus & extends inferiorly to form posterior part of pituitary gland
EPITHALAMUS
houses the pineal gland which releases melatonin & is involved in control of our circadian rhythms
BRAINSTEM
- made of midbrain, pons & medulla
- houses 10 of the cranial nerves
MIDBRAIN
- vision, hearing, arousal, motor control, sleep, wakefulness
- lies above & below cerebral aqueduct
CEREBRAL AQUEDUCT
joins 3rd & 4th ventricles allowing CSF to flow between them
HINDBRAIN
consists of pons, medulla oblongata & cerebellum
PONS
- connected to cerebellum by cerebellar peduncles & coordinates activity of cerebellum
- houses neurones for regulating respiratory rhythm
MEDULLA OBLONGATA
contains neurones regulating resp, HR, vomiting
CEREBELLUM
connected to dorsal side of brainstem & involved in fine motor control & memory of motor skills (e.g. bike ride)
MENINGES
3 layers (PAD) of connective tissue which completely cover brain, spinal cord: pia mater (super thin & closely adheres to brain surface & covers surface of gyri & sulci), arachnoid (slightly thicker & has the blood vessels & the role is to hold the liquid CSF in subarachnoid space (which also contains cerebral blood vessels which carry oxygenated blood to brain & the veins that drain into venous sinuses)), Dura mater (thickest layer & most superficial & protects brain from physical trauma)
MENINGEAL LAYER (PAD)
tightly adhered to endosteal layer (the periosteum of skull bones) unless there are Dural venous sinuses (in this case, the 2 layers of dura meter are separated)
ROLE OF CSF
provide cushioning & buoyancy to brain to protect it from high-energy impacts
BLOOD BRAIN BARRIER (BBB)
- ensures that blood vessels of CNS are tightly sealed (by semipermeable border of endothelial cells with tight junctions between them) to prevent their contents from directly communicating with CNS tissues
- BBB restricts passage of pathogens, diffusion of solutes & large molecules into CSF but allows diffusion of hydrophobic molecules (O2, CO2, hormones)
TRAUMA
- coup contrecoup (coup injury is brain bruise under point of impact but contrecoup injury is on opposite side of brain from where impact occurred)
- Shaking baby syndrome (brain moves around & this can lead to damage of nerves)
VENTRICULAR SYSTEM
- 2 lateral ventricles & also 3rd & 4th
- 3rd & 4th linked by cerebral aqueduuct
- CSF produced in choroid plexus (in the 2 lateral ventricles)
- after leaving 4th ventricle, CSF flows into spine & surrounds brain
HYDROCEPHALUS
brain damage due to excess pressure as CSF flow blocked
