Ch. 3 CNS Flashcards
Embroynic Development
day 20: neural plate starts to dip; crest cells (PNS)
day 23: lumen formed
day 28: forebrain, midbrain and hindbrain
day 42: cerebrum and diencephalon; midbrain stay the same; medulla, pons, and cerebellum
11 wks: cerebrum has rapid growth; all grow
The Brain
Forebrain: 1. cerebrum- cerebral cortex and basal nuclei 2. diencephalon- hypothalamus and thalamus Cerebellum: 1. spinocellum 2. cerebrocellum 3. vestibulocellum Brain Stem: pons, medulla and midbrain
Functional Class of Neurons
Afferent: to the CNS
Interneurons: classic neurons; create complexity (behaviour, emotion)
Efferent: from the CNS
Glial Cells in PNS
Schwann Cells: myelin; neurotropic factors
Satellite cells: form capsules around cell bodies; called ganglia
Glial Cells in CNS
Oligodendrocytes: form myelin sheath
Astrocytes: form tight junctions from secreted paracrine signals (form BBB); form neurotrophic factors
Microglia: stationary until commanded; immune cells; misbehaviour: Alzheimers, dementia, brain degeneration (AIDS)
Ependymal cells: line cavities of brain (ventricles); secretion of CSF; stem cells for new neurons; disease: hippocampus (Alzheimer’s)
Alzheimer’s
Microglia- overactice
genetically- chromosome 1, 14, 19, 21
environmental factors eg. drug use
- age related
Meningies
Dura matter: veins
Arachnoid matter: subarchanoid space “archanoid villi”; sucks up wastes from CNS and into dura matter
Pia matter: arteries, bring blood in; very thin; were infections are found ex. meningitis
CSF
- floats in salty solution
- high Na+ content- action potentials
- 3x every day (150mL)
- produced by epidermal cells- 3&4 ventricles (choroid plexus)
- shock absorber
- floats= buoyancy- reduces weight by 1/3
BBB
astrocytes: paracrine signal
- require carrier
eg. Parkinson’s Disease: dopaminergic neurons destroyed; treatment: L-Dopa can cross barrier
- absent in vomiting center and hypothalamus
Cerebrum
2 cerebral cortex
- corpus callosum
- white matter: 1 mylinated, axon layer
- grey matter: 6 layers, cell bodies and junction formation
- sulcus: increase surface area
- 4 lobes: occipital, temporal, parietal, frontal
- dominance or lateralization
Parietal/central sulcus
sensation emerge “somesthetic”
- homunculus sensory
- “littleman” drawn upside down
- parts of body= important= area devoted
eg. lips, tongue, genital, hand - pain, touch, temperature, itch, ect
- proprioception
Frontal/central sulcus
motor homunculus
- tongue, fingers and thumb, no genitial
Wernicki’s Area
- receive’s info (hear/see)
- interface (parietal-temporal-occipital)
- comprehend words
disorder: stroke- cannot understand; speech doesn’t make sense; receptive aphasia
Broca’s Area
- programs sound pattern
- speech production
disorder: stroke- failure of word formation; expressive aphasia
Association Areas
Prefrontal association cortex: creativity, personality, planning, decision making
parietal-temporal-occipital: integration of all sensory input, important in language; in-tune with external environment
Limbic: inner and bottom surface of temporal lobe, motivation, emotion and memory
Basal Nuclei
- inhibit unnecessary motor activity
- encourages useful motor activity
how? “a loop”
- higher cortex to basal nuclei to thalamus to higher cortex
diseases:
Parkinson’s Disease (3rd level):
- lack of dopamine, low in basal nuclei, tremors, difficult walking, shuffling gait
Huntington’s Disease: fatal genetic, neurodegenerative; lose cognitive, dementia, bedridden, motor discoordination
Dienchephalon
Thalamus: relay station (basal nuceli to higher cortical)
- processing all sensory input (except smell)
- crude awareness of activity
- aware of stimuli of special interest eg. parent/child
Hypothalamus: temperature control and osmomclarity/isotonic
- hunger/satiety, sympathetic nerves
- endocrine glands: pineal gland- circadian rhythm and pituitary: anterior (gonads, FSH & LH) and posterior (oxytocin-milk release and vasopressin or ADH)
Spinocellum
- muscle tone
- middle management: intention of higher cortex, performance of muscles, make/adjust changes
- co-ordinator, voluntary movement
Cerebrocellum
- planning activity
- procedural memories
Vestibulocellum
- balance (inner ear)
- eye movement
Brain Stem
- has reticular activating system
- involved in: breathing, sleep cycles/arousal, stretch, modulation of pain, b.p, muscle tone
- controlled by medulla, pons and midbrain
- origin of cranial nerves (12 pairs)
- CN10: vagus nerve, abdominal cavity- heart
Medulla
- breathing, b.p., swallowing, vomiting
Pons
- attach medulla to midbrain, control breathing
Midbrain
“mesencephalon”
- eye movement and reflexes
- ear relfexes
Amygdala
- fear
- butterflies, flight and flight response
Hippocampus
- new neurons
- memory retention, declarative memory, specific times/places
- first lost in Alzheimer’s
Spinal Cord
dermatomes (map) - clinical use: know damage to a region cauda equina (spinal tap) - gather sample of CSF eg. meningitis - epidermal, during child birth
