UNIT 2: Cerebral Hemispheres Flashcards
what divisions are included under the CNS
Cerebral cortex
cerebellum
diencephalon
brainstem
spinal cord
what divisions are included under the PNS
cranial nerves
spinal nerves
what are the 2 functional divisions of the NS
somatic and autonomic
somatic sys
aspects of bodily function under conscious and voluntary control (motor control sys and sensory sys)
autonomic sys
involuntary activities of visceral muscle (smooth muscle, glands) and maintenance of homeostasis
where does motor control arise in the somatic NS
from the precentral region of the cortex - descending motor tracts thru brainstem and spinal cord
what are the 2 divisions of the autonomic NS
sympathetic and parasympathetic
sympathetic NS
vasoconstriction, inc blood pressure, pupil dilation, cardiac acceleration - “flight, fight, fright”
parasympathetic NS
slowing heart rate, dec blood pressure, pupillary constriction - counteracts preparatory action of sympathetic sys - “energy saving”
where does the autonomic NS arise from aka controls from
prefrontal crotex, hypothalamus, thalamus, hippocampus, brainstem, cerebellum, spinal cord
functional unit of the NS
neuron aka communicating tissue… responds to stimulation w inc activity (excitation) or dec activity (inhibition)
3 types of neurons
sensory (afferent), motor (efferent), interneurons
sensory (afferent) neurons
classified by sensory properties - ex. mechanical, thermal, pain, visual, auditory, taste
motor neurons (efferent)
activate response in muscles or glands, known for long myelinated axons, differ by size/conduction velocity/myelination
interneurons
most common
communication bw other neurons
confined to CNS
white matter
collections of myelinated axons - in the CNS can be tracts/fibre tracts/ pathways/ peduncles/ fasciculus/lemniscus/ capsules/commissures - in the PNS can be nerve/nerve fascicles
Gray matter
neural tissue consisting of cells bodies - grouped into a cortex/nucleus/ganglion
at week 3 in development of the embryo what are the 3 cell layers
ectoderm, mesoderm, endoderm
ectoderm becomes
CNS and skin
mesoderm becomes
muscles
endoderm becomes
insides like digestive tract and lungs
what is neurulation
to develop the CNS/PNS there is a thickening of the ectoderm called the neural plate - cells migrate and proliferate to form the neural plate - notochord signals the dec of the neural plate to start happening
what does the neural plate further develop into
the neural folds and neural groove - creates a trough and folds come into contract to fuse w one another
what does the neural groove further develop into
neural tube and some of the cells break off to create neural crest cells (dorsal to neural tube) which becomes the PNS and meninges
spina bifida occurs because of
a lack of fusion of the neural tube
mesencephalon and rhombencephalon
spinal cord
prosencephalon becomes
cerebrum
telencephalon becomes
cerebrum… most neurons accumulating here
the diencephalon becomes
thalamus and third ventricle
cerebrum function
higher functions (cognition, language, memory)
integrates sensorimotor functions and perception
limbic system
regulates motivational and emotional states
basal ganglia
regulates motor movements and muscle tone
thalamus
mediates sensation to cerebral cortex
hypothalamus
regulates body functions such as temp, satiation, water balance, emotional behaviour, sexual response
cerebellum
regulates coordination of skilled movements
midbrain
mediates auditory and visual reflexes
maintains cortical arousal
houses cranial nerve nuclei
pons
houses cranial nerve nuclei
medulla
regulates respiration, phonation, heartbeat, blood pressure
regulates reflexes
how are the 2 symmetrical cerebral hemispheres organized in terms of gray and white matter?
external gray matter - cerebral cortex
internal white matter - fibre tracts (association, commissural, projection)
internal gray matter (basal ganglia, amygdala, hippocampal formation)
what is the cerebral cortex?
the thin rim of gray matter that covers the cerebral hemispheres - about 2-4 mm thick and contains billions of neurons
how many cell layers are in the cerebral cortex
6 cell layers
what is in layer I of the cerebral cortex
axons, glial cells
what is in the layer II of the cerebral cortex
many stellate and small pyramidal
what is in layer III of the cerebral cortex
some stellate and medium pyramidal
what is in layer IV of the cerebral cortex
densely packed stellate cells (sensory afferents)
what is in layer V of the cerebral cortex
large pyramidal cells only (motor efferents)
what is in layer VI of the cerebral cortex
stellate and pyramidal (back to thalamus)
5 lobes of the cerebral cortex
frontal, parietal, occipital, temporal, insular
what are the 3 main sulcus/fissure of the cerebral cortex
longitudinal fissure, central sulcus, lateral sulcus
what are brodmann’s areas? (BA)
- Brodman examined cytoarchitecture of the cerebrum
- labelled approx 50 diff areas based on function
- can describe the function of the various regions as: primary regions, association regions (unimodal or multimodal), or limbic regions
- aka mapped the brain based on the cell layers: where it is thick w sensory cells and where is it thick with motor cells