What are the functions of the nervous system? 1) Detect stimuli (environment & self) 2) Conduct impulses, integrate, evaluate impulses (stimuli), memory 3) Respond (movements, maintain homeostasis etc.) Nervous System http://asymptotia.com/wp-images/2007/08/ homer-simpson-wallpaper-brain-1024.jpg
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What are the functions of the nervous system? 1) Detect stimuli (environment & self) 2) Conduct impulses, integrate, evaluate impulses (stimuli), memory.
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Associated with blood-brain barrier which is formed by endothelial cells of blood vessels.
Nervous System
Ependymal cells:
Line the ventricles (cavities) of CNS, create cerebral spinal fluid and aid in its circulation.
What are the types of glial cells and what tasks do they accomplish?
Nervous System
Microglia:
Small specialized macrophages that attract to areas of damage in the CNS and phagocytize debris
What are the types of glial cells and what tasks do they accomplish?
Nervous System
Oligodendrocytes:
Cells in the CNS that have multiple extensions that wrap around multiple axons forming myelin sheaths.
What are the types of glial cells and what tasks do they accomplish?
Nervous System
Schwann cells:Cells in the PNS that wrap around single axons forming myelin sheaths.
The gaps in between Schwann cells are called Nodes of Ranvier
What are the types of glial cells and what tasks do they accomplish?
Nervous System
The Brain: development…
Our central nervous system has humble origins early in our development (by 3rd wk.)
A plate (neural plate) of cells develop crests (neural crests) that rise and eventually meet and fuse leaving the hollow dorsal nerve cord & and ventricles of our CNS
Nervous System
The Brain: development…
Swellings around 3 continuous chambers are precursors to forebrain (prosencephalon), midbrain (mesencephalon) and hindbrain (rhombencephalon)
The brain and spinal cord are protected by meninges
3 layers:Dura mater ~ outermost, tough, continuous with periosteum
Arachn oid mater ~ middle layer, spider-web appearance
Pia mater ~ innermost layer, not visible to naked eye
Nervous System
The Brain: from the outside in…
100-160ml of CSF circulates throughout the ventricles, down the central canal of the spinal cord and throughout the subarachnoid space.
CSF is reabsorbed back into blood primarily at the venous sinuses found within the dura mater.
Nervous System
The Brain: from the outside in…
Ventricles are comprised of 4 major cavities:1&2 ~ Right and Left Lateral ventricles
3rd ventricle space within thalamus
4th ventricle between cerebellum and brainstemchannel connecting 3rd and 4th cerebral (mesencephalon) aqueduct and if blocked can result in hydrocephaly
Nervous System
The Brainstem: Medulla oblongata
Most inferior portion, functions as a conduction pathway (descending motor neuron pathways decussate here) Contralateral/IpsilateralReflex centers for:
regulating heart rate
blood vessel diameter
coughing, sneezing
breathing
swallowing
Nervous System
The Brainstem: Pons
Superior to Medulla oblongata.
Contains more ascending and descending pathways.
Relays information from cerebrum to cerebellum.
Also includes sleep and respiratory centers.
Nervous System
The Brainstem: Midbrain
Small section superior to the pons.
Part of the auditory pathways and visual reflexes
Also involved in regulating muscle tone/activity and coordination
Nervous System
The Diencephalon: Thalamus
“Gateway to cerebral cortex”
Most sensory stimuli project to the thalamus, which in turn projects to the cerebrum.
Thalamus also influences moods and activities associated with strong emotion.
(Two concepts: Sensory integration and Mood)
Nervous System
The Diencephalon: Hypothalamus Major control center of autonomic nervous system and endocrine system.