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Chapter 8 Nervous System (Kahoot! (the ion needed to initiate the release…

- - - - Somatic Nervous System
        
        skeletal muscles, conscious control
      - Autonomic Nervous System
        
        Parasympathetic- homeostasis/acetylcholine/cholinergic
        
        Sympathetic-fight or flight/norepinephrine/adrenergic
- - - - Oligodendrocyte: looks like eyeball, function: produces myelin
      - Astrocyte= star-shaped, function: nourishes neurons
      - Microglia= looks like spider, function: phagocytosis
      - Ependymal cells= epithelial-like layer, function: lines spaces in CNS, brain=ventricles, spinal cord=central canal
  - - - somatic receptors
        
        external receptors (touch, pressure, temp., sight, smell, hearing, & touch)
        
        proprioceptors (position and movement)
        
        visceral receptors (digestive, respiratory, cardiovascular, urinary, reproductive, taste, deep pressure, and pain)
  - - - somatic motor neurons(skeletal muscles)
      - visceral motor neurons(muscles and glands)
        
        sympathetic (adrenergic)
        
        parasympathetic (cholinergic)
- - - - K+=high inside
      - Na+=high outside
      - Cl-=high outside
      - negatively charged proteins or anions: high inside
  - - - the cell membrane of a neuron must be depolarized (to approx. -55mV) in order for a certain ion channels to open and therefore start a nerve impulse
- - - - the period following a NI when a threshold stimulus cannot produce another NI
        
        the RMP has to be restored before it can be depolarized again (dominos must be put back up to be knocked over again)
    - - is a nerve cell responds at all, it responds completely
      - subthreshold stimulus (5mV)= no AP, no NI
      - threshold stimulus (15mV)= yes AP, yes NI
      - threshold stimulus (20mV)= yes AP, yes NI but no greater intensity than above
    - - many subthresholds stimuli received one after another may allow threshold potential to be reacher, trigger an AP and begin a NI on neuron
    - - the manner in which the NI runs down the neuron/nerve fiber
        
        unmyelinated nerve fibers=NI must travel the length of the nerve fiber, slow
        
        myelinated nerve fiber= saltatory conduction, NI jumps from node of ranvier to node of ranvier, very fast transmission
  - - - glutamate, asoartate, GABA (gamma aminobutyric acid), glycine
- - - - dura mater
        
        outermost membrane that is attached to the inner periosteum of the skull, tough, white fibrous CT, contains many blood vessels and nerves, DM splits into two layers where it encloses the dural sinuses (that collect venous blood from the brain)
      - arachnoid mater
        
        middle layer, thin net-like membrane, beneath the arachnoid mater lies a wide space called the subarachnoid space, space is filled with cerebrospinal fluid (CSF) and serves as a cushion for the brain
      - pia mater
        
        inner layer that clings to brain surface, very thin and delicate CT, many nerves and blood vessels (nourishment), dips into grooves and contours
    - - note that the dura mater is not attached to bone of the vertebra ( as in the brain where it is attached to the skull)
      - the space between the dura mater and the bone is called the epidural (subdural) space, and is filled with loose Ct and fat
      - CSF fills the subarachnoid space and central canal
  - - - are continuous with central canal of spinal cord, are filled with cerebrospinal fluid, are lined by ependymal cells (remember this neuroglial cell in CNS?)
    - - CSF is secreted by specialized capillaries in choroid plexuses into the lateral ventricles (1 and 2)
      - then it circulates down into the 3rd and 4th ventricle, and then into either
        
        central canal of spinal cord
        
        subarachnoid space of meninges
      - CSF is then reabsorbed back into the bloodstream through arachnoid granulations that project into dural sinuses
      - csf movement is aided by cilia
- - - - posterior (dorsal) horns, lateral horns, and anterior (ventral) horns
      - note the location of central canal, gray commissure, anterior median fissure, posterior median sulcus
    - - posterior (dorsal) funiculi or white column, lateral funiculi or white column, anterior (ventral) funiculi or white column
      - the white matter of the spinal cord represents the location of our major nerve pathways called "nerve tracts"- most cross over, consist of 2-3 successive neurons, exhibit somatotrophy (tracts from/to upper body are located on the outside, to/from lower body is on the inside), all pathways are paired left and right
        
        asceding tract= posterior columns and conduct sensory afferent impulses from body parts to brain
        
        descending tract= anterior columns and conduct motor efferent impulses from brain to effectors
  - - - ganglion= a bundle of cell bodies outside the CNS
      - DRG contains the cell bodies of sensory afferent neurons bringing impulses to the CNS