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Unit 6: Nervous System Lauren Palla, Period 6 - Coggle Diagram

- - - - Ischemia- tissue deprived of blood supply, resulting in the death of brain tissue
      - Hemiplegia- paralysis on one side, or sensory and speech deficits may occur
      - Tissue Plasminogen Activator (TPA)- only approved treatment for stroke
      - Transient Ischemic Attacks (TIAs)- temporary episodes of reversible cerebral ischemia
    - - Concussions- temporary altercation in function
      - Contusion- permanent damage
      - Cerebral Edema- swelling of brain
      - Subdural/Subarachnoid Hemorrhage- pressure from blood may force brain stem through foramen magnum, resulting in death
    - - Alzheimer's Disease (AD)
        
        Progressive degenerative disease of brain that results in dementia
        
        Symptoms include memory loss, short attention span, disorientation, eventual language loss, irritability, moodiness, confusion, hallucinations
        
        Brain shrinks
        
        Neurofibrillary tangles interfere with transport mechanisms, killing neuron
      - Parkinson's Disease
        
        Degeneration of dopamine-releasing neurons of substantia nigra
        
        Basal nuclei deprived of dopamine become overactive
        
        Treatment includes L-dopa, deep brain stimulation, gene therapy
      - Huntington's Disease
        
        Fatal hereditary disorder caused by accumulation of protein huntingtin
        
        Leads to degeneration of basal nuclei and cerebral cortex
        
        Treated with drugs that block dopamine effects
        
        Initial symptoms include wild, jerky "flapping" movements
        
        Later marked by mental deterioration
  - - - Paresthesias- caused by damage to dorsal roots/sensory tracts; leads to sensory function loss
      - Paralysis- caused by damage to ventral roots/horn cells; leads to motor function loss
      - Transection of Spinal Cord- results in total motor and sensory loss in regions inferior to cut
        
        Paraplegia- transection btwn. T1 and L1
        
        Quadriplegia- transection in cervical region
      - Spinal Shock- transient period of function loss caudal to lesion
    - - Caused by environmental factors and genetic mutations involving RNA processing; involves glutamate excitotoxicity
      - Drug riluzole interferes with glutamate signaling
      - Symptoms include loss of ability to speak, swallow, and breathe
- - - - Innervate smooth muscles, cardiac muscles, and glands
      - Makes adjustments to ensure optimal support for body activities
        
        Shunts blood to areas that need it
        
        Adjusts heart rate, blood pressure, digestive processes, etc.
      - Operates via subconscious control
  - - - Effectors
        
        Somatic Nervous System- skeletal muscles
        
        Autonomic Nervous System- cardiac/smooth muscle, glands
      - Efferent Pathways and Ganglia
        
        SNS- cell body @ CNS, and a single, thick myelinated group of axon extends in spinal/cranial nerves to skeletal muscles.
        
        ANS- pathway uses a 2-neuron chain
        
        Preganglionic Neuron - cell body @ CNs with thin, lightly myelinated preganglionic axon that extends to ganglion
        
        Postganglionic Neuron- cell body synapses with preganglionic axon @ autonomic ganglion with nonmyelinated postganglionic axon that extends to effector organ
      - Target Organ Responses to Neurotransmitters
        
        SNS- releases acetylcholine (ACh)
        
        ANS- releases ACh or norepinphrine (NE)
    - - Higher brain centers regulate and coordinate both systems
      - Most spinal and cranial nerves contain both somatic and autonomic fibers
      - Adaptations usually involve effectors from both systems (skeletal muscles and visceral organs)
- - - - Astrocytes- most abundant neuroglia that clings to neurons, synaptic endings, and capillaries
        
        Guide migration of young neuron
        
        Controls chemical environment
        
        Plays role in exchanges btwn. capillaries and neurons
        
        Responds to nerve impulses and neurotransmitters
        
        Support and brace neurons
        
        Info processing @ brain
      - Microglial Cells- small, ovoid cells that touch and monitor neurons
        
        Migrate towards injured neurons
        
        Transform to phagocytized micro. and neuronal debris
      - Oligodendrocytes- branched cells
        
        Processes wrap CNS nerve fibers, forming myelinated sheaths
      - Ependymal Cells- squamous or columnar cells that may be ciliated
        
        Line central cavities of brain and spinal column
        
        Forms permeable barrier btwn. CSF and tissue fluid bathing CNS cells
    - - Satellite Cells- cells that surround neuron cell bodies @ PNS
        
        Functions like astrocytes
      - Schwannn Cells- cells that surround all peripheral nerve fibers and form myelinated sheaths
        
        Functions like oligodendrocytes
        
        Vital to regeneration of damaged peripheral nerve fibers
- - - - Ventral Roots- bundle of motor neuron axons that exit spinal cord
      - Dorsal Roots- sensory input
    - - 3 areas of gray matter are found on each side of the center:
        
        Dorsal Horns- interneurons that receive somatic and visceral sensory input
        
        Ventral Horns- some interneurons; somatic motor nuerons
        
        Lateral Horns- sympathetic neurons
      - Gray matter is divided into 4 groups:
        
        Somatic Sensory
        
        Visceral Sensory
        
        Somatic Motor
        
        Visceral Motor
    - - Dorsal (posterior)
      - Lateral
      - Ventral (anterior)
- - - - Structural Classification
        
        Multipolar- 3+ processes (1 axon, other dendrites)
        
        Bipolar- 2 processes (1 axon, 1 dendrite)
        
        Unipolar- 1 T-like process (2 axons)
      - Functional Classification
        
        Sensory- transmits impulses from sensory receptors towards CNS
        
        Motor- carry impulses from CNS to effectors
        
        Interneurons- shuttles signals through CNS pathways; lies btwn. motor and sensory neurons
    - - Extreme longevity
      - Amitotic
      - High metabolic rate (requires continuous supply of oxygen and glucose)
      - All have cell body
- - - - Regulates hunger
      - Regulates water balance and thirst
      - Regulates body tempurature
      - Regulates sleep-wake cycles
      - Initiates physical responses to emotion
      - Controls endocrine system functions (ex. secretion of anterior pituitary gland)
      - Controls Autonomic Nervous System
  - - - Cardiovascular Center- adjusts force and rate of heart contraction; regulates blood pressure
      - Respiratory Center- generates respiratory rhythm; controls rate and depth of breathing
      - Other centers regulate: vomiting, hiccuping, swallowing, coughing, sneezing
    - - Cerebral Penduncles- 2 ventral bulges that form pillars that hold up cerebrum
      - Cerebral Aqueduct- channel running through midbrain that connects the 3rd and 4th ventricles
  - - - Parietal- sensation, language comprhension
      - Occipital- vision
      - Frontal- higher intellect, self control, inhibition, emotions, voluntary movement, motor skills development
      - Temporal- memory, auditory sense
      - Insula
    - - Basal Nuclei- closely associated with diecephalon and midbrain
        
        Putamen
        
        Globus Pallidus
        
        Caudate Nucleus
      - White Matter- responsible for communication btwn. cerebral areas, and btwn. cortex and lower CNS; classified by direction they run
        
        Commissural
        
        Projection Fibers
        
        Association
      - Cerebral Cortex- site of conscious mind; contains three types of functional area
        
        Sensory Areas- conscious awareness of sensation
        
        Association Areas- integrate diverse info
        
        Motor Areas- control voluntary movement
    - - Sulci- shallow grooves that separate the each hemisphere into 5 lobes
        
        Parioto-occipital Sulcus- separates occipital and parietal lobes
        
        Central Sulcus- separates precentral gyrus of frontal lobe and postcentral gyrus of pariental lobe
        
        Lateral Sulcus- outlines the temporal lobes
      - Fissures- deep grooves
        
        Longitudinal Fissure- separates the two hemispheres
        
        Transverse Fissure- separates the cerebrum and cerebellum
      - Gyri- ridges
      - Meninges- covers and protects the CNS, protects blood vessels and encloses venous sinuses, forms partitions in skull
        
        Arachnoid Mater- middle layer with spiderweb-like extensions
        
        Pia Mater- delicate C.T. that clings tightly to brain, following each convolution; contains tiny blood vessels that feed brain
        
        Dura Mater- strongest meninx
      - Blood Barrier- helps maintain stable environment for brain
      - Cerebrospinal Fluid (CSF)- forms liquid cushion of constant volume around brain
        
        Gives buoyancy to CNS structures, protect CNS from trauma, nourishes brain and carries chem. signals
- - - - Somatic Nervous System- contains somatic (voluntary) motor nerve fibers; conducts impulses from CNS to skeletal muscle
      - Autonomic Nervous System- contains visceral (involuntary) motor nerve fibers; conducts impulses from CNS to cardiac muscle, smooth muscle, and glands
        
        Sympathetic Division- mobilizes body systems during activity
        
        Parasympathetic Division- conserves energy
- - - - Only leakage channels for Na+ and K+ are open
      - Maintains resting membrane potential
    - - Depolarizing local currents open voltage-gated Na+ channels, and Na+ rushes into cell
      - Na+ influx causes more depolarization, which opens more N+ channels
    - - Na+ channel inactivation gates close and membrane permeability to Na+ declines
      - Voltage-gated K+ channels open
      - Returns to resting membrane potential
    - - After repolarization, Na+/K+ pumps restore ionic conditions
- - - - Sensory nerves of smell
      - Fibers synapse in olfactory bulbs
      - Pathway terminates in primary olfactory cortex
    - - Aries from retinas
      - Passes through optic canals, converge, optic chiasma
      - Run to occipital cortex
      - Continues to thalamus; synapse
    - - Only cranial nerve that extend beyond head/neck region (internal regions)
      - Regulate activities of heart, lungs, abdominal viscera
      - Sensory fibers carry impulses, baroreceptors, chemoreceptors, and taste buds
    - - Functions in raising eyelids, directing eyeballs, etc.
      - Extends from ventral midbrain through superior orbital fissures
    - - Innervate extrinsic and intrinsic muscles of tongue that contribute to swallowing and speech
    - - Primary motor nerve that directs eyeball
    - - Formerly spinal accessory nerve
      - Formed from ventral rootlets
      - Innervates trapezius and sternocleidomastoid muscles
    - - Largest cranial nerves; extend from pons to face
      - Convey sensory impulses from various areas of face
      - 3 divisions: ophthalmic, maxillary, mandibular
    - - Primarily a motor, innervating lateral rectus muscle
    - - Chief motor nerves of face with 5 major branches
      - Facial expression, parasympathetic impulses to lacrimal and salivary glands
      - Sensory function (taste) from anterior 2/3 of tongue
    - - Mostly sensory function
      - Formerly auditory nerve (hearing)
    - - Motor Functions: innervate part of tongue and pharynx for swallowing, provide parasympathetic fibers to salivary glands
      - Sensory Functions: conducts taste
- - - - Acetylocholine (released @ Neuromuscular Junction)
      - Biogenetic Amines (widely used in brain)
        
        Catecholamines
        
        Dopamine
        
        Norepinephrine
        
        Epinephrine
        
        Indolamines
        
        Seratonin
        
        Histamine
      - Endocannabinoids
      - Amino Acids
      - Gas and Lipids
      - Peptides
      - Purines
    - - Effects (excitatory vs. inhibitory)
      - Actions (direct vs. indirect)
  - - - Acetylocholine (ACh)- released by cholinergic fibers @ ANS preganglionic and parasympathetic preganglionic axons
      - Norepinephrine (NE)- released by adrenergic fibers @ sympathetic postganglionic axons (except sweat glands