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Nervous System consists of:
- Central Nervous System (brain and spinal cords)
- Peripheral Nervous System (peripheral nerve)
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Nervous System Functions
- 1. Sensory input (afferent)
- Travel from sensory receptor to sensory neuron (in PNS)
- Sent to CNS
- 2. Integration
- Interneuron in between brain and spinal cord
- Receives information from sensory and passes message to motor output
- 3. Motor output (efferent)
- Motor neuron sends message to effector cells
- Ex: effector cells: muscle cells (dropping pan when it's hot)
- Ex: cut an onion and you tear up
- Back to PNS
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Nervous Tissue
- Gray is where all cell bodies of neurons are
- Most of brain is white (where dendrites and axon are)
- Cell bodies are in ganglion
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Neuron Structure
- Cell body: nucleus, organelles (in gray matter)
- Dendrites: short extensions receive signals from other neurons in different directions
- Axon Hillock
- Axon: nerve impulse away from neuron
- Axon terminals
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Myelin Sheath in CNS
- Neuroglial cells protect neuron
- Oligodendrocytes: few processes come out (arms wrap itself around axon - myelin)
- If you destroy axon, oligodendrocytes die (do not regenerate)
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Myelin Sheath in PNS
- Schwann Cell: pushes nucleus to outside (bubble wrapping)
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Node of Ranvier
Gaps in between myelin sheath
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Myelin: Saltatory Conduction
- Nerve impulse jumps from node to node
- Human nerve signals can travel faster than a NASCAR racer
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Resting Axon
- Inside cell: lot of potassium (-)
- Outside cell: lot of sodium (+)
- Sodium-Potassium: uses active transport to move sodium OUT of the axon; potassium INTO the axon
- 3 potassium on one side for 1 sodium on the other
- If threshold reached: sodium gates open
- Sodium rushes in and will make equilibrium polarity
- 1. Depolarization
- 2. Repolarization
- 3. Reestablishment of resting potential
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Depolarization
- Sodium moves into the axon
- Sodium channels open
- Sodium diffuses in
- Membrane depolarizes
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Repolarization
- Potassium moves out of the axon
- Sodium channels close
- Potassium channels open
- Potassium diffuses out
- Membrane repolarizes
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Resting potential
- Sodium and potassium channels closed
- Sodium-Potassium pump matches rate of leakage
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Reestablishment of the resting potential
Potassium channels close
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Axon Terminal
Impulse goes here
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Synapse
- Neuron receives messages from axon terminals and dendrites
- Where messages are going to be passed between2 neurons
- Gap is called synaptic cleft
- Receiving neuron
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Synaptic transmission
- Presynaptic neuron
- Postsynaptic neuron
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Neurotransmitters
- Change electrical signal to chemical signal
- Can leave through exocytosis
- Vesicles filled with neurotransmitters
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Neurotransmission
- Action potential reaching axon terminal
- Calcium ? axon terminal
- Released to synaptic cleft: go to receptor where they fit (post synaptic neuron)
- Ion channel opens and ions flow into postsynaptic neuron causing action potential
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What can happen after Calcium binds to postsynaptic cleft?
- Can cause excitatory (depolarize postsynaptic cell) or inhibitory (hyperpolarize: more negative inside)
- Neurotransmitter released
- Ion channels close
- May be broken down in synapse
- May reuptake and repackage
- May reuptake and be destroyed
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What are neurotransmitters?
- Transmits a signal from a neuron to its target
- Acetylcholine for muscle contraction
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Meninges
- 1. Dura mater ("tough mother")
- Hard to tear
- 2. Arachnoid mater (looks like cob webs)
- 3. Pia mater (thin, no consistency)
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Ventricular System and Central Canal
- Holes in brain filled with Cerebrospinal fluid
- Goes down brain stem and middle of spinal
- Comes from blood, brings glucose, go back to blood
- Helps it float
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Spinal cord
- Foramen magnum
- Ends at L2 and rest is spinal nerves spreading out
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Cerebral Hemisphere
- Frontal Lobe
- Parietal Lobe
- Occipital Lobe
- Temporal Lobe
- Cerebellum
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Frontal Lobe
- Central sulcus: dividing line between frontal lobe and parietal lobe
- Pre-central gyrus (hill)
- Motor area (movement)
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Parietal Lobe
- Post-central gyrus
- Primary sensory area
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Occipital Lobe
- Post-central gyrus
- Primary sensory area
- Visual area
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Cerebellum
- Coordinates basic body movements
- Makes smooth coordinated movements
- Ex: tying a shoe, shifting a car, or hitting a home run
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Pre-Frontal Cortex
- Helps us asses risks of behavior
- Critical thinking
- Helping you mature
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Executive Functions
- Abstract reasoning (connect dots)
- Problem solving
- Learning from experience
- Forethought
- Concentration
- Behavioral inhibition
- Programming and planning goal-oriented behaviors
- Executive a sequence of responses to avoid negative consequences or interactions
- Generating alternative socially-adaptive behavioral responses
- Verbal ability
- Attention
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3rd Ventricle
- Thalamus: (Gray matter) senses go here and goes to right part of brain
- Hypothalamus: controls pituitary gland
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Brainstem
- Midbrain: relay track between cerebellum, spinal cord, and cerebrum
- Pons: helps regulate breathing
- Medulla Oblongata: lowest part of brain regulated heart and blood pressure
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Limbic System
- Biological drawings: eat
- Emotion: anger, fear
- Memory formation
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Reticular Formation/RAS
Reticular Activating System (RAS) determines the level of alertness
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Peripheral Nervous System
- Cranial nerves
- Spinal nerves
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Reflex Arc
- 1. Sensory receptor
- 2. Sensory neuron
- 3. Interneuron (s)
- 4. Motor neuron
- 5. Effector organ
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Peripheral Nervous System Divisions
- Somatic nervous system (voluntary)
- Autonomic nervous system (involuntary)
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Autonomic Nervous System
- 2 neurons
- Stimulates/inhibits:
- Cardiac muscle
- Smooth muscle
- Glands
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Autonomic Nervous System Ganglia and Neurotransmitters
- Neurotransmitters of Autonomic Nervous System
- Acetylcholine (ACh)
- Noradrenaline (NA) AKA norepinephrine (NE)
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Sympathetic Nervous System
- Fight or Flight:
- Heart rate and blood pressure increase
- Airways dilate
- Use skeletal muscle, more ATP, more oxygen, more blood flow
- Blood flow to skeletal muscle increases
- Causes orgasm
- Norepinephrine is postganglionic
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Parasympathetic Nervous System
- Rest and Digest:
- Pupils contract
- Heart rate slows
- Digestion increases
- Causes erection
- Acetylcholine is neurotransmitter
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Sympathetic and Parasympathetic Similarity
Keep us in homeostasis
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