Week 5: Nervous System Flashcards
Nervous System into:
Central and Peripheral
Central NS into:
Brain and Spinal Cord
Peripheral NS into:
Somatic and Autonomic
Autonomic NS into:
Sympathetic and Para
Afferent Nerves
(PNS)
Sensory
Messages from body to CNS
Efferent Nerves
(PNS)
Motor
Messages from CNS to body.
Somatic controls
Voluntary movement
Autonomic Controls
Functions of internal organs
Involuntary
Hypothalamus
Control center.
Sympathetic
Arousing
Parasympathetic
Calming
Neuron
Nerve Cell
Cell Body
Dendrites
Axon
Dendrites
Conduct impulses towards the cell body
Usually short, branched.
Axons
Conducts impulses away from cell body.
Single, long.
Multipolar Neuron
Typical.
Most brain and spinal cord
Single axon, many dendrites.
Bipolar Neuron
Retina, inner ear, olfactory.
2 extensions (one axon, one dendrite, cell body in middle)
Unipolar Neuron
Sensory neurons for touch or stretch.
Soma off to the side.
Neuroglia
More numerous than neurons
Support, segregate and insulate neurons, protection, promote health and growth.
Myelinated Neuron
Schwann cells in PNS and oligodendritic cells in CNS
Surround axon with layers of plasma membrane (lipid and protein)
Electrically insulates axon, increase speed of nerve impulse conduction.
Ganglion
Collection of cell bodies of neurons outside the CNS
Nerve Structure
Bundle of neuron fibres outside the CNS
Collection of many axons.
Grey Matter
Nerve cell bodies inside CNS
White Matter
Neuron fibres within CNS
Tract
Bundle of neuron fibres inside the CNS
From brain to Spinal Cord
White from myelin sheaths.
Brain Areas
Cerebrum
Diencephalon
Brain Stem
Cerebrum Areas
Cerebral Cortex
Diencephalon Areas
Thalamus
Hypothalamus
Brain Stem Areas
Midbrain, Pons, Medulla
Cerebrum
Located in the front, 2 hemispheres, separated by a fissure.
Perception/interpretation of sensory.
Emotional and intellectual processes.
Control of motor movements.
Diecephalon
Central core of forebrain
Encloses third ventricle.
Thalamic Function
Afferent impulses converge and synapse
Similar impulses sorted and sent in groups
All sense to Cerebral Cortex pass through.
Mediates some sensation (pain, temp, light touch, pressure)
Role in limbic system (pain/pleasure)
Hypothalamus
Location/Function
Below thalamus
Intermediary between NS and Endocrine
Infundibulum
Stalk of hypothalamus
Connects to Pit gland
What does the Hypothalamus Control?
Autonomic NS, Heart rate, Water balance, thirst, food movement through GIT, thermoregulation, sleep.
Brain Stem
Location/Function
Central trunk of brain
midbrain, pons, medulla.
Automatic behaviours for survival
Pathway for tracts between higher and lower brain
Midbrain
Loc/Fun
Between diencephalon and pons
Reflex centre for head and eye movements in response to sight and sound
Pons
Loc/Fun
Bulging brain stem region b/t midbrain and medulla
bridge between cerebellum and brain stem
sensory and motor fibres pass through
Pneumotaxic regulates respiration
Medulla
Loc/Fun
Inferior part of brain stem
cardiac, respiratory, vasometer (blood pressure) centres.
Also regulates swallowing, sneezing, vomiting.
Cerebellum
Loc/Fun
Back of skull
Precise timing, patterns of skeletal muscle contraction, posture, equillibrium from inner ear sensory input
Spinal Cord
31 segments with pair of spinal nerves
Begins at occipital bone, ends at vetebral disc b/t first and second lumbar vertebrae
Cauda Equina
Nerves for lower lumbar and below, end of spinal cord (conus medullaris)
Spinal Cord Functions
2 way conduction to and from brain
Convey sensory impulses from PNS to brain, conducts motor impulses from brain to PNS
Reflex Centers
Components of Reflex Arc
Sensory receptor, Sensory Neuron, Integrating Center (CNS), Motor Neuron, Effector.
Reflex Arc Acts:
fast, automatic unplanned sequence of actions.
Skeletal Muscle Effector (RA)
Somatic Reflec
Smooth, Cardiac, or Gland Muscle Effector (RA)
Autonomic (Visceral) Reflex.
Neurotransmitters between Sympathetic and Para
Different
Action Potential
When a neuron sends information down an axon - away from cell body.
Resting Membrane Potential
Inside of cell membrane is negative relative to outside the cell
How do cells maintain their resting potential
Sodium/Potassium pump
Leaky potassium channels
Negatively charged protein that cannot leak outside
Leaky Potassium Pumps
More K+ cells inside than out, leaky channels allow K+ to leave cell by facilitated diffusion along concentration gradient.
Ligand-Gated Channels
Open with binding of specific Neurotransmitter
Mechanically-Gated Channels
Open/close in response to mechanical stimulation (vibration, touch, pressure)
Voltage-Gated Channels
Open/close in response to membrane potential
Propagation
An action potential occurs at one point along a membrane and causes another action potential to occur
Depolarization
Mechanically gated or ligand gated Na+ gates open in response to stimulus.
Enough Na+ enters to cause interior of membrane to reach voltage threshold - then Na+ voltage regulated gates open.
Repolarization
When action potential reaches 30mV
Na+ channel gates close, K+ channels open. K+ begin to leave, membrane becomes negative again.
Eventually Na+ inactivation gates open, return to resting when K+ gates close.
Refractory Period
Sodium gates need to reset - cannot generate another action potential, can only go one way.
Saltatory Conduction
When the electrical signal jumps from each myelin sheath, across the nodes of Ranvier.
Voltage-gated channels that trigger action potentials.
Synaptic Transmission
Nerve impluse at axon bulb
Voltage gated Ca2+ open, Ca2+ rushes in
Pushes vesicles with NT to presynaptic membrane, exocytosis, releseas into synaptic cleft
NT diffuse across cleft
NT fit into ligand-gated Na+ gates - opens them
Na+ rushes into cell - action potential
Acetylcholine
NT
Neuromuscular junctions
Excitatory or inhibitory
Norepinephrine
NT
Maintains alertness and arousal
Dopamine
NT
Motor control
Deficit in Parkinson’s
Serotonin
NT
Temp regulation
Sensory Perception
Sleep onset
Peptides (NT)
Endorphine Enkephalins
Natural opiates - reduce pain perception
Bind to same receptors as opiates and morphine
