Spinal and peripheral nerves Flashcards
Define central and periphary?
Central- brain and spinal cord
Peripheral- everything else
Is somatic inhib or stim?
Stimulatory
What is automatic split into?
Symp- fight or flight
Para- rest and digest
Function somatic ns?
Function autonomic system?
Voluntary- skeletal
Involuntary- hr, urination, pupils, digest
What nerves present in somatic and autonomic?
Somatic- afferent (sensory), efferent (motor)
Autonomic- motor neurons (eff)
What are afferent nerves?
What are efferent nerves?
Afferent- sensory
Efferent- motor
Somatic and autonomic- how many neurons?
Somatic- one neuron link CNS and effector
Autonomic- two neuron act link CNS and effector
What does somatic and autonomic release?
Somactic- ACh
Autonomic- ACh, norepinephrine
What does somatic and autonomic release?
Somactic- ACh
Autonomic- ACh, norepinephrine
Explain action potential?
1) Resting potential- higher conc Na+ outside -70mV
2) Cell depolarises
3) Threshold -55mV for AP fired
4) Increase Na+ ions until cell membrane +30mV
5) Voltage gated sodium channels close and K+ channels open
6) Repolarisation
7) Delay potassium channels closing- hyperpolarisation
8) Absolute refractory period- impossible fire ap- inactivation Na
Relative refractory- need large stimulus
Draw ap graph?
What is resting membrane potential value?
-70mV
What is threshold for ap?
-55mV
When do voltage gated sodium channels close (max)?
-30mV
What are 2 types sensory receptors?
Function sensory receptors?
Respond stimuli
Tonic- slow adapting
Phasic- rapid adapting
What are slow adapting receptors?
What are rapid adapting receptors?
Tonic- slow
Phasic- rapid
Explain sensory receptors?
1) Sensory receptor activity triggered by stimulus-ion channels opening (if the stimulus is large enough)
2) Afferent neurons have 2 processes
Once to site of reception
Once to spinal cord to synapse with interneurons
3) Interneurons synapse with ascending neurons in corresponding pathway to stimulus
4) Information passed to brainstem and thalamus before reaching the somatosensory cortex for processing
How many processes in afferent neuron?
Once to site of reception
Once to spinal cord to synapse with interneurons
What are nociceptors?
What are mechanoreceptors?
Nociceptors- pain
Mechanoreceptors- touch
Name 4 diff types nociceptors?
Phasic or tonic
Mechanical, thermal, chemical, polymadal
All phasic
Name 3 mechanoreceptors?
Merkels discs
Meissners corpuscles
Pacinian corpuscles
Explain merkels disc? Phasic or tonic
Tonic receptor- respond pressure
Explain meissners corpuscles? Phasic or tonic
Phasic receptor- dermic- enable fine touch
Explain pacinian corpuscles? Phasic or tonic
Phasic- most abundant
Respond pressure change and vibration
What is most common mechanoreceptor?
Pacininan corpuscles- respond pressure and vibration change
What spinal nerves control knee jerk?
L3/4
Outline knee jerk reflex?
1) Patellar ligament is struck
2) Stimulate intrafusal muscle spindle in quadraceps
2) Stimulate afferent (sensory) signal travels to spinal cord
3) Afferent neurons synapses with motor neuron (efferent) in spinal cord
Afferent synapse with interneuron- inhibit motor neuron of opposing muscle (hamstring)- action unopposed (polysynaptic)
4) Efferent (alpha motor) cause extrafusal muscle fibres of quadraceps to contract- increasing muscle tone- contraction quadraceps
5) Extensor muscle contracts, flexor muscle relaxes
6) Knee jerk
Monosynaptic
What is monosynaptic?
Single synapse between afferent and efferent
What type of reflex is knee jerk?
Monosynaptic
Also called the patellar reflex
The sudden kicking movement of the lower leg
Controlled by L3/L4
Patellar ligament is struck, afferent signal travels to spinal cord
Synapses with 1 interneurons and 2 alpha-motor neurons
Inhibitor, via interneuron, goes to flexor (hamstrings)
Polysynaptic
Excitatory, via alpha motor neurons, to extensor
Quadr iceps (monosynaptic)
Extensor muscle contracts and flexor muscle relax 🡪 knee jerks
