Spinal and peripheral nerves

Question 1

Define central and periphary?

Answer 1

Central- brain and spinal cord
Peripheral- everything else

Question 2

Is somatic inhib or stim?

Answer 2

Stimulatory

Question 3

What is automatic split into?

Answer 3

Symp- fight or flight
Para- rest and digest

Question 4

Function somatic ns?
Function autonomic system?

Answer 4

Voluntary- skeletal
Involuntary- hr, urination, pupils, digest

Question 5

What nerves present in somatic and autonomic?

Answer 5

Somatic- afferent (sensory), efferent (motor)
Autonomic- motor neurons (eff)

Question 6

What are afferent nerves?
What are efferent nerves?

Answer 6

Afferent- sensory
Efferent- motor

Question 7

Somatic and autonomic- how many neurons?

Answer 7

Somatic- one neuron link CNS and effector
Autonomic- two neuron act link CNS and effector

Question 8

What does somatic and autonomic release?

Answer 8

Somactic- ACh
Autonomic- ACh, norepinephrine

Question 9

What does somatic and autonomic release?

Answer 9

Somactic- ACh
Autonomic- ACh, norepinephrine

Question 10

Answer 10

Question 11

Answer 11

Question 12

Explain action potential?

Answer 12

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

Question 13

Draw ap graph?

Answer 13

Question 14

What is resting membrane potential value?

Answer 14

-70mV

Question 15

What is threshold for ap?

Answer 15

-55mV

Question 16

When do voltage gated sodium channels close (max)?

Answer 16

-30mV

Question 17

What are 2 types sensory receptors?
Function sensory receptors?

Answer 17

Respond stimuli
Tonic- slow adapting
Phasic- rapid adapting

Question 18

What are slow adapting receptors?
What are rapid adapting receptors?

Answer 18

Tonic- slow
Phasic- rapid

Question 19

Explain sensory receptors?

Answer 19

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

Question 20

How many processes in afferent neuron?

Answer 20

Once to site of reception
Once to spinal cord to synapse with interneurons

Question 21

What are nociceptors?
What are mechanoreceptors?

Answer 21

Nociceptors- pain
Mechanoreceptors- touch

Question 22

Name 4 diff types nociceptors?
Phasic or tonic

Answer 22

Mechanical, thermal, chemical, polymadal
All phasic

Question 23

Name 3 mechanoreceptors?

Answer 23

Merkels discs
Meissners corpuscles
Pacinian corpuscles

Question 24

Explain merkels disc? Phasic or tonic

Answer 24

Tonic receptor- respond pressure

Question 25

Explain meissners corpuscles? Phasic or tonic

Answer 25

Phasic receptor- dermic- enable fine touch

Question 26

Explain pacinian corpuscles? Phasic or tonic

Answer 26

Phasic- most abundant
Respond pressure change and vibration

Question 27

What is most common mechanoreceptor?

Answer 27

Pacininan corpuscles- respond pressure and vibration change

Question 28

What spinal nerves control knee jerk?

Answer 28

L3/4

Question 29

Outline knee jerk reflex?

Answer 29

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

Question 30

What is monosynaptic?

Answer 30

Single synapse between afferent and efferent

Question 31

What type of reflex is knee jerk?

Answer 31

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