Unit 4: Week 2 Flashcards
What is a reflex and as well as _ what can they be used of?
It’s an involuntary response to a stimulus/change to maintain homeostasis. They can be used alongside pain, light, touch, vibration and temperate can be used to test neurological pathways in an area of the NS to see neuro function
What is a reflex arc and what are the different types?
Reflex arc- single wiring of a reflex.
Could be monpsynaptic (stretch)- only one synapse between afferent and efferent neurons they synapse directly.
Or could be polysynaptic- more than one synapse between afferent efferent neurons- may use interneuron
What are the steps of a monosynaptic (stretch) reflex?
- The muscle spindle strech receptors react to a Stimulus by sending an electrical signal, nerve impulse, to an electricity excitable nerve cell. in quadricepse
- The afferent neuron transmits the impulse towards the CNS away from the periphery.
- The impulse is processed in the spinal cord (CNS) at the integration center
- The sensory afferent neuron synapses with the efferent motor neuron and sends the signal towards the effector
- The effector muscle contracts away from stimulus in the patella reflex
- message sent to back of thigh preventing contraction
What happens during a polysynaptic reflex?
- The muscle spindle receptors react to a Stimulus by sending an electrical signal, nerve impulse, to an electricity excitable nerve cell.
- The afferent neuron transmits the impulse towards the CNS away from the periphery.
- The impulse is processed in the spinal cord (CNS) at the integration center
- The sensory afferent neuron synapses with 1 or more interneurons, which can distribute the signal to other one or more efferent motor neuron, sending the signal towards the effectors. The effects could be excitatory or inhibitory
- Some signals are sent to the brain to learn from the experience
Interneuron sends info to motor neuron for output and also to brain so you become conscious of it
What is integration?
Processing and interpreting sensory information and activating the right area of the nervous system in response
the correct pathway from sensory to effector is decided by interneurons in a process called integration- interneurons allow for integration to other areas of the nervous system eg agonist contracts and antagonist relaxes, learning in the brain, memory for later in life
What are receptor cells/sense organs?
They detect change/stimuli in internal/external environments. This is then transmitted as an electrical signal via an afferent neuron.
The sense organs contain groups of specialised cells called receptor cells which respond to specific stimuli.
Skin- Temperature, pressure and pain
Tongue- Chemical tastes (in food and drink)
Nose- Chemical smells (in the air)
Eye- Light
What is the target of the SNS and ANS?
SNS: only targets skeletal muscle- coordinates voluntary movement
ANS: targets smooth muscle in visceral organ and blood vessels, cardiac muscle and ducts regulates involuntary processes
What is the function of the SNS and ANS?
SNS: only causes and contraction- excitory function. voluntary operator
ANS: can cause contraction and relaxation- excitiory/inhibitory via sympathetic and parasympathetic systems. Involuntary coordinator
What types of efferent neurons are in the SNS and ANS?
SNS: Type A- heavily myelinated, thick- good for long distances as there is no ganglia. Minimal signal degradation. Insulation helps signals travel fasts for rapid response
ANS: Type B&C- preganglionic fibers typically thin and lightly myelinated/post ganglion in fibers are typically thinner and unmyelinated- signals are not as urgent and ganglion are relay stations. Slower conduction
What are the pathways for SNS and ANS motor neurons?
SNS: no ganglia- better speed. Better for fine motor control
ANS: ganglia present as relay stations so they area junctions between autonomic nerves originating from the central nervous system (preganglionic) and autonomic nerves innervating their target organs in the periphery (postganglionic)- for widespread effect
What neurotransmitter is used in SNS and ANS?
SNS: acetylcholine always has an excitory effect
ANS: preganglionc are colinergic
Postganglionic sympathetic fibers use noradrenaline
Postganglionc parasympathetic fibers use acetylcholine
The exception is postganglionic sympathetic fibers for sweat glands use ACh
What spinal centre is used in the SNS and ANS?
SNS: starts at the anterior horn cell- closer to the nerve root. Increase speed and decrease distance
ANS: lateral horn cell- further away due to signals less urgent
What is a plexus and how many are there?
They are a network of intersecting spinal nerves that supply the same area of the body.
Cervical P Brachial (arm) P Lumbar P Sacral P Coccygeal P
There is no thoracic P as intercostal nerves pursue independent paths
What are dermatomes?
An area of the skin is supplied by a single spinal nerve
Referred pain is where pain originating from another area is felt on a separate area of the body due to the two nerves sharing the same nerve root. Pain receptor stimulus from one activates another.
What is the structure and functions of the SANS?
SANS nerves originate from the thoracolumbar region.
Preganglionic fibres synapse with the ganglia chain which sits closer to the spine. The longer postganglionic with effectors
Due to the chain ganglia that can stimulate many areas as ganglia act as relays, the SANS is widespread
Dilate pupils, increase in HR RR (dilate bronchi), stimulate adrenaline release. inhibit bladder contraction. inhibit Peristalsis. liver for glycogen to glucose
