Chapter 13 Flashcards
What is a reflex?
The integration of sensory information into an involuntary response
What is an example of an autonomic/visceral reflex?
gagging to keep something harmful from coming into the body
How many classifications for reflexes are there?
8
What is the term for reflexes that are developed over time?
Acquired/learned reflexes
What is the term for the reflexes that are genetically or developmentally determined?
Innate reflexes
What is the term for reflexes that control skeletal muscle and include stretch reflexes?
Somatic reflexes
What is the term for reflexes that control the actions of glands, smooth and cardiac muscle?
Visceral/autonomic reflexes
What is the term for a reflex arc that has one synapse?
Monosynaptic
What is the term for a reflex arc that anywhere from 2 to several hundred synapses?
Polysynaptic reflexes
What is the term for reflexes that are processed in the spinal cord?
Spinal reflexes
What is the term for reflexes that are processed in the brain?
Cranial reflexes
How many different types of visceral/autonomic reflex receptors are there? And what are they called?
6
Osmoreceptors
Chemoreceptors
Baroreceptors
Touch Receptors
Thermoreceptors
Special senses
What do osmoreceptors detect?
blood osmolarity
What to chemoreceptors detect?
chemicals like pH
What do baroreceptors detect?
pressure like blood pressure
What do touch receptors detect?
Mechanical receptors
What do thermoreceptors detect?
temperature
What do special sensors detect?
Light, sound, taste and smell
Are the visceral/autonomic receptors under tonic or phasic control?
Some of them are under tonic control
What is an example of a visceral receptor that is under tonic control?
Baroreceptors in the blood vessels are constantly under tonic control because they have to be in a state of partial constriction at all times even though the amount of constriction will vary as needed.
What is the minimum of neuron to neuron synapses in the visceral/ autonomic reflex arc?
3 because there is always at least 1 interneuron in there
In the autonomic reflex arc is the the intergration center more likely to be in the spinal cord or the brain?
The brain but both are possible
What are the possible autonomic/visceral reflexes integration locations in the brain?
Thalamus
Hypothalamus
Brainstem
limbic system
What could the brain stem control that would be present in an autonomic reflex?
Blood pressure or vomiting
What does the limbic system control that could be present in visceral reflexes?
Emotions like fear that could cause a visceral response
If a visceral reflex is associated with blood osmolarity where in the brain would that information be intergrated?
The hypothalamus because that is where homeostasis is regulated
What is unique about the autonomic reflex arc compared to the somatic reflex arc?
- contains a ganglion (pre and post ganglionic neuron) in the efferent pathway
- most of the time the intergration center is in the brain
- targets glands, smooth, and cardiac muscle
What is unique about the somatic reflex arc compared to the autonomic reflex arc?
- Spinal cord is the main intergrating center
- targets skeletal muscle
When a somatic reflex does get intergrated in the brain, where does it go?
it goes to the cerebellum
In the somatic reflex arc, what response(s) can the interneurons produce?
excitatory or inhibitory
What is a somatic alpha motor neuron?
It is the one motor neuron in the somatic pathway going from the spinal cord to the target
What happens when a muscle can be excited but not inhibited?
That is when people get tremors
Which reflex arc has 2 motor neurons?
Autonomic/visceral
What is different about somatic alpha motor neurons compared to the normal motor neurons?
Nothing the name is just so they can be distinguished from more detailed muscle fibers
What is unique about extrafusal muscle fibers?
Nothing they are just like the normal muscle fibers its just to help help distinguish them from other kinds of muscle fibers such as intrafusal
Can muscle fibers be excited and inhibited? And why?
They can only be excited and not excited because the release of ACh has a all or nothing effect on the muscle fibers
Are somatic motor neurons tonic or phasic? And how does it contribute to the tone of a muscle?
They are tonic meaning they are always partially contracted even when sleeping which contributes to muscle tone
What are the sensory receptors for the somatic motor system called?
Proprioceptors
What are the 3 types of proprioceptors?
- Joint receptors
- Golgi tendon organs
- Muscle spindles
What are joint receptors stimulated by?
Mechanical distortion or are mechanoreceptors
How are the mechanoreceptors of the joint receptors organized?
They are free nerve endings that are encapsulated in conntective tissue
What are the two types of joint receptors?
Pacinian corpuscles (fast changes)
Ruffian corpuscles (slow changes)
What are the Golgi tendon organ stimulated by?
They are stimulated by muscle tension
Where do the Golgi tendon organs send information about the muscle tension to? and what are they sending information about?
the cerebellum and information about which muscles in the body are contracting
What are muscle spindles stimulated by?
They are stimulated by stretch or are stretch receptors
Where is the Golgi tendon organ found?
Where the muscle connects to the tendon
In a muscle spindle, where are the extrafusal muscle fibers located and what are they stimulated by?
They are located superficially on the muscle itself and are stimulated by the alpha motor neurons
In a muscle fiber, where are the intrafusal muscle fibers located?
They are located deep to the surface of the muscle
In a muscle fiber, what are intrafusal muscle fibers stimulated by?
They are stimulated by gamma motor neurons and contain sensory receptors that are stimulated by stretch
In the intrafusal muscle fibers where are the free nerve endings located?
They are wrapped around the muscle fiber itself
Are the sensory neurons tonically or phasically active? And where do they send their info to?
They are tonically active and are constantly sending their signals about the stretch of the muscle that changes based on if its being strectched
What is a myotactic unit?
The unit of synergist and antagonist muscle groups that make a certain action possible at a joint
What is the purpose of the stretch reflex?
To ensure that there is optimum overlap between actin and myosin in the sarcomeres
What happens in the stretch reflex?
The stretch reflex begins with a muscle stretching which means the intrafusal fibers are sending an increase of stretch signals to the spinal cord. As a result there is an increase in the efferent output through the alpha motor neurons and it causes the muscle to contract to make sure that it doesn’t stretch too far
What is an example of a stretch reflex?
The patellar reflex
How can the patellar reflex be categorized?
Innate, somatic, and a monosynaptic spinal reflex
What are the two types of muscle units that are found in the myotactic unit?
Synergists and antagonists
What are synergists?
A group of muscles that work together to accomplish the same action specifically the motion that is needed for the current reflex
What is an example of a synergist muscle group for the extension of the leg at the knee?
The quadriceps of the leg
What is an antagonists?
A group of muscles that work perform the opposite action of the synergist group
When thinking about the extension of the knee what group of muscles would the antagonists?
Hamstrings
What is reciprocal inhibition?
In a reflex it is the inhibition of the antagonist muscles
How does reciprocal inhibition affect the actions of the muscles in a reflex?
It stops the antagonsitic muscles form preforming the opposite action so they synergist muscles can perform the action that is needed for the reflex
What makes a reflex monosynaptic?
That there only a synapse between the sensory and motor neuron
What is the goal of flexion (withdrawal) reflexes?
To move parts of the body away from harmful (noxious) stimuli
What is an example of a flexion/withdrawal reflex?
Pulling your hand away from a hot pan
Can a reciprocal inhibition reflex be present in a flexion/withdrawal reflex as well?
Yes, to make sure that proper muscle is moving in the right direction away form the dangerous thing
How can a withdrawal/flexion reflex be classified as?
An innate, somatic, polysynaptic spinal reflex
What is different about the flexion/ withdrawal reflex in the lower limbs?
The crossed extensor reflex will come into play to make sure you don’t fall over
What happens in the crossed extensor reflex?
When you move one leg near the dangerous object off of the ground the other leg is going to extend (or the extensors of the leg will contract) to make sure that you don’t fall over
Is the crossed extensor reflex only used to keep you away from danger?
No, it used to help keep us in balance when we are doing other activities such as walking or running
Is reciprocal inhibition present in the crossed extensor reflex?
Yes, in both legs actually. To ensure that the one that needs to be flexed is flexed and that the other one that needs to be extended can be
Do animals that walk on four legs have the crossed extensor reflex on both the front limbs and back limbs?
Yes it is what is needed to keep them in balence
Because cardiac and smooth muscle are not connected to bones that means they have a __________ range of movements
broader
When cardiac and smooth muscle contract they do so to …..
move lumenal contents
What can smooth and cardiac muscles be controlled by?
internal pacemaker
Intrinsic gap junctions
ANS
hormones
