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Reflex:
rapid, predictable, involuntary motor responses to simuli
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Five essential components of a reflex arc:
- receptor
- sensory neuron
- integration center
- motor neuron
- effector
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What is the importance of reflex testing in a routine physical examination?
to test for spinal cord or brain damage
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Somatic reflexes in which higher brain centers participate:
- plantar reflex
- corneal reflex
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Can the stretch reflex be elicited in a plithed animal?
yes, as long as they have been plithed recently
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Reflex arc of the patellar reflex:
- sensory receptors in the quadriceps muscle
- patellar tendon is tapped
- causes a stretch in the quads
- stimulates the length receptors
- fires an action potential in the sensory neuron which goes to the spinal cord (afferent)
- innervates the motor neuron (efferent) to the same muscle (receptor)
- Assuming the stimulus was strong enough motor neuron also fires an action potential
- causes a contraction in the quads
- resulting in a slight kick of the lower leg
- reflex arc is an example of negative feedback
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Factor that increases the excitatory level of the spinal cord:
effect of simultaneous muscle activity in another body area
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Factor that decreases the excitatory level of the mucles:
fatigue
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Ciliospinal reflex:
sympathetic
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salivary reflex:
parasympathetic
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pupillary light reflex:
- parasympathetic
- prevents eye damage
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corneal reflex
protect the eye from damage and light
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crossed-extensor reflex:
its used to be a withdrawl reflex to maintain balance and coordination
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pupillary consensual response:
- contralateral
- protection for not having too much light in that eye
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somatic reflexes:
include those that involve stimulation of skeletal muscles
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autonomic reflexes:
include those that activate smooth muscle, cardiac muscle, glands, involuntary parasympathetic actions.
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Micturition:
- organ: bladder
- receptor stimulated: bladder; stretch receptors
- action: detrusor contracts and urethra relaxes allowing bladder to empty
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interoceptor:
- respond to stimuli arousing within the body
- doing sit ups; proprioceptors
- the "too full" sensation; visceral/ stretch
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exteroceptor:
- reacts to stimulus in external environment; found close to body surface
- backing into a sun-heated iron railing; pain
- someone steps on your foot; pain
- reading a book; photoreceptor
- seasickness; eqilibrium-inner ear
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Explain how sensory receptors act as transducers:
- they convert one form of signal to another form
- pain recepor -> chemical signal
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Stimulus:
something that rouses or incites to activity
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What was demonstrated by the two-point discrimination test?
measures the smallest distance at which two points of contact can be felt
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Punctate Distribution:
clustering of cutaneous sensory receptors; instead of being uniformly distributed
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which cutaneous receptors are the most numerous?
simple pain receptors
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Cold receptors:
appear to be more numerous
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Referred Pain:
pain that is felt in a part of the body at a distant from the area of pathology
- gall bladder -> right inferior thorax
- kidneys -> lumbar
- appendix -> right lumbar; abdominal surface
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Probable explanation of referred pain?
nerves carry the signal to other body parts so your brain interprets the pain from being from distal parts also
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What region of the cerebrum interprets the kind and intensity of stimuli that cause cutaneous sensations?
somatosensory association area
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Adaptation of sensory receptors:
when a stimulus is applied for prolonged period, the rate of receptor response slows and our conscious awareness of stimulus declines or is lost until some stimulus change occurs
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Why is it advantageous to have pain receptors that are sensitive to all vigorous stimuli?
- they act as protection of us
- make us aware of our surroundings
- send messages to brain
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Why is nonadaptability of pain receptors important?
if we adapted we would eventually pay no mind to pain
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No cutaneous organs = very dangerous. Why?
- self harming incidences would increase
- you would be less efficient at maintaining body temperature
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Type 1 Diabetes:
- pancreas doesnt work at all
- need to inject insulin
- symptoms progress more rapidly and can be worse
- usually diagnosed in children and young adults
- only 5% of the people with diabetes have type 1
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Type 2 Diabetes:
- pancreas works but not as well as it should
- can be controlled by diet/ exercise
- sometimes need oral medication
- some need insulin injects
- symptoms include: excessive thirst and urination, weight loss, hunger, tiredness, blurred vision, decreased resistance to infection, dehydration
- most common
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Insulin:
hormone used by the body to turn sugar, carbohydrates, and starch into energy
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Resistin:
- found in fat cells
- overactive in those suffering from obesity
- people suffering from obesity are at higher risk for being diagnosed with type 2 diabetes
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