first test

Which spinal tracts carry action potentials generated by nociceptors?

lateral spinothalamic tracts

After injuring her back, 22-year-old Tina exhibits a positive Babinski reflex. What does this imply about her injury?

possible damage is done to the descending motor pathways.

Describe the three classes of mechanoreceptors

proprioceptors- monitor position of joints and muscles (muscle spindle) baroreceptors- pressure change in blood vessels and portions digestive, reproductive, and urinary tracts tactile receptors- sensations of touch, pressure, vibration

Define stretch reflex

-Best known: monosynaptic reflex -Provides automatic regulation of skeletal muscle length -Example: patellar reflex -muscle spindles are sensory receptors of stretch reflex

During a withdrawal reflex of the foot, what happens to the limb on the side opposite the stimulus? What is this response called?

-Limb on the side opposite is inhibited -crossed extensor reflex straightens uninjured -leg/supports shifting weight

What is dual innervation?

-all target organs served by both division, cause opposite effects (heart) -the heart consists of cardiac muscle tissue triggered by specialized pacemaker cells parasympathetic: acetylcholine release decreases heart rate sympathetic: norepinephrine release accelerates

Define reinforcement as it pertains to spinal reflexes (dont worry ab this)

-can facilitate or inhibit motor neurons or interneurons involved -facilitation = reinforcement example: voluntary movement to pull apart clasped hands can reinforce stretch reflexes and increase response (bigger kick after patellar tap)

What are cholinergic receptors? What are adrenergic receptors? What is an agonist? An antagonist?

-cholingeric: surface of cells that get activated when they bind to acetylcholine -adrenergic: bind adrenaline using norepinephrine and epinephrine agonists: bind receptors to excite them antagonist: inhibit/block example: beta blockers

What are the 4 E's? What are the physiologic responses to stimulation by the sympathetic division of the ANS?

-emergency, excitement, embarrassment, exercise -prepares body for emergency situations responses: increased heart rate, dilation of pupils, airways, constriction of blood vessels

What is a ganglion, postganlionic neuron and preganglionic neuron?

-ganglion: area where pre and post meet -preganglion: short, originates in brain stem, release acetylcholine -postganglion: long, outside CNS, acetylcholine activates nicotinic acetylcholine receptors on post

What organ functions are regulated by the ANS?

-heart rate -respiratory rate -defecation -digestion -urination

Identify the basic characteristics of polysynaptic reflexes

-involve at least one interneuron, one sensory, and one motor -longer delay between stimulus and response due to increase number of synapses -responsible for automatic actions involved in complex movements -Examples: walking and running -may involve sensory and motor responses on the same side of body or opposite sides same side: ipsilateral (stretch, withdrawal) opposite side: contralateral (crossed extensor)

Define sensory homunculus

-maps somatic sensations to discrete areas in cerebral cortex -located in post central gyrus

Define reflex and list the components of a reflex arc.

-reflexes are rapid, automatic responses to specific stimuli for the purpose of preserving homeostasis -reflex arc: 1. arrival of stimulus and activation of receptor 2. axon of a sensory neuron 3. information processing (interneuron CNS) 4. activation of a motor neuron 5. response of peripheral receptor

What purpose does reflex testing serve?**

-reflexes used in diagnostic testing Babinski reflex: stroking lateral side of sole of foot Positive response: toes fan due to lack of inhibitory control of reflex response from descending motor pathways Negative response: toes curl due to development and normal reflex response=Plantar reflex Abdominal reflex: Light stroking of skin of anterior abdomen produces reflexive twitch of abdominal muscles -Absence of response may indicate damage to descending tracts

What are common characteristics of reflexes

-require a stimulus, -quick(minimal synapsing delay), -involuntary(you don't have to think about it), -stereotyped(same response/reflex every time)

Describe the role of the corticobulbar tracts

-synapses occur in motor nuclei of cranial nerves -provide conscious control over skeletal muscles that move eye, jaw, face, and some muscles of neck/pharynx

Define corticospinal tracts

-visible along ventral surface of medulla oblongata as pair of thick bands go from cortex to spinal cord, descending pathway controls movement of limbs/ trunk

Describe the flexor reflex

-withdrawal reflex and involves muscles contracting to withdraw the body part away from a painful stimulus. -It involves pain receptors (nociceptors). -the painful stimulus initiates a nerve signal that is transmitted by a sensory neuron to the spinal cord. Interneurons receive the signal and stimulate motor neurons to the flexor muscles which contract in response.

In the patellar reflex, identify the response observed and the effectors involved

1. Patellar tendon tapped by physician, quadriceps tendon receptors stretch 2. Receptors stimulate sensory neuron that extends into spinal cord, sensory neuron synapses with motor neuron 3. Information processing at motor neuron cell body 4. Motor neuron activated and action potential is generated 5. Stimulation of skeletal muscle fibers leads to contraction of knee extensors

Describe the various classifications of reflexes

1. their development 2. Nature of resulting motor response 3. Complexity of neural circuit involved 4. Site of information processing somatic reflexes: involuntary control of skeletal muscles autonomic reflexes: smooth and cardiac muscle

Explain adaptation, and differentiate between peripheral adaptation and central adaptation.

adaptation: reduction in sensitivity in the presence of a constant stimulus 1. peripheral: occurs at a receptor, receptor activity decreases with time 2. central: occurs along CNS pathways, involves inhibition nuclei along pathway

What is autonomic tone and what part of the CNS controls it?

general activity rate of the ANS, both divisions regulated by hypothalamus

List the four types of general sensory receptors based on function, and identify the type of stimulus that excites each type

nociceptor- pain receptors thermoreceptor- temperature receptors mechanoreceptor-sensitive to stimulus that distort their plasma membrane chemoreceptor- respond to water and lipid soluble substances

Where do the preganglionic neurons of the parasympathetic and sympathetic divisions of the ANS originate and where do they synapse with post-ganglionic neurons. Which neurons are myelinated and which are unmyelinated. What does myelination means in regard to speed of impulse?

parasympathetic: preganglionic nerves arise from the brainstem form part of cranial nerves and travel to synapse with post ganglion neurons sympathetic: axons emerge from thoracic and lumbar segments, near spinal cord preganglions; myelinated postganglions: non myelinated myelinations increase speed

What is SLUDD? What are the physiologic responses to stimulation by the parasympathetic division of the ANS?

salvation, lacrimation, urination, digestion, defecation decrease: heart rate, airway diameter, physical activity

Why are sympathetic responses more widespread and longer lasting than the parasympathetic responses? ( short answer)***

sympathetic neurotransmitter, norepinephrine is broken down at a slower rate than acetylcholine, so post ganglionic cells are stimulated longer in sympathetic

Which neurotransmitters are released by preganglionic neurons and post-ganglionic neurons of the ANS? Are there differences between the sympathetic and parasympathetic division?

sympathetic: prepares body fight or flight preganglion: acetyl postganglion: norepineprhine parasympathetic: inhibits body from overworking/ restores the body to a calm state pre and post: acetyl