Physiology Lectures 8 & 9 Week #

Front 1

Our creation of reality is really?

Back 1

A best guess construction

Front 2

2 major divisions of nervous system

composed of?

Back 2

Central NS : brain and spinal cord

Peripheral NS: everything else

Front 3

2 directions for informtaion

Back 3

Afferent NS (PNS): going towards (A)t the CNS

(sends info about everything it can detect to CNS)

Efferent NS (PNS): (E)xiting the CNS sends info and instructions to the periophery out of the CNS

Front 4

All neurons contain the ______ which is important for _________

Most neurons have ______

Back 4

All have cell body which is important for providing proteins to replace those which have been damaged or to change bow the cell might respond.

Most have an axon hillock (important for generation of AP)

Front 5

Where is the axon hillock in different types of neurons?

Back 5

Axon hillock in output system and in the interneuron system is locked near the soma

In afferent nervous system the axon hillock is located next to the sensory receptor, the part of the cell which responds to given stimulus. Cell body is located further away

Front 6

The terminal fields of axons are important for _____

Back 6

communicating with other cells

Front 7

Flow of info starting from stimulus in NS

Back 7

1. Sensory neurons receptors are activated

2. AP initated at axon hillock and goes down axon to interneuron

3. Interneuron intiates AP at its axon hillock travels down to the next neuron

4. An output neuron is stumulated and initates an AP at hillock which travels down the axon to effect some effector system

Front 8

The way the nervous system figures out the kind and intensity of stimulus is based on _____

Back 8

receptor selectivity, labeled lines (keeps the info about a specific location of type of stimulus separate frmo others) and frequency of AP

Front 9

Is it possible to have sensory neuron be the motor neuron? advantages? disadvantages?

Seen where?

Back 9

YES

advantages: speed

disadvantages: lack of decision making in output

Seen in some types of reflexes

Trade off (speed vs integretion)

Front 10

First order sensory neuron

Back 10

sensory receptor or the cell that responds directly to the stimulus and sends the info to the rest of the ns

Front 11

Second order sensory neuron

Back 11

neuron is usually in spinal cord but can be in other locations depending on the location and type of the sensory receptor and recieves stimulus info from first order neuron and relay the info further on in the NS

Front 12

Sensory receptors

Back 12

The cells (neurons) that can detect a given modality of a stimulus

Front 13

Sensory transduction

Back 13

the conversion of a stimulus into a receptor potential or into a change in the metabolic state of the sensing cell

Front 14

Stimulus

Back 14

an informational packet from the environment (both external and internal) that can eb detected by the NS

Front 15

Third order and higher sensory neuron

Back 15

These sensory neurons are usually in the thalamus and the cortex and receive the sensory info so as to process it either for further relaying or for decision making about the stimulus

Front 16

Perception requires _____ and is limited to _____

Back 16

requires a conscious awareness about the stimulus and also a set of neuronal relays through the thalamus) some info may not making it through to higher levels of CNSand is limited to what you can detect

Front 17

The ______ manipulates the data from sensory to make sense of it given what you have experienced in the past

Back 17

cerebral cortex

Front 18

Reason some information doesnt make it up to higher levels of CNS

Back 18

thalamus can regulate what information makes it to the cortex

Front 19

Detection limitation

Back 19

refers to the limitation of receptors you have you can only detect stimuli for which you have dectors thus although you recieve stimului in the UV and infrared regions of the electromeagnetic spectrum you have nothing that can detect these stimuli so you are ignorant of this info

Front 20

Cortical integration

Back 20

what the brain must to in order to make sense of sensory info it recieves. does this by comparing info it has recieved in the past creates best guess

Front 21

Prior experience

Back 21

Prior experience determines the data that the brain uses to create present reality things you have learned or experienced before effect for you percieve the present

Front 22

modality

Back 22

certain receptors only respond to specifity forms of stimuli so when these neurons fire you know what the stimulus is.

Front 23

Pacinian corpuscles found in the skin

Back 23

respond to vibrations and deep pressure

Front 24

stereocilia in inner ear

Back 24

respond only to vibrations that result in sound waves

Front 25

Receptors location links to specific region of the brain _____

Back 25

mapping

Front 26

how to tell a small stimulus from big

Back 26

The intensity of the receptors response (number of APs) and also how many receptors are activated

Front 27

4 things that help brain differentiate different stimuli

Back 27

Modality

Mapping

# of receptors activated and how many APs

Time when recetor is activated, stops firing and CNS integrates

Front 28

The labeled line code

Back 28

Different types of info are initially kept separate within labeled lines

the axons of the receptors function as modality-specific lines of communication between periphery and CNS

Different types of receptors have different sets of connections in the CNS

(different types of receptors for different stimuli have unique pathway to brain that helps identify them)

Front 29

Labeled lines

Back 29

Each modality maps to a different location

within each region there exists an internal map

Maps vary between individuals and are dynamic

Different regions ultimately interact (to produce the sense of reality)

Front 30

Likely it is _____ that give us the sense of real time

Back 30

timing of the signals

Front 31

Adequate stimulus

Back 31

The stimulus modaility that a given sensory receptor is designed to detect is that sensory cells adequate stimulus

Front 32

Labeled lines

Back 32

Incoming sensory info is kep in specific neuron pathways that depend on the location and type of sensory modality and connect to specific parts of the thalamus and then cortex thus the specificity of the stimulus and where it was detected are kept separate from other incoming signals

Front 33

Primiary sensory areas of cortex

Back 33

areas of the cortex specialized to interpret specific types of stimuli

Somatosensory, visual, olfactory, auditory, gustatory

Front 34

Thalamus

Back 34

a very important bilateral structure deep in the brain through which most sensory info is passed on to the appropriate part of cortex

Front 35

Example of you brain integrating mutliple stimulu into one picture

How?

Back 35

When fireworks are near you see them before you hear them but your brain will put it together as if you are seeing and hearing them together

Produce sounds quicker than we produce light

Front 36

experiment with light and sound

Back 36

with no delay for sound nearly everyone heard the sound first

As the distance of the object increased, the more lag was needed for sound for the two to be percieved as simultaneous

Front 37

The detection of sound has to occur _______ with _______ that depends on ______

Back 37

has to occur after that of light with a specific delay that depends on the distance from the object

Front 38

The speed with which the brain processes any given form of stimulus is _____

Back 38

always optimum for that modality and does not change

Front 39

Processing speed

Back 39

of each sensory system is always carried out at max speed for that system and does not chang e the speed of processing for any given system based on the info from other sensory systems. It is the brain which must decide based on the sensory system what events are likely to have taken place simultaneously

Front 40

Time maps

Back 40

are important to how the brain interprets info from several sensory modalities to assign and and effect timing these maps are primarily based on experience and are plastic they are changed and updated with time to make sense

Front 41

Receptors are

Back 41

specialized sensory neurons that respond to only one kind of stimulus (modality) and convert that stimulus into a series of APs

Front 42

Stimulus intensity

Back 42

frequency of APs and the number of neuron responding

Front 43

When proper stimulus acts on the sensing part of the receptor neuron _____

Back 43

it usually causes a catonic channel to open, thus allowing mainly sodium to enter the cell and in the process, depolarizing the cell this travels down the sening process of the cell to the axon hillocl wehre depolarization can trigger the opening of voltage gated sodium channels and the generation of an AP

Front 44

the stimulus must be ______ in order to trigger response

Back 44

specific for that receptor and strong enough to trigger an AP

Front 45

If signal is not strong enough depolarization will _____

Back 45

will not trigger AP and no signal will reach the terminal field

Front 46

Describe function of receptor system where receptor doesnt fire APs

Back 46

Very similar the sensing cell responds to appriciate stimulus by opening a cationic channel which depolarizes the cell and causes opening of voltage gated calcium channel, the entry of calcium triggers release of neurotransmitter which is then sensed by the second neuron and causes the opening of a ligand geted cationic channel. usually causes entry of sodium which depolarizes the neuron and causes AP

Front 47

Receptors can adjust their responses to sustained stimuli by _____

Back 47

decreasing their depolarization in response to stimuli

Front 48

2 types of adaptations for long term stimulis

Back 48

One type is found in neurons where as long as the stimulus is present they continue to fire APs

Another types is found in neurons that stop firing APs after the onset of stimulus and then fire another series of APs when the stimulus has stopped

Front 49

Adaptation where fire APs as long as stimulus is present found in_____ called_____

Back 49

some touch receptors, pain receptors and temp receptors

called tonic or slow adapting receptors

Front 50

Adaptation where APs fired when stimulus starts and stops called _____ found ____

Back 50

phasic or rapidly adapting

found on some touch receptors

Front 51

Slow adapting sensors are important for ______

Rapidly adapting sensors important for ____

Back 51

Slow important for telling you that the stimulus is still present

Rapid important at emphasizing when a stimulus started and stopped

Front 52

Receptor field

Back 52

the region covered by a receptor of a given type

Front 53

The more closely spaced receptor fields are ____

Back 53

the greater the acuity

Front 54

In an unmodified response when a narrow probe is applied to the skin it causes distortion of an area of the skin. _______

Back 54

the receptors whose receptive fields are under these areas will respond by firing APs and the freuqency of APs will depend on the strength of the stimulus. Because of this it is expected that the most affected part of the skin will cause those receptors to fire a higher frequency of APs than those less effected.

Front 55

In the case of lateral inhibition we can _______ by ______

Back 55

increase the acuity by decreasing the respones of the secondary sensory neurons to areas less affected by the stimulus. When lateral inhibition is present the primary sensory neurons not only pass on info to the secondary sensory neurons but they synapse on inhibitory interneurons. The inhibitory interneuron getting the highest level of stimuluation will have the greatest inhibitory effect and thus will shut down the release of neurotransmitter by neighboring primary sensory neurons. In this way the signal from the most stimulated primary neuron will cause its secondary sensory neuron to fire at the highest level and neighboring secondary sensory neurons will signal less. Causes great acuity

Front 56

Acuity

Back 56

Refers to how distant two points of stimulation need to be in order to be sensed as separate. The closer two points of stimulation can be felt as separate the higher acuity that sensory system has.

Front 57

Acuity depends on

Back 57

the density of sensory neurons with each sensory neuron sensing and area called the receptive field. The larger the receptive field the lower the acuity

Front 58

Adaptation

Back 58

The ability of some sensory neurons to decrease their response to a continueous stimulus even though the intensity of the stimulus is not diminished

Front 59

Phasic receptors

Back 59

These are sensory receptors that show strong adaptation to stimulus.

Front 60

Receptive field

Back 60

the area of the skin that a specific type of sensory receptor can detect stimuli in

Front 61

Receptor potentials

Back 61

The change in membrane potential caused by stimulus in given sensory receptor

Front 62

Tonic receptors

Back 62

these are sensory receptors that do not adapt to a stimulus or show weak adapation. Tonic receptors are important for information that must continusouly monitored by the NS such as the length and tension of skeletal muscle

Front 63

Somatosensory receptors are found _____

Back 63

widely distributed throughout the body surface, internal organs and bone and muscle

NOT FOUND IN CNS

Front 64

The somatosensory system is in charge of _____

Back 64

detecting a myriad of sensory stimuli

Front 65

Mechanosensation

Back 65

the ability to detect pressures or movements applied to a cell. Touch is an example

Front 66

Mechanosensation involved detecting ____ which can include

Back 66

mechanical changes in tissues or cells. which can include

Touch on skin

Pressure on viscera

Proprioception of body limbs

Front 67

Thermosensation

can be ____ but normally ____

Back 67

thermal sensation gives us info about the general temp of our bodies and how different parts may be different temps this sense

can be brought to consciousness but normally works in the unconscious background

Front 68

reasonably good at detecting _____ different temp ranges

list

Back 68

7

Freezing cold, cold, cool, indifferent, warm, hot, burning hot

Front 69

What area of temp is labeled indifferent

Back 69

30-37 degrees so close to body temp hard to tell difference

Front 70

Nociception

normally concious or unconcious

Back 70

sense of pain occurs when there is damage to an area or when functions are outside normal ranges

normally a concious stimuli

Front 71

Pain sensation can be caused by _____

Back 71

directly by noxious stimulus

indirectly by release of chemical mediators from damaged cells

Front 72

pain can be ____ or _____

Back 72

sharp and highly localized or dull and more diffuse

Front 73

Compound sensations

strictly due to ____

Back 73

a form of somatosensation for which specific receptors do not exisit (combinations of elementary modalities can generate distinct sensations for which there is no specific receptor) Example (wetness)

Strictly due to central nervous system construction

Front 74

most somatosensory info enters the spinal cord through ____ except for most ______ which ______

Back 74

dorsal root ganglia except for facial and buccal systems which use the trigeminal nerve

Front 75

In most of the body the somatosensory neuronal axons are bundled together and use ______ then _______

Back 75

spinal nerves to guide them to the nerve cord

then part of the spinal nerve enters a structure known as the dorsal root ganglion

Front 76

The dorsal root ganglion contains _____

Back 76

the cell bodies of the sensory neurons remember that the soma of sensory neurons are located off to the side of the axon. These cell bodies reside in the bulgin of the sinal cord

Front 77

The trigenimal nerve uses _______ to

Back 77

one of 3 branches to conduct sensory information depending on whether the information is coming from the forehead and nose, the maxillary structures or the mandibular structures

Front 78

The spinal nerves are ____ meaning they are _____ as the spinal nerve enters the area of the dorsal root gangilon ______

Back 78

are mixed, contain both afferent and efferent axons

as the spinal nerve enters the area of the dorsal root ganglion, the nerve splits into dorsal and ventral roots

Front 79

The dorsal root of the spinal cord contains

Back 79

axons of sensory neurons or the afferent nervous system

Front 80

the ventral root of the spinal cord caontains

Back 80

axons of motor neurons or efferent NS

Front 81

Sensory neurons enter the spinal cord through the _______ where they can either _____ or ____

Back 81

enter through the dorsal horn hwere they can either continue up the spinal cord to higher areas of CNS or synapse on interneurons of the dorsal horn

Front 82

Interneurons of dorsal horn can _____ or ____

Back 82

send info up to the thalamus or if part of spinal reflex can synapse on motor neurons directly to cause a specific behavior

Front 83

Patient comes into office and tells you they can't feel half their face should you worry?

Back 83

yes, possible damage to trigenimal nerve, possible stroke, possible tumor

Front 84

Anatomy of somatosensory cells

Back 84

Sensory receptors for cold, heat and damage are all anatomically indistinguishable nerve endings, but functionally they only respond to the appropriate modality

Front 85

Somatic sensory system

Back 85

The sensory system involved in detecting touch,, temp, pain and level of stretch of skeletal muscles

Front 86

Different modalities are carried by _____ which effects _____

Back 86

by different sized axons which effects the speed which which the information is relayed to the CNS

Front 87

____ and ____ effect the rate at which APs can travel

Back 87

size and myelination

Front 88

Within the myelinated fibers we have ____ sizes ranging from ___ to ___

Back 88

3 sizes ranging from 1 to 20

Front 89

Within myelinated fibers ____ are the fastest with speeds of about ______

Back 89

alpha fibers fastest with speeds of 80-120 meters per second

Front 90

alpha fibers are represented by ____ and ____

Back 90

pacinian and meissner corpuscles

Front 91

The A- beta fibers are ____ and are represented by ____

Back 91

intermediate in size and can conduct at 35-75 meters per second

represented by merkel disks and ruffini endings

Front 92

____ are the smallest conducting myelinated fibers with conducting speeds of _____ and are represented by ___

Back 92

A-delta speeds of 5-30 meters per second represented by mechanonociceptors responsible for sharp pain

Front 93

in unmyelinated types of fibers we have ____ fibers which conduct at speeds ____ represented by _____

Back 93

C fibers which can conduct from .5 to 2 meters per second and are represented by the polymodal nociceptors which carry dull pain

Front 94

Explain stubbed toe effect

Back 94

initially feel sharp pain then dull pain because

sharp pain is much faster than dull pain

Front 95

Temperature receptor fibers

Back 95

two types, the cold receptors ( a lightly myelinated thin fibers (A-delta) and those of the warmth receptors are unmyelinated (small fibers C)

Front 96

touch receptor fibers

Back 96

are all myelinated whole axon diameters vary. (fall into A-beta and A-delta types)

Front 97

Consider the temp and pain sensations path from sensor to brain

Back 97

when these specialized nerve endings are activated they send their axons through the spinal nerve to the dorsal root ganglion then through the dorsal root unto the dorsal horn of the spinal cord. Here synapse on second order sensory interneurons the second order sensory interneurons then cross over the midline of the spinal cord or decussate and go up the spinal cord to the medulla using the anterlateral tract on the contralateral side. From here the fibers transverse the medulla and pons until they reach and synapse with the thalamus. Thalamic interneurons then send projections to the appropriate part of the somatosensory cortex for interpretation

Front 98

After synapsing on secondary interneurons in spinal cord what happens to temp and pain sensations

Back 98

cross over midline of spinal cord or decussate and go up the spinal cord to the medulla using the anterolateral tract on the contralateral size from here, fibers traverse the medulla and pons until they reach and synapse with the thalamus

Front 99

Path of touch and proprioception sensation to brain

Back 99

neuron activated send axonal projections to the dorsal horn of spinal cord through the spinal nerve, dorsal gangion and the dorsal root, once these axons enter the dorsal horn they project up the spinal cord on the same size as they entered (ipsilateral) using the dorsal column medial lemniscal tract when they arrive at lower medulla they synapse with their second order interneurons at the gracile and cuneate nuclei of the medulla. The second order sensory interneurons then decussate to the medial lemniscus and proceed up the pons and midbrain to the thalamus

Front 100

What happens after touch and proprioception signal into dorsal horn of spinal cord

Back 100

do not synapse on second order sensory neuron, instead they project up spinal cord on same side they entered ipsilateral usuing dorsal column medial lemniscal tract. when they arrive at lower medulla they synapse with their second order interneurons at the gracile and cuneate nueclei of the medulla. The second order sensory interneurons then decussate to the medial lemniscus and procedd up through the pons and midbrain to the thalamus

Front 101

What happens after touch and proprioception stimulus synapse on second order sensory neuron

Back 101

Synapse at gracile and cuneate nuclei of medulla. then decussate to the medial lemniscus and proceed through pon and midbrain to the thalamus

Front 102

Somatosensory projections continue from the medulla ______

Back 102

from the medulla to the contraleteral thalamus to the somatosensory cortex

Front 103

Information from different submodalities that was kept segregated in the spinal cord, brainstem and thalamus is

Back 103

integrated at the somatosensory cortex

Front 104

The primary somatosensory cortex, also known as ___ is located in _____

Back 104

somatosensory area I is located in the anterior parietal lobe just behind the central sulcus

Front 105

The somatosensory area I recieves _____

Back 105

first receives somatosensory information from the thalamus about the contralateral side of the body

combines the different modalities of somatosensation for a given part of the body and having done so sends this info to both the ispilateral and contralateral somatosensory area II for further processing

Front 106

Somatosensory area II located _____ gets into from

Back 106

deep part of the parietal lobe called insula recieves info from somatosensory area I

Front 107

The primary somatosensory cortex only deals with _____ but the somtosensory area II ____

Back 107

info from the contralateral part of the body but the somtosensory area II gets info about both sides

Front 108

Job of somatosensory area II

Back 108

not well understood but is believed to be important in constructing the more global picture of what is going on and plays a role in self awareness

Front 109

Anterolateral tract

Back 109

A CNS projection pathway carrying info for pain, temp and crude touch from the sensory receptors. 1st order sensory neurons for this track synapse in the dorsal horn and second order interneurons then cross over to the contralateral side. the info makes connections in the reticular activating system, the messencephalon (used in orientation) and the thalamus

Front 110

Dorsal column medial lemniscal tract

Back 110

a CNS pathway for carrying info about fine touch and proprioception

1st order sensory neurons do not synapse in the dorsal horn but project ipsilaterally up to the medulla where they synapse with second order sensory interneurons the second order neurons then dessucate and send info straight to the thalamus

Front 111

Dorsal root ganglia

Back 111

A bulding near the spinal cord of the dorsal nerve that contains the cel bodies of sensory receptors. contains only afferent fibers

Front 112

Somatosensory cortex

Back 112

area of the parietal lobes just dorsal to the central sulcus that is the primary integrator of somatic info. Info relayed here from thalamus

Front 113

Mechanosensation is the ______

Back 113

conversion of mechanical action to a neuronal signal

Front 114

Mechanoreceptors are critical for _____

Back 114

critical for monitoring a variety of physiologigical activities

touch

proprioception

hearing

balance

blood pressure

Front 115

Meissners corpuscles

found?

respond to?

fiber type?

Back 115

rapidly adapting, located in superfical skin, small receptive fields, responds to low frequency vibrations, and light only on hairless skin (lips palms)

FAST because they use A-alpha fibers

Front 116

Merkel cells

found?

respond to?

fiber type?

Back 116

Slow adapting, located in superficial skin

small receptive fields

preferentially respond to light sustained touch

found both hairless and haired skin

A-beta fibers

Front 117

Pacinian corpuscles

found?

respond to?

fiber type?

Back 117

rapid adapting located in deeper tissue,

large receptive fields responds to high frequency vibrations

A-alpha types

Front 118

Ruffini endings

found?

respond to?

fiber type?

Back 118

Slow adapting, found in deeper skin, larger receptive fields.

A-beta

Respond to deep pressure

Front 119

hair follicle receptors

found?

respond to?

conduction speed?

Back 119

Present only in hairy skin

found entwined around hair follices

respond to any disturbance of hair and to gentle touch

fast adaptiation fast conduction A-alpha or A-beta? (mylinated)

Front 120

When pressure is applied to teeth_____ this implies ____

Back 120

electrical responses can be measured in muscles

this implies there is a touch receptor near teeth or working in conjunction with them

(when pressure is applied there is a response by the muscle)

Front 121

Why would you need touch receptors for your teeth? where might these be located?

Back 121

It is important to sense the level of pressure being applied to teeth to protect them from cracking or being damaged (tooth is not glued to alveolar bone or gingiva but rather suspended by periodental ligament.)

pressure sensors in periodental ligament (become more taught as pressure is applied)

Front 122

What structure is found in the periodontal ligament

Fiber type?

Back 122

Ruffini endings which are tonic meaning pressure on the tooth can be continuously sensed

A-delta type

Front 123

_____ and ____ receptors are not myelinated

Back 123

temp and pain

Front 124

Although we can sense about ____ temp ranges we have ____ temp sensors

describe them

how does this work?

Back 124

7 ranges 4 sensors

cold nociceptor : activated (5-15 C)

cool nociceptor: peak activity (24 C)

warm nociceptor: peak activity (42 C)

hot nociceptor: peak activity (above 45 C)

Combining singals from all 4 receptors gives us a sense of overall temperature

Front 125

Because the temp map is based on _____ you might expect

Back 125

based on experience you might expect that different people experience temp is different ways

Front 126

Experiment with probe being put on skin at 35 and dropping rising

Back 126

Some where better and telling when it had cooled vs heated and vice versa. Some took more of a change to notice everyone is different

Front 127

Why is it not easy to identify the channels on the sensors membrane that are responsible for sensing temp. How have we been able to learn about possible temp sensing channels?

Back 127

because as we change the temp of a cell we affect many processes that probably have little to do with temp sensing. learned through chemicals that give us specific temp sensations

Front 128

Chemicals that give temp sensations

Back 128

Menthol and eucalyptol = cool

Capsaicin: hot

Front 129

A whole family of channels that respond to these temp chemicals are characterized _____

Back 129

transient receptor potential channels

Front 130

Combinatorial code

Back 130

a possible mothod used by the brain to determine the general temp in the body by integrating the combined inputs from all thermosensing cells

Front 131

receptor channels that respond to temp have been able to pull a large number of chanel proteins that belong to this famiy note that these ________

Back 131

are channel proteins and not temp sensory neurons of which only 4 types exist these channels have the ability to activate at different temps allowing the cell to become depolarized

Front 132

____ channel respons to menthol and is found in ______

Back 132

TRPM8 found in temp sensory neurons that are of the cool type

Front 133

_____ is one channel that responds to capsaicin and is found ______

Back 133

TRPV1 found in temp sensory neurons that signal hot nociception

Front 134

TRPVI is a channel that responds to a variety of stimlui such as ______ by _____

Back 134

heat, acid, capsaicin by opening up a cationic channel that allows the entry of primarily sodium and calcium

Front 135

What causes the TRPVI channel to open?

closed when? open when?

Back 135

if you warm it up

closed at 22 degrees C

starts to open at 44 degrees C

Also opens with capsaicin and aciditiy