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Vert physiology > Chapter 10 > Flashcards

Chapter 10 Flashcards

1
Q

Perception

A

The conscious interpretation of the world based on the sensory systems, memory, and other neural processes

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2
Q

Visceral afferents

A

Visceral receptors transmit info to the CNS by this class of afferent neurons

Chemoreceptors- monitor O2, CO2, H+ lvls in blood
Baroreceptors- certain vessels that monitor blood pressure
Mechanoreceptors- gastrointestinal that monitor stretch or distention

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3
Q

Somatosensory system

A

Necessary for perception of sensations in the skin(somesthetic) and position of limbs (proprioception) which depends on muscles and joint receptors

Sensations: pressure, temperature, pain, and body position

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4
Q

Special senses

A 
Vision
Hearing
Balance
Equilibrium 
Taste
Smell
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5
Q

Adequate stimulus

A

The modality which a receptor responds best to

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6
Q

Sensory transduction

A

Receptors convert the energy of a sensory stimulus into changes in mem potential call receptor potential or generator potentials (opening and closing of ion channels)

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7
Q

Sensory receptor forms

A

1: specialized structure at the peripheral end of an afferent neuron uses mem potential to propagate action potentials
2: separate cell that communicates through a chemical synapse with an associated afferent neuron used the release of neurotransmitters

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8
Q

Slowly adapting or tonic receptors

A

Show little adaptation and can function in signaling the intensity of a prolonged stimulus

Best respond to pressure

Ex. Muscle stretch receptors

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9
Q

Rapidly adapting or phasic receptors

A

Adapt quickly and thus function best in detecting changes in stimulus intensity

Best responds to vibration

Off response- some show a second smaller response upon termination of a stimulus

Ex. Olfactory receptors, pacinian corpuscles, which detect vibration in the skin

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10
Q

Labeled lines

A

The specific neural pathways that transmit info pertaining to a particular modality, each modality follows its own line

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11
Q

Sensory unit

A

Comprises a single afferent neuron and all the receptors associated with it of the same type

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12
Q

Receptive field

A

The area over which and adequate stimulus can produce a response in the afferent neuron

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13
Q

First order neuron

A

The afferent neuron that transmits info from the periphery to CNS

They may diverge within the CNS and communicate with several interneurons

Interneurons may receive converging input from several first order neurons

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14
Q

Thalamus

A

Major relay nucleus for sensory input, consist of second order neurons

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15
Q

Third order neurons

A

Form synapses with second order neurons, and transmit info to the cerebral cortex for sensory perception

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16
Q

Sensory coding

A

How a sensory receptor determines the location, strength, and type of stimulus

Stimulus type- coded by receptor and pathway(s) activated

Sensory strength- coded by the frequency of action potential and number or receptor activated

Sensory location (tactile, proprioceptive, and visual stimuli)- coded by receptive fields

17
Q

Acuity

A

Precision with which the location of a stimulus is perceived

Depends on size, number, and overlap of receptive fields called lateral inhibition

Localization is more accurate in places of smaller receptive fields, however done by the overlapping of fields

18
Q

Lateral inhibition

A

A stimulus that strongly excites receptors in a given location inhibits activity in the afferent pathways of other nearby receptors

19
Q

Synesthesia

A

May hear colors, see sounds, or taste shapes

Due to developmental anomalies in the wiring of CNS, where different pathways intertwine

20
Q

Two point discrimination

A

Measure of tactile acuity, the ability of a person to perceive two fine points pressed against the skin as two distinct points

Two point discrimination threshold; The minimum distance between two points to be perceived as separate of two diff afferent neurons

Close areas: lips finger tips (great acuity)
Further apart: back, thigh, upper arm (low acuity)

21
Q

Somatoreceptors

A

Proprioreceptors- muscles joints
Mechanoreceptors- pressure force vibration
Thermoreceptors- skin temp
Nociceptors- tissues damaging pain, noxious stimuli

Widest variety of Receptor types

22
Q

Free nerve endings

A

Somatic sensory receptor types that lack identifiable specialized structures

23
Q

Mechanoreceptors in skin

A

Superficial layers epidermis: Merkel’s disks and Meissner’s corpuscles ( only hairless glabrous areas)

Inner layer dermis: hair follicle receptors, pacinian corpuscles, Ruffini’s endings

Size of receptive fields vary greatly

24
Q

Thermoreceptors in the skin

A

Respond to temp change around receptors and tissues not external air.

Warm receptors: respond to 30°C-45°C TRPV
Cold receptors: respond to 35°C-20°C TRPM, TRPA

Actions potentials frequency increases to 45°C, then decrease rapidly

Free nerve endings with temp sensitive ion channels called (TRP) channels

25
Q

Transient receptor potential channels (TRP)

A

Some Open or close solely in response to thermal stimuli, others to chemical stimulus include with thermal and pain transduction

26
Q

7 subfamilies of TRP receptors

A

TRPV1-4 activated by heat

TRPM TRPA activated by cold

TRPV1+TRV2 respond to 43°C + found in nociceptors

TRPV3 and TRPV4 respond to 27°C-42°C found in warm receptors

TRPM8 responds to temp less than 25°C

TRPA1 responds to temp less than 17°C

27
Q

Chemical responses to TRP receptors

A

TRPV3- responds to warm inducing sensations from using camphor

TRPM8 responds to methanol and eucalyptus oil causing cold sensation

TRPA1 receptors respond to mustard oil, garlic, and cinnamon

TRPV1 receptors responds to acid and capsaicin (chilli)

28
Q

Nociceptors in the skin

A

Mechanical nociceptors: responds to intense mechanical stimuli

Thermal nociceptors: respond to intense heat 44°C+

Polymodal nociceptors: respond to all of the above and chemicals released by damaged tissue

*chemicals released from damaged tissue: histamine, bradykinin, and prostaglandins

29
Q

The somatososensory cortex

A

Where somatic sensations from all over body originate

Vertical columns are organized according to sensory modality such as vibration cold pressure etc

30
Q

Somatosensory pathways

A

Transmit info from peripheral sensory info to the thalamus, then to primary somatosensory cortex

1: Dorsal column medial lemniscal pathway
2: Spinothalamic tract

Both pathways enter the spinal cord on one side and cross to the other before reaching the thalamus right

31
Q

Dorsal column medial lemniscal pathway

A

Transmits info from mechanoreceptors and proprioceptors to the thalamus, crosses to other side of CNS in medulla oblongata

1st order neurons originate in periphery and enter dorsal horn of spinal cord, terminate in medullary dorsal column nuclei to form synapses with 2nd order neurons

2nd order neurons cross over to contralateral side of medulla (medulla lemnicus) then ascends to thalamus

3rd order synapses with 2nd, transmitting info from thalamus to somatosensory cortex

Axon ascends from spinal cord to ipsilateral brainstem in the dorsal columns

32
Q

The spinothalamic tract

A

Transmits info from thermoreceptors and nociceptors to the thalamus; crosses over to other side of CNS in spinal cord before brain

First order neurons originate in the periphery at thermo or nociceptors and enter dorsal horn of spinal cord, may ascend or descend within Lissauers tract

2nd order neurons cross over to contralateral side of spinal cord,ascend in anterolateral quadrant of spinal cord thru brainstem and terminate in thalamus

3rd order form synapses with 2nd in thalamus that ascend to the somatosensory cortex

33
Q

Response to pain

A

Autonomic responses- blood pressure heart rate, dilation of pupil, ^ blood glucose

Emotional responses- fear and anxiety

Reflexive withdrawal from the stimulus

34
Q

Fast pain

A

Perceived as a sharp pricking sensation that can be easily localized

Transmitted by A-delta fibers, thin lightly myelinated axons 12-30m/sec

35
Q

Slow pain

A

Perceived as a poorly localized dull aching sensation; transmitted by C fibers, thin unmyelinated axons 0.2-1.3 m/sec

36
Q

How pain is transducted

A

A-delta or C fibers, form synapses with 2nd order neurons (dorsal horn of spinal cord)

1st and 2nd order communicate with neurotransmitters substance P and Glutamate from 1st order neuron

2nd order neurons ascend to the thalamus via spinothalamic tract to the reticular formation of the brainstem, hypothalamus, and limbic system

37
Q

Referred pain

A

Activation of nociceptors in viscera

Due to second order neurons also receiving input from somatic afferents

38
Q

Gate control theory

A

States that somatic signals of non painful sources can inhibit signals of pain at the spinal level

The basis for using transcutaneous electrical nerve stimulation (TENS) to treat pain

TENS: a small current applied through skin overlying a nerve activated large diameter afferents which relieves pain

39
Q

Endogenous analgesia system

A

Activated by an area in the midbrain called periqueductal gray matter, which communicates with the nucleus raphe magnus and lateral reticular formation in medulla

Neurons Descend to spinal cord where they block communication between nociceptors afferent neurons and 2nd order neurons

Inhibitory neurons release endogenous opiate neurotransmitter enkaphalin, can inhibit the release of substance P

Vert physiology (8 decks)

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