Topic 3: Sensory Receptors

Question 1

A ________ ________(organ) is a structure that recognizes a stimulus.

Answer 1

Sensory receptor

Question 2

A ________ is a detectable change in the internal or external environment.

Answer 2

Stimulus

Question 3

Under the appropriate circumstances, a receptor can transducer (convert) the stimulus into a _____ signal. These signals are then carried into the CNS to be analyzed.

Answer 3

Nerve

Question 4

T/F: A sensory receptor may be a specialized portion of the neuronal membrane, a separate cell associated with a neuron ending, or a group of such cells. Sometimes the receptor and the neuron itself are together referred to as a receptor.

Answer 4

True

Question 5

Each sensory receptor responds most readily to one particular form of energy. This is called its ________ ________.

Answer 5

Adequate stimulus

Question 6

__________ : the magnitude or intensity that must be exceeded for a certain reaction or condition to occur.

Answer 6

Threshold

Question 7

T/F: Receptors can only respond to their adequate stimulus.

Answer 7

False: Receptors also respond to forms of energy other than the adequate stimulus, but the threshold for these nonspecific responses is much higher.

Question 8

__________ is the process by which stimuli are converted to action potentials (APs) by sensory receptors.

Answer 8

Transduction

Question 9

__________ is the process by which nerve signals enter and ascend the CNS in various tracts.

Answer 9

Transmission

Question 10

_________ is the process by which electrochemical activity from other ascending inputs for example, touch, or signals descending from the brain (via emotions) can increase or decrease sensory transmission. In this manner the intensity of sensory input to the cerebral cortex can be controlled.

Answer 10

Modulation

Question 11

__________ is the process which results in subjective feelings. It is a poorly understood combination of transduction, transmission, and modulation. It can be altered by many phenomena including sleep and emotions such as fear, rage, and depression.

Answer 11

Perception

Question 12

T/F: All unipolar neurons are attached to some sort of

sensory receptor.

Answer 12

True

Question 13

All unipolar cell bodies form a cluster called a ______ ____ ________ at every level of the spinal cord.

Answer 13

Dorsal root ganglion

Question 14

Unipolar neurons enter the ______ ____ at each level and on both sides of the spinal cord.

Answer 14

Dorsal horn

Question 15

Unipolar neurons in cranial nerves that have a sensory component, for example CN V, also have _______.

Answer 15

Ganglia

Question 16

__________ _________ is the smallest amount of change needed in a stimulus before a change is noticed.

Answer 16

Difference threshold

Question 17

_______’s ___ states that the change needed to notice a difference between two stimuli is proportional to the original intensity of the stimulus.

Answer 17

Weber’s Law

Question 18

Every receptor has a defined area in the periphery, over which it can receive input. This is called the _______ _________, and each one is the responsibility of a single axon.

Answer 18

Receptive Field

Question 19

_______ __________ is the ability to accurately locate the site of stimulation and to detect that neighbouring stimuli are actually separate.

Answer 19

Spatial discrimination

Question 20

_______ _________ depends in part on the density of receptors and the size of the receptive fields in a particular skin region.

Answer 20

Tactile sensitivity

Question 21

More sensitive areas have _______ fields and a _______ concentration of receptors.

Answer 21

More sensitive areas have smaller fields and a higher concentration of receptors.

Question 22

The ____-______ threshold is the minimal distance in which two separate stimuli can be distinguished as separate.

Answer 22

Two-point

Question 23

In different parts of the skin, the concentration of the various sensory receptors changes and this accounts for varying abilities in _______ _________ in different regions.

Answer 23

spatial discrimination

Question 24

On the back, the density of tactile receptors is greatly _______, and spatial discrimination is relatively ____.

Answer 24

On the back, the density of tactile receptors is greatly reduced, and spatial discrimination is relatively poor.

Question 25

A ___________ is an area of the skin that is a combination of the adjacent receptive fields of the sensory receptors of a single nerve. They are named according to the peripheral nerve which supplies them.

Answer 25

Dermatome

Question 26

T/F: Dermatome maps are incredibly accurate and there is very little overlap.

Answer 26

False!! There is considerable overlap. This means that the loss of a single nerve root rarely produces significant loss of skin sensitivity.

Question 27

_________ _____s are found in small patches in the distal extremities.These are distinct and non- overlapping areas of skin.

Answer 27

Autonomous zones

Question 28

_____ __________ have a confusing arrangement stemming from limb rotation during development at about 5 weeks as an adaptation to the erect position.

Answer 28

Limb dermatomes

Question 29

Dermatomes are useful in localizing the site of damage in the spinal cord and brainstem particularly in __________ (caused by compression, inflammation and/or injury to a spinal nerve).

Answer 29

Radiculopathy

Question 30

A _______ ____ with nerve compression is by far the most common cause of a radiculopathy.

Answer 30

Herniated disc

Question 31

Viruses that infect spinal nerves, such as herpes zoster infections (shingles), can reveal their origin by showing up as a painful (unilateral) _________ area.

Answer 31

Dermatomic

Question 32

______ _____, a virus that can be dormant in the dorsal root ganglion, migrates along the spinal nerve to affect only the area of skin served by that nerve (dermatome).

Answer 32

Herpes zoster

Question 33

The receptors that respond best to change are called fast adapting receptors or ______ receptors, for example, olfactory receptors.

Answer 33

Phasic

Question 34

_________ is the decrease in sensory receptor sensitivity during a long-lasting stimulus.

Answer 34

Adaptation

Question 35

_____ receptors or fast adapting receptors are in part responsible for the fact that we can cease paying attention to constant stimuli.

Answer 35

Phasic

Question 36

Receptors which continue to respond throughout the duration of a prolonged stimulus are termed slow adapting or _____ receptors.

Answer 36

Tonic

Question 37

In this way they convey information about the duration of the stimulus. An example of a tonic receptor is a _________.

Answer 37

Nociceptor

Question 38

______________ are the largest category of sensory receptors and respond to a deformation in a body part. This group includes haptic receptors, receptors that are involved in contributing to the perception of touch.

Answer 38

Mechanoreceptors

Question 39

______ ________ (endings) detect skin stretch, deformation within joints. They monitor slippage of objects along the surface of the skin, allowing modulation of grip on an object.

Answer 39

Ruffini terminals

Question 40

_______ corpuscles detect transient pressure and high-frequency vibration.

Answer 40

Pacinian

Question 41

_______ corpuscles are rapidly adapting touch receptors.

Answer 41

Meissner’s

Question 42

_ _______ _____have been linked to pleasant touch and are most responsive during slow gentle stroking in hairy skin.

Answer 42

C tactile fibres

Question 43

_____ hair is the fine, wispy hair that covers most of the body. C-tactile touch receptors wrap half -way around the base of hair follicles. This enables them to detect deflection in one direction versus the other for example to help notice a potentially dangerous insect. That is why stroking against the grain feels different.

Answer 43

Vellus

Question 44

The ______ is involved in processing pleasant, “slow” touch, taste (especially disgust), pain and emotion.

Answer 44

Insula

Question 45

The ___________ cortex (of the parietal lobe) responds to spatial location, pressure and pinpricks.

Answer 45

somatosensory

Question 46

__________ are receptors that detect noxious or potentially damaging stimuli. They are often called free nerve endings because unlike other receptors they are not surrounded by connective tissue.

Answer 46

Nociceptors

Question 47

T/F: The term nociceptors can also include the afferent neuron attached to them.

Answer 47

True

Question 48

Nociceptors respond to stimuli that could potentially ______ the body, such as extreme heat or cold, pressure, pinching, and chemicals.

Answer 48

Damage

Question 49

T/F: Nociceptor is an AKA for a pain receptor.

Answer 49

False: The signals they pass on to the brain often but not always result in pain perception.

Question 50

____________ refers to a signal arriving at the CNS as a result of stimulation of nociceptors. It is the physiological process by which body tissues are protected from damage.

Answer 50

Nociception

Question 51

__________ pain implies damage to the nervous system itself, due to disease or trauma.

Answer 51

Neuropathic

Question 52

________ ____ is defined as pain perceived at a location other than the site of the painful stimulus. In other words, your brain misperceives the location of the pain.

Answer 52

Referred pain

Question 53

Your ________ is a four-inch, pear-shaped organ when full of bile. It is positioned under your liver in the upper-right section of your abdomen. It stores bile which allows some nutrients to be more easily absorbed into the bloodstream.

Answer 53

Gallbladder

Question 54

The gallbladder lies next to the right ________, therefore inflammation can spread to the __________.

Answer 54

Diaphragm

Question 55

The right _______ nerve from the diaphragm enters the CNS via the right spinal nerves at C3, 4 & 5.

Answer 55

Phrenic

Question 56

Afferent signals from the right shoulder, dermatome _, also converge on spinal nerve roots C3-5.

Answer 56

Dermatome 4

Question 57

A _______ is a fast, predictable sequence of involuntary actions. It occurs in response to certain stimuli. The example above is the famous “Knee Jerk”

Answer 57

Reflex

Question 58

Reflex ____ are anatomic pathways having afferent and efferent components that carry out reflex responses.

Answer 58

Arcs

Question 59

In a reflex arc, a receptor transduces stimuli to APs, then an afferent neuron that carries APs to ___________ (the stretch reflex is the only monosynaptic reflex). Efferent neurons then carry APs to Effectors (muscles or glands).

Answer 59

Interneurons

Question 60

Reflexes form the basis of all ____ motor activity. They occur at all levels of the _____. Important bodily functions such as respiration, digestion, posture, defensive movement, micturition, sexual function, and walking are controlled through reflexes.

Answer 60

CNS

Question 61

Most powerful activities involve a ____________ during which the muscles involved are first stretched and then shortened to accelerate the body or limb.

Answer 61

Countermovement

Question 62

___________ is the ability to know where your body is in space without the use of vision. The category of proprioceptors includes muscle spindles.

Answer 62

Proprioception

Question 63

The ______ _______ is a sensory receptor that monitors a change in the length of a muscle and how fast it is being stretched.

Answer 63

muscle spindle

Question 64

The ______ ______ is an involuntary muscular contraction in response to a fast stretch of the muscle.

Answer 64

stretch reflex

Question 65

Muscle Spindles are ________ in shape meaning they bulge in the middle and taper at both ends.

Answer 65

fusiform

Question 66

_________ fibres are tiny muscle fibres that are located inside the muscle spindle. They are miniture versions (4-10 mm) of extrafusal muscle fibres, all the same microspcopic stuffings - myofibrils, myofilaments (actin & mysosin).

Answer 66

Intrafusal

Question 67

_________ muscle fibres are located outside the muscle spindle. In other words they are normal skeletal muscle fibres.

Answer 67

Extrafusal

Question 68

Muscle spindles are found in greatest abundance in muscles capable of delicate, fine, contractile activity like in the ____ and ____.

Answer 68

Hand and foot

Question 69

___ is the name given to the sensory neurons that carry a nerve impulse to the CNS. They respond to a change of length in the muscle spindle.

Answer 69

Ia

Question 70

T/F: If the extrafusal fibres are being stretched then the Intrafusal fibres of the muscle spindle inside them are also being stretched.

Answer 70

True

Question 71

_____ _____ ______ are motor neurons that innervate extrafusal muscle fibers. Extrafusal fibres are the normal skeletal muscle fibres that surround the muscle spindle and allow you to move.

Answer 71

Alpha Motor Neurons

Question 72

_____ _____ _______ are motor neurons that innervate intrafusal fibres.

Answer 72

Gamma Motor Neurons

Question 73

For patients with excess “_____ ____”, the 1a sensory endings within muscle spindles are discharging too frequently causing there to be more muscle activity than appropriate. This hyperactivity can cause spasticity.

Answer 73

“gamma bias”

Question 74

___________ is defined as overresponsive reflexes.

Answer 74

Hyperreflexia

Question 75

The _____ ______ _____ is a proprioceptive receptor that is located within the tendons found on each end of a muscle. It responds to increased contraction exerted on the tendon, by inhibiting further muscle contraction.

Answer 75

Golgi Tendon Organ