unit 6 senses

Question 1

somatic senses (conscious or unconscious, function)

Answer 1

aka general senses, conscious, associated with receptors in skin (touch , temp, pain, itch, proprioception- position of body)

Question 2

special senses (conscious or unconscious, function)

Answer 2

conscious, vision, hearing, taste, smell, equilibrium

Question 3

somatic stimuli (conscious or unconscious, function)

Answer 3

unconscious (sensations not in cerebral cortex), muscle length and tension, proprioception

Question 4

visceral stimuli (conscious or unconscious, function)

Answer 4

unconscious (sensations not in cerebral cortex), blood pressure, lung inflation, ph of plasma, etc (things going on inside)

Question 5

which senses provide us information about external body and ourselves

Answer 5

somatic (senses), visceral, and special senses

Question 6

specific form of stimulus

Answer 6

sensory modality

Question 7

receptor acts on the

Answer 7

transducer

Question 8

what can stimulus do to gated ion channels

Answer 8

cause them to open or close (depends on receptor type or modality), and this can cause depolarization/hyperpolarization

Question 9

adequate stimulus

Answer 9

modality or form of energy to which the receptor is most responsive (Receptors can sometimes respond to other modalities but only if the stimulus strength has a high enough intensity. ex: temp receptors with chemical receptors pf hot sauce causing you to feel heat)

Question 10

types of adequate stimulus:
Mechanoreceptors, Thermoreceptors, Chemoreceptors

Answer 10

1. detect physical forces/stimuli (touch, pressure, stretch, vibrations,
   gravity, soundwaves, etc.) Includes baroreceptors (detect pressure/stretch in blood
   vessels, lungs, etc.
2. detect hot and cold temperatures.
3. detect chemicals – e.g. olfactory neurons;

Question 11

types of adequate stimulus: Photoreceptors, Nociceptors, Proprioceptors

Answer 11

1. detect light. Includes the rods and cones (transducer cells) in the retina
   of the eye.
2. detect pain
3. detect body position and movement.

Question 12

adaptation of receptors: tonic receptors

Answer 12

slowly adapting receptors
fire rapidly upon stimulus, then decrease firing rate but maintaining firing rate under a constant stimuli

Question 13

adaptation of receptors: phasic receptors

Answer 13

rapidly adapting receptors. Fire at onset of stimulus, then stop if stimulus intensity remains constant
(adaptation).

They do not fire again until there is a change in the
intensity of the stimulus.

Question 14

graded potential produced on the receptor cell is called a________ triggered by _____

Answer 14

receptor potential, adequate stimulus (aka prefered stimulus of receptor cell type

Question 15

Primary (first order) sensory neurons

Answer 15

1. unipolar neurons
2. first neuron in the pathway

are the receptor in which transduction occurs (in the dendrites) OR they are the unipolar
neurons that receive the transduced signal from the non-neuronal receptor cell

Question 16

Secondary (second order) sensory neurons

Answer 16

Multipolar neurons
Cell bodies in dorsal horn of spinal cord or in medulla depending on the sense involved

Question 17

Tertiary (third order) sensory neurons

Answer 17

Multipolar neurons

Cell bodies in thalamus with axons relaying to cortex.

Question 18

Receptive field

Answer 18

physical area in which
the presence of a stimulus will activate the receptor and alter the firing of a sensory neuron

Question 19

receptive field

Answer 19

often associated with cutaneous (skin) receptors and the retina

Question 20

what allows spatial summation of signals on the secondary neurons

Answer 20

Primary sensory neurons converging onto secondary neurons

Question 21

Sensory Acuity (and when is it low/high)

Answer 21

how accurately a stimulus can be
located.

The more convergence of primary sensory neurons onto secondary sensory neurons, the
larger the receptive field and the lower the sensory acuity

less convergence the receptive
fields associated with each individual primary sensory neuron do not overlap, so easier to locate

Question 22

Each part of the body can be mapped

Answer 22

to a specific area of the primary somatosensory cortex

These maps were developed by electrically stimulating the different regions of the cortex in people undergoing brain surgery

Question 23

Areas of the body that appear larger on the map, have

Answer 23

greater acuity/sensitivity (less
convergence, opposite (etc)

Question 24

sensation vs perception (and examples)

Answer 24

Sensation occurs when sensory information is detected by receptors in the peripheral nervous system.

ex: auditory receptors detect a loud, high pitched ringing noise

Perception occurs in the brain and involves awareness, organization and interpretation (assigning of meaning) of the sensation.

ex: the high pitched ringing noise is a fire alarm and you need to gather your things and leave the building

Question 25

Sensory information travels

Answer 25

1. From spinal cord to brain via ascending (sensory) pathways comprised of primary, and secondary neurons and in many cases tertiary neurons.
2. Directly to brainstem via cranial nerves (exception – pathway for olfaction – olfactory nerves)

Question 26

The four main properties of a stimulus are:

Answer 26

modality: interpretation of the type of stimulus. E.g. Touch, temperature, pain, sound, light, taste etc.

location: interpretation of where on the body the stimulus occurred

intensity: interpretation of strength of stimulus (e.g. how to tell if a feather has dropped on your foot vs. a brick).

duration (interpretation of how long the stimulus is applied/present)

Question 27

Modality encoded by:

Answer 27

Labelled line coding

it is the pathway that
determines the modality, not the receptor (turning on kitchen light wont turn on bedroom light)

Question 28

Location encoded by

Answer 28

Determined by which receptive fields are activated

Labeled line coding ensures that when a particular
receptive field is simulated, the pathway of neurons
to the brain will connect to the specific region of the
brain associated with the area stimulated

Question 29

Intensity Encoded by

Answer 29

The number of receptors activated (population coding

And The frequency of action potentials reaching the brain

A feather touching the bottom of your foot
may only activate a few touch receptors. A brick falling
on your foot, would activate, touch, pressure, and
possibly pain receptors. With more receptors activated,
there would be an increase in the frequency.
of APs reaching the brain

Question 30

Duration encoded by

Answer 30

duration of action potentials
in neurons.

The longer a stimulus is present, the longer action potentials will continue to be sent to the brain

Question 31

Pathways to cortex have

Answer 31

primary, secondary and tertiary neurons.

Question 32

Secondary neurons

Answer 32

decussate – cross over to the
opposite side of body in either the

spinal cord - for nociception, temperature and coarse touch

medulla - for fine touch, proprioception and vibration

Question 33

All secondary neurons connect with

Answer 33

tertiary neurons in the thalamus

Question 34

Sensations are perceived in the

Answer 34

primary somatosensory cortex