Sensory Physiology Flashcards
1
Q
What are the 2 divisions of the nervous system?
A
- CNS- brain and spinal cord
- Peripheral nervous system
- somatic system: voluntary, moving muscles
- ANS: SNS, PSNS
2
Q
What are the 4 different views of the brain?
A
- dorsal: looking down on top of it
- ventral: looking below up at it
- lateral: looking at the side of it
- medial: cutting it and half and looking inside
3
Q
What are the 3 different planes of the brain?
A
- midsagittal: midline
- horizontal
- coronal
4
Q
Describe the cerebrum (cerebral cortex)?
A
- two hemispheres divided by the sagittal fissure (midline)
- concerned with contralateral movement and sensation
5
Q
Describe the cerebellum?
A
ipsilateral motor control
6
Q
Describe the brain stem?
A
- most primitive part of the brain
- life functions: respiration, body temp
7
Q
Describe the spinal cord?
A
- -conduit for info to and from the brain
- sensory and motor losses following damage to the spinal cord
8
Q
What is included in the forebrain?
A
- cerebral cortex
- corpus callosum
- thalamus
9
Q
What is included in the midbrain?
A
- tectum
- tegmentum
10
Q
What is included in the hindbrain?
A
- cerebellum
- pons
- medulla
11
Q
What is grey matter?
A
neurons
12
Q
What is white matter/
A
axons
13
Q
How many segments does the spinal cord have?
A
31 pairs
14
Q
What are dorsal roots in the spinal cord?
A
sensory info
15
Q
What are ventral roots in the spinal cord?
A
motor info
16
Q
What are the 5 regions in the spinal cord and how many spinal segments does each have?
A
- cervical (head)-> 8
- thoracic (chest/abdomen)-> 12
- lumbar (legs)-> 5
- sacral (butt)-> 5
- coccygeal (very bottom)-> 1
17
Q
What is the sensory region on the skin surface called?
A
dermatome
18
Q
PNS: What makes up the somatic system (voluntary system)?
A
- spinal nerves
- dorsal root ganglia
19
Q
PNS: What makes up the visceral system (ANS)?
A
- involuntary system
- pupil constriction, BP, sweating, crying, salvation
20
Q
How many cranial nerves are there?
A
12 pairs
21
Q
What are the 3 types of meninges that cover the brain?
A
- Dura matter- “thick like leather”
- Arachnoid- “spider”
* CSF in the subarachnoid space* - pia matter “gentle mother”
22
Q
What is CSF produced by?
A
choroid plexus
most of choroid plexus is found in the ventricular system
23
Q
What are the spaces between parts of the brain filled with CSF called?
A
ventricles
24
Q
What does the ventricular system do?
A
move CSF wishing the brain and transport in and out to the subarachnoid space
25
How much CSF does your ventricular system contain?
150mL
26
How much CSF do you produce a day?
500mL
27
What are the 4 different lobes of the brain and what are they responsible for?
1. frontal: decision making, personality
2. parietal: sensation
3. occipital: vision
4. temporal: hearing
28
What happens during hydrocephalus?
CSF is unable to be drained
29
What are the 4 main sensory receptors?
1. chemoreceptors
2. mechanoreceptors
3. thermoreceptors
4. photoreceptors
30
What is threshold?
the minimum amount of stimulus required to activate a sensory receptor
31
What are mechanoreceptors sensitive to?
stretch, bending, distortion of skin, pressure, texture, vibration
32
What is proprioception?
sense of limb position in space
33
What is kinesthesis?
sense of limb movement
34
How are somatosensory sense unique?
receptors are not concentrated in one location, like the retina or cochlea
35
What are the two skin types?
hairy and glabrous
36
What are the 2 layers of the skin?
epidermis (outer)
| dermis (inner)
37
What are the 4 types of mechanoreceptors?
1. merkels disks- surface
2. messier's corpuscles
3. ruffinis endings
4. pacinian corpuscles- deepest
38
What are the characteristics of Merkel's disk mechanoreceptors?
- disk shaped
- small size
- slow adaptation rate
- high sensitivity
39
What are the characteristics of Meissner's corpuscles mechanoreceptors?
- stack of flattened cells
- small size
- rapid adaptation rate
- highly sensitive
40
What are the characteristics of Ruffini's endings mechanoreceptors?
- branched fibres in a capsule
- deep
- large size
- slow adaptation rate
- low sensitivity
41
What are the characteristics of Pacinian corpuscles mechanoreceptors?
- layered capsule that surrounds a nerve
- large size
- rapid adaptation rate
- low sensitivity
42
What is tactile acuity?
measured on the bodys surface by measuring two point discrimination
43
What is the somatosensory pathway to the brain?
stimulus-> sensory receptors-> dorsal root-> spinal cord-> somatosensory cortex
all sensory info from one side of the brain to the other
44
Where is the somatosensory cortex located?
postcentral gyrus
45
Somatic sensation of pain is received by what?
nociceptors
46
What is hyperalgesia?
an increased sensitivity to painful stimuli, a decreased pain threshold
47
What is analgesia?
inability to sense pain
48
What is the visible light range?
400-700nm
49
What are the 4 retinal targets?
1. LGN: 90% of axons go there
2. SC: targeting movement of head and eyes
3. pretectum: controls pupil constriction
4. hypothalamus (SCN): day and night cycle
50
What is considered legal blindness?
20/200 or worse
51
Diagram of the eye?
page 72/73
52
Where is your blind spot?
on the optic disk
53
What are the 5 basic cell types in the retina?
1. photoreceptors
2. bipolar cells
3. ganglion cells
4. horizontal cells
5. amacrine cells
54
What are 3 important facts about the retina?
1. retina is a sheet of several layers of cells that lie against the back of the wall
2. retina is set up backwards
3. a pigment epithelium lines the back of the retina
55
What are the 2 types of photoreceptor cells?
1. Rods
- light sensitive
- dim lighting
- concentrated in the periphery
- 120 million on sides of each retina
2. Cones
- colour sensitive
- daylight
- concentrated in the fovea
- 5 million in each retina
56
Colourblindness facts?
- dirchromats lack red or green pigment
| - 8% of men have a form of colourblindness
57
What crosses at the optic chiasm?
nasal retina axons cross to the contralateral side
| temporal retina axons stay ipsilateral
58
What happens if you have a lesion in the optic nerve?
lose monocular vision in the eye that was cut
59
What happens if you have a lesion in the optic track?
lose opposite hemifield vision
| same damage as LGN and optic radiation
60
What happens if you have a lesion in the optic chiasm?
lose 2 crescents, left with tunnel vision
61
What experiment did Hubel and Wiesel do regarding V1 neurons?
they found that V1 neurons respond best to bar like stimuli with specific orientations
62
What happens in the dorsal stream?
- visual control of movement
| - motion
63
What happens in the ventral stream?
-object and pattern identification
64
What do we use audition for?
- communication
- help
- danger
65
What are the 2 main variables in sound?
1. frequency in Hz (# of cycles/second)
| 2. Intensity (loudness, volume)
66
What is the human frequency range for audition?
20-20000 Hz
67
What are the most sensitive frequencies for humans?
2000-4000 Hz
| human speech operates
68
What are the 3 major division of the auditory system?
1. outer ear (everything you can see)
- auricle
- auditory canal
2. middle ear
- ear drum
- ossicles (3 small bones)
3. inner ear (fluid filled)
- oval window
- cochlea
69
What is the auditory canal?
- 3cm long
- protects the ear drum
- enhances the intensities of sound by means resonance
70
What are the 3 ossicles?
malleus (hammer)
incus (anvil)
stapes (stirrup)
71
What is the purpose of the auditory tube?
an airway between the middle ear and the pharynx that is important for changing air pressure
72
Why are the ossicles necessary?
- sound vibrations are ineffective for moving a fluid
- ossicles amplify the force exerted against the oval window
- convert air pressure into mechanical pressure
73
What is contained within the inner ear?
-cochlea which is a spiral shaped tube (2.75 turns, 3.5cm), within cochlea there is the oval and round window
74
What is the structure of the cochlea?
```
scala vestibuli - filled with perilymph
reissner's membrane
scala media - filled with endolymph
bailar membrane
scala tympani - filled with perilymph
```
75
Why is the basilar membrane important?
contains the Organ of Corti- where the hair cells are
76
How does sound move through the cochlea?
oval window-> scala vestibule-> helicotrema-> scala tympani-> round window
77
What are the characteristics of the Organ of Corti?
- lies on the basilar membrane
- contains hair cells
- tips of hair cells contact the tectorial membrane
- hair cells depolarize when the stereocillia bend
78
What do inner hair cells do?
responsible for auditory transduction and perception of pitch
79
What do outer hair cells do?
amplify the response of inner hair cells
80
What is the process of the auditory pathway?
diagram page 93
81
What happens in the primary auditory cortex?
low frequencies are represented anteriorly and high frequencies are represented posteriorly
82
What happens in deafness?
- -loss of ability localize sound in the opposite hemifield
- mostly due to death or destruction of hair cells
- hair cells do not regenerate
