205 NS - Physiology Flashcards
1
Q
Describe the formation, circulation, and removal of cerebrospinal fluid (CSF).
A
- Formed in the choroid plexus of ventricles (mainly lateral)
- Enters the third ventricle through foramen of Monro
- Enters the fourth ventricle through the aqueduct of Sylvius
- Enters cisterna magna behind medulla & beneath cerebellum
- Though midline foramen of Magendie & 2 lateral foramina of Lushka, it enters the subarachnoid space
- Removed by arachnoid villi into dural venous sinuses
2
Q
Broca’s area - location, #, function
A
Location: near the motor cortex, inferior frontal gyrus
#: Area 44
Function: production of speech
3
Q
Wernicke’s area - location, #, function, lesion
A
Location: posterior 1/3 of lateral superior temporal gyrus; close to the auditory cortex
#: Area 22
Function: for comprehension - receives sensory, auditory & visual info
Lesion: causes difficulty in attributing meaning to words
4
Q
Wernicke’s aphasia
A
Inability to comprehend speech
5
Q
Broca’s aphasia
A
Inability to produce speech
6
Q
Global Aphasia
A
Both Wernicke’s & Broca’s area affected
7
Q
What happens when there’s a lesion in the angular gyrus?
A
Dyslexia - visual info not processed & transferred to Wernicke’s
8
Q
4 stages of NREM sleep & its waves
A
Stage 1 - frequency ↓, amplitude ↑
Stage 2 - frequency ↓, amplitude ↑; sleep spindle
Stage 3 - low frequency, high amplitude
Stage 4 - low frequency, high amplitude; delta waves
9
Q
Physiological changes during sleep
A
During NERM → BMR ↓
During REM → BMR ↑ - w rapid eye movement
10
Q
Hypothalamic regions modulating sleep
A
Lateral hypothalamus - secretes orexin/hypocretin - maintain awake state Ventral preoptic (VLPO) nucleus - activity inhibits brainstem areas - sleep
*balance of 2 determines awake/sleep
11
Q
What is REM sleep?
A
Low amplitude high-frequency waves, as seen in the awake state
12
Q
What’s the reward & punishment center of the brain?
A
Ventromedial nucleus
13
Q
Neural circuits mediating sleep
A
Stimulate RAS → awake
Low-frequency stimulation of thalamus → sleep
14
Q
Brainstem regions that maintain an awake state & their secretions
A
Raphae nucleus - serotonin
Locus coeruleus - norepinephrine
Tuberomamillary nucleus of hypothalamus - histamine
15
Q
Signs of LMN lesion (6)
A
Individual muscles affected Severe atrophy Fasciculations seen Flaccid paralysis - hypotonia Tendon reflex absent Normal plantar reflex (flexion)
16
Q
Signs of UMN lesion (6)
A
Usually affects groups of muscle No atrophy No fasciculations Spasticity is seen - hypertonia Tendon reflex exaggerated Extensor plantar reflex (Babsinki sign)
17
Q
Parts of Basal ganglia
A
Caudate, Putamen, Globus pallidus - cerebrum
Substantia nigra - midbrain
Subthalamic nucleus - diencephalon
18
Q
Decorticate rigidity
A
Flexion of UL, extension of LL
by damage to upper midbrain
19
Q
Decerebrate rigidity
A
Extension of all limbs
by damage to lower midbrain & upper pons
20
Q
Role of Basal ganglia
A
Planning & programming of voluntary movement
21
Q
What forms the striatum?
A
Caudate + putamen
22
Q
What is seen in viral (aseptic) meningitis?
A
Lymphocyte count increases
Glucose levels normal
23
Q
What is seen in bacterial (pyogenic) meningitis?
A
Protein concentration of CSF increases
Glucose levels decrease
Neutrophil count increases
24
Q
What cannot pass through BBB?
A
Proteins
Non-lipid soluble substances
25
What can pass through BBB?
Lipid soluble substances: gases, alcohol, anaesthetics
26
What can pass through blood-CSF barrier?
Water, lipid soluble substances & gases
27
Function of blood-brain barrier
Maintains constant electrolyte levels
Prevents entry of toxins into brain
Prevents leak of neurotransmitters into blood
Prevents entry of bilirubin into the brain
Premature babies have leaky barrier
28
What forms the blood-brain barrier?
Foot process of astrocytes around capillaries
29
Virchow–Robin space
Perivascular space, space between artery and brain tissue
30
Function of thalamus
Acts as a relay center, receiving and distributing information between the peripheries and higher centers
31
Connections of Basal ganglia
Cortical neurons → striatal neurons (stimulatory)
Striatal neurons → globus pallidus (inhibitory)
Globus pallidus → thalamus (inhibitory)
Thalamus → cortical neurons (stimulatory)
32
What are the 2 classifications of senses?
Somatic senses
| Special senses
33
3 types of somatic senses
Mechanoreceptive
Thermoreceptive
Nociceptive
34
5 types of special senses
```
Vision
Hearing
Smell
Taste
Vestibular
```
35
7 sense receptors
```
Free nerve endings
Meissner's corpuscle
Merkel's disc
Hair end organ
Ruffini's endings
Pacinian corpuscles
```
36
Free nerve endings
Superficial
| i.e. thermoreceptor
37
Meissner's corpuscles
```
Superficial
Fingertip, lips
Adapt rapidly
Sense movement over skin
Detect low frequency vibration
```
38
Merkel's disc
Superficial
Texture
Adapt slowly
39
Hair end organ
```
Superficial
Free nerve ending at base of hair
Adapt rapidly
Sense initial touch
Sense movement of hair
```
40
Ruffini's ending
Dermis
Adapt slowly
Joint capsule
Detect pressure/stretch
41
Pacinian corpuscles
Dermis
Adapt rapidly
High-frequency vibrations
Deep pressure
42
How are mechanical receptors stimulated?
By deformation
43
Adequate stimulus
Receptors respond maximally to 1 stimulus
44
Where & when is action potential generated?
1st node of Ranvier when threshold is reached
45
How do Pacinian corpuscles adapt rapidly?
Due to fluid shifts within the corpuscles
46
Rapidly adapting receptors respond only during ______ of stimuli
beginning or end
47
Slowly adapting receptors respond to ______ stimuli
sustained
48
What type of neuron has highest conduction velocity?
A alpha
49
What type of neuron has lowest conduction velocity?
C
- nonmyelinated
50
Which is the only non-myelinated type of neuron?
C
51
Purpose of labeled line principle
Helps brain to identify the type of stimulus producing the sensation
52
Sensory unit
Each sensory neuron with all its branches and receptors
53
Receptive field
Area of skin innervated by each sensory neuron
54
Lateral inhibition
Increases contrast of sensory info
| Because it spreads to sides of excitatory signal and inhibit adjacent neurons
55
Higher stimulus intensity stimulates ______ sensory neurons & ______ number of ______
more; increases; action potential
56
Recruitment of neurons
Higher stimulus intensity stimulates more sensory neurons
57
Somatosensory cortex located?
Behind central sulcus
58
Primary somatosensory area Brodmann's area #?
3, 1, 2
59
Primary somatosensory area concerned with?
Reception & interpreation of sensations
60
Secondary somatosensory area Brodmann's area #?
5, 7
61
Secondary somatosensory area concerned with?
Higher order processing of sensory info
62
Larger areas for ______ & ______ in the sensory homunculus.
lips; fingers
63
Which layer of somatosensory cortex do ascending nuerons synapse?
Layer 4
64
Lesion in primary somatosensory cortex causes?
Abnormal tactile localization
2-point discrimination lost
Astereognosis
Graphaesthesia
65
Abnormal tactile localization
Inability to localize site of sensation
66
Astereognosis
Inability to detect shape or form of objects
67
Graphaesthesia
Inability to identify what is written on skin
68
2-point discrimination
Ability to identify closely applied touch stimuli as 2 separate stimuli
- greater in fingertips & lips bc they have smaller receptive fields
- can distinguish 2 mm
69
Static proprioception
Info about position of diff body parts in space
| In relation to each other
70
Dynamic proprioception
Info on rate of movement (kinesthesia)
71
Vibration sense is due to?
Repeated cutaneous stimulation
72
What fiber carries vibration sense?
A beta fibres
73
Pain is caused by?
Tissue damage
74
Fast pain
WIthin seconds
Sharp pain, picking pain, acute pain, electric pain
Superficial
75
Slow pain
Seconds to minutes
Burning pain, throbbing pain, aching pain, nauseating pain
Superficial & deep
76
What type of receptors are pain receptors?
Free nerve endings
| "nociceptors"
77
Why is pain sensation non-adapting?
So that we reaact to the pain quickly to prevent further damage
78
Fast pain is carried by?
A delta fibres
79
Slow pain is carried by?
C fibres
80
How does serotonin suppress pain?
Stimulate interneurons that secrete enkephalins
81
Stimulation of tactile ______ fibres can suppress pain
A beta
82
Referred pain
Pain in viscera referred to surface of body
| bc both have same dermatomal segment origin in embryo
83
Where does cardiac pain refer to?
Left-arm
84
What may cause visceral pain?
Ischemia
Distension
Spasm
Chemical stimuli
85
Visceral pain is carried by ______ fibres.
C
86
Visceral inflammation stimulates ______ & ______ pain fibres?
visceral; parietal
87
Where does appendicitis pain refer to?
Around umbilicus
88
What carries parietal pain?
C fibres carried in autonomic neurons
89
What causes parietal pain?
Carried by spinal nerves and cause localized pain
90
What fibres carry thermal sensation?
A delta & C fibres
91
At what temperature are cold receptors stimulated maximally?
24°C
92
Brown Sequard Syndrome
Hemi section of spinal cord
Pain, temperature lost on contralateral side
Vibration, light touch, motor lost on ipsilateral side
93
Phantom limb
Sensations in amputated area - stimulation of nerve stump
94
Where do dorsal column sensations cross?
Medulla
95
Where do spinothalamic pathways cross?
Spinal cord
96
Dorsal column sensations
Fine touch
Vibration
Position
97
Spinothalamic sensations
Pain
| Temperature
98
UMN lesion - face
Spare upper face - as it has bilateral innervation
99
LMN lesion - face
Weakness in lower & upper face
100
Role of premotor cortex
Idea for movement from prefrontal cortex
| Converted to plan by basal ganglia & lateral cerebeluum
101
UMN vs LMN
UMN - CNS - brain + spinal cord
| LMN - PNS - others
102
Direct pathway of basal ganglia
Facilitates intended movement
103
Indirect pathway of basal ganglia
Suppresses non-synergistic & competing movement
104
Lead pipe rigidity
Hypertonic state throughout the range of motion
Seen in Parkinson's disease
105
Cog-wheel rigidity
Hypertonic state with superimposed ratchet-like jerkiness and is commonly seen in upper extremity movements
Lead pipe rigidity + tremor
Seen in Parkinson's disease
106
Oculomotor loop of basal ganglia
Saccadic eye movement
107
Prefrontal loop of basal ganglia
For cognition - initiating planning
108
Limbic loop of basal ganglia
For emotions - switching from one mood to another
109
Cerebellar function
Helps in motor agility
| Error correction & motor learning
110
How does the cerebellum connect w UMN?
Through thalamus
111
Superior cerebellar peduncle
Sends output from the cerebellum
112
Inferior cerebellar peduncle
Receives input for cerebellum from spinal cord & brainstem
| Also sends out impulses
113
Middle cerebellar peduncle
Largest
| Gets inputs for cerebellum through pontine nuclei from cortex
114
Vermis of cerebellum
Co-ordinates movements of proximal muscles
115
Major afferents to cerebellum
Pontine nuclei
Vestibular nuclei
Spinocerebellar & cuneocerebellar tract
Inferior olive
116
Inferior olive concerned w
Motor learning & error correction
117
Climbing fibres
Can modulate synaptic connection between parallel fibres & Purkinje cells
Weaken the parallel fibre synapse w Purkinje cells by LTD (long-term depression)
118
Signs of cerebellar disease
```
Dysmetria/Dysdiadochokinesia
Ataxia
Nystagmus
Intension tremor
Scanning speech
Hypotonia
```
119
Scanning or staccato speech
Talking syllable by syllable w gap between every syllable
Seen in cerebellar lesion
120
Why does cerebellar lesions cause ipsilateral problems?
bc spinocerebellar pathways are ipsilateral
