Neurosensory (2) Flashcards
1
Q
What are the cells of the Central nervous system?
A
Ependymal cells
Oligodendrocytes
Astrocyte
Microglia
2
Q
What are ependymal cells?
A
- Line ventricles in the brain and the central canal in the spinal cord
- Assist in producing, circulating and monitoring of the CSF
3
Q
What are Oligodendrocytes?
A
- Myelination of central nervous system axons (equivalent of schwann cells in PNS)
- Provide structural framework
4
Q
What are Astrocytes?
A
Maintain the blood-brain barrier and provide structural support
- Regulate ion, nutrient and dissolved gas concentrations as well as absorbing and recycling neurotransmitters
- Form scar tissue after injury
5
Q
What are Microglia?
A
- Removes cell debris, wastes and pathogens by phagocytosis
6
Q
Functions of the frontal lobe?
A
- Movement of the body
- Personality
- Concentration & planning
- Problem solving
- Meaning of words
- Emotional reactions
- Speech
- Smell
7
Q
Functions of the parietal lobe?
A
- Touch and pressure
- Taste
- Body awareness
- Visual
- Spatial processing
8
Q
Functions of the occipital lobe?
A
- Vision
9
Q
Functions of the cerebellum?
A
- ‘Little brain’
- Fine motor control
- Balance
- Coordination
10
Q
Functions of the temporal lobe?
A
- Hearing
- Recognizing faces
- Emotions
- Long term memory
- Visual analysis
11
Q
What is broca’s area?
A
- Production of speech
- Frontal lobe of the left hemisphere
- Responsible for precise control of the mouth and laryngeal muscles
- If damaged, the patient is still fully able to understand language.
- However they cannot form words properly and speech may be slow or slurred
- Patients often get frustrated with this
12
Q
What is Wernicke’s area?
A
- Understand speech
- Left temporal lobe
- Responsible for understanding of written and spoken language
- If damage, the patient may not be aware of their own or other peoples speech
- Or they may put words together that don’t make sense
13
Q
What is the Motor association area/Pre-motor cortex?
A
- Occupies Brodmann’s area 6
- Located immediately anterior to the primary motor cortex
- Plays a role in planning and anticipating specific motor acts
- ‘Mental rehearsal of movements’ before performing a complex function
14
Q
What is the Primary motor cortex?
A
- Highest level of motor function
- Function is the action of precise, skillful and intentional movements
- The regions of the motor cortex mirror the regions of the body (homunculus)
- The regions of the body that require more precise control occupy larger regions of the motor cortex
15
Q
What is the Sensory association area?
A
- Lies immediately posterior to the primary somatosensory cortex
- Functions to integrate different sensory inputs (eg: touch and pressure)
- Draws upon stored memories of past sensory experiences
16
Q
What is the Primary sensory cortex?
A
Located on the postcentral gyrus
- Receives information about the body sensation (ie: touch)
- The area of the cortex relates to the sensitivity of the body part (homunculus)
17
Q
What is the Visual cortex?
A
- Located in the occipital lobe
- Highly specialized for processing information about static and moving
objects - Excellent at pattern recognition
- Further divided into special regions to process colour, space, depth, texture and motion
18
Q
What is homunculus?
A
- A cortical homunculus is a distorted representation of the human body
- The homunculus allows us to say ‘how much’ of the cortex relates to each body part
19
Q
Names of the things that can go wrong in the brain?
A
Aphasia Agnosia Alexia Agraphia Ataxia Apraxia
20
Q
What is Aphasia?
A
Impairment of the language affecting the production or comprehension of speech, reading and writing (several types – Broca’s, Wernicke’s, Conduction)
21
Q
What is Agnosia?
A
Inability to interpret sensations and hence the inability to recognise things
22
Q
What is Alexia?
A
Disorder of reading
23
Q
What is Agraphia?
A
Disorder of writing
24
Q
What is Ataxia?
A
Lack of voluntary coordination of muscle movements including a gait abnormality
25
What is Apraxia?
Difficulty with motor planning and performance of a task/movement
26
What roles does the midbrain have?
Vision, hearing, eye movement and body movement
27
What roles does the pons have?
Involved in motor control and sensory analysis
28
What roles does medulla oblongata?
Vital body functions such as heart rate and respiratory rate
29
What s the diencephalon made up of?
Hypothalamus
| Thalamus
30
Hormones in the hypothalamus:
The hormones from the hypothalamus govern physiologic functions such as temperature regulation, thirst, hunger, sleep, mood, sex drive, and the release of other hormones within the body
31
What is the thalamus?
The thalamus is a small structure within the brain located just above the brain stem between the cerebral cortex and the midbrain and has extensive nerve connections to both. The main function of the thalamus is to relay motor and sensory signals to
the cerebral cortex.
32
What is the Limbic system?
- Set of brain structures located on both sides of the thalamus, inferior to the cerebrum
- Made up of the hippocampus, amygdala, fornix, cingulate gyrus,
anterior thalamic nuclei, olfactory bulbs and mammillary body
33
What is the limbic system involved in?
motivation, memory, learning and emotion
34
What is the hippocampus?
- Hippocampus allows us to lay down new memories
35
What is the amygdala?
- Located deep in the medial temporal lobe
- Receives highly processed information
- Responsible for emotional
membrane
- Produces instinctive emotional output
36
Your working memory is......
prefrontal cortex (short term, few seconds)
37
Your long term memory is......
```
Explicit memory (declarative = episodic and semantic) + implicit
(skills = cerebellum) (conditioned reflexes = cerebellum) (emotion - amygdale)
```
38
Episodic =
things we know day to day (how was your first day at work)
39
Semantic =
things we just know (ie: what is a city)
40
Consciousness =
The state of being aware of and responsive to one’s surroundings
41
What is the Blood Brain Barrier made up of?
Astrocyte foot processes and tight junctions
42
What is the Blood Brain Barrier?
- A semipermeable membrane separating the blood from the cerebrospinal fluid,
and constituting a barrier to the passage of cells, particles and large molecules
- The BBB prevents many harmful substances passing to the brain, but it is useless
against: Alcohol, nicotine, anaesthesia, fat soluble molecules
- Overall, it aims to maintain a constant environment for the brain
43
What is cauda regions?
Bundles of nerves the spinal cord terminates in.
44
Grey matter:
Unmyelinated, cell bodies and dendrites, synapses
45
White matter:
Myelinated, divided into columns and tracts
46
Both the brain and spinal cord are heavily protected by :
the bone, adipose
| tissue, meninges and liquid cushion (CSF)
47
The 3 layers of meninges
| are:
1. Dura mater
2. Arachnoid mater
3. Pia mater
48
CSF is also present in____
brain ventricles and the central canal of the spinal cord
49
What are the cells in the peripheral nervous system?
Satellite cells
| Schwann cells
50
Satellite cells:
- Surround neuron cell bodies in the ganglia
- Regulate O2, CO2, nutrient and neurotransmitter levels around neurons in
the ganglia
51
Schwann cells:
- Surround axons in the PNS, and are responsible for myelination of peripheral nerves (equivalent of oligodendrocytes in the CNS)
- Participate in repair process after injury
52
What nerves dont exist in nerves?
Unipolar nerves. They only exists in invertebrates
53
Humans have what kind of neurons?
pseudo-unipolar neurones
54
Pseudo-unipolar neurones are
axons and sensory
55
Bipolar neurones have two processes extending from the cell body. Which are?
one axon and one
| dendrite
56
Where can bioplar neuronses NOT be found?
the olfactory epithelium and the retina
57
The majority of neurones in our body are____
multipolar
58
A multipolar neurone has ______
one axon and several dendrites extending from the cell body
59
Which nerve is the LARGEST and LONGEST nerve in the body?
Scoatic nerve
60
Which nerve in the thigh supplies the upper leg?
Femoral nerve
61
Saphenous nerve is______
the nerve below the knee supplying sensation to the ant/medial leg
62
What is the Pudendal nerve?
– Main nerve of the perineum, sensory and motor supply to the anus and perineum
63
Axillary nerve –
– Originates from the brachial plexus at the level of the axilla (armpit) carrying C5 & C6
64
Vagus nerve –
10th cranial nerve giving parasympathetic control to the heart, lungs and GI tract
65
What are some of the actions of the sympathetic ns?
- pupil dilation
- increased HR,
- bronchodilation
- inc sweat gland activity
- inc adrenaline from adrenals
- increased blood flow to skeletal muscles
66
Sympathetic=
fight or flight
67
Parasympathetic=
rest and digest
68
Sympathetic nerves come from what region?
Thoracolumbar
69
What kind of fibres does sympatheric neurons have?
- Short pre-ganglionic fibers
| - Long post-ganglionic fibers
70
Paraympathetic nerves come from what region?
Craniosacral
71
What kind of fibres does parasympatheric neurons have?
- Long pre-ganglionic fibers
| - Short post-ganglionic fibers
72
What are some of the actions of the parasympathetic ns?
- pupil constriction
- saliva flow stimulation
- decreased HR
- bronchoconstriction
-increased digestion so
- increased peristalsis
- secretions and bile release, also bladder
contraction
73
Brachial plexus=
a network of nerves
| formed by the anterior rami of the lower 4 cervical nerves and first thoracic nerve
74
What is influences the activity of the skeletal muscles?
The CNS through two sets of neurones
75
Upper Motor Neurons are (UMN):
• Responsible for conveying impulses for voluntary motor activity through
descending motor pathways
• UMN’s send fibers to the LMN’s
• UMN’s arise from the cortical areas of the brain (inc primary motor cortex,
somatic sensory cortex etc…)
• UMN’s control LMN’s through two pathways
1. Pyramidal tract (Corticospinal)
2. Extra pyramidal tract (Reticulospinal, vestibulospinal etc…)
76
Lower Motor Neurons (LMS) :
• All voluntary movement depends upon excitation of lower motor neurons
by UMN’s
• These are the only neurons that innervate the skeletal muscle fibres
• They function as the final common pathway (ie: the final link between the
CNS and skeletal muscles)
• LMN’s arise from motor neurons in the spinal cord and the motor
component of the cranial nerve nuclei in the brain stem
77
Lower motor neurons can be two types. What are they?
ALPHA MOTOR NEURONS
| and GAMMA MOTOR NEURONS
78
ALPHA MOTOR NEURONS:
```
- INNERVATE EXTRAFUSAL MUSCLE FIBRES
(EXTRAFUSAL ARE THE MOST NUMEROUS
TYPE OF MUSCLE FIBRE)
- EXTRAFUSAL MUSCLE FIBRES ARE THE ONES
INVOLVED IN CONTRACTION
```
79
GAMMA MOTOR NEURONS:
- INNERVATE INTRAFUSAL MUSCLE FIBRES
- INTRAFUSAL MUSCLE FIBRES + SENSORY
AFFERENTS COMPOSE THE MUSCLE SPINDLES
- THESE ARE PART OF THE SYSTEM OF SENSING
BODY POSITION (PROPRIOCEPTION)
80
How are peripheral nerve fibres grouped?
based on their diameter, signal conduction velocity and myelination state of the axons
81
What a A fibres?
- Largest fibers
- Myelinated
- Sensory and motor function
- Further subdivided into alpha, beta, delta and gam
82
What a B fibres?
- Myelinated
- Only in preganglionic
sympathetic nerves
- Slower conduction velocity
than A fibers
- Faster conduction than C
83
What a C fibres?
- Smallest fibers
- Unmyelinated
- Mostly in visceral and
cutaneous nerves
- Generally in postganglionic
sympathetic nerves
84
Motor tracts (descending) consists of:
Corticospinal tract
| - Extrapyramidal tracts (vestibulospinal, tectospinal, reticulospinal and rubrospinal)
85
Sensory tracts (ascending) consists of:
- Posterior column tract
- Spinothalamic tract
- Spinocerebellar tract
86
What is The Posterior column tract made up of ?
Made up of fasciculus gracilis and fasciculus cuneatus
87
Spinothalamic tract transmit?
- Transmits pain and temperature sensations to the thalamus (lateral)
- Transmits crude touch and pressure sensations to the thalamus (anterior)
- The thalamus (aka relay station) then transmits the impulse to the cerebrum
88
Spinocerebellar Tract:
- Transmits proprioception sensations to the cerebellum
- There are posterior and anterior spinocerebellar tracts
- Posterior tract decussates at the spinal level
- Anterior tract decussates at the medulla oblongata
89
Corticospinal Tract:
- Involved in conscious control of skeletal muscle
- There are anterior and lateral corticospinal tracts
- There is also a corticobulbar tract which has conscious control over the eye, jaw and face muscles
- Tract decussates at the medulla
90
What does the posterior column tract do?
- Responsible for fine touch, vibration and proprioception
| - Fibers decussate at the medulla oblongata
91
Facts of cerebellum?
* The cerebellum is the largest part of the hindbrain
* It lies posterior to the pons and medulla forming the roof of the 4th ventricle
* Separated from posterior part of the cerebrum by the tentorium cerebelli
92
Functions of Cerebellum:
• Facilitating movement by
detecting errors that occur in the course of movement and correcting them
• This allows the movement to be completed correctly next time
• It is also involved in motor learning to reduce errors in the future
93
The cerebellum can be split into two hemispheres called?
- cerebrocerebellum
| - spinocerebellum
94
The cerebrocerebellum receives input from____
the cerebral cortex (involved in planning and initiating
| movements)
95
The spinocerebellum receives information about____
proprioception and touch/pressure sensation from the spinal cord (this adjusts a limb position based on its position to avoid errors)
96
What is the vermis?
involved in posture, limb movements and eye movements (part of the spinocerebellum)
97
What is the e vestibulocerebellum/ flocculonodular lobe?
important in maintaining balance, equilibrium and
| posture
98
Cerebellum is connected to brainstem in _ parts?
3
99
Which part of the cerebellum connects with the midbrain?
Superior cerebellar peduncle
100
Which part of the cerebellum connects with the pons?
Middle cerebellar peduncle
101
Which part of the cerebellum connects with the medulla?
Inferior cerebellar peduncle
102
The cortex of the cerebellar can be split into 3 layers. What are they called?
1. Granular layer (innermost layer)
2. Cerebellar cortex
3. Molecular layer (outermost layer)
103
The posterior column can also be known as_____
dorsal column–medial lemniscus
104
What do granule cells do?
are excitatory neurons that send their axons to the molecular layer
105
What happens when axons arrive at the molecular layer (outermost layer?
* they split into two and go in opposite directions
* The axons of neighboring granule cells line up to form parallel fibers
* Purkinje cells project dendrites into the molecular layer and axons to the deep cerebellar nuclei
* Synapses form between the dendrites of purkinje cells and the parallel fibers
106
The dendritic trees are at __ degrees to the parallel fibers of the granule cells.
90
107
Inhibitory interneurons are also found in the cerebeelar cortex. What do these do?
provide inhibition to balance the surrounding circuit
108
Explain Cerebellar output
* The axons of the purkinje cells end by synapsing on the neurons of the deep cerebellar nuclei
* The axons of the neurons that form the cerebellar nuclei constitute the efferent outflow from the cerebellum
* A few purkinje cell axons pass directly out of the cerebellum to the lateral vestibular nucleus
* The efferent fibers from the cerebellum connect with the red nucleus, thalamus, vestibular complex and reticular formation
109
Explain one method of input to the cerebellum? (mossy fibres)
• via mossy fibers
• mossy fibers synapse onto the cerebellar cortex and deep cerebellar nuclei
• They provide input to the granule cells and give information about
voluntary limb movements
110
Explain one method of input to the cerebellum? (climbing fibers)
* Climbing fibers come from the inferior olivary nucleus in the medulla oblongata (the ION receives input from the spinal cord and motor cortex)
* Each climbing fiber wraps around purkinje cells forming synapses
* Each purkinje cell receives input from only one climbing fiber
111
Main function of spinocerebellum?
Control of tone and posture
| • Proprioception is received from the spinocerebellar tract and a reflex correct in muscle tone is initiated
112
Main function of the vestibulocerebellum?
Control of equilibrium
• Change in head position or acceleration causes labyrinth afferent fibers to project via the vestibulocerebellar tract.
• A reflex correction of muscle tone is initiated
113
What are the main functions of the cerebellum?
1. Control of tone and posture
2. Control of equilibrium
3. Control of voluntary movement
4. Learned new skilled voluntary movements
114
What is basal ganglia?
The “basal ganglia” refers to a group of subcortical nuclei responsible primarily for motor control, as well as other roles such as motor learning, executive functions and behaviors, and emotions
115
What is basal ganglia made up of?
caudate, putamen, globus pallidus, substantia nigra and the subthalamic nucleus
116
Location of babsal ganglia?
deep in the cerebral
| hemisphere
117
Where does input to the basal ganglia come from?
Cerebral cortex to the striatum (caudate and putamen)
118
Where does output from the basal ganglia come from?
Globus palidus and substantia nigra to the thalamus/brainstem
119
The basal ganglia causes movement. TRUE OR FALSE
FALSE
THE BASAL GANGLIA DOES NOT CAUSE MOVEMENT!
It acts on other parts of the brain (i.e cortex) to influence its activity. This is due to different basal ganglia pathways (inhibitory and excitatory)
120
What are the pathways for basal ganglia?
- Direct: Excitatory/Stimulate the cortex
| - Indirect: Inhibitory
121
Which hormone is responsible for the balance between the indirect and direct pathways of basal ganglia?
Dopamine
122
Dopamine is a hormone and a ______
Neurotransmitter
123
Dopamine D1 receptor =
Increases activity of direct pathway
124
Dopamine D2 receptor =
Decreases activity of indirect pathway
125
Describe what happens in the direct pathway of basal ganglia?
- Excitates the striatum
- Causes inhibition of the GPi and the substania nigra PR
- When these are inhibited, their output it reduced
- So they are less able to inhibit the thalamus
- In which case, the thalamus is not inhibited
- Thalamus output therefore reaches the cortex and can excitate neurons
126
Describe what happens in the indirect pathway of basal ganglia?
- Excitates the striatum
- Causes inhibition of the GPe
- GPe has been inhibited so is less able to inhibit the subthalamic nuclei
- This enables the subthalamic nuclei to excite the SNR
- The SNR then can inhibit the thalamus
- The thalamus is then unable to excite the cortex
127
With regards the cell body, what direction does a
| dendrite carry the impulse?
Towards the cell body
128
The striatum of the basal ganglia is made up of…
Caudate and Putamen
129
What does the (lateral) spinothalamic tract carry?
Pain and temperature to the thalamus
