nervous physiology Flashcards
1
Q
What are the divisions of the autonomic nervous system?
explain each
A
- sympathetic = fight or flight
- parasympathetic = rest & digest
2
Q
What are the control centers of the ANS ?
state their functions
A
- spinal cord = simple reflexes
- brain stem= more complex reflexes
- hypothalamus = body temp, hunger, thirst, fluid retention
3
Q
What are the components of a neuron?
hint: fiber & neurons
A
- preganglionic neuron = before the ganglion
- preganglionic fiber = goes toward the ganglion
- ganglion = has NTs
- postganglionic fiber = leaves the ganglion
- postganglionic neuron = after ganglion
4
Q
Where do preganglionic fibers emerge from in the SNS?
A
T1-L2 of spinal cord
5
Q
Where is the ganglion located in the SNS?
A
near CNS
6
Q
Why are preganglionic fibers short in the SNS?
A
because the ganglion is closer to the CNS (doesn’t need to go far)
7
Q
Where do preganglionic fibers emerge from in the PNS?
A
brainstem & S2-S4 (sacral)
8
Q
Where is the ganglia located in the PNS?
A
Near the effector organ
9
Q
Why are preganglionic fibers long in the PNS?
A
Ganglia is located closer to effector organ = farther distance so fibers need to be long to reach ganglia
10
Q
Which neurotransmitters are released in the SNS?
A
acetylcholine (Ach) & norepinephrine (NE)
11
Q
Where are NTs: Ach & NE released in the SNS?
A
Ach = preganglionic
NE = postganglionic (final step before activating target cells during the fight or flight response)
12
Q
Which NTs are released in the PNS?
A
Acetycholine (Ach)
13
Q
Where is Ach released in the PNS?
A
pre & post-ganglionic
* allows for a more precise and localized regulation of bodily functions
14
Q
What enzyme breaks down Ach?
state how long it takes
A
acetylcholineresterase (AchE)
* fast bc it’s an enzyme
15
Q
How is NE broken down?
A
via reuptake
* reabsorbed by postganglionic neurons
* slow
16
Q
What do you call the fibre that secretes Ach at the axon terminal?
explain how they do it
A
cholinergic fibers
* Ach binds to cholinergic receptor to activate it
17
Q
What is the name of the fibre that secretes NE & E at the axon terminal?
explain how it is secreted
A
adrenergic fibers
* NE or E binds to adrenergic receptors to activate it
18
Q
What are the types of adrenergic receptors?
A
- alpha adrenergic receptors
- beta adrenergic receptors
19
Q
Which adrenergic receptor acts on smooth muscles in the GI tract & peripheral blood vessels?
A
alpha adrenergic receptors
20
Q
Which adrenergic receptor acts on the majority of organs?
A
beta adrenergic receptors
21
Q
List and explain the 2 types of alpha adrenergic receptors
state function
A
- alpha adrenergic 1 = constriction (excitatory)
- alpha adrenergic 2 = dilation (relaxation)
22
Q
List and explain the 2 types of beta adrenergic receptors
A
- beta adrenergic 1 = increases HR & skeletal muscle activity
- beta adrenergic 2 = bronchodilation
23
Q
What is the physiological effect of the SNS on blood vessels?
coronary arteries, sk muscle arteries, visceral arteries, cutaneous
A
coronary arteries = vasoconstriction
skeletal muscle arteries = vasoconstriction
visceral arteries = vasoconstriction –> redirects blood flow to more important organs (heart, brain)
cutaneous arteries = vasoconstriction –> conserve body heat during periods of high stress or exercise & redirect blood to more important organs (heart, brain)
Rationale = in periods of high stress, NE is released and binds to alpha adrenergic receptors causing vasoconstriction.
result = increased resistance to blood flow and an increase in blood pressure
24
Q
What is the physiological effect of the PNS on blood vessels?
coronary arteries, sk muscle arteries, visceral arteries, cutaneous
A
coronary arteries = vasodilation
skeletal muscle arteries = vasodilation
visceral arteries = vasodilation
cutaneous arteries = vasodilation
25
What is the physiological effect of the **SNS** on **iris of the eye**?
**pupil dilates**
**rationale** = pupil dilates to take in as much information in the room in stressful situations or when stimulated
ex. low light conditions
26
What is the physiological effect of the **PNS** on **iris of the eye**?
**pupil constricts**
**rationale** = reduce size of pupil when there is too much information in environment
ex. too sunny
27
What is the physiological effect of the **SNS** on **heart rate**?
Increases HR
28
What is the physiological effect of the **PNS** on **heart rate**?
decreases HR
calm & relaxed
29
What is the physiological effect of the **SNS** on **the respiratory system**?
| rate & depth of breathing, bronchioles
rate & depth of breathing = increased
bronchioles = dilates --> allow for more air intake
30
What is the physiological effect of the **PNS** on **the respiratory system**?
| rate & depth of breathing, bronchioles
rate & depth of breathing = decreased
bronchioles = constricts
31
What is the physiological effect of the **SNS** on **the GI system**?
| tract, sphincter, salivary glands, liver
GI tract = decreased activity
GI sphincter = decreased activity
salivary glands = decreased activity/secretion
Liver = increased activity --> increase glucose availability so body has energy to respond to environmental stimulus/threat
**rationale** = body diverts/mobilizes energy to where it needs it most --> heart & brain. brain needs sugar to function especially in stressful or stimulating situations
32
What is the physiological effect of the **PNS** on **the GI system**?
| tract, sphincter, salivary glands, liver
GI tract = increased activity
GI sphincter = increased activity
salivary glands = increased activity
liver = increased activity --> increase secretion of bile
rationale = GI system dominates during rest & digest
33
What is the physiological effect of the **SNS** on **the urinary system**?
| urinary bladder; sphincters
decreased activity
urinary bladder = relaxes bladder
urethral sphincters = relaxed
34
What is the physiological effect of the **PNS** on **the urinary system**?
| urinary bladder; sphincters
increased activity
urinary bladder = constricts
urethral sphincters = constricts
35
What is the physiological effect of the **SNS** on **the adrenal medulla**?
increased activity
rationale = releases adrenaline in response to stress
36
What is the physiological effect of the **PNS** on **the adrenal medulla**?
decreased activity
rationale = no threat so body is calm
37
What is the physiological effect of the **SNS** on **sweat glands**?
increased sweat production
38
What is the physiological effect of the **PNS** on **sweat glands**?
decreased sweat production
39
List the cerebral tracts
1. commissural tracts
2. projection tracts
3. association tracts
40
What is the function of **commissural tracts**?
connects both hemispheres together
41
What is the function of **projection tracts**?
| list types
carries info to and from the brain (up & down)
**ascending tract** = carry info to the cerebral cortex
**descending tract** = carry info down from cortex
42
What is the function of **association tracts**?
connects regions *within a single hemisphere*
43
What is the **limbic system** and what organs are associated with it?
| state function
**emotional brain**
* linked to memory & emotions
* amygdala & hippocampus are associated with this
44
List the functions of the limbic system
* linked to **emotional aspects of behaviour** = pain, pleasure, fear, rage, sorrow, affection
* links **conscious** intellectual functions of the **cerebrum** with **unconscious** autonomic functions of **brain stem**
* memory storage & retrieval
45
What condition occurs when basal ganglia degenerate?
Parkinson's disease
* motor issues & inhibition of movements
46
List the functions of cerebal nuclei
| other names = basal ganglia, basal nuclei
* receives input from entire cerebral cortex
* **cognition** & **coordination** of movement
* **gross, autonomic movements**
* regulates **muscle tone** throughout the body
47
What part of the brain is the automatic processing center?
cerebellum
48
List the functions of the cerebellum
* compares motor commands with input from proprioceptors
* mainatins **posture, muscle tone, balance**
* coordination of **smooth, complex sequences**
* **real time fine tuning** of movements
49
List the motor pathways
1. pyramidal (corticospinal) tracts
2. extra-pyramidal tracts
50
Where do motor pathways start and end?
start = motor cortex
end = spinal cord
51
Which tract is the direct pathway to LMN ?
| motor pathways
pyramidal (corticospinal) tract
52
Explain the pathway of pyramidal tracts
| motor pathway
1. starts in the *pre-central gyrus*
2. goes through midbrain
3. **90% decussate/cross over** at the **medulla** --> descends as **lateral corticospinal tracts**
4. **10% descend uncrossed** as **anterior corticospinal tracts**
5. the **10% crosses at the spinal cord**
6. go towards the **LMN** --> muscles
*rationale* = decussation allows for the precise and coordinated control of movements on the opposite side of the body --> smooth & efficient control
53
Which tract is responsible for fine, voluntary movements ?
| list other functions
pyramidal tracts
other functions: muscle tone control, excitatory
54
Which tract is the indirect pathway to LMN ?
| motor pathway
extra-pyramidal tracts
55
Explain the pathways of extrapyramidal tracts
| motor pathway
1. starts in the pre-central gyrus
2. Makes stopover in medulla oblongata/brain
3. goes to motor neuron
| think indirect flight bc lots of stopovers
56
What is the function of extra pyramidal tracts?
| motor pathway
* **unconscious movements**
* **gross movements** --> posture, balance, coordination
57
Where are upper motor neurons located?
start in the **primary motor area** & end in **ventral horn** of spinal cord
58
Where are the cell bodies of UMNs located?
in the brain
59
What are lower motor neurons (LMNs) ?
* peripheral neurons that **stimulate effector muscles**
* **cell bodies** are in the **ventral horn** of spinal cord
60
What is spastic paralysis?
| state cause & symptoms
cause = **UMN lesion**
manifestations = exaggerative reflexes; missing voluntary movmements
61
What would be the effect of a UMN lesion?
* interrupts pulses from motor area to the spinal cord --> causes an imbalance of excitatory
* reflexes would not be affected bc they go straight to the spinal cord
62
What is flaccid paralysis?
| cause & symptoms
cause = **LMN lesion**
manifestations = absent reflexes, no voluntary movement
63
What is the overall effect of a LMN lesion?
* signals will not be able to get to effector muscles
* reflexes will also not be able to get to effector muscles
64
Which type of lesion is most dangerous? Why?
**LMN lesion**
* LMN is the only pathway from ventral horn to the effector --> once damaged, it can't be replaced
* UMN lesions can be compensated bc there are several patwhays from the brain to the ventral horn
65
What is the function of ANS?
**involuntary movement**
* smooth muscle (GI, bladder, blood vessels)
* cardiac muscle
* glands
* muscles of respiration
maintains **homeostasis**
* cardiovascular function
* respiration
* digestion
* excretion
* reproduction
66
What are the anatomical divisions of the nervous system?
1. CNS = brain + spinal cord
2. PNS = cranial & spinal nerves
67
Which neurons carry information towards the CNS?
afferent neurons
68
Which neurons carry information away from the CNS?
efferent neurons
* goes towards effector muscles
69
Describe the pathway of a signal going from the brain to the effector muscle
| mention tracts & neuron
1. brain sends signal
2. signal goes down **descending tract** to **spinal cord**
3. goes to **efferent neuron**
4. efferent neuron carries signal to **effector**
70
Describe the pathway of a signal from a receptor going to the brain
| mention tract & neuron
1. external stimulus is picked up by **receptor**
2. information is carried to the spinal cord by **afferent neuron**
3. goes up the **ascending tract**
4. to **brain**
71
What would cause a more severe injury: an injury higher or lower on the spinal cord ?
injury higher up on the spinal cord
72
what neurons carry information within the CNS?
association neurons
* transfer information
73
How many neurons make up the sensory pathway ?
| explain each
**first order** = peripheral neuron
- cell body is in the *dorsal root ganglion*
- sends impulses to spinal cord or brainstem
**second order** = carries impulses to the thalamus
- cell body in* grey matter *of the spinal cord/brainstem
**third order** = carries impulses from the thalamus to the primary sensory cortex
- cell body in the thalamus
- no 3rd order neurons in the cerebellum
74
What is the organization of the spinal cord?
| grey and white matter
**grey matter** = divided into horns
-dorsal horn (on the side of the dorsal root ganglion), ventral horn
**white matter** = divided into funiculi (columns)
-dorsal columns, ventral columns, lateral columns
75
What is the term for "same side"?
ipsilateral
76
What is the term for "opposite side"?
contralateral
77
What are the dorsal columns?
| function, location
location: dorsal funiculus of spinal cord
* ascends **ipsilaterally** to the brainstem
* 2nd order neurons: crosses at medulla & ends in thalamus
* 3rd order neuron: ends at primary sensory cortex
function = transmit information from receptors in skin, muscles, joints
* pressure
* vibration
* fine touch
* stereogenesis
| 3 neurons
78
What are the spinothalamic tracts ?
| types, functions, location
location:
* 1st order: carries impulse to spinal cord
* 2nd order: crosses in spinal cord & **ascends contralaterally to the thalamus**
* 3rd order: ends at primary sensory area
types: 2 = lateral & anterior
functions:
1. lateral = pain & temperature
2. anterior = crude touch, itch/tickles, pressure from bowels, bladder, sexual sensation
| 3 neurons
79
What are the spinocerebellar tracts?
| functions, how many neurons
* ascends contralaterally or ipsilaterally
* 2 neurons only
* some cross in spinal cord
* ends at the cerebellum
functions:
* unconscious proprioception
* posture, balance
* coordination of complex movements
| 2 neurons
80
What is the thalamus?
* sensory relay center
* has **cell bodies of 3rd order sensory neurons**
* forms lateral walls of the third ventricle
81
What system regulates level of alertness & consciousness?
**RAS = reticular activating system**
* diffuse network of brainstem neurons
* constantly sends impulses to the cerebral cortex (keeps it awake)
* filters background noise but not pain
* *pain passing through the system arouses the brain*
82
Explain the cerebal topography
| grooves, fissures, folds
**Sulcus** = shallow groove --> central sulcus
**Gyrus** = outward fold of brain tissue --> precentral gyrus & postcentral
**Fissure** = deep groove --> lateral fissure & transverse fissure
83
Are cerebral hemispheres equal?
| explain
No
* because of **cerebral dominance**
84
What is the dominant hemisphere?
**left hemisphere**
* 90% of the population
* dominates: language, mathematical abilities, logical reasoning
85
What is the non dominant hemisphere?
**right hemisphere**
* 10% of the population
* dominates: art, music, spatial & pattern perception, recognition of emotion in language
* usually **left handed & male**
86
Is it possible for neither of the hemispheres to dominate?
yes
* **co-dominance** = neither hemisphere dominates
* ambidextrous
87
Are the hemispheres dependent to each other?
| explain
Yes
* connected via corpus callosum (continuous communication)
* right --> fantasizing & spontaneous behaviour
* left --> logical & inhibits rash emotional displays
88
List the lobes of the brain
| state function
1. Frontal lobe
2. Parietal lobe
3. Temporal lobe
4. Occipital lobe
89
What are the motor areas of the frontal lobe?
| explain each (4)
1.**Primary motor area** = pre-central gyrus
* *voluntary movement of skeletal muscles*
* **somatotopically** organized = each area corresponds to an area of the body
* amount of cortex for each body part is proportional to the precision of motor control = **motor homunculus**
2.**Premotor area** = anterior to primary motor area
* *plans* or prepares for exact movement
3.**Broca's area** = frontal lobe; near lateral fissure; left hemisphere
* *motor speech area* = how your mouth moves to form words
4.**Prefrontal area** = anterior region of frontal lobes
* abstract ideas, conscience, judgement, motivation, intelligence, personality
* modified by experiences
90
What parts of the body will have higher amount of cortex devoted to it?
mouth, nose, eyes, hands, fingers
91
What are the sensory areas of the parietal lobe?
| explain each (3)
1.**Primary sensory cortex**= post-central gyrus
* sensory input from receptors in skin & proprioceptors in muscles
* size of area is proportional to sensitivity (somatotopically organized) = **sensory homunculus**
2.**Somatosensory association area**= posterior to primary sensory area
* *interprets sensory input*
3.**Gustatory area** = tongue area of somatosensory cortex
* *sensory input from taste buds*
92
What are the functional areas of the temporal lobe?
| explain each (5)
1.**Primary auditory area** = receives impulses from the cochlea in the ear
2.**Auditory association area** = determines if sounds is noise, speech or music
3.**Olfactory area** = smell (olfactory receptors); close to limbic system
4.**Wernicke's area** = left hemisphere; comprehension & understanding
5.**Affective language area** = right hemisphere corresponding to broca & wernicke's areas; emotion in language
93
What is aphasia?
loss of ability to produce or comprehend language
94
What are the manifestations of a stroke in Broca's area?
* slurred speech
* non-fluent aphasia = can't express themselves
* can still understand
95
What are the manifestations of a stroke in Wernicke's area?
* fluent aphasia; receptive aphasia
* speak a lot but it's nonsense
* makes up words
* trouble understanding speech
96
What are the functional areas of the occipital lobe?
| explain each (2)
1. **Primary visual area** = receives impulses from retina (thalamus); vision
2. **Visual association area** = interprets visual input; beside primary visual area
