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Physiology IIA: > Module B > Flashcards

Module B Flashcards

1
Q

what is a voluntary movement

A

Voluntary movement is the expression of thought through action. Virtually all areas of the central nervous system are involved in this process

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2
Q

name the three motor system generates

A

reflexive
- can be carried out automatically without conscious control

rhythmic
- can be carried without conscious country control of all aspects of the movement such as walking, breathing

voluntary
- Voluntary movements are goal-directed and improve with practice as a result of feedback and feedforward mechanisms.

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3
Q

what is the central nervous system

A

it controls most of the functions of the body and mind.

it consists of two parts which is the brain and the spinal cord

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4
Q

how the voluntary movement is being controlled by the previous system?

A

the brain controls voluntary arm and hand movement by sending decreasing motor commands to the pattern generating circuitry in the spinal cord.

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5
Q

name the major components of the motor system?

A

1- cerebral cortex and descending pathways
= Are groups of myelinated nerve fibers that carry motor information from the brainstem to the effector’s muscles by the spinal cord.
2- basal ganglia (nuclei)
= involved in initiating movement and postural adjustment
3- cerebellum
= properly compares planned action to actual action
4- brainstem
= origin of descending brainstem pathways to the spinal cord (expect corticospinal tract)
5- motor neuron and interceurones
= capable of stereotypes reflect behaviors

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6
Q

what are the 3 levels of the hierarchy of motor control

A

The highest level (planning)
- development of strategies and motor plans to achieve the goal

Middle level (commanding)
        - the middle-level structures specify the postures and movements needed to carry out the intended action.

The lowest level (execution)
- integration of sensory afferent and decreasing pathways input into the spinal circuits of interneurons.

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7
Q

what is a sensory and motor system

A

Sensory and Motor Systems is allowing how the brain allows us to see, hear, feel, test and smell
- sensory and motor stem uses information carried y a number of anatomically distinct pathways.

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8
Q

what is somatosensory cortex 1

A

the mapping of the bodies surface sensation into a structure in the brain is called somatotopy

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9
Q

what is somatosensory cortex 2

A

providing sensory information required for specific planning invitation and ongoing movement.

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10
Q

what is somatosensory cortex 3

A

sensory neurons can adapt due to amputation a clinical condition known as phantom limb.

phantom limb is the felling of sensation in limb that has been removed, which it is because the brain continues to get massage form nerves that used to feel for the missing limb

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11
Q

what is motor contex 1

A

motor homunculus showing the distributions of motor output form the primary motor cortex to different parts of the body.

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12
Q

name each section of motor cortex 2

A

primary motor cortex
= controles simple features of movement
premotor cortex
= involved in the planning and coordination of movement in response to sensory inputs.
supplementary motor area
= active during the planning and coordinating of internally-guided movement.

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13
Q

what is spinal cord 1

A

The spinal cord is the link between the brain and the nerves in the rest of the body.

a spinal nerve consists of afferent fibres that entre through the dorsal roots and efferent fibres that exit through the ventral roots

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14
Q

what is spinal cord 2

A

the motor nuclei of the spinal cord are arranged along a medial-lateral axis according to function

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15
Q

what is a medial motor

A

medial motor nuclei contain the motor neurons innervating (عصب کشی) axils (زیر بغل) muscles of the neck and back

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16
Q

what is the function of the spinal cord

A

performs two basic functions
1- the link between brain and body
2- integration (اختلاط) of afferent input and efferent output.

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17
Q

what are afferent input and efferent output?

A

neurons that receive information from our sensory organs (eyes, skin ) and transmit this input to the central nervous system are called afferent neurons

neurons that send impulses from the central nervous system to your limb and organs are called efferent neurons.

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18
Q

what is plasticity?

A

the connection in the brain can be modified by experience or injury is plasticity.

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19
Q

can neurons function in isolation?

A

no, because they are organized into circuits that process specif information

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20
Q

what is Excitation-Contraction Coupling

A

refers to the series of events linking muscle excitation (the presence of an action potential in muscles fibers) to muscle contraction

= commands for voluntary originate in the brain
= action potential conveyed to skeletal muscle by motor neurons through a neuromuscular junction

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21
Q

what is the neuromuscular junction

A

it is the synapse between a neuron and muscles is called neuromuscular junction

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22
Q

neuromuscular transmission

A

is a process that permits the central nervous system to control the movement of muscle in the body.

nerve impulses cause the release of neurotransmitters, acetylcholine (ACh) into the junction between the nerve cell and the muscle cell.

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23
Q

what is the structure of skeletal muscle 1

A

muscles consist of a number of muscle fibers lying parallel to one and held together by connective tissue.

= Single skeletal muscle cell is known as a muscle fiber (10-100 microns)

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24
Q

what is the structure of skeletal muscle 2

A

display alternating dark and light giving the appearance of striation

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25
what is the structure of skeletal muscle 3
during muscle contraction, the thin filaments slide over the thick filaments, but the filaments themselves done change the length
26
what is the structure of skeletal muscle 4
contractile forces are produced by the interaction of the thick and thick filaments
27
what are the thick filaments consists of
of mycosis molecules, where the thin filaments comprise actin, troponin, and tropomyosin
28
muscle contraction is produced by
the interaction of the actin and myosin.
29
what is the role of calcium in the body
strengthening bones and teeth. regulating muscle functioning, such as contraction and relaxation. regulating heart functioning. blood clotting.
30
the role of calcium
tropomyosin = covers actin sites blocking interaction that leads to muscles contraction troponin = With tropomyosin out of way, actin and myosin bind, interact at cross-bridges, resulting in muscle contraction.
31
calcium and cross-bridge interaction
the cross bright interaction between actin and myosis brings about muscle contraction of the sliding filament mechanism
32
what is cross bright
The molecular mechanism, where the myosin and acting myofilaments slide over each other is termed the cross-bridge cycle. During muscle contraction, the heads of myosin myofilaments quickly bind and release in a ratcheting fashion, pulling themselves along the actin myofilament.
33
T Tubules and Sarcoplasmic Reticulum 1
The sarcoplasmic reticulum is the source of Ca2+that repositions troponin and tropomyosin to permit cross-bridge binding.
34
what is muscle contraction
Muscle contraction is the activation of tension-generating sites within muscle cells. muscle tension changes but the muscle length remains the same.
35
stages of muscle contraction
1- Ach (acetylcholine) from the nerve terminal 2- AP generated in muscle fiber and down T-tubule 3- AP (action potential) triggers calcium release from SR 4- calcium binds to troponin moving tropomyosin 5- myosin binds to actin and producing the power stroke 6- calcium (ca2) taken up by SR 7- tropomyosin back to blocking position.
36
electrical vs, contractile activity
contractile activity far outlasts the electrical activity that initiated it
37
each axon terminal of a motor neurons forms a
neuromuscular junction with a single muscle fibre.
38
Signals are passed between the nerve terminal and the muscle by
means of the chemical messenger acetylcholine (ACh).
39
The ion movement depolarises
the motor endplate, generating a muscle fibre action potential.
40
Myosin forms the thick filaments whereas the
actin is the main structural component of thin filaments.
41
§During contraction,
cycles of cross-bridge binding and bending pulls the thin filaments inward.
42
Calcium is the link between
excitation and contraction.
43
Muscle relaxation occurs when
electrical activity stops and Ca2+ is returned to the sarcoplasmic reticulum.
44
types of muscle contraction
different types of muscle contraction occurs by altering the amount of forces produced in the muscle relative to the external load.
45
what is muscle force
the force that a muscle can exert depends on the excitation provided by the nervous system and the properties of the muscle
46
neural factors that influence muscle force include:
1- numbers of muscle fibers contracting within a muscle ( recruitment) 2- Twitch summation of each contracting fiber by increasing rate of action potentials (rate modulation)
47
Muscular and Mechanical factors that influence muscle force include:
- muscle size - muscle fiber type muscle fiber length - velocity (سرعت ) of shortening - muscle torque (گشتاور)
48
what is motor units
a single motor units is a single motor neuron and all the muscle fibres that it innervates
49
The number of muscle fibers among different motor units (innervation ratio)
an innervation ratio of 20 is typically for muscles involved in the small precise movement (eyes, hand) - an innervation ratio of 20 is typically for muscle in powerful movement (arm, legs)
50
muscular factor-PCSA (physiological cross-sectional area)
- maximum force that a muscle can exert depends on its physiological cross-sectional area(PCSA), which is a measure of the number of cross-bridges that are in parallel. - Muscles with a larger PCSA produce larger forces, but have short muscle fibres and a lower contractile velocity.
51
name 3 physiological properties of motor units of the muscles fibers
twitch characteristics, tension characteristics fatigability.
52
Muscular Factors –Contraction Velocity
the force that a muscle fiber can exert varies with the velocity of the contraction The load and velocity of shortening are inversely related to shortening (concentric) contractions. The load and velocity are more directly related to lengthening (eccentric) contractions.
53
Mechanical Factors –Torque
Bones, muscles, and joints interact to form lever systems | - The action of a muscle about a joint depends on the torque that it exerts.
54
Contractions of whole muscles can be of varying strength,
result in isometric, concentric, or eccentric contractions.
55
Motor units are activated in a consistent order during a
voluntary contraction.
56
Modulation of muscle force involves the
concurrent variation in the number of active motor units and discharge rate.
57
Increases in motor unit discharge rate results in
increased twitch summation.
58
Mechanical factors include the torque generated at a joint, which is determined by
the force produced by the muscle multiplied by the length of the lever arm.
59
feedforward
Feedforward control is used during rapid movements and anticipatory postural adjustments.
60
feedback
Feedback control involves the sensory receptors providing information on the changes that occur, which modifies the command signals to accommodate the change in the Controlled System.
61
strategies for the control of movement.
Performing a rapid movement like raising one arm requires some CNS activity to compensate for the off-balance activity that movement would produce. -These are known as anticipatory postural adjustments.
62
Muscle spindles
Muscle spindles are proprioceptors that consist of intrafusal muscle fibers enclosed in a sheath (spindle). They run parallel to the extrafusal muscle fibers and act as receptors that provide information on muscle length and the rate of change in muscle length.
63
gamma motor neurons
Alpha-gamma coactivation maintains muscle spindle sensitivity during muscle contraction.
64
Golgi tendon organs
Golgi tendon organs connect to extrafusal fibers near the tendon’s junction to muscle. They detect tension generated by active muscle to protect the muscle and surrounding connective tissue from sudden or excessive load.
65
sensory feedback
the nervous system uses receptors to determines the status of things in the real world
66
sensory feedback- vision
vision is often called the dominant sense- Movements can be performed without relying on vision through kinesthetic sense.
67
voluntary movements are
goal-directed and improve with practice as a result of feedback and feedforward mechanisms.
68
receptors important for motor control include
the eyes, muscle spindles, Golgi tendon organs, joint receptors, and cutaneous receptors.
69
vision is important for
most motor skills that we perform.
70
The visual pathway that mediates conscious perception includes
the lateral geniculate nucleus (LGN) of the thalamus and the primary visual cortex.
71
We can predict the types of visual deficits that would result
from an injury at different levels
72
The sensory receptor for the stretch reflex is the muscle spindle, which contains
both an afferent (Ia and II) and efferent (gamma motor neuron) innervation.
73
Golgi tendon organs are sensitive to
muscle force
74
Articular (joint) receptors are sensitive to both
joint angle (anatomical limits) and joint capsule tension.
75
Skin and subcutaneous receptors measure pressure
on the skin
76
Neural adaptations with training
Neural adaptations with resistance training that increase muscle strength include: = Increased central nervous system activation =Decreased antagonist muscle activation = Greater efficiency in neural recruitment patterns (coordination) = Increased motor neuron excitability = Improved motor unit activity through synchronization and increased firing rates.
77
Muscle hypertrophy
Hypertrophy is an increase and growth of muscle cells. Hypertrophy refers to an increase in muscular size achieved through exercise.
78
Muscle damage and the repeated bout effect
- A repeated bout of the same eccentric exercise results in reduced symptoms of damage and soreness compared with the initial bout. This protective adaptation to a single bout of eccentric exercise has been referred to as the repeated bout effect.
79
Eccentric muscle contractions
An eccentric (lengthening) muscle contraction occurs when a force applied to the muscle exceeds the momentary force produced by the muscle itself, resulting in the forced lengthening of the muscle-tendon system while contracting
80
Central fatigue
- Central fatigue can be assessed with the interpolated twitch technique. This involves stimulating the muscle or brain during a maximal voluntary contraction
81
six factors of Strength Training -muscle mass
``` physical activity nutritional status genetics endocrine influences nervous system activation environmental factors ```
82
strength training- adaptation
Relative roles of neural and muscular adaptations in strength improvement with resistance training.
83
Muscle Damage –Structure and Function
- Eccentric exercise produces structural and functional changes in the neuromuscular system = Structural Changes Disruption of sarcomeres Damage to the muscle cell membrane Disruption of cytoskeletal elements involved in force transmission ``` = Functional Changes Loss of maximum force production The shift in the length-tension curve Impaired excitation-contraction coupling Increased muscle soreness/pain (delayed Initiation of the inflammatory process/swelling (delayed) ```
84
Muscle strength increases with training are due to
early neural adaptations and later muscle hypertrophy.
85
Eccentric contractions involve muscle contraction while it is
forcibly lengthened.
86
unaccustomed and intense eccentric contractions results
is a series of events that lead to muscle damage and soreness.
87
Fatigue is a reduction of the force-generating capacity of the neuromuscular system that occurs with
muscle activity, and can be central or peripheral in origin
88
The interpolated twitch technique is used
to measure central fatigue.
89
The main effect of CNS fatigue is a decline in motor unit activity throughout a
fatiguing contraction.
90
The basal ganglia: Parkinson’s disease
The basal ganglia influence the motor cortex via the thalamus to facilitate movement. The basal ganglia inhibit the motor cortex at rest to prevent unwanted movements, and remove this inhibition when movement is required. They are involved in sequencing movement fragments or different movements. They may also be involved in brain functions such as cognition and memory.
91
The cerebellum
The cerebellum consists of 3 functionally distinct parts with different roles concerned with subconscious control of motor activity.
92
3 parts of Cerebellum
Vestibulocerebellum = is important for maintaining balance and controls eye movements. Spinocerebellum = enhances muscle tone and coordinates skilled, voluntary movements. Cerebrocerebellum =plays a role in planning and initiating voluntary activity by input to cortical motor areas.
93
what is the cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It has up to six layers of nerve cells. Between 14 billion and 16 billion neurons are found in the cerebral cortex.
94
PET- cerebral cortex
Positron Emission Tomography (PET) is one of many techniques that are used to examine how a brain functions during different behaviours in awake patients.
95
motor areas- cerebral cortex
The motor areas of the cerebral cortex consist of the primary motor cortex (M1), premotor cortex (PMA), and supplementary motor area (SMA). Damage to motor areas are common after stroke, resulting in an inability to move (paralysis) the contralateral upper and lower limbs and facial muscles.
96
Parietal Lobe - Cerebral Cortex
Lesions to the parietal lobes cause a defect in the ability to recognize sensory stimuli without a defect in the sense (agnosia). = Astereognosia involves an inability to recognize objects by touch.
97
Descending Motor Pathways
The cerebral cortex acts on spinal motor neurons directly through two descending corticospinal pathways.
98
what is the corticospinal tract
s the largest descending fibre tract.
99
spinal cord
The spinal cord is responsible for the integration of many basic reflexes The spinal cord extends through the vertebral canal and is connected to the spinal nerves. = It is about 45 cm long and 2 cm in diameter
100
Muscle Atrophy- spinal cord
Damage to the spinal cord results in muscle weakness or paralysis. A pronounced decrease in muscle size (atrophy) occurs after weeks to months.
101
Depending on their site and extent, cortical lesions lead to
a variety of motor, sensory and cognitive consequences.
102
Stroke is a leading cause of damage to the motor areas of the brain, and can
lead to paralysis or motor apraxia.
103
A lesion in the sensory cortical areas can lead
to agnosia.
104
Parkinson’s disease results from a loss of dopamine in the basal ganglia and is characterized by
tremor, rigidity, bradykinesia (slowness), and impairments in postural control.
105
Cerebellar lesions lead to gross motor disorders known as ataxia that can include
rigidity, tremor, reduced muscle tone, and poor interjoin coordination of voluntary movements.
106
Amyotrophic lateral sclerosis leads to
progressive death of alpha-motor neurons, resulting in muscle denervation and a loss of voluntary muscle control.

Physiology IIA: (6 decks)

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