practical 2 Flashcards
Smooth muscle
*resides in the walls of hollow organs
*involuntary/ not striated
*contracts slowly and rhythmically
Cardiac muscle
*involuntary
*own intrinsic contraction rhythm
Skeletal muscle
*make up 40% of body mass
*voluntary
*can contract rapidly, but tires rapidly
upper motor lesion
loss of muscle function as a consequences of strokes damaging neurons in the brain
Excitability
ability of muscle cells (muscle fibers) to respond to stimuli, such as nerve impulses or electrical signals. When stimulated, muscle cells generate action potentials
Contractility
All muscle cells shorten when stimulated
Extensibility
All muscle cells can be stretched, sometimes even more so than their resting lenght
Elasticity
All muscle cells, after being stretched, can recoil to their resting length
skeletal muscle is not _________. (Meaning the muscle does not contract rhythmically)
autorhythmic
What are some functions of muscles?
*generate movement
*Keeps us stationary to maintain posture and balance
*stabilize joints
*generate a lot of heat
tendons connect _______ to _______
tendons connect muscle to bone
when referring to AOI’s, what does the insertion of a muscle imply
the insertion of a muscle refers to the bone or structure that moves
when referring to AOI’s, what does the origin of a muscle imply
the origin of a muscle refers to the bone or structure that is stationary
what is the difference between a direct attachment and an indirect attachment?
direct: the
periosteum/perichondrium is fused with the muscle’s epimysium
indirect: more common, durable, and small (example: tendon). they can blend into the fascia of other muscles to form an attachment
what is a tendon
aka aponeurosis is an example of an indirect attachment. tendons are mostly collagen and rope-like extensions of a muscle’s connective tissue.
- pass around friction points such as boney projections or joints
two or more muscles often work ___________(against each other)
antagonistically; if one muscle is contracting, the other is extending
true or false: skeletal muscle fibers are very large, and multinucleated
true
the sarcolemma of a muscle is known to be the cell ____________; while the sarcoplasm is the ___________
membrane; cytoplasm
_____________ are repeating units of myofibrils, which are themselves repetitive units of skeletal muscle
sarcomeres
sarcomeres display alternating dark __ bands and light __ bands
A; I
- A bands contain thick filaments
- I bands contain thin filaments
sarcomere
runs from Z line to Z line
what protein bisects the H zone
myomesin
what is the contractile unit of muscle
sarcomere
what is the area around the z disc with only thin filaments
light I band
myofilaments
Are made up of Actin and Myosin (aid in muscle contraction)
what is known as the center of the H zone, and within the A band
M line
what is the filament that is composed of myosin proteins.
thick filaments
Tropomyosin
Forms a polypetide strand that spirals around actin to reinforce it.
-*in relaxed muscle fiber, tropomyosin blocks actin’s myosin-binding sites.
what is the filament that is composed of actin proteins
thin filaments
what defines the boundary of each sarcomere
z-discs
___________ fiber is composed of many myofibrils
muscle
define what a t-tubule is?
conducts electrical signals deep into the cell
what is the name of the cell membrane of the muscle fiber
sarcolemma
Troponin
Composed of three globular polypetides, each of which have different function.
what band contains both thick and thin filaments
A band
what does the sarcoplasmic reticulum store
it stores calcium ions
when you hear the word cross bridge cycle think muscle contraction
the cross bridge cycle is a sequence of molecular events that enables muscle contraction.
The Z line is mostly made up of the protein…?
alpha-actinin
Myofibrils are connected together at Z lines by…?
desmin filaments
What are elastic filaments made up of?
Titan
how many steps are in the cross bridge cycle?
there are 4 steps in the cross bridge cycle
elastic filaments run from___to____
the Z line ; thick filaments
-to hold them in place and provide flexible recoil to the sarcomere
list the name of the four steps of the cross-bridge cycle?
- binding (cross bridge)
- power stroke
- detaching
- cocking
Dystrophin links___ to the____, and when deficiently expressed, leads to the pathology______.
thin filaments; sarcolemma; muscular dystrophy
what is happening in the binding (power stroke) phase?
a myosin head binds to an exposed myosin-binding site on the actin filament
what is happening in the power stroke phase
ADP and inorganic phosphate are released from the myosin head, returning to its low-energy state, resulting in a power stroke
3 thick filaments surround each___
and
6 thin filaments surround each____
thin filaments
thick filaments
what is happening in the detaching phase
ATP binds to the myosin head, causing detachment.
what is happening in the cocking phase
hydrolysis of ATP into ADP and inorganic phosphate repositions the myosin head in its high-energy configuration. the cycle repeats
sarcoplasmic reticulum
specialized type of endoplasmic reticulum found in muscle cells, particularly in skeletal and cardiac muscle fibers
each myofibril is surrounded by interconnecting sarcoplasmic reticulum
when talking about electrical events… all plasma membranes carry a resting charge or polarization where the inside of the cell is more negative relative to the outside
the main point to take away from this card is that we will be focusing on the sarcolemma when talking about muscle action potential.
- the sarcolemma is the plasma membrane of muscle fibers
terminal cisterns
large perpendicular cross channels that form the sarcoplasmic reticulum at the A band I band junction
At the A band and I band junction, elongated tube extensions of the sarcolemma dive deeply into the cell and are termed_____.
Ttubules
what is a triad?
T tubule plus terminal cisterns on either side
When a nerve stimulates a muscle, an electrical signale travels down the___, and since___are just tube extensions of it, the electrical signal can thus be carried deep into the muscle.
the initiation and propagation of a muscle action potential involves three steps. what are they?
- acetylcholine binds to its receptor which triggers the opening of chemical ligand gated ion channels for sodium and potassium
- the voltage gated sodium channels respond to change in charge and open allowing positive sodium to enter down its electrochemical gradient
- once the voltage becomes sufficiently less negative, this change closes the voltage-gated sodium channels and opens the voltage gated-potassium channel
Each individual muscle fiber is innervated by a branch of….?
a motor axon
What is a motor unit?
The motor neuron together with all of the individual muscle fiber that innervates
the____ the motor unit, the____the control of the movement in that muscle
smaller; finer
in this card you will find the 3 steps of initiation and propagation of a muscle action potential
- Depolarization: Acetylcholine triggers the opening of voltage-gated sodium channels. Sodium ions rush into the neuron, causing the internal voltage to become less negative.
- Repolarization: After reaching a peak voltage, sodium channels close and voltage-gated potassium channels open. Potassium ions flow out of the neuron, reversing the depolarization by making the inside more negative again.
- Hyperpolarization: Potassium channels close slowly, causing an overshoot that temporarily makes the neuron even more negative than its resting state before it returns to the resting potential.
One motor unit contains how many motor neurons?
one
T/F, the muscle fibers from a single motor unit are typically clustered together.
FALSE; they are typically spread throughout the entire muscle, thus allowing graded control of the entire muscle and just a small portion of it
important note to remember when thinking about action potentials
while repolarizing, the cell cannot be stimulated again until the membrane is sufficiently negative - this is termed the refractory period
where does the muscle action potential travel
it travels along the sarcolemma and down the t-tubles where the depolarization causes voltage-sensitive tubule proteins to undergo a change in shape which leads to opening of calcium release channels in the termina cisterns
when you see the term actin myosin cross bridge cycling
think tropomyosin physically blocks the myosin binding active sites on actin where intracellular calcium is low
The intrinsic muscles of the hand contain___motor units, each innervating only a few muscle fibers.
small
Large muscles like the quadriceps contain___ motor units, each innervating muscle fibers
large
_____in the synaptic cleft quickly breaks down acetylcholine to acetic acid and choline to…..?
Acetylcholinestarase; terminate the signal thus allowing for fine control of the muscle activation
true/false: during a muscle contraction, the thick and thin filaments do not change length
true; they slide past one another which causes the sarcomere as a whole to decrease in physical length- this is referred to as the sliding filament theory
how does skeletal muscle contract
skeletal muscle contracts when a motor nerve stimulates an electrical action potential that propagates along the sarcolemma leading to brief rises in intracellular calcium resulting in completion of excitation-contraction coupling.
what is the term called that refers to the nervous system controlling the number of twitching muscle fibers
recruitment
in what disease are acetylcholine receptors deficient due to autoimmune destruction of the receptors?
Myasthenia gravis
T/F; muscle contraction always shortens the muscle
FALSE; not always
how is a muscle controlled/moved
a whole muscle is controlled by the firing of up to hundreds of motor axons
Isometric muscle contraction
The muscle contracts, but your joints do not move and muscle fibers maintain a constant length.
*muscle tension increases but the muscle length remains constant
what does the term threshold stimulus refer to?
a threshold stimulus is achieved when the stimulus is just strong enough to generate an observable contraction
Isotonic muscle contraction
A body part is moved, and the muscle fibers shorten or lengthen. muscle tension remains constant but the muscle length changes
what is the term used to describe the process by which the nervous system controls the strength of muscle contraction?
recruitment
Isotonic contractions are concentric if…?
The muscle length decreases
Isotonic contractions are eccentric…?
if the muscle length increases during contraction.
What’s an example of an eccentric contraction?
in calf muscles as you walk uphill to prevent over rotating the ankles and to keep you stable as you move.
What’s an example of concentric contraction?
In the biceps while curling a barbell
Action potentials arriving at the axon terminal trigger the release of____into the____
Acetylcholine ; synaptic cleft of the NMJ
Activity in a whole muscle is called
electromyogram (EMG)
what happens during the “recruitment” process of muscle fibers?
during recruitment, the number of active motor units increases, which enhances the strength of muscle contraction. smaller motor units are recruited first, followed by larger ones as more force is required
explain the size principle in the context of motor unit recruitment.
the size principle states that motor units are recruited in order based on their household and size, starting with smaller motor units and progressing to larger ones as the stimulus intensity increases.
define “ tetanus” in muscle physiology and explain how it is achieved.
tetanus is a sustained muscle contraction that occurs when the frequency of stimulation is so high that the muscle does not have time to relax between stimuli, resulting in a smooth and continuous contraction
what is the difference between unfused and fused tetanus
unfused or incomplete tetanus, occurs when a muscle receives stimuli at a rate where there is a partial relaxation phase between contraction. fused tetanus, or complete tetanus happens when stimuli are given at such a high frequency that no relaxation is observed, resulting in a smooth, sustained contraction
In the EMG, you are observing a….?
compound muscle potential (CMP)
The___of the CMP reflects the number of motor units active
magnitude
What neurotransmitter is released at the NMJ?
Ach (Acetylcholine)
What are the three main mechanisms by which ATP is regenerated during muscle contraction?
ATP is regenerated through creatine phosphate directly phosphorylating ADP, anaerobic glycolysis, and aerobic respiration.
What is the brief increase in calcium ions called in muscle fibers?
Intracellular concentration of calcium ions [Ca^2+] increases.
What are the three parts of a muscle twitch?
The latent period, the period of contraction, and the period of relaxation.
For how long can creatine phosphate provide energy during intense muscle activity?
Creatine phosphate can provide energy for about 15 seconds during intense muscle activity.
What happens to pyruvic acid during anaerobic glycolysis when there is not enough oxygen?
Pyruvic acid is converted into lactic acid during anaerobic glycolysis when oxygen supply is limited.
When does the period of relaxation begin?
When calcium levels drop in the sarcoplasm.
Why do some muscles twitch and relax more rapidly than others?
Due to differences in enzyme composition and metabolic properties.
How many ATP molecules can be produced from one molecule of glucose through aerobic respiration?
Aerobic respiration can produce about 32 ATP molecules from one molecule of glucose.
When does excitation-contraction coupling occur?
During the latent period.
What is the difference between anaerobic and aerobic exercise in terms of energy use?
Anaerobic exercise relies on energy systems that do not require oxygen and can exceed the speed at which the cardiovascular system can deliver oxygen for aerobic metabolism. In contrast, aerobic exercise relies on oxygen and is powered by aerobic glycolysis and the oxidative system.
What is “oxygen debt” and how is it “repaid” after exercise?
Oxygen debt refers to the amount of extra oxygen the body’s muscles need to restore themselves to a resting state after intense activity. It is repaid by breathing in more oxygen post-exercise to replenish ATP, remove lactic acid, and restore oxygen levels in myoglobin and blood hemoglobin.
Which factors affect the force of muscle contraction?
The force of muscle contraction is affected by the number of muscle fibers recruited the frequency of stimulation, the size of the muscle fiber, and the muscle’s length-tension relationship.
What occurs during the period of contraction?
Cross bridges are cycling, and tension peaks.
How are muscle fibers categorized and what are the main types?
Muscle fibers are categorized based on the speed of ATPase activity and their metabolic processes. The main types are slow oxidative fibers, which are fatigue-resistant and rely on aerobic metabolism, and fast glycolytic fibers, which provide quick bursts of energy through anaerobic glycolysis but fatigue more rapidly.
Electromyography
technique that measure the electrical activity of muscles and the nerves controlling the muscles.
What happens to muscles when they are not regularly exercised, and how does exercise affect muscle fibers?
Without regular exercise, muscles can atrophy, meaning they will decrease in size and strength. Exercise stimulates muscle fibers, leading to hypertrophy (increase in size) and an increase in myofilaments. Different types of exercise affect muscle fibers differently; endurance exercises enhance slow oxidative fibers, while intense, short-duration exercises enhance fast glycolytic fibers.
How does resistance exercise affect muscle fibers compared to endurance exercise?
Resistance exercise typically leads to hypertrophy of fast glycolytic fibers, increasing their diameter and strength. Endurance exercise improves the efficiency of slow oxidative fibers and can convert some fast glycolytic fibers to a more oxidative type, enhancing their endurance.
Why do some people excel at certain sports or activities compared to others?
This is partly due to the distribution of muscle fiber types, which varies among individuals and is influenced by genetics. Some people have a higher proportion of slow oxidative fibers, making them better suited for endurance sports, while others have more fast glycolytic fibers, giving them an advantage in activities that require short bursts of power.
What is muscle fatigue, and what factors contribute to it?
Muscle fatigue is the decline in ability of a muscle to generate force. It is associated with a depletion of ATP, nutrients, and oxygen within muscle fibers, as well as changes in the perception of effort and motivation. The grip force experiment examines how the perception of fatigue can be influenced by verbal encouragement and by measuring maximum grip strength
learned reflexes
result from repetition, such as practice, and the activity is mostly automatic and subconscious (ex. Those used while driving a car)
Inborn (or innate) reflexes
rapid, predictable, involuntary, and unlearned motor response to a stimulus that is a part of all our neural pathways; these are below consciousness and serve functions such as maintaining breathing and posture, controlling viscera, and avoiding pain
Autonomic reflex
controls visceral effectors such as smooth muscle, cardiac muscle, or a gland
Direct light or Pupillary reflex
when a light is pointed toward the eye, the pupillary sphincter muscle in the iris constricts, reducing the diameter of the pupil (miosis); this is an ipsilateral reflex; integration center is within the midbrain
Consensual light reflex
this occurs when the opposite eye constricts at the same time (**this is placed under direct light because you cannot have the consensual light reflex without the direct light reflex)
Why is consensual light reflex a contralateral reflex?
because it occurs on the opposite side of the body from the stimulus
Somatic reflex
activates skeletal muscle
Spinal Reflexes
do not involve higher brain centers for the reflex arc to function; Integration center is within spinal cord
Monosynaptic reflex
there is a single synapse between a motor and sensory neuron at the integration center within the spinal cord in the pathway to & from the muscle that detected the stimulus
no interneuron = ?
direct communication via one synapse
Myotatic or Stretch reflex:
stimulates muscle contraction when muscle length is increased or the muscle is stretched (contraction of the muscle following passive stretching)
*these help coordinate smooth movements of skeletal muscles and maintain posture; these are all ipsilateral & monosynaptic
Knee jerk reflex:
Striking the patellar tendon stretches the tendon and, in turn, slightly stretches to quadriceps muscle. Stretch receptors known as muscle spindles detect this stretch, ultimately leading to contraction of the quadriceps muscles & inhibition of the hamstrings muscles
__occurs in kneee jerk reflex to inhibit contraction in the antagonist muscle while the agonist contracts
Reciprocal inhibition
Polysynaptic reflex:
has MULTIPLE synapses and an interneuron is located between all of the different sensory and motor neuron pathways (thus there is no direct communication between the sensory and motor neurons at any point)
Difference between Miosis and Mydriasis
● Miosis = pupillary constriction (pupil gets smaller)
● Mydriasis = pupillary dilation (pupil gets bigger)
Difference between Afferent and Efferent
Afferent= sensory
Efferent= Motor
Flexion Withdrawal reflex:
the reflexive withdrawal of a limb from a painful stimulus (ex. lifting your arm after touching something hot); this is ipsilateral
*sensory receptors are nocireceptors for this reflex
*reciprocal inhibition (flexor contracts and extensor relaxes)
Pain stimulus causes _____ of flexors and ____ of extensors
stimulation; inhibition
flexion withdrawal causes ____of flexors and ____ of extensors
inhibition; stimulation
Crossed Extension reflex
occurs in association with the flexion withdrawal reflex, where the opposite reaction occurs in the opposite limb (**this is placed under flexion withdrawal because the crossed extensor reflex can’t occur without the flexion withdrawal reflex)
Example of Crossed extension reflex?
If you stepped on a tack with your right leg, the quadriceps muscles would flex/contract to lift the leg and the hamstrings muscles would relax in the right leg. At the same time, the hamstrings will contract and the quads will be inhibited in the left leg
(The initial withdrawal reflex reflex is ipsilateral but the subsequent response in the opposite leg makes crossed extension a contralateral reflex)
Golgi tendon reflex
causes the muscles to relax in circumstances of high tendon tension; this is the opposite response of most other reflexes because the muscle that detects the stimulus (tension in this case) is the same one that becomes inhibited/relaxed.
**Aids in preventing tendons and muscles from tearing when excess stretching force is applied.
Nociceptive
stimulation of pain
____occurs in Golgi tendon reflex, where the contracting muscle with the stretched tendon is inhibited and the antagonist muscle is activated to relieve tension on the tendon.
Reciprocal activation
What is the proprioceptor of the Golgi tendon reflex?
Golgi organ
Superficial reflexes
evoked by cutaneous stimulation; ipsilateral
Plantar reflex
elicited by running a blunt object down the lateral aspect of the sole of the foot; should result in flexion of the toes
Babinski’s sign
abnormal reflex where the corticospinal tract or primary motor cortex is impaired.
-Instead of the toes flexing, the great toe dorsiflexes and the other toes laterally fan.
Abdominal reflex
elicited by stroking the lateral skin of the abdomen on any side of the umbilicus; typically produces an abdominal contraction which moves the umbilicus into the direction of the stimulus
Generally, an auditory stimulus only takes___ ms to reach the brain but a visual stimulus takes____ ms.
8-10; 20-40
Ipsilateral
Same side of the body
Extrafusal muscle fibers
Alpha efferent fibers (these are the large efferent motor neurons that are associated with motor units, the NMJ connects the axon terminal of the alpha efferent fiber to the motor end plate on the extrafusal muscle fiber)
Annulospiral endings
Endings of large axons; wrap around the center of the muscle spindle and are stimulated by the degree of stretch and the rate if stretch
Flower spray endings
Smaller axons; supply the ends of the muscle spindles and are only stimulated in response to the amount of stretch
Gamma efferent fibers
Maintains tension in the intrafusal fibers so they do not slack as the muscle contracts and thus lose sensitivity
Intrafusal muscle fibers
modified skeletal small muscle fibers that make up muscle spindles
Extrafusal muscle fibers
Regular muscle fibers surrounding a muscle spindle
External stretch
The muscle spindle is stretched when the muscle lengthens, such as when weight is applied or the
Internal stretch
The gamma motor neurons can also cause the intrafusal fiber ends to contract, which will stretch the spindle’s middle
What is Alpha-gamma coactivation
coordinated activation of two types of muscle fibers in our body: alpha motor neurons and gamma motor neurons.
-When we move, both types of neurons are activated simultaneously to ensure that the muscle spindle remains sensitive to changes in muscle length, even when the muscle contracts.
Contralateral
Opposite side of the body
The nerve is wrapped in an outer covered called…?
Epineurium
The____separates the axons into bundles, called fascicles
Perineurium
Inside a fascicle, the____ surrounds each axon and isolates it from neighboring axons
Endoneurium
What are the two types of cells in the nervous system?
glial cells and neurons
The CNS has four types of glial cells:
*astrocytes,
*microglia
*ependymal
*oligodendrocytes.
The PNS
has two types of glial cells:
*satellite cells
*Schwann cells
Astrocytes
*Description: Most abundant and versatile glial cells in the CNS.
*Functions:
-Facilitate exchanges between capillaries and neurons.
-Help determine capillary permeability.
-Guide the migration of young neurons.
-Assist in synapse formation.
Microglia
*Description: Small oval cells with long “thorny” processes.
*Functions:
-Monitor the health of nearby neurons.
-Migrate towards injured or troubled neurons to provide support and defense.
Ependymal cells
*Description: Line the central cavities of the brain and spinal cord.
*Functions:
-Form a semi-permeable barrier between cerebrospinal fluid and central cavities.
-Cilia help circulate cerebrospinal fluid, which cushions the brain and spinal cord
Oligodendrocytes
*Description: Line up along thicker neuron fibers in the CNS.
*Functions:
Wrap processes tightly around fibers to produce insulating myelin sheaths.
Satellite cells
*Description: Surround neuron cell bodies in the PNS.
*Functions: Thought to perform similar functions to astrocytes in the CNS.
Schwann cells
*Description: Surround and form myelin sheaths around larger nerve fibers in the PNS.
*Functions:
-Vital for regeneration of damaged peripheral nerve fibers.
-Increase the speed of transmission of nerve impulses.
What are the most abundant cells in the NS?
Glial cells
Fibrous astrocytes are found in____of the cerebral cortex and are surrounded by _____
the gray matter; neuropil
Dendrites
*Description: Main receptors or input regions of neurons.
*Function: Receive signals from other neurons and convey messages toward the cell body.
*Signal Type: Graded potentials (short-distance signals).
Cell body (perikaryon, soma)
*Description: Surrounds the nucleus and contains organelles like mitochondria and ribosomes.
*Notable Features: Rough endoplasmic reticulum groups in the soma are called Nissl bodies.
*Location: Most neuron somas are found in the CNS. Clusters are termed nuclei (CNS) or ganglia (PNS
Axon
*Description: Transmits signals from the cell body to other neurons.
*Structure: Begins with the initial segment extending from the axon hillock, then divides into collateral branches and telodendria.
Synaptic Terminals:
Distal tips of the telodendria contain synaptic terminals with synaptic vesicles containing neurotransmitters.
Myelin Sheath
*Description: Covers many nerve fibers, especially long or large-diameter fibers.
*Function: Protects and electrically insulates fibers, increasing the speed of nerve impulse transmission.
*Conductivity: Myelinated fibers conduct impulses rapidly, while unmyelinated fibers conduct impulses slowly.
**Note: Myelin sheaths are associated only with axons; dendrites are always unmyelinated.
Bare plasma membrane
Voltage decays because current leaks across the membrane
Unmyelinated axon
Voltage-gated Na+
and K+
channels regenerate the action potential at each point
along the axon, so voltage does not decay. Conduction
is slow because movements of ions and of the gates of
channel proteins take time and must occur before voltage
regeneration occurs.
Myelinated axon
myelin keeps current in axons and
voltage does not decay much. Action potentials are
generated only in the nodes of Ranvier and appear to
“jump” rapidly from node to node.
Olfactory Nerve I
Sensory
These are tiny sensory nerves of smell, which run from the nasal mucosa to the olfactory bulbs.
Optic Nerve II
Sensory
responsible for transmitting visual information from the retina to the brain for processing and perception.
Oculomotor Nerve III
Motor
This nerve’s name means “eye mover” because it supplies four of the six extrinsic muscles that move the eyeball in the orbit. These muscles are the inferior oblique, medial rectus, inferior rec-
tus and superior rectus.
Trochlear Nerve IV
Motor
This nerve’s name means “pulley” and it innervated the superior oblique, and extrinsic eye muscle that loops through a pulley-shaped ligament in the orbit, termed the trochlea.
Trigeminal Nerve V
Both Motor and Sensory
Three branches spring from this, the largest of the cranial nerves. It supplies sensory fibers to the face
and motor fibers to the chewing muscles.
Abducens Nerve VI
Motor
This nerve controls the lateral rectus and the extrinsic eye muscles that abducts the eyeball (turns it laterally).
Facial Nerve VII
Both Motor and sensory
A large nerve that innervated muscles of facial
expression (among other things)
Vestibulocochlear VIII
Sensory
This is a sensory nerve for hearing and balance.
Glossopharyngeal Nerve IX
Both Motor and Sensory
This nerve’s name means “tongue and pharynx,” revealing the structures it innervates. It is primarily sensory to the throat.
Vagus Nerve X
Both Motor and Sensory
This nerve is the only cranial nerve to extend beyondthe head and neck to supply motor and sensory fibers
to the visceral body organs of the thorax and abdo-
men.
Spinal Accessory Nerve XI
Motor
This nerve is primarily motor supplying the trapezius and sternocleidomastoid muscles.
Hypoglossal Nerve XII
Motor
This nerve’s name means “under the tongue” and runs inferior to the tongue and innervates some tongue-moving muscles.
T/F the cerebrum is the largest region of the brain and is divided into R and L cerebral hemispheres by the LONGITUDINAL FISSURES.
true
what are the folds in the cerebral cortex called
gyrus
what are the shallow grooves of the cerebral cortex called
sulcus
what is the name of the white matter called that connects the cerebral hemispheres
corpus callosum
the inferior portion of the corpus callosum is known as the __________and meets with the ______________
fornix; anterior commissure
what forms the outer convoluted surface of the cerebral hemispheres and the foliated surface of the cerebellum
gray matter
white matter lies ________(superficialor or deep) to the cerebral and cerebellar cortices
deep
what is made of multipolar neuron cell bodies and attendant dendrites
cortical gray matter
many of the multipolar neurons of the cortex are classified as ___________ cells
pyramidal
what are the 5 layers of the cerebral cortex
- the molecular layer
- the outer granular layer
- the outer pyramidal cell layer
- the inner granular layer
- the inner pyramidal and polymorphic layer
the molecular layer of the cerebral cortex contains ____________ that are synapsing with cortical neuron axons
dendrites
the outer granular layer of the cerebral cortex is mostly made up of ___________ cells, _________ and _____________
stellate cells; axons; dendrites
the outer pyramidal cell layer of the cerebral cortex is mostly made up of _____________ cells that increase in size as you move deeper into the layer
`pyramidal
the inner granular layer of the cerebral cortex is mostly made up of densely packed __________ cells
stellate
The diencephalon consists of what 3 paired structures?
*thalamus
*hypothalamus
*epithalamus
the cerebellum is located _________ to the pons and medulla oblongata
dorsal
the cerebellum is primarily involved in the coordination of somatic motor function, primarily ____________ muscle contractions
skeletal
***learned muscle patterns are stored/processed in the cerebellum
Thalamus
relay of station for incoming information, such as sensory or integration destined for cerebral cortex and other higher brain areas
(forms the superolateral walls of the third ventricle)
the cerebellum functions in coordination of ___________ movements
complex
Hypothalamus
Controls the autonomic control center, center for emotional response, body temp regulations, regulation of food intake, water balance and thirst, regulation of sleep-wake cycles and control of endocrine system functioning
(forms the inferolateral walls of the third ventricle)
like the cerebrum the cerebellum is divided into three layers what are they
molecular layer
intermediate layer
deepest layer (granular layer)
the molecular layer of the cerebellum contains _______________ fibers and scattered ____________ cells and ______________cells
unmyelinated fibers; basket; stellate
What is the infundibulum?
A stalk of hypothalamic tissue that connects to the pituitary gland
the intermediate layer of the cerebellum contains __________ cells (weird word)
Purkinje
the deepest layer (granular layer) of the cerebellum contains _______________ cells and is therefore called the granular layer
granule
Epithalamus
Contains the pineal gland that secretes the hormone melatonin
(forms the roof of the third ventricle)
Pineal gland
located in the epithalamus, it is under control of a complex feedback loop with the suprachiasmatic nucleus (SCN) of the hypothalamus
*secretes melatonin
the dorsal root ganglion is a visible _______________ within the dorsal root of each spinal nerve. These ___________(same word) contain an aggregate of unipolar cellular bodies and satellite cells
swelling/s
What is the brain stem made up of?
Medulla oblongata, pons, and the midbrain
what is the function of Meissner’s corpuscles?
they function as light pressure receptors of the dermis and are located within the dermal papillae just below the epidermal/dermal border
Corpora quadrigemina
*Description: Collection of nuclei in the midbrain with four dome-like projections on its dorsal surface.
Components:
-Superior Colliculi: Visual reflex centers coordinating head and eye movements.
-Inferior Colliculi: Part of the auditory relay center from hearing receptors of the ear.
-Substantia Nigra: Located deep to the cerebral peduncle; contains dopamine-releasing neurons.
axons branch to _________ nerve endings or (neuromuscular junctions)
motor
neuromuscular junctions provide targeted release of what excitatory neurotransmitter
acetylcholine
the motor endplate is enriched with ___________ gated ion channels
acetylcholine
the peripheral nerves often provide ________-way communication (afferent and efferent) containing large numbers of bundled axons.
two
Parkinson’s Disease
**Description: Neurodegenerative disorder characterized by the death of dopamine-generating cells in the substantia nigra.
**Pathology: Accumulation of alpha-synuclein protein into Lewy bodies in neurons; insufficient dopamine formation and activity.
**Symptoms: Motor symptoms result from dopamine deficiency, including tremors, rigidity, and bradykinesia (slowed movements).
Pons
Located between the midbrain and medulla oblongata; composed of conduction tracts connecting higher brain centers, spinal cord, motor cortex, and cerebellum.
Medulla Oblongata
**Description: Most inferior part of the brainstem.
**Functions:
-Control over cardiovascular and respiratory systems.
-Relay of sensory and motor information between the brain and spinal cord.
Spinal Cord
**Description: Part of the central nervous system, with its own organization of gray and white matter.
**Structure:
-Gray Matter: Butterfly-shaped region, bilaterally symmetrical about the anterior median fissure.
White Matter:
what surrounds the nerve
epineurium
within the epineurium bound region, axon clusters are bound to into fascicles by the _____________
perineurium
Gray matter
Butterfly-shaped region, bilaterally symmetrical about the anterior median fissure.
each individual axon within a fascicle is ensheathed by _________________
endoneurium
White matter
Composed of axonal tracts propagating afferent and efferent impulses, projecting contralaterally and ipsilaterally, and into ventral nerve roots.
what encases axons
the myelin sheath encases axons
what is the myelin sheath derived from
glial cells known as schwann cells
what is the purpose of Schwann cell myelination?
insulate axons from one another
what allows actions potentials to “jump” from node to node
nodes of ranvier
________________ (“jumping”) conduction increases action potential velocity
saltatory
