Comprehensive Muscle, Nervous System, and Special Senses Review

A set of 150 practice flashcards in question-and-answer format covering muscle anatomy, physiology, neuromuscular control, nervous system divisions, the brain, spinal cord, reflexes, autonomic pathways, and special senses based directly on the lecture notes.

What are the seven primary functions of muscle tissue?

Movement, keeping posture, stabilizing joints, making heat, helping communication (such as facial expressions), controlling body openings, and supporting the body.

What does excitability mean in muscle tissue?

The ability of a muscle to respond to electrical signals.

What does conductivity mean in muscle tissue?

The ability of an electrical signal to spread through the muscle.

What does contractility mean in muscle tissue?

The ability of a muscle to shorten.

What does extensibility mean in muscle tissue?

The ability of a muscle to stretch.

What does elasticity mean in muscle tissue?

The ability of a muscle to return to its normal shape after being stretched.

What are the structural and functional characteristics of skeletal muscle?

Skeletal muscle is striated, contains many nuclei, is voluntary, and is consciously controlled.

What are the structural and functional characteristics of cardiac muscle?

Cardiac muscle is striated, usually contains $1$ nucleus, is involuntary, branched, and found in the heart.

What are the structural and functional characteristics of smooth muscle?

Smooth muscle has no striations, contains $1$ nucleus, is involuntary, is spindle-shaped, and is found in internal organs.

How does skeletal muscle primarily grow, and what does this process involve?

Muscle mostly grows by hypertrophy, which means the existing muscle cells get bigger rather than increasing in number.

What is the anatomical difference between superficial fascia and deep fascia?

Superficial fascia separates muscle from the skin, whereas deep fascia separates nearby muscles from each other.

What muscle structure does the epimysium surround?

The epimysium surrounds the entire (whole) muscle.

What muscle structure does the perimysium surround?

The perimysium surrounds a fascicle (a pack or bundle of muscle fibers).

What muscle structure does the endomysium surround?

The endomysium surrounds one individual muscle fiber.

What is the structural hierarchy of muscle organization from largest to smallest?

Muscle $\rightarrow$ Fascicle $\rightarrow$ Fiber $\rightarrow$ Myofibril $\rightarrow$ Myofilament.

What is the difference between a muscle fascicle and a muscle fiber?

A fascicle is a bundle of muscle cells, whereas a fiber is one individual muscle cell.

What are the sarcolemma and sarcoplasm of a muscle fiber?

The sarcolemma is the muscle cell membrane, and the sarcoplasm is the muscle cell cytoplasm.

What structures compose a muscle triad and what do they do?

A triad consists of $1$ T tubule and $2$ terminal cisternae; it functions to carry electrical signals deep into the cell and release stored calcium from the sarcoplasmic reticulum.

What is a sarcomere and what defines its boundaries?

A sarcomere is the basic functional unit that causes muscle contraction, located inside myofibrils and running from Z disc to Z disc.

What are the distinct zones and bands that make up a sarcomere?

The A band is the thick myosin area, the I band contains thin actin only, the H zone contains myosin only, the M line is the middle, and the Z discs are the ends.

What proteins compose the thick and thin myofilaments?

The thick filament is composed of myosin (which has heads that attach to actin), and the thin filament is composed of actin, together with troponin and tropomyosin.

What are the resting membrane potential and threshold values in a neuron?

At rest, the inside of the neuron is about $-70\text{ mV}$; when it reaches the threshold of about $-55\text{ mV}$, ion channels begin to open.

Which ion movements cause depolarization and repolarization during an action potential?

Sodium ($\text{Na}^+$) moving into the cell causes depolarization, and potassium ($\text{K}^+$) moving out of the cell causes repolarization.

What is saltatory conduction along a myelinated axon?

The movement of the electrical signal jumping from one Node of Ranvier to the next along a myelin-insulated axon.

What are the three essential components of a chemical synapse?

The presynaptic ending (sends the neurotransmitter), synaptic cleft (small gap between cells), and postsynaptic ending (receives the neurotransmitter using receptors).

What is the neuromuscular junction (NMJ) and which neurotransmitter is used there?

The NMJ is the synapse where a motor neuron connects to a muscle fiber; the neurotransmitter used is acetylcholine (ACh).

What is a motor unit and what does motor unit recruitment mean?

A motor unit is one neuron and all of the muscle fibers it controls; recruitment means activating more motor units to produce a stronger contraction.

What occurs during the excitation phase of muscle contraction?

The motor neuron releases acetylcholine (ACh), which opens ion channels and causes an electrical signal to travel along the muscle cell and down the transverse tubules (T-tubules).

How does an electrical signal in the T-tubules lead to calcium release?

The signal traveling down the T-tubules stimulates the sarcoplasmic reticulum (SR) to release calcium ($\text{Ca}^{2+}$).

How does calcium allow actin and myosin to interact during contraction?

Calcium ($\text{Ca}^{2+}$) binds to troponin, causing tropomyosin to move, which exposes binding sites and allows myosin to bind to actin.

What is a cross-bridge and what occurs during the power stroke?

A cross-bridge is the attachment of the myosin head to actin; during the power stroke, the myosin head uses ATP energy to pull the actin filament inward.

What three events are necessary for a contracted muscle fiber to relax?

The neuron stops sending the signal, acetylcholinesterase (AChE) removes acetylcholine (ACh), and calcium ($\text{Ca}^{2+}$) is pumped away from the filaments.

What is the sequential pathway of muscle contraction from initial signal to power stroke?

Neuron signal $\rightarrow$ acetylcholine (ACh) $\rightarrow$ transverse tubules (T-tubules) $\rightarrow$ sarcoplasmic reticulum (SR) releases $\text{Ca}^{2+}$ $\rightarrow$ calcium binds troponin $\rightarrow$ tropomyosin moves $\rightarrow$ myosin binds actin $\rightarrow$ power stroke $\rightarrow$ muscle contraction.

Where are ligand-gated $\text{Na}^+$ channels located and what electrical change do they produce?

They are located at the dendrites and cell body (receiving end); when opened, sodium enters from the high outside concentration, changing the charge from $-70\text{ mV}$ to $-55\text{ mV}$.

Where are voltage-gated $\text{Na}^+$ and $\text{K}^+$ channels located in a neuron?

They are located from the axon hillock and beyond, extending all the way down to the axon terminus.

How many neurons control a single muscle fiber, and how many ATP molecules are used per cross-bridge cycle?

A single muscle fiber is controlled by only $1$ neuron, and exactly $1$ ATP molecule is used for one cross-bridge cycle.

In muscle gross anatomy, what are the origin, insertion, belly, and action?

Origin is the attachment that stays more still; insertion is the attachment that moves; belly is the thick middle part; action is the movement produced.

What are the functional roles of an agonist (prime mover), an antagonist, and a synergist?

The agonist (prime mover) is the main muscle producing the movement; the antagonist produces the opposite movement; the synergist helps the prime mover.

What criteria can be used to name skeletal muscles?

Action, location, origin and insertion, fiber direction, shape or size, and number of heads/origins.

What do the muscle naming clues "rectus," "oblique," and "orbicularis" mean?

Rectus means straight fibers, oblique means angled fibers, and orbicularis means a circular shape.

What do the size-related naming clues "major," "minor," "maximus," "medius," and "minimus" indicate?

Major means larger, minor means smaller, maximus means largest, medius means medium, and minimus means smallest.

What do the naming prefixes "biceps," "triceps," and "quadriceps" describe?

Biceps means $2$ heads, triceps means $3$ heads, and quadriceps means $4$ heads.

What do the terms "adductor," "abductor," "flexor," and "extensor" indicate regarding muscle actions?

Adductor brings a body part toward the body, abductor moves it away, flexor causes flexion, and extensor causes extension.

What is a circular fascicle arrangement and what is an example?

Fibers form a ring around an opening; an example is the orbicularis oris.

What is a parallel fascicle arrangement and what is an example?

Fibers run in the same direction and look strap-like, giving good endurance but moderate strength; an example is the rectus abdominis.

What is a convergent fascicle arrangement and what is an example?

Fibers spread out and come together at one attachment, resembling a fan; an example is the pectoralis major.

What are the three types of pennate fascicle arrangements and their examples?

Unipennate (fibers on one side, e.g., extensor digitorum), bipennate (fibers on both sides, e.g., rectus femoris), and multipennate (several feather-like sections, e.g., deltoid).

Based on the provided comparison chart, what are the primary features of the three skeletal muscle fiber types?

Slow Oxidative (Type I) is best for endurance, has lots of myoglobin, and is long-lasting; Fast Oxidative (Type IIa) is best for walking/running, has some myoglobin, and is a mix of speed and endurance; Fast Glycolytic (Type IIb) is best for strength, has very little myoglobin, and is fast and powerful.

What are the metabolic and cellular characteristics of Slow Oxidative (Type I) muscle fibers?

They contain lots of mitochondria and lots of myoglobin, use cellular respiration, and are specialized for long-lasting stamina and endurance activities.

What are the metabolic and cellular characteristics of Fast Oxidative (Type IIa) muscle fibers?

They use cellular respiration, have a lot of glycogen, can generate fast ATP via anaerobic glycolysis, contain some myoglobin, and are used for activities like walking and running.

What are the metabolic and cellular characteristics of Fast Glycolytic (Type IIb) muscle fibers?

They primarily rely on anaerobic glycolysis, have very little myoglobin, and are specialized for short, fast, powerful strength movements.

What are the three essential components of an anatomical lever system?

The fulcrum (fixed point where movement occurs), effort (force that causes movement), and load/resistance (force or weight resisting movement).

In a biceps curl, which anatomical structures correspond to the fulcrum, effort, and load?

The elbow joint is the fulcrum, the biceps muscle contraction is the effort, and the weight in the hand plus forearm is the load.

What are the component arrangements and body examples for the three classes of levers?

First-class has the fulcrum in the middle (Effort—Fulcrum—Load, e.g., head/neck movement); second-class has the load in the middle (Effort—Load—Fulcrum, e.g., standing on toes); third-class has the effort in the middle (Fulcrum—Effort—Load, e.g., biceps curl).

What is the three-step sequence of nervous system information processing?

Sensory input $\rightarrow$ Integration $\rightarrow$ Motor output.

What anatomical structures make up the Central Nervous System (CNS) and the Peripheral Nervous System (PNS)?

The CNS includes the brain and spinal cord; the PNS includes cranial nerves, spinal nerves, ganglia, and sensory receptors.

What is the structural difference between a nerve and a ganglion in the peripheral nervous system?

A nerve is a collection of axons in the PNS, whereas a ganglion is a cluster of neuron cell bodies in the PNS.

What is an effector cell in the nervous system?

A cell that executes the response signaled by a motor neuron, such as a muscle cell or gland cell.

What are the three fundamental physiological properties of neurons?

Excitability (ability to respond to a stimulus), conductivity (ability to carry electrical signals), and secretion (ability to release chemical messengers like neurotransmitters).

What is the functional role of sensory (afferent) neurons?

They carry sensory information toward the Central Nervous System (CNS), beginning at sensory receptors and terminating in the brain or spinal cord.

What are interneurons, where are they found, and what proportion of neurons do they represent?

Interneurons are located inside the CNS where they process, store, and retrieve information and help make decisions; they make up about $90\%$ of all neurons.

What is the functional role of motor (efferent) neurons and what effectors do they supply?

They carry motor commands away from the CNS to effector cells, which include skeletal muscle, smooth muscle, cardiac muscle, and glands.

What are the sequential steps in chemical synaptic transmission?

1. Signal reaches axon terminal $\rightarrow$ 2. $\text{Ca}^{2+}$ enters terminal $\rightarrow$ 3. Synaptic vesicles release neurotransmitter $\rightarrow$ 4. Neurotransmitter crosses synaptic cleft $\rightarrow$ 5. Binds to postsynaptic receptors $\rightarrow$ 6. Ion channels open $\rightarrow$ 7. A new electrical response begins.

What does it mean that an action potential is an "all-or-none" event?

If the membrane reaches the threshold voltage, a complete action potential occurs; if the threshold is not reached, no action potential occurs at all.

How are neurons structurally classified into multipolar, bipolar, and unipolar types?

Multipolar neurons have many dendrites and one axon; bipolar neurons have one dendrite and one axon; unipolar neurons have one main process that branches.

What are the primary functions of astrocytes in the CNS?

They are the most abundant CNS glial cells; they nourish neurons, regulate extracellular ion concentrations, and remove glutamate from synapses.

What are the primary functions of microglia in the CNS?

They are the least abundant CNS glial cells; they destroy invading microorganisms and clear away dead neurons.

What is the function of ependymal cells in the CNS?

They line fluid-filled spaces containing cerebrospinal fluid (CSF) and assist in circulating the CSF.

What is the function of oligodendrocytes in the CNS?

They produce the myelin sheaths that insulate axons in the Central Nervous System (CNS).

What are the functions of satellite cells and Schwann cells in the PNS?

Satellite cells surround neuron cell bodies within peripheral ganglia; Schwann cells form the myelin sheaths around axons in the Peripheral Nervous System (PNS).

What are the three connective tissue coverings of a peripheral nerve?

Endoneurium (surrounds each individual axon), perineurium (surrounds a fascicle of axons), and epineurium (surrounds the entire nerve).

What is the sequential process of PNS axon regeneration after injury?

The axon is damaged $\rightarrow$ the distal axon breaks down $\rightarrow$ cleanup cells remove debris $\rightarrow$ Schwann cells form a regeneration tube $\rightarrow$ the axon grows through the tube $\rightarrow$ new myelin forms $\rightarrow$ connection to the effector is restored.

What are the four main anatomical divisions of the brain?

Cerebrum, diencephalon, brainstem, and cerebellum.

What are the three cranial meninges from outermost to innermost?

Dura mater (tough outer layer), arachnoid mater (middle layer), and pia mater (thin inner layer adhering directly to the brain surface).

What space around the brain contains cerebrospinal fluid (CSF)?

The subarachnoid space (located between the arachnoid mater and pia mater).

Where is cerebrospinal fluid (CSF) produced and what are its three main functions?

It is produced by the choroid plexus; it provides buoyancy (helps the brain float), cushions and protects the brain, and carries nutrients while removing waste.

What is the pathway of cerebrospinal fluid flow through the brain ventricles?

Lateral ventricles $\rightarrow$ third ventricle $\rightarrow$ cerebral aqueduct $\rightarrow$ fourth ventricle.

What is the function of the blood-brain barrier (BBB)?

It acts as a selective filter that allows essential nutrients like oxygen and glucose to enter while preventing harmful chemicals and pathogens from reaching brain tissue.

What anatomical features define the cerebrum?

The cerebral cortex (outer gray matter), white matter (deeper tract layer), corpus callosum (connects hemispheres), gyri (raised folds), sulci (grooves), and longitudinal fissure (separates hemispheres).

What are the three major functional types of areas in the cerebral cortex?

Motor areas (control voluntary movements), sensory areas (provide conscious awareness of sensations), and association areas (integrate and process information).

What functional cortex areas are located within the frontal lobe?

The primary motor cortex (voluntary movement), Broca's area (speech production), and the prefrontal cortex (planning, personality, judgment).

What primary functions and sensory areas are located in the parietal lobe?

The primary somatosensory cortex (conscious awareness of touch and body sensations), sensory interpretation, and taste processing.

What primary sensory areas and language centers are located in the temporal lobe?

The primary auditory cortex (hearing), Wernicke's area (understanding spoken language), and the primary olfactory cortex (smell).

What functional cortical areas are situated within the occipital lobe?

The primary visual cortex (receives incoming visual input) and the visual association area (interprets visual meaning).

What does the motor homunculus depict and what is contralateral control?

The homunculus is a map where body parts with greater motor control occupy larger cortex areas; contralateral control means the left hemisphere controls the right side of the body and vice versa.

What are the basal nuclei and what role do they play in movement?

They are deep gray matter regions that help initiate movements, terminate movements, regulate movement intensity, and suppress unwanted movements.

What three major structures form the diencephalon?

Epithalamus, thalamus, and hypothalamus.

What is the primary function of the thalamus?

It serves as the main sensory relay station that routes almost all conscious sensory information to the cerebral cortex, with the exception of smell.

What endocrine gland is located in the epithalamus and what cycle does it regulate?

The pineal gland, which controls the circadian rhythm (the body's sleep-wake cycle).

How does the hypothalamus physically connect to the pituitary gland?

It is located below the thalamus and connects directly to the pituitary gland via the infundibulum.

What three structures compose the brainstem from superior to inferior?

Midbrain $\rightarrow$ Pons $\rightarrow$ Medulla oblongata.

What are the specific functions of the superior colliculi, inferior colliculi, and substantia nigra in the midbrain?

Superior colliculi control visual reflexes, inferior colliculi control auditory reflexes, and the substantia nigra helps suppress unwanted movements.

What physiological functions are associated with the pons?

Assisting with breathing, hearing, facial sensations, facial movements, and balance/equilibrium.

What essential survival functions are regulated by the medulla oblongata?

Automatic survival functions including heart rate, blood pressure, and breathing.

What is the reticular formation and what is habituation?

It controls consciousness, alertness, and wakefulness; habituation is the brain's process of learning to ignore repetitive, non-critical sensory information.

What are the primary functions of the cerebellum?

Coordinating voluntary muscle movements, ensuring movements are smooth, and maintaining posture and balance/equilibrium.

What are the specific functions of the hippocampus, amygdala, and cingulate gyrus in the limbic system?

The hippocampus handles long-term memory formation, the amygdala manages fear and emotional memories, and the cingulate gyrus helps express emotions.

What is the difference between ascending pathways and descending pathways in the CNS?

Ascending pathways convey sensory impulses upward toward the brain, whereas descending pathways transmit motor commands downward from the brain.

What are the five anatomical regions of the spinal cord?

Cervical, thoracic, lumbar, sacral, and coccygeal.

Which body regions are supplied by the cervical and lumbosacral enlargements of the spinal cord?

The cervical enlargement supplies the upper limbs, and the lumbosacral enlargement supplies the lower limbs.