form by fusion of many myoblasts

stimulates clustering of ACh receptors at neuromuscular junctions

What two muscle myoblasts do not fuse, but develop gap junctions

When does cardiac muscle cells begin pumping

like skeletal muscle satellite cells have limited regenerative ability

can divide at modest rate, but injured heart muscle is mostly replaced by connective tissue

what regenerates throughout life

What kinds of muscles can lengthen and thicken in growing child and in adults leads to hypertrophy

reflects neuromuscular coordination

Development occurs head to toe, and proximal to distal

A baby can lift its head before it is able to walk

What occurs by mid-adolescence

Athletics and training can continue to improve neuromuscular control

Which gender skeletal muscle makes up 36% of body mass

Which gender skeletal muscle makes up 42% of body mass, primarily because of testosterone

have greater ability to enlarge muscle fibers also because of testosterone

true or false body strength per unit muscle mass is the same in both sexes

What does connective tissue and muscle do with age

By what age does loss of muscle mass(sarcopenia) begins

What reverses sarcopenia

may block distal arteries, leading to intermittentclaudication (limping) and severe pain in leg muscles

 will improve your body mechanics and help avoid injury to yourself and your patient

What are the contractile tissues that muscle tissue consist of

What can muscles only do

What are the 3 main functional groups of muscle actions and interactions

major responsibility for producing specific movement

opposes or reverses a particular movement

are located on opposite sides of joint across which they act

opposes or reverses a particular movement

helps prime movers

Adds extra force to same movement

Reduces undesirable or unnecessary movement

Fixators

type of synergist that immobilizes bone or muscle's origin rather than enhancing movement of prime movers

Gives the prime mover a stable base on which to act

Skeletal muscle functional groups:

in one movement

Skeletal muscle functional groups:

for a different movement

Skeletal muscle functional groups:

for a third movement

What does all skeletal muscle consist of

vary, resulting in muscles with different shapes and functional capabilities

What are the four most common patterns of fascicle arrangements

fascicles arranged in concentric rings (example: orbicularis oris)

a broad origin with fascicles converging toward a single tendon insertion (example: pectoralis major)

fascicles parallel to the long axis of straplike muscle (example: sartorius)

spindle-shaped muscles with parallel fibers (example: biceps brachii)

short fascicles attach obliquely to a central tendon running length of the muscle (example: rectus femoris)

fascicles attach only to one side of the tendon (example: extensor digitorum longus)

fascicles insert from opposite sides of the tendon (example: rectus femoris)

appears as feathers inserting into one tendon (example: deltoid)

determine muscle’s range of motion/amount of movement when muscle shortens

Determine muscle's power

Longer fibers are more parallel to long axis and shorten more. They are usually not as powerful

Power depends on number and concentration of muscle fibers

What muscles have most fibers in a particular area → shorten little but are more powerful

What moves using leverage

What are the components of lever system

rigid bar (bone) that moves on a fixed point called fulcrum (joint)

force (supplied by muscle contraction) applied to lever to move resistance (load)

resistance (bone+tissues+any added weight) moved by the effort

allow a given effort to move heavier load or to move load farther or faster

Depends on the fulcrum position relative to load and effort

Is this a mechanical advantage or disadvantage in levers

(power lever): the load is close to the fulcrum, with the effort far from the fulcrum

A small effort can move a large load

Is this a mechanical advantage or disadvantage in levers

(speed lever): the load is far from the fulcrum, with the effort close to the fulcrum

The load moved rapidly over large distance; offers wider range of motion

Which are the two basic principals of levers

What is based on relative position of effort, fulcrum, load

The fulcrum is between the load and effort

Example: seesaw, scissors

The load is between the fulcrum and effort

Example: wheelbarrow, standing on toes

The effort is applied between the fulcrum and load

Example: tweezers, forceps, most skeletal muscles

With mechanical disadvantage (speed levers) force is lost, but speed and range of movement are gained

Systems operating under mechanical advantage (power levers) are slower, but more stable

Used where strength is a priorit

will help you be aware of how drugs affect a patient’s nervous system

is one of the major master controlling and communicating systems of body (along with the endocrine system)

What communicate via electrical and chemical signals

Rapid and specific

Usually cause almost immediate responses

What are the three overlapping functions of the nervous system

Information is gathered by sensory receptors about internal and external changes

Processing and interpretation of sensory input

Activation of effector organs (muscles and glands) produces a response

What two principal parts is the nervous system divided into

Brain and spinal cord of dorsal body cavity

Integration and control center

Interprets sensory input and dictates motor output

The portion of nervous system outside CNS

Consists mainly of nerves that extend from brain and spinal cord

Spinal nerves to and from spinal cord

Cranial nerves to and from brain

What is sensory (afferent) division and motor (efferent) division the two functional divisions of

somatic sensory fibers

Visceral sensory fibers

What convey impulses from the skin, skeletal muscles, and joints to the CNS

convey impulses from the visceral organs of the chest, abdomen, and pelvis to the CNS

Transmits impulses from CNS to effector organs

Muscles and glands

1.Somatic nervous system

2.Autonomic nervous system

Somatic motor nerve fibers conduct impulses from the CNS to skeletal muscle for voluntary/conscious control and reflexes

Therefore, it is also known as the voluntary nervous system even if reflexes can be triggered involuntarily

Consists of visceral motor nerve fibers that conduct impulses from the CNS to smooth muscle, cardiac muscle, and glands

Therefore, it is known as the involuntary nervous system

Work in opposition to each other

What is

Sympathetic and parasympathetic functional subdivision of

What two principal cell types does nervous tissue consist of

astrocytes

Microglial cells

Ependymal cells

Oligodendrocytes

Satellite cells

Schwann cells

small cells that surround and wrap delicate neurons

(nerve cells) excitable cells that transmit electrical signals

Most abundant, versatile, and highly branched of glial cells

Cling to neurons, synaptic endings, and capillaries

Support and brace neurons

Play role in exchanges between capillaries and neurons (BBB)

Guide migration of young neurons

Control chemical environment around neurons

Respond to nerve impulses and neurotransmitters

Influence neuronal functioning

Participate in information processing in brain

Small, ovoid cells with thorny processes that touch and monitor neurons

Migrate toward injured neurons

Can transform to phagocytize microorganisms and neuronal debris

Range in shape from squamous to columnar

May be ciliated

Cilia beat to circulate CSF

Line the central cavities of the brain and spinal column

Form permeable barrier between cerebrospinal fluid (CSF) in cavities and tissue fluid bathing CNS cells

Branched cells

Processes wrap CNS nerve fibers, forming insulating myelin sheaths in thicker nerve fibers

Range in shape from squamous to columnar

May be ciliated

Cilia beat to circulate CSF

Line the central cavities of the brain and spinal column

Form permeable barrier between cerebrospinal fluid (CSF) in cavities and tissue fluid bathing CNS cells

What are the two major neuroglia seen in PNS

Surround neuron cell bodies in PNS

Function like astrocytes of CNS

(neurolemmocytes)

Surround all peripheral nerve fibers and form myelin sheaths in thicker nerve fibers

Similar function as oligodendrocytes

Vital to regeneration of damaged peripheral nerve fibers

are structural units of nervous system

Large, highly specialized cells that conduct impulses

All have a cell body and one or more processes

What is this special characteristic of

Extreme longevity (lasts a person’s lifetime)

Amitotic, with few exceptions

High metabolic rate requires a continuous supply of oxygen and glucose

What is also called the perikaryon or soma

Synthesizes proteins, membranes, chemicals

Rough ER (also called the chromatophilic substance, or Nissl bodies)

What maintain the shape of the neuron

Some neurons contain pigments (neuromelanin – protects from oxidative stress)

What is part of the receptive region that receives input info from other neurons

Where are most neuron cell bodies in the CNS

clusters of neuron cell bodies in the CNS

clusters of neuron cell bodies in the PNS

extend from the cell body of all neurons

The CNS contains both neuron cell bodies and their processes

The PNS contains chiefly neuron processes

are bundles of neuron processes in CNS

are bundles of neuron processes in PNS

What are the two types of neuron processes

Motor neurons can contain 100s of these short, tapering, diffusely branched processes

Contains the same organelles as in the cell body

Receptive (input) region of neuron

Convey incoming messages toward the cell body as graded potentials(short distance signals)

are highly specialized to collect information

Contain dendritic spines, appendages with bulbous or spiky ends

Each neuron has one axon that starts at a cone-shaped area

are short or absent; in others, comprises almost the entire length of cell

Some can be over 1 meter long

What are long axons called

 have occasional branches called axon collaterals

branch profusely at their end (terminus)

Can number as many as 10,000 terminal branches

Distal endings are called axon terminals or terminal boutons

What is the conduction region of a neuron

What generates nerve impulses and transmits them along axolemma (neuron cell membrane) to the axon terminal

can excite or inhibit neurons it contacts

region that secretes neurotransmitters, which are released into the extracellular space

region that secretes neurotransmitters, which are released into the extracellular space

Carries on many conversations with different neurons at same time

rely on cell bodies to renew proteins and membranes

Quickly decay if cut or damaged (regeneration is not possible in the CNS, remodeling is)

What are molecules and organellse moved along axons by

In the axon what ways does movement occur

away from the cell body

Examples: mitochondria, cytoskeletal elements, membrane components, enzymes

toward the cell body

Examples: organelles to be degraded, signal molecules, viruses, and bacterial toxins

Certain viruses and bacterial toxins damage neural tissues by using retrograde axonal transport

Example: polio, rabies, and herpes simplex viruses, and tetanus toxin

Composed of myelin, a whitish, protein-lipid substance

What is this a function of

Protect and electrically insulate axon

Increase speed of nerve impulse transmission

segmented sheath surrounds most long or large-diameter axons

do not contain a sheath

conduct impulses more slowly

Formed by Schwann cells

Wraps around an axon in jelly roll fashion

One cell forms one segment of myelin sheath

is the peripheral bulge containing nucleus and most of cytoplasm

What in the PNS plasma membrane

have less protein

No channels or carriers, so good electrical insulators

Interlocking proteins bind adjacent myelin membranes

Gaps between adjacent Schwann cells

Sites where axon collaterals can emerge

Formerly called nodes of Ranvier

Thin fibers not wrapped in myelin; surrounded by Schwann cells but no coiling; one cell may surround 15 different fibers

What in the CNS is formed by the processes of oligodendrocytes, not whole cells

Each cell can wrap up to 60 axons at once

Myelin sheath gap is present

No outer collar of perinuclear cytoplasm

Thinnest fibers are unmyelinated, but covered by long extensions of adjacent neurog

What is this in CNS

regions of the brain and spinal cord with dense collections of myelinated fibers

Usually fiber tracts

What is this in CNS

mostly neuron cell bodies and nomyelinated fibers

What are the structural classification of neurons

three or more processes (1 axon, many dendrites)

Most common (99%) and major neuron type in CNS

two processes (one axon, 1 one dendrite)

Rare (ex: retina, ear, and olfactory mucosa)

one T-like process (cell body in the middle of the axon)

Also called pseudounipolar

Peripheral (distal) process is associated with sensory receptor

Proximal (central) process enters CNS

Transmit impulses from sensory receptors toward CNS

Almost all are unipolar

Cell bodies are in ganglia in the PNS

Carry impulses from the CNS to effectors

Multipolar

Most cell bodies are in the CNS (except some autonomic neurons)

Also called association neurons

Lie between motor and sensory neurons

Shuttle signals through CNS pathways

Most are entirely within the CNS

99% of the body’s neurons are interneurons

Like all cells, neurons have a resting membrane potential

Unlike most other cells, neurons can rapidly change resting membrane potential

Neurons are highly excitable

Opposite charges are attracted to each other

Energy is required to keep opposite charges separated across a membrane

Energy is liberated when the charges move toward one another

When opposite charges are separated, the system has potential energy

a measure of potential energy generated by separated charge

Measured between two points in volts (V) or millivolts (mV)

Called potential difference or potential

Charge difference across plasma membrane results in potential

Greater charge difference between points = higher voltage

is the flow of electrical charge (ions) between two points

Can be used to do work

Flow is dependent on voltage and resistance

is the hindrance to charge flow

Insulator: substance with high electrical resistance

Conductor: substance with low electrical resistance

gives the relationship between voltage, current, and resistance

Current (I) = voltage (V)/resistance (R)

Greater the voltage (potential difference), greater the current

No net current flow between points with same potential

the greater the resistance the smaller the current

serve as selective membrane ion channels

K+ ion channel allows only K+ to pass through

What are the two main types of ion channels

channels which are always open

channels, in which part of the protein changes shape to open/close the channel

chemically gated, voltage—gated, or mechanically gated

Open only with binding of a specific chemical (example: neurotransmitter)

Open and close in response to changes in membrane potential

Open and close in response to physical deformation of receptors, as in sensory receptors

what channels does this happen

are open ions diffuse quickly

Along chemical concentration gradients from higher concentration to lower concentration

Along electrical gradients toward opposite electrical charg

True or false

Electrochemical gradient is electrical and chemical gradients combined

True or false

ion flow creates an electrical current, and voltage changes across membrane

Expressed by rearranged Ohm’s law equation:

V = IR