A + P exam 3

3 muscle tissue types

Skeletal, cardiac, smooth

Characteristics of skeletal muscle tissue

Striated, attached to bones or skin, voluntary

Characteristics of cardiac muscle tissue

Striated, walls of the heart, involuntary

Charateristics of smooth muscle tissue

No striations, involuntary, walls of hollow organs

Muscle functions

Movement, maintain posture, stabilize joints, generate heat, protection, breathing, communication

How do skeletal muscles work

They cause movement by exerting force on tendons, which pull on bones or other structures

Origin

The attachment of a tendon to the stationary bone

Insertion

The attachment of the muscles tendons to the moveable bone

Fasciles

Bundle of fibers

Circular muscles

Concentrically arranged fascicles that control material passage through an opening

Sphincter

Can open or close

Parallel muscles

Fascicles run parallel to the muscles long axis and have an expanded central belly (like bicep)

Convergent muscles

Fascicles merge toward a common attachment site and can pull in varying directions

Pennate muscles

Fascicles organized as if part of a large feather (3 subtypes)

Unipennate

Fascicles on the same side of the tendon

Bipennate

Fascicles on both sides on the tendon; most common

Multipennate

Branches of tendon within a muscle and fascicles arranged around both sides of each tendon branch

Coordination fact among muscles

What one muscle does, another undoes

Primary mover (agonist)

Provides the main movement

Antagonist

Reverses the main movement

Synergist

Helps the prime mover by adding extra force or by reducing unnecessary movement

Fixator

A synergist that immobilizes the muscles origin, giving a stable base for the prime mover

What 4 main characteristics do all muscles share

Excitability, contractility, extensibility, elasticity

Excitability

Ability to receive and respond to stimuli

What could be a reason for a response (excitability)

Gated channels, neurotransmitters, voltage change in the plasma membrane

Contractility

Ability to shorten forcefully when stimulated by an AP (2 types: isometric and isotonic)

Isometric

Contract without shortening

Isotonic

Tension causes shortening

Extensibility

Ability to be stretched

Elasticity

Ability to recoil to the resting length

Satellite cells

Help regenerate damaged muscle fibers

Connective tissue

Surrounds myofibers ,fascicles

When do we reach full number of muscle fibers

Before birth and most cells last a lifetime

Hypertrophy

Growing of muscles and stimulates testosterone and human growth hormone

Motor neurons

Neurons that stimulate skeletal muscles to contract

What is each muscle fiber in close contact with

Capillaries

What do contracting muscles require

Lots of oxygen and nutrients and need waste products removed quickly

What does axon somatic motor neuron do

Branches many times and then branches extend to different skeletal muscle fibers

Fascia

A sheet or band of irregular CT (collagen) that surrounds muscles or other organs

Sheaths from external to internal

Epimysium, perimysium, endomysuim, tendon, aponeurosis

Epimysium

Dense irregular CT surrounding the entire muscle, may blend in with fascia

Perimysium

Fibrous CT surrounding fascicles

Endomysium

Fine areolar CT surrounding each fiber

Tendon

Cord that attach a muscle to a bone

Aponeurosis

Broad, flattened tendon

Deep fascia

Between adjacent muscles, groups muscles together

Superficial fascia (hypodermis)

Under the skin

What do my - , mys - , or sarco - refer to

The muscle

What does endomysium contain

Myofibrils and myofilaments (actin and myosin)

Myoblasts

Embryonic stem cells, fuse to form a skeletal muscle fiber

What do muscle fibers contain

Nuclei

Sarcolemma

Cytoplasm of a muscle fiber

Mitocondria

Location of aerobic respiration responsible for high amounts of ATP production

Myoglobin

Releases oxygen when needed for ATP synthesis

Glycosomes

Glycogen storage (used for ATP synthesis) (glucose molecules)

Myofibrils

Rod like structures with a contractile function (makes up 80% of muscle cells)

Myosin

Thick filaments; thin tail with 2 heads on it (changes form to contract muscle)

Hinge point

Where the tail meets the two heads in myosin (atp and actin binding sites)

Z dics

Middle of thick filament

Actin

Thin filaments; oval shaped proteins

Regulatory proteins

Tropmyosin and troponin

Tropmyosin

Blocks myosin binding sites in relaxed muscle

Troponin

Binds tropomyosin, binds actin and bonds calcium

Types of myofibrils

Striated, A band, I band

Striated

A and I bands

A bands

H zone/m line (darker areas)

I band

Z disc/line (lighter areas)

Structural proteins

Align the thick and thin filaments, provide elasticity and extensibility and link the myofibrils to the sarcolemma

Titin/connectin

Stabilizing the position of myosin; anchors thick filament to both z disc and m line (stretching)

Dystrophin

Links thick filaments to sarcolemma

Sarcomere components of z disc

Separate one sarcomere from the next, anchor point for thin filaments

Sarcomere components of A band

Darker middle part of the sarcomere, thin and thick filaments overlap

Sarcomere components of I band

Lighter, contains thin filaments only, z disc passes through center of each I band

Sarcomere components of H zone

Center of A band, contains only thick filaments

Sarcomere components of M line

supporting filaments that hold the thick filaments together in H zone

Exocytosis

An active transport process where cells move molecules, waste, or neurotransmitters out of the cell by packaging them into vesicles that fuse in the plasma membrane

Active and passive transport

Active - up/against a concentration gradient (rq energy) Passive - down/along concentration gradient

Transport proteins

Regulate movements of substances across the plasma membrane

Cell surface receptors

Bind molecules to ligands

Membrane potential resting

Electrical charge difference between inside and outside of the cell

Which part of the cell is more negative

Inside

Membrane potential action

Rapid temporary reversal of membrane potential, impulse is being sent

Slow oxidative, fatigue resistant fibers

Red fibers, smallest type, abundant in muscles, often found in marathon runners

Fast (oxidative or glycolic), fatigable fibers

Have very fast acting myosin, contain abundant amounts of oxygen

Muscle tone

Determined by altering motor units of a muscle organ even when the muscle is not at rest

Multiple motor unit summation

How a smooth increase in muscle force is produced

Tetanus

Continued sustained smooth contraction due to rapid stumulation

Wave summation

The situation in which contractions become stronger due to stimulation before complete relaxation occurs

Maximal stimulus

The stimulus above which no stronger contraction can be elicited, because all motor units are firing in the muscle

Calcium ions

The final chemical messenger and trigger for muscle contraction. It binds to troponin

Creatine phosphate

Used to convert ADP to ATP by transfer of a high energy phosphate group. A reserve high energy compound

Sodium ions

It diffuses across the cell membrane resulting in depolarization

Actetylocholinestrerase

Breaks down ACH into its building blocks, rendering it ineffective

Acetylcholine

A neurotransmitter released at motor end plates by the axon terminals

Direct phosphorylation

Weight lifting

Aerobic pathway

Marathons

Anaerobic pathway

25 meter swim

What is the role of tropomyosin in the skeletal muscle

Serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules

Which muscle cells have the greatest ability to regenerate

Smooth muscles

Most skeletal muscles contain what?

A mixture of fiber types