A and P TEST REVIEW MUSCULAR SYSTEM

Muscles are organs that generate force to:

1. Cause all types of movement 

2. Maintain posture and balance

3. Stabilize joints

muscles function to :

generate body heat.

Skeletal Tissue

Location : Skeletal Muscle

Function : Movement of bones at joints, maintenance of posture

Striations : Present

Nucleus : Many nuclei

Special features : Well-developed transverse tubule system

Control : Voluntary

Contracts and relaxes rapidly when stimulated by a motor neuron

Smooth Tissue

Location : Walls of hollow viscera blood vessels

Function : Movement of viscera, peristalsis, vasoconstriction

Striations : Absent

Nucleus : Single

Features : Lacks transverse tubules

Control : Involuntary

Contracts and relaxes slowly; single unit type is self-exciting; rhythmic

Cardiac Tissue

Location : Wall of the heart

Function : Pumping action of the heart

Striations : Present

Nucleus : Single Nucleus

INTERCALATED DISCS

Features : Well-developed transverse tubule system; intercalated discs separating adjacent cells

Control : Involuntary

Network of cells contracts as a unit; self-exciting; rhythmic

Sacrolemma

Cell membrane of a muscle fiber is the

Cytoplasm of a muscle cell is the ________; it contains many mitochondria and nuclei

sacroplasm

Sarcoplasm contains parallel _______, which are active in muscle contraction:

myofibrils

Thick filaments in myofibrils consist of the protein _______

Myosin

Thin filaments in myofibrils are mainly composed of the protein _____ but also contain troponin and tropomyosin

ACTIN

The organization of these filaments produces bands called _____

Striations

Skeletal muscle fibers contract only when stimulated by a __________

motor neuron

______ a synapse between a motor neuron and a muscle fiber that it regulates

Neuromuscular junction

Each skeletal muscle fiber (cell) is functionally (not physically) connected to the axon of a motor neuron, creating a ________

synapse

Muscles are made of units called ______

• MAIN = A small bundle of muscle fibers within a muscle

Fascicles

______ contains altering thick and thin filaments

Myofibrils

The outermost layer of connective tissue of a muscle is the ( Covers the entire muscle)

Epimysium

The thick myofibril filament of a sarcomere is composed of a protein

myosin

The muscle primarily responsible for a movement is the______

Prime Mover (AGONIST)

The neuron and the collection of muscle fibers it innervates is called a

Motor Unit

The functional contractile unit of a muscle fiber (cell) is a

Sarcomere

The plasma membrane of a muscle fiber (cell) is called the

Sarcolemma

STUDY THIS GRAPH FOR REAL

Sheet of dense connective tissue that separates individual muscle and helps hold them in position

• Covers Skeletal muscle

• MAIN = CONNECTIVE TISSUE LOCATED BETWEEN ADJACENT MSUCLE

FASCIA

Small bundle of skeletal muscle fibers

Fascicle

A nerve composed of axons (nerve fibers ) of a motor neruon

• _____ stimulate muscle fiber to contract

Motor neuron

_____ that contain thick filaments (myosin) and thin (actin)

_____ play a fundamental role in muscle contraction = striations

Myofibrils

Within each myofibril there are repeating functional units called _______ BETWEEN THE TWO Z LINES

Sacromeres

Cordlike structures of connective tissues that attach MUSCLE TO BONE

Tendons

tissue that connects BONE TO BONE to keep the joint together

Ligaments

The immovable end of a skeletal muscle is it’s _______ (a fixed arch)

MAIN = THe _____ of a muscle is usually attached to a fixed location

ORIGIN

The MOVABLE end of a skeletal muscle is its _____

Insertion

_______ are muscle that OPPOSE a movement

Antagonist

Muscle that work together to assist movement

Synergists

WHen muscle contractions its insertion is ______ toward the orgin

PULLED

decrease in the angle between bones at a joint

Flextion

Increase in the angle between bones at a joint

Extension

Skeletal muscles are named according to any of these:

• size

• shape

• location

• action

• number of attachments

• direction of its fibers

______ filaments form cross bridges (linkages) with ______ filaments

Myosin , Actin

_____ (neurotransmitter ACh) released the end of a motor neuron stimulates a skeletal muscle fiber at the _________ (nerve connecting with muscle )

Acetylcholine , Nueromuscular junction

the sarcoplasmic reticulum to release

calcium ions

______ breaks down acetylcholine on the receptors

Acetylocholinesterase

Downward,

plantar flextion

Upward

Dorsiflextion

moving a body part away from the midline

Abduction - arm go up and down

moving a body part toward the midline

Adduction

The arm and leg go foward

Flexion

the leg and arm go backward

extenstion

Palm upward

Supination

Palm downward

Pronation

Muscle contraction involves several events, that result in the shortening of _______, and the pulling of the muscle against its attachments

SARCOMERES

_____________is the neurotransmitter for skeletal muscle fiber contraction at the neuromuscular junctions

Acetylcholine

Upon receipt of the muscle impulse, the _______ releases its _____ to the cytosol of the muscle fiber

sarcoplasmic reticulum , stored calcium

Acetylcholinesterase decomposes acetylcholine, and the muscle fiber membrane is no longer stimulated.

Calcium ions are actively transported into the sarcoplasmic reticulum.

ATP breaks cross-bridge linkages between actin and myosin filaments without breakdown of the ATP itself.

Breakdown of ATP “cocks” the myosin heads.

Troponin and tropomyosin molecules block the interaction between myosin and actin filaments.

The muscle fiber remains relaxed, yet ready, until stimulated again.

MUSCLE RELAXTION

impulse travels down motor neuron, release of acetylcholine into neuromuscular junction, release of calcium ions into muscle fiber, binding sites on actin are exposed, myosin forms cross-linking, thin filaments are pulled toward the center of sarcomere.

MUSCLE CONTRACTION

Energy for muscle fiber contraction and relaxation comes from molecules of __________ (IMPORTANT)

ATP

___________is present to initially regenerate ATP from ADP and phosphate, as it also contains high energy bonds.

CREATINE PHOSPHATE

_______is a complete breakdown of glucose; it is ______ (requires oxygen) and occurs in the mitochondria, myoglobin

Aerobic respiration

____ occurs in the absence of oxygen faster reaction but produces less ATP leads to lactic acid formation

Anaerobic respiration

Pathway : Aerobic

Waste : Carbon dioxide is exhaled

Blood flow provided sufficient oxygen

Low to moderate intensity:

Oxygen supply is not sufficient <

Anaerobic respiration

Lactic acid accumulates FATIGUE

High intensity

A muscle exercised strenuously for a prolonged period may have a decreased ability to contract a condition called ________-

• When a muscle loses its ability to contract during strenuous exercise, it is referred to as______

FATIGUE

Make up majority of muscle fibers

Rapid movements, reach maximum force quickly, fatigue quickly

Large diameter

Few mitochondria, store glycogen; anaerobic metabolism

Powerful contractions, but best for short-term activities

White Meat

Fast fibers:

• Small diameter

• Takes longer to reach peak tension, but resistant to fatigue

• Provide prolonged contraction

• Many mitochondria and capillaries; aerobic metabolism

Slow fibers:

the force of individual twitches combine by the process of

SUMMATION.

the minimum stimulus required to generate a impulse through the muscle fiber, release calcium ions, activate cross-bridges, and contract the muscle.

Threshold Stimulus

frequency of stimulation is very high and the sustained contraction lacks any relaxation, it is called a

TETANY

_______ consists of a cycle of contraction and relaxation.

TWITCHES

An increase in the number of activated motor units

RECRUITMENT

Summation + recruitment together can produce a _______of increasing strength.

sustained contraction

Strain

tear in the muscle and or tendons that attach muscle to bone

Muscular Dystrophy = Genetic Condition

inherited condition in which muscles waste away.

• caused by abnormal genes unable to control muscled development and function

Myasthenia Gravis

AUTOIMMUNE DISEASE causing weakening of voluntary muscles