Muscular System

Functions of the Muscular System

Body Movement, Maintain Posture, Body Heat Production, Communication, Organ and Vessels Contraction, Heart Contraction

Types of Muscles

Skeletal, Smooth, Cardiac

Properties of Muscle

Contractility, Excitability, Extensibility, Elasticity

Contractility

Ability of muscle tissue to shorten forcefully, or contract

Lengthens passively

Muscles ______ when contracting

Excitability

Ability of muscle tissue to respond to electrical stimulus

Extensibility

Ability of muscle tissue to stretch beyond normal resting length

Elasticity

Ability of muscle tissue to recoil back to normal resting length

Titin

Protein that allows for muscle tissue extensibility and elasticity

Skeletal Muscle

Attached to the bone, long cylindrical, multinucleated, striated, voluntary

Cardiac Muscle

Muscle tissue of the heart, branched, single nucleus, intercalated disks, striated, involuntary

Smooth Muscle

Muscle in the walls of hollow organs, blood vessels and glands, spindle-shaped, single nucleus, cell-to-cell attachments, non-striated, involuntary

Skeletal Muscle

Named because it is attached to the bones

Skeletal Muscle

Longest of muscle types

Skeletal Muscle Order [L-S]

1. Fascicle, 2. Muscle Fiber/Cells, 3. Sarcomere, 4. Myosin

Skeletal Muscle Tissues

Epimysium, Perimysium, Endomysium

Epimysium

Found between adjacent muscles and muscle to skin; forms a connective sheath that surrounds each skeletal muscle

Permysium

Subdivides each whole muscle into numerous visible muscle fibers

Perimysium

Passageway for blood vessels and nerves supplying the fascicles

Endomysium

A delicate layer of connective tissue that separates the individual muscle fibers with each fascicle

Endomysium

Passageway for nerve fibers and blood vessels that supply each separate muscle fiber

Fascicles

Bundles of Muscle Fibers

Sarcolemma

Flesh and Husk

Sarcolemma

Plasma membrane of the long, cylindrical muscle fibers

T-Tubules

Internal transverse tubules that carry impulses to the center of muscle fibers

Sarcoplasmic Reticulum

Secrete high amounts of Calcium with numerous membranous networks inside the fiber

Myofibril

Long threadlike bundles of myofilaments

Myofilaments

Actin and Myosin

Sarcomere

Smallest functional unit of a muscle fiber that can contract

Sarcomere

The space between the two Z lines constitutes the

Actin

Thin myofilament that resemble two strands of pearlS

Actin

calcium binding site, myosin binding site

Myosin

Thick myofilament that resemble golf clubs

Myosin

ATPase- binding site, actin-binding site

Myosin Heads

Binds to attachment sites on the actin myofilaments

Myosin Heads

Bend and straighten during contraction

Myosin Heads

Break down ATP and release energy

Troponin

Attachment site on actin for calcium

Troponin

Anchors to actin and prevents tropomyosin from uncovering G-actin

Tropomyosin

Filament on grooves of actin

Tropomyosin

Attachment site on actin for myosin

Tropomyosin

Block the myosin myofilament binding sites on the actin myofilaments

Closed

In Resting Membrane Potential Na channels are ___

Extracellular Resting Membrane Potential

+ charge, Higher Na+ concentration, Na+ channels are closed

Intracellular Resting Membrane Potential

- charge, Higher K+ concentration, Some K+ channels are open,

True

RMP exists because the cell membrane is more permeable to K+ than it is to Na+ and there are many K+ leak channels

Depolarization

negative to positive charge; intracellular becomes more positively charged

Threshold

if and only if _____is met, then action potential will take place

Action Potential

if threshold is met, then __________ will take place

Action Potential

Results to muscle contraction

Sodium

Main extracellular ion

Sodium

Depolarization of the cell membrane occurs when there is a rapid influx of _____ ions.

Potassium

Main intracellular ion

Motor Neurons

Specialized nerve cells that stimulate muscle contraction

Motor Unit

Consists of a neuron and muscle cells stimulated by that neuron.

Synaptic Cleft

Space between axon terminals and post-synaptic membrane

Neuromuscular Junction

Junction of branch of axon and sarcolemma

Components of Actin

Troponin, Tropomyosin, Actin

Cross-Bridging

Result of binding of actin filaments and myosin heads; causes bending of myosin heads aka sliding filament theory

Acetylcholine (Ach)

Released from presynaptic vesicles

Depolarization Action Potential

Nerve impulse triggers gated sodium channels to open; RMP is changed to initiate Muscle Contraction

Repolarization Action Potential

Sodium channels are closed, changed back to RMP

True

Skeletal Muscle Fibers do not contract unless they are stimulated by motor neurons

Synaptic Vesicles

Stores neurotransmitters

Muscle Contraction

Occurs as actin and myosin filaments slide past one another causing the sarcomeres to shorten

Sliding Filament Model

This model describes the contraction of the muscle.

Calcium

When the sodium enters the sarcolemma of a muscle cell during an action potential, it stimulates__________ to be released from the sarcoplasmic reticulum.

relaxing muscle

When a muscle gets longer and thinner, it is a __________________ muscle.

Stimulates cellular contraction by opening voltage-gated ion channels

Role of acetylcholine in calcium release

a relaxed muscle fiber

A resting membrane potential exists in a

ATP and Calcium

For muscle contractions to occur, the body needs ___________________

False

Once the neurotransmitter attaches to receptors on the sarcolemma, it becomes impermeable to sodium.

1

How many ATPs is/are produced per one creatine phosphate molecule? _____

True

Aerobic respiration occurs in the mitochondria and involves a series of metabolic pathways that use oxygen.

Calcium

Action potentials in the T tubules cause the sarcoplasmic reticulum to release

ATP

help form cross-bridge formation between myosin and actin

myosin heads

ATP is stored in

Aerobic Respiration

Products are 36 ATP/glucose, carbon dioxide and water; provides enough ATP for hours of muscle contraction

Anaerobic Respiration

Products are 2 ATP/glucose and lactic acid; produces only enough ATP to power muscle contractions for 30–40 seconds

2 ATPs

________ per glucose molecule in Anaerobic Respiration

Creatine Kinase Pathway

Products are ATP and creatine

Myokinase Pathway

Products are 1 ATP and 1 AMP; Adenylate kinase

Location, Origin, Shape, Size, Orientation of Fascicles, Function

Muscle Nomenclature

True

Aerobic respiration occurs in the mitochondria and involves a series of metabolic pathways that use oxygen.

Pectoralis Major

Located in the chest

Sternocleidomastoid

Has origin on the sternum and clavicle and its insertion on the mastoid process of the temporal bone

Deltoid

Triangular

Orbicularis, teres

Circular, round

Platy

Flattened, plate-like

Quadratus

Rectangular

Rhomboideus

Diamond-shaped

Trapezius

Trapezoidal

Brevis

Short

Longus

Long

Magnus

Large

Maximus

Largest

Medius

Moderately-sized

Minimus

Smallest

Oblique

Diagonal to the body's midline

Rectus

Parallel, straight