Three Types of muscle
skeletalcardiacsmooth
type of muscle that is striated, light and dark, voluntary, neuron controlled
skeletal
type of muscle that is striated, involuntary, autorhythmiciity, hormones and neurotransmitters change heart rate, etc
cardiac
type of muscle that has walls of internal strucutres, non-striated, involuntary, and autorhythmicity
smooth muscle
Functions of muscle
1. producing body movements - involving integrated functions of muscle, joints, and bones2. stabilizing - postural positions, sustained contractions3. storing and moving substances - sustaned contraction, sphinters4. generate heat - thrmogenesis, involuntary shivering (skeletal muscles)
ringlike bands of smooth muscle that close off outlets by the contraction and relaxation of smooth muscle, and also found in gi tract, urine, flow of lymph, and returns blood to the heart
sphincter
four properties of muscle tissue
electrical excitabilitycontractibilityextensibilityelasticity
electrical signals as a responce to stimuli that travel down the plasma membrane of cell
action potential
types of stimuli
autorhythmic electrical signalschemical stimuli by neurotransmitters, hormones, or ph change
stiulation of actin potential that leads to a sliding of thin filaments across thick filaments
contractility (correct spelling)
strecthability," stomach, carciac muscles, allows muscle to contract forcefully when strecthed
extensibility
ability to return to original size and length
elasticity
muscle cells are refered to as
muscle cells
connective tissue surrounds and protects muscular tissue which includes
subcutaneous layerfascia epimysiumperimysiumfasciclesendomysiumtendonaponeurosistendon sheaths
also referred to as hypodermis, it separates muscle from skin and is composed of areolar connective tissue and adipose. provides a pathway for nerves, blood vessels, and lymphatic vessels to enter and exit muscles
subcutaneous layer
stores most of the body's triglycerides and seves as an insulating layer that reduces heat loss, and protects muscle form physical trauma
adipose tissue
dense shee of dense irrgular connectve tissue that lines tha body walls and limbs and supports and surrounds muscles and other organs of the body; allows free movement
fascia
three layers of connctive tissue in skeletal muscle
epimysiumperimysiumendomysium
type of connective tissue encircling the entire muscle; dense irregular
epimysium
type of connective tissue surrounds groups of 10-100 muscle fibers separating them into bundles called fascicles; dense irregular
perimysium
type of connective tissue that penetrates the interior of each fascicle and separates individual muscle fibers from one another; also a thin sheath of areolar connective tissue
endomysium
cord of dense regulare conncective tissue; parallel bundles of collagen fibers; connects muscle to bone
tendon
connective tissue elements that extend as a braod, flat later; type of tendon
aponeurosis
tubes of connective tissue containing an inner layer called visceral layer attached to the surface area and an outer layer called parietal layer with attached to the bone
tendon sheaths
stimulates skeletal muscle; threadlike axon entends from spinal cord to a group of skeletal muscle fibers
somatic motor neurons
small blood vessels found in muscle tissue
capillaries
enlargement of fibers
hypertrophy
increase in the number of fibers
hyperplasia
plasma membrane of the cell
sarcolemma
thousands of tiny invaginations of sarcolemma; open to the outside of cell; filled with interstitial fluid; where mucle action potiontial travel along sarcolemma and through T tubules to spread throughout mucscle tissue quickly
transverse tubules
cytoplasm," involves glycogen involved in ATP synthesis; myoglobin
sarcoplasm
only in muscles and binds oxygen to diffuse into muscle resulting in the release into muscle for ATP production
sarcoplasm
contractile organelles of skeletal muscle that entend the entire length of muscle fiber
myofibrils
inside myofibrils and involved in contraction process; includes thick and thin filaments
filament
2:1 ratio over thick filaments, anchored by z discs, actin
thin filaments
mysoin proteins is associated with which filament
thick filament
compartment that contains the filament; basic subunit of myofibrils
sarcomere
sarcomere includes
z discsA bandI bandH zoneM line
separation of sarcomeres
z disc
dark, middle; entire length of thick filament; zone of overlap in sarcomere
A band
lighter less dense; only thin filaments present with z disc in middle
I band
only thick filament found here in sacromere
H zone
middle; proteins that hold thick filaments together at center of H zone
M line
Muscle proteins include three kinds of proteins found in the myofibrils
contractile - generate force furing contractionregulatory - help switch the contraction process on and offstructural proteins - keep the thick and thin filaments in the proper alignment, elasticity and extensibility to myofibrils and likn them to the sarcolemma and extracelluar matrix
keep the thick and thin filaments in the proper alignment, elasticityand extensibility to myofibrils and likn them to the sarcolemma andextracelluar matrix
structural
contracilte proteins in muscle
myosin and actin
motor protein" that push and pull cellular structures to acheive movement by the conversion of ATP, a chemical energy, into mechanical energy; myosin head and myosin tail
mysoin
contains myosin binding sites where myosin head attaches; contains the regulatory proteins tropomyosin and troponin
actin protein
In a relaxed muscle, myosin is blocked from binding to actin becase strands of ______ cover the mysoin-binding sites on actin
tropomyosin
holds tropomyosin strands in place and undergoes a cange in shape when Ca++ binds to it resulting in moving tropomyosin away from mysoin-binding site
troponin
calcium binds to troponin and chages shap to move tropomyosin away from myosin-binding site on actin where myosin binds to actin
contraction
structural protein results in stability, extensibility, and elasticity of myofibrils and includes the following proteins
titin molecules - connect z discs to m-line and return musclealpha-actin - bind actin to titinmyomesin - m-linenebulin - long, nonelastic, wrapped around entire moleculedystrophin - cytoskeletal protein liks thin filaments to sacromere
contraction and relaxation of skeletal muscle fibers involves
ATP hydrolysisAttachment of myosin to actin (crossbridges)Power Stroke (sliding of thin filament over thick filament)Detachment of mysoin from actin
process that is essential for contraction of muscle to occur
sarcoplasmic reticulum releases calcium ions into cytosol; calcium binds to troponin; troponin moves tropmysin away from myosin binding sites
the first step of conctraction cycle
mysoin head with ATP binding site and ATPase results in the hydolysis of ATP which reorients mysoin head and energizes it
second step of contraction cycle
attachment of the myosin head with myosin-binding site located on the actin; formation of crossbridge as a release of phosphate group from ATP hydolysis
third step of contraction cycle
Power Stroke as a result of an opening on the crossbridge where ADP is bound releasing ADP; release of ADP results in the rotation of the myosin crossbridges toward the center of the sarcomere
forth step of contraction cycle
Detachment of mysoin from actin. Involves the binding of ATP to mysoin head so that crossbridges detach from actin
Step connecting muscle action potential propagating along sarcolemma and through T-tubules to cause a contraction or sliding of filaments
Excitation-contraction coupling
increase of Ca++ at cytosol
results in the contraction of muscle
contains large resevoir of Ca++ to be released into the cytosol
sarcoplasmic reticulum
miscule action traveling along sarcolemma and into t-tubules results directly in the release of calcium from to where
from sarcoplasmic reticulum membrane to cytosol
plasma membrane of the muscle cell
sarcolemma
uses ATP to move Ca++ from cytosol to SR
Calcium active transport
propagation of action potential means that calcium release channels are open or closed
open
calcium binding protein in SR which helps SR to have 10000x as many calcium molecules as cytosol in relaxed muscle
calsequestrin
indicates how forcefulness of muscle contraction depends on length of the sarcomeres within a muscle before contraction begins
length-tension relationship