skeletal, cardiac, smooth
3 types of muscle tissue are:
True
TRUE:
The 3 types of muscle tissue are classified by:
-structure, contractile props, location, & control mechs
Skeletal muscle
-muscle type mostly attached to bones (some attached to skin or other muscle of this type)
Skeletal muscle
-muscle contraction --> skeletal movement
Skeletal muscle
-muscle controlled by somatic division of nervous system (VOLUNTARY control)
~most also controlled subconsciously ex: diaphragm
Skeletal muscle
-microscopic appearance of this muscle type: alternating transverse light & dark bands (striated)
Cardiac muscle
-muscle type found in the heart wall
Cardiac muscle
-muscle contraction --> propels blood through circulatory system
Cardiac muscle
-muscle controlled auto-rhythmically (built-in pacemaker); adjusted by autonomic nervous system & hormones (INVOLUNTARY control) (NO direct conscious control)
Cardiac muscle
-microscope appearance of this muscle type: striations, intercalated discs
Smooth muscle
-muscle type that surrounds hollow organs & tubes
ex: GI tract, airways, blood vessels, uterus, bladder
Smooth muscle
-muscle type found as single cells or in small groups
Smooth muscle
-contraction --> propulsion of luminal contents or flow regulation
Smooth muscle
-controlled by autonomic nervous system, hormones, & intrinsic factors (INVOLUNTARY)
Smooth muscle
-microscope appearance: smooth, NO striations
True
TRUE:
Functions of muscular tissue:
-producing body movements, stabilizing body positions, storing & moving subsets within the body, and generating heat
True
TRUE:
Properties of muscular tissue:
-electrical excitability, contractility, extensibility, and elasticity
Excitability
property of muscle tissue- ability to receive and respond to stimuli by action potential production
Contractibility
property of muscle tissue- ability to shorten
Extensibility
property of muscle tissue- ability to stretch
Elasticity
property of muscle tissue- ability to recoil
Skeletal muscle
Muscle type that contains:
~Muscle fibers- individual muscle cells
~CT- surrounds muscle fiber & whole muscle
~blood vessels and nerves
Connective Tissue (CT)
____________ ________components:
1. layers surrounding and protecting
2. fascia
3. skeletal muscle attachments
Epimysium
CT that surrounds the ENTIRE muscle
Perimysium
CT that penetrates the muscle and separates and surrounds the muscle fibers fascicles
Fascicle
bundle of 10-100 muscle fibers
Endomysium
thin CT extensions enveloping each muscle FIBER
Fascia
CT sheets which are continuations of the epimysium
Deep fascia
fascia between neighboring muscles (carry nerves, bvs, etc.)
Superficial fascia
fascia (hypodermis) (subcutaneous layer): between muscle and skin (adipose)
Tendons
white, fibrous cords of dense regular CT that attach muscle to bone
Aponeurosis
sheet-like layer of CT joining a muscle to the part that it moves
Origin
the more STATIONARY bone to which the muscle is attached (head) (usually proximal)
Insertion
the more MOBILE end of bone (usually distal)
Belly
the bulk of the muscle; between the origin and insertion
Myoblasts
the immature cells giving rise to muscle cells (fibers)
-fuse --> multinucleated mature muscle fiber (cannot divide)
Satellite cells
inactivate myoblasts associated with mature muscle fibers;
-have the potential to divide
-higher number in young children
Hypertrophy
enlargement of existing muscle fibers
-accounts for muscle growth after birth in response to hGH
Fibrosis
replacement of muscle fibers by fibrous scar tissue following damage
Sarcolemma
plasma membrane
Sarcoplasm
cytoplasm
T (transverse) tubules
in-folding of sarcolemma; carries electrical current (charge) from surface to cell interior --> Ca++ release from terminal cisternae
Myofibrils
Muscle fiber is made up of smaller _______________.
Sarcoplasmic reticulum (SR)
membranous sacs encircle myofibril; stores Ca++
Terminal cisternae
dilated sacs of SR alongside T-tubules
Triad
T-tubule + 2 terminal cisternae (on either side)
True
TRUE:
muscle-->fascicle-->fiber-->fibril-->filament
Thick filaments
-mainly made up of the contractile protein MYOSIN
-large protein molecule with a globular head attached to a long tail
-300 myosin molecules
-tails: lie along long axis
-heads: extend outwards (form cross-bridges)
-myosin molecules in the 2 halves of each
Thin filaments
-made up of the contractile protein ACTIN, plus proteins tropomyosin & troponin
Actin (thin filament)
globular (G) actin subunints (contain myosin BINDING site)
-G actin subunits are helically intertwined into a filament = F actin
Tropomyosin (thin filament)
thread-like protein extending end to end along the actin surface (1 per 7 G-actin subunits); covers myosin binding site which prevents contraction
Troponin (thin filament)
small protein bound to tropomyosin; can bind Ca++; "unlocks" tropomyosin so now myosin can bind to actin and you have cross bridging and then contraction
blocks
Tropomyosin _________ myosin binding sites (active site) on actin
A-Band
dark band; extends entire length of thick filament
=thick filament + overlapping thin & thick filaments
~H zone
~M line
H zone
lighter region in middle of A band (NO thin fils)
M line
proteins at center of H zone of A band (middle of sarcomere)
I band
lighter band; thin filaments only
~Z disc
Z disc
narrow line bisecting I band
-protein to which thin filaments are anchored
Sarcomere
compartmental arrangement of the filaments
-each segment of myfibril from Z to Z
-functional contractile unit of muscle fiber