BGSU BIOL 3310 Lecture Exam 2- Muscles

skeletal, cardiac, smooth

three types of muscular tissue

skeletal muscle

long, cylindrical, multinucleate (located peripherally), striated

voluntary

most commonly attaches tendons to bones

cardiac muscle

branched cylindrical fiber with one centrally located nucleus; intercalated discs joing neighboring fibers, striated

smooth muscle

fiber is thickest in the middle, tapered at each end, has one centrally positioned nucleus; not striated

-excitability

-contractility

-extensibility

-elasticity

Properties that enable muscle to functionand contribute to homeostasis

excitability

ability to respond to stimuli

contractility

ability to contract forcibly when stimulated

extensibility

ability to stretch without being damaged

elasticity

ability to return to an original length

cells, connective tissue, blood, nerves

skeletal muscle components

anchor and structure

role of connective tissue in skeletal muscle

signals and nutrients

why do muscles need extensive nerve and blood supply

epimysium

Outermost layer

Surrounds numerous bundles of fascicles

fibrous sheath surrounding the entire muscle

outer surface grades into the fascia

inner surface sends projections between fascicles to form perimysium

Perimysium

Separates 10-100 muscle fibers into bundles called fascicles

slightly thicker layer of connective tissue

fascicles - bundles of muscle fibers wrapped in perimysium

carry larger nerves and blood vessels, and stretch receptors

endomysium, perimysium, epimysium, fascia

connective tissues of a muscle

Endomysium

thin sleeve of loose connective tissue surrounding each muscle fiber

allows room for capillaries and nerve fibers to reach each muscle fiber

fascia

sheet of connective tissue that separates neighboring muscles or muscle groups from each other and the subcutaneous tissue

lines body wall, limbs

occupies space between muscles

rich in blood and nerves

myoblasts

skeletal muscle cells arise from

hypertrophy

increase in cell size

same

_________ number of muscle cells at birth as the rest of your life time (usually)

wraps around all muscles and body parts

difference between fascia and other connective tissue

ligaments

bone to bone

does not

heavily damaged muscle _______ repair

tendon

Connects muscle to bone

fascicle

bundle of muscle fibers

muscle fiber

a single muscle cell

satellite cell

can fuse to make new fibers (but heavily damaged muscle does not repair)

aponeurosis

A broad, flat tendon

somatic motor neurons

Neurons that stimulate skeletal muscle to contract are _________________

fusiform

spindle-like shape that is wide in the middle and tapers toward both ends

biceps brachii

example of fusiform muscle

parallel

muscle fascicles (bundles of fibers) that run in the same direction as the long axis of the muscle

rectus abdominis

ex of parallel muscle

triangular

muscle fibers that spread widely across a broad origin (base) and pull together toward a single, narrow insertion point (apex)

pectoralis major

ex of triangular muscle

Unipennate

the muscle fascicles are positioned on only one side of a central tendon

palmar interosseous

example of unipennate muscle

bipennate

muscle fibers (fascicles) are arranged on both sides of a central tendon, resembling the structure of a regular feather

rectus femoris

example of bipennate muscle

multipennate

features muscle fibers that approach a central tendon from multiple angles, branching out around or within the tendon to resemble a complex feather or multi-headed structure

deltoid

ex of multipennate

circular

muscle fibers arranged in concentric rings that act as sphincters to control body openings

orbicularis oris

example of circular muscle

orientation of its facicles

strength of a muscle and the direction of its pull are determined partly by the __________________________________________

origin

bony attachment at stationary end of muscle

belly

thicker, middle region of muscle between origin and insertion

insertion

bony attachment to mobile end of muscle

indirect attachment to muscle

tendons bridge the gap between muscle ends and bony attachment

direct attachment to bone

little separation between muscle and bone muscle seems to emerge directly from bone

prime mover

muscle that produces most of force during a joint action

ex. brachialis

synergist

Muscle that assists a prime mover

stabilizes the nearby joint

modifies the direction of movement

ex. biceps brachii

antagonist

opposes the prime mover

relaxes to give prime mover control over an action

preventing excessive movement and injury

antagonistic pairs - muscles that act on opposite sides of a joint

ex. triceps brachii

fixator

muscle that prevents movement of bone

ex. rhomboids

intrinsic muscles

contained within a region, such as the hand

both origin and insertion in the same region

extrinsic muscles

acton a designated region, but has its origin elsewhere

fingers - in the forearm

myofibrils

Muscle fibers are full of _____________, but also contain a number of notable chemicals and structures

sarcolemma

plasma membrane of muscle fiber

transverse tubules

tunnel-like indentions of the sacrolemma

sarcoplasm

cytoplasm of a muscle fiber

myoglobin

a cytoplasmic protein that binds oxygen in a muscle fiber

glycogen

Storage form of glucose

sarcoplasmic reticulum

network of membranous sacs around the myofibrils.

calcium

the sarcoplasmic reticulum stores ___________ ions

myofibril

contractile organelle

contraction

in the SR, release of Ca++ triggers myofibril ___________

nucleus

1

sarcomere

2

z disc

3

m line

4

h band

5

a band

6

i band

7

contractile proteins, regulatory proteins, structural proteins

the three kinds of proteins that build a myofibril

contractile proteins

generate force during contraction

actin and myosin

the 2 contractile proteins

myosin

thick filaments

actin

thin filaments

regulatory proteins

switch the contraction process on and off

tropomin and tropomyosin

the two types of regulatory proteins

structural proteins

align the thick and thin filaments properly

provide elasticity and extensibility

link the myofibrils to the sarcolemma

myosin, actin

the 2 contractile proteins

myosin

Functions as a motor protein which can achieve motion

Convert ATP to energy of motion

Projections of each myosin molecule protrude outward (myosin head)

actin

______ molecules provide a site where a myosin head can attach

Tropomyosin and troponin are also part of the thin filament

In relaxed muscle

titin, dystrophin

2 structural proteins

titin

Stabilize the position of myosin

accounts for much of the elasticity and extensibility of myofibrils

Extends from Z disc to M line

where does ca++ bind in a muscle contraction

sarcolemma

dystrophin links thin filaments (actin) to this

Tropomyosin

Covers myosin-binding sites, keeps myosin from engaging actin

troponin

Bind to tropomyosin

In the presence of Ca++, causes tropomyosin to uncover myosin binding sites, allowing contraction to begin.

ca++

if there is a muscle contraction what needs to bind to troponin

action potential

what causes ca++ to release in a muscle contraction

transverse tubule

action potential travels along the______

thin filament, myosin

when ca++ binds to troponin on the __________ it exposes the binding sites for ___________

thin filaments, actin

where do myosin heads hook on

troponin

when a muscle wants to contract where does ca++ bind

skeletal muscle

in _______ almost all ca++ is stored in the SR

cardiac muscle

in __________ most ca++ is stored in the SR and some comes from outside the cell

smooth muscle

in ________ almost all ca++ comes from outside the cell

tropomyosin, troponin

2 regulatory proteins

rigor mortis

hardening of muscles and stiffening of the body beginning 3 to 4 hours after death