BIO220: Identifying Muscle Microanatomy

Nuclei

Striations

Sacromere

1?

H-Band

2?

Actin

3?

Myosin

4?

Z line

5?

A Band

6?

I band

7?

M Line

8?

T-Tubules

Terminal Cisternae

Sacroplasmic Reticulum

Myofibril

Myofilament, Myofibril, Muscle fiber, Fascicle, Muscle

organization of Skeletal Muscles smallest to largest?

I band

1?

A-Band

2?

motor neuron

Entire image?

nucleus

1?

soma

2?

dendrites

3?

myelin sheath

4?

axon

5?

muscle fiber

6?

neuromuscular junction

7?

nerve

1?

blood vessel

2?

bursa

3?

synovial membrane

4?

fibrous capsule

5?

joint capsule

6?

bone

7?

joint cavity

8?

articular cartilage

9?

tendon sheath

10?

tendon

11?

fibrous layer 

13?

cellular layer

14?

periosteum

15?

synovial joint

type of joint found between bones that move freely

articular cartilage

provides smooth surface

joint cavity 

encloses articular surfaces

fibrous capsule

dense irregular connective tissue, continuous with fibrous layer of the periosteum. Portions may thicken to form ligaments.

synovial membrane

membrane lines inside of joint capsule except at actual articulation of articular cartilages. Thin, delicate. Sometimes separated from fibrous capsule by areolar C.T. and fat, sometimes merged with fibrous

synovial fluid

complex mixture of polysaccharides, proteins, fat and cells. Hyaluronic acid- slipper

epithelial, connective, nervous, muscular

the four basic tissues?

skeletal, smooth, cardiac

3 types of muscular tissue

flexion

a movement that decreases the angle between two body parts

extension

extension a movement that increases the angle between two body parts, returning them to anatomical position

contractility

ability of a muscle to shorten with force

excitability

capacity of muscle to respond to a stimulus (usually from nerves)

extensibility 

muscle can be stretched beyond its normal resting length and still be able to contract

elasticity

ability of muscle to recoil to original resting length after stretched.

muscular fascia

muscle connective tissue layer that surrounds individual muscles

epimysium

muscle connective tissue layer that surrounds muscles

perimysium

muscle connective tissue layer that surrounds fascicles

endomysium

muscle connective tissue layer that surrounds muscle fibers

capillary

the smallest blood vessel in the body, forming networks between arterioles and venules

myoblasts

Embryonic muscle cells that serve as the building blocks for skeletal muscle fibers. proliferate, then fuse together to form multinucleated muscle fibers.

triad

the name for the sandwich of terminal cisterna and transverse tubules (t tubules)

sarcolemma

the plasma membrane of skeletal muscle fiber

connective tissue, muscle fascicles, blood vessels, nerves

skeletal muscle is composed of…

muscle fibers

muscle fascicles is composed of individual….

sarcolemma, t-tubules, sarcoplasm, multiple nuclei

muscle fibers contain…

sarcoplasmic reticulum, myofibril, mitochondria, glycogen granules

sarcoplasm consists of

glycogen granules

Small, dense clusters of stored glycogen found in the cytoplasm (sarcoplasm) of cells, especially in skeletal muscle fibers and hepatocytes (liver cells).

sacromere

myofibril is composed of…

troponin, actin, tropomyosin, myosin, titin, nebulin

sacromeres consist of ..

thin filaments

consist of actin, tropomyosin, and troponin.

thick filaments

consist of myosin

tropomyosin

A long, rope-like protein that covers the myosin-binding sites on actin when the muscle is relaxed.

troponin

A globular protein complex attached to tropomyosin. - Binds calcium ions (Ca²⁺) during stimulation, causing a shape change that moves tropomyosin off the binding sites.

titin

A giant elastic protein that anchors the thick filaments (myosin) to the Z disc in a sarcomere.

nebulin

A structural protein found in skeletal muscle, associated with thin filaments (actin). Helps align actin

myofilament

protein filament within a myofibril that plays a direct role in muscle contraction. consists of actin and myosin.

I band, H zone

which bands/zones shorten during contraction?

Motor neuron fires AP, Muscle fiber fires AP, AP travels into T-Tubule, Opens Ca2+ channels, causes sarcomeres to contract

Contraction Pathway?

Neuron AP, Volrage-gated Ca2+ channels open, Ca2+ triggers ACh vesicles to fuse with membrane, ACh released into synaptic cleft, ACh diffuses across cleft and bindsto ACh receptors, ACh receptor channels open (Na+ flows in and a little K+ out), end-plate potential (EPP) forms, if threshold met voltage-gated Na+ channels open, muscle ap generated

NMJ sequence?

troponin

Where on the sacromere does Ca2+ bind

contraction, SERCA pump, Ca2+ into SR, Ca2+ decreased in icf, Ca2+ detach from troponin, tropomyosin block actin:myosin binding, relaxation.

relaxation pathway?

stimulus, receptor, input, integrating center, output, target(s), tissue response(s), systemic response

general reflex pathway

deltoid muscle spindle stretch (shoulder abduction), muscle spindle in deltoid (intrafusal fibers), sensory neuron to spinal cord (afferent pathway), spinal cord, motor neuron to deltoid (efferent pathway), deltoid muscle fibers (extrafusal fibers), deltoid contraction, deltoi muscle spindle stretch decreased (shoulder stabilized)

specific reflex with one muscle

sudden load in hand, muscle spindle stretch in biceps brachii, sensory neuron to spinal cord, spinal cord, motor neuron to biceps brachii and brachialis, bicieps brachi and brachialis, elbow flexion to counteract load, muscle spindle feedback from both muscles stabilizing arm

specific reflex with two muscles