Exam 4

Muscles & Muscle Tissue

Myology

Study of Muscles

Skeletal Muscle

Voluntary, Striated, multinuclied

Cardiac Muscle

Heart, striated, branched, involuntary

Smooth muscle

Stomach, intestine, small intestine

Functions of Muscles

1. Movement of body parts and organ contents

2. Stability: maintain posture and prevent unwanted movement (fixing a joint)

3. Communication - speech, expression & writing

4. Control of openings and passageways

5. Body heat production: Skeletal muscles produce up to 85% of body heat

Charateristics of Muscle

Responsiveness- Receive and respond to stimuli

Conductivity- The ability to conduct an electrical signal

Contractility – The ability to shorten when stimulated

Extensibility -- The capacity to stretch

Elasticity – The ability to return to its original resting length after being stretched

fascicles

muscle fiber or muscle cell bundled up together

Epimysium

Membrane that surrounds the entire muscle

Perimysium

Membrane that surrounds the fascicles

Endomysium

Membrane that surround individual muscle fibers

Direct attachment

Muscle is directly attached to the bone without a tendon

Indirect attachment

connected by a tendon

Voluntary

striated muscle attached to bone

multinuciled

unbranched

Myofibril

Make up muscle fibers

Sarcolemma

Muscle Cell membrane

transverse tubules

tunnel-like in foldings that conducts the electrical signal into the inside of the cell interior.

Sarcoplasm

Cytoplasm of the Muscle cell

Myofibrils

Long thin strands bundles of proteins

Glycogen

for stored energy & myoglobin for binding oxygen

Sarcoplasmic reticulum

Stores calcium in muscle fibers and funnels is

terminal cisternae

storage sacs at the end of the Sarcoplasmic reticulum that’s store calcium

Sarcomere

smallest functional unit of a muscle fiber & the region between z disk - z disk.

Myosin: thick filament Actin: thin filament

Contractile proteins do the work of contraction

Troponin & Tropomyosin

Regulatory proteins regulate contraction found on the actin filament. troponin binds to calcium.

motor neurons

structure that branches to send signals to the muscles

motor unit

the individual fiber that benches in the motor neurons

Fine Control

Few muscle fibers per nerve fiber found in Eye muscles

Strength control:

• Calf muscle has 1000 fibers per nerve fiber

Synapse

region where a nerve fiber makes a functional connection with its target cell. inbetween nervous and muscle.

Neurotransmitter

chemical messengers ex. (ACh)

Synaptic knob

is swollen end of nerve fiber tip of Hershey kiss (Ach) found at the tip

Motor end plate

is specialized region of muscle cell surface

ACh receptors

are found on the motor end plate

Schwann cell

structures on that wrapped around the synaptic knob

Muscle Contraction & Relaxation process

1. Excitation

2. Excitation-contraction coupling

3. Contraction

4. Relaxation

Spastic paralysis

constant state of contraction and unable to relax.

Flaccid paralysis

unable to contract muscles

Botulism

type of food poisoning caused by a neuromuscular toxin.

Isometric muscle contraction

Develops tension without changing length

Isotonic muscle contraction

Tension development while shortening = concentric

eccentric

Tension development while lengthening

Phosphagen system

Pi groups transferred to ADP

2 ways to produce ATP

Aerobic respiration & Anaerobic respiration

Once phosphagen system is exhausted

anaerobic fermentation takes over. by product is lactic acid

Slow-twitch fibers

arobic with oxygen endurance running

Fast-twitch fibers

quickly fatigue sprinting running