Muscular System

Muscle

a tissue that contracts (shortens) to facilitate locomotion and support

Origin

fixed proximal end of a muscle

Insertion

distal moveable end of a muscle

Flexor

closes/angulates a joint

Extensor

opens/straightens a joint

Agonist

muscle that produces desired movement

Antagonist

opposes movement of agonist

Which skeletal muscle group…

• Produces skin twitch

• Has little to no attachment to bone

cutaneous

Which skeletal muscle group…

• Controls facial expression

• Facilitates neck and sensory structure movement

head and neck

What skeletal muscle group…

• Supports organs

• Flexes the back

• Facilitates defecation and urination

• Aids in parturition

abdominal

What skeletal muscle groups…

• Aid in locomotion

• Provides abduction and adduction of the shoulder and lower limbs

thoracic and pelvic limbs

Muscle fiber

single muscle cell

Muscle myofibril

composed of myofilaments; hundreds run together lengthwise to make up muscle fibers

Protein filaments

actin and myosin; contractile proteins

Fascicle

bundles of skeletal muscle fibers within a muscle

Endomysium

connective tissue around individual muscle fibers

Perimysium

connective tissue around a bundle of muscle fibers

Epimysium

dense connective tissue sheet covering a whole muscle

Neuromuscular junction

where motor neuron terminal axon meets muscle fibers with a chemical synapse

Sarcolemma

muscle cell membrane

The sarcolemma is a site for…

nervous system interaction

Sarcoplasmic reticulum

muscle equivalent to ER; stores calcium

T-tubule

extend inward from sarcolemma to carry nerve impulses into the cell

energy stores

Glycogen acts as _____________ for muscles.

Sarcomere

repeating contractile unit

multinucleated

In terms of nuclei, skeletal muscle cells are….

Gap junctions

connect cardiac muscle cells, allowing electrical impulse to flow rapidly and ensure synchronized contractions

Intercalated discs

attachment sites between cardiac muscle cell network

Sinoatrial node (SA) pacemaker

The impulse that triggers the involuntary contraction of cardiac muscle is controlled by the…

increases heart rate and blood pressure

What does norepinephrine do for the muscular system?

waves

Smooth muscle cells produce large, rhythmic ______ of contraction.

visceral

Smooth muscle cells are __________; they’re found in large sheets inside organ walls.

Peristalsis

series of wave-like contractions that push substance through tube-like structures, especially in the digestive or urinary systems

increases

As tissue stretches, contraction strength _________.

Smooth muscle cells are not capable of fine movement, with the exception of…

multiunit smooth muscle (ex. blood vessels, air passages)

Crossbridge

where actin and myosin come into contact and pull Z lines together

Acetylcholine

neurotransmitter for specified action potential

maximizes muscle longevity and endurance

What is the function of creatine phosphate?

phosphates

In order to turn ADP into ATP, the body needs…

shorten

When Z lines are brought together, muscle fibers _________.

Band H

“disappears” during muscle contraction

Band A

length of myosin within sarcomere

Band I

sarcomere region containing only thin myofilaments

List the steps of muscle contraction and relaxation. (Hint: 6 steps)

1. Electric impulse arrives through chemical synapse

2. Calcium ions release from SR

3. Troponin binds to calcium, changing shape and pulling tropomyosin away to expose myosin’s binding sites

4. Myosin, using ADP and Pi, binds with actin and the H-band disappears

5. ATP binds with myosin’s head and it releases actin (relaxation)

6. Calcium returns to SR through active transport

Summation

whole muscle contracting at various lengths

Spacial summation

several excitatory postsynaptic potentials travel down MULTIPLE presynaptic neurons and arrive at axon at the same time as an action potential

Temporal summation

several excitatory postsynaptic potentials travel down a SINGLE presynaptic neuron in quick succession

What type of muscle contraction…

• Shortens muscle (flexes)

concentric

What type of muscle contraction…

• Lengthens muscle (extends)

eccentric

What kind of muscle contraction…

• Stays the same length

• Changes in tension

• Produces no movement

isometric

What kind of muscle contraction…

• Changes length

• Maintains the same tension

• Produces movement

isotonic

adaptive

Muscle is the most __________ tissue in the body.

Hypertrophy

enlargement; increase in muscle cell size

Hyperplasia

enlargement of muscle by increase in number of muscle fibers

Atrophy

muscle shrinkage due to lack of use or denervation

Classify the muscle fiber. (Think: long distance)

• Dark

• Aerobic

• Slow twitch

Type I

Classify the muscle fiber. (Think: 400/800m run)

• Fast twitch

• Intermediate

• Anaerobic

Type IIA

Classify the muscle fiber. (Think: short sprints)

• Light

• Fast twitch

• Aerobic

Type IIB

Skeletal

Identify the muscle type.

Cardiac

Identify the muscle type.

Smooth

Identify the muscle type.

latissimus dorsi

Identify the muscle indicated by the green dot.

superficial gluteal

Identify the muscle indicated by the blue dot.

trapezius

Identify the muscle indicated by the green dot.

semitendinosus

Identify the muscle indicated by the blue dot.

deltoid

Identify the muscle indicated by the yellow dot.

triceps brachii

Identify the muscle indicated by the yellow dot.

What is the cheek muscle known as?

Masseter

gluteobiceps

In small ruminant animals, the biceps femoris is known as the…