HMS: Muscular System

Question 1

Muscular System

Answer 1

Links the Nervous System & Skeletal System, and is responsible to generate the forces that move the human body.

Question 2

Skeletal Muscle duties

Answer 2

Produce movement thru contraction

Stabilize the body

Assist w/ homeostasis by maintaining body heat.

Question 3

Muscle Anatomy: Fascia

Answer 3

First layer of connective tissue that surrounds skeletal muscle and connects them to other muscles.

Question 4

Muscle Anatomy: Epimysium

Answer 4

The layer of fascia that directly surrounds an entire muscle. Also called “deep fascia”

Question 5

Muscle Anatomy: Fasicles

Answer 5

The largest bundles of fibers within a muscle.

Question 6

Muscle Anatomy: Perimysium

Answer 6

The connective tissue that wraps each individual fascicle.

Question 7

Muscle Anatomy: Endomysium

Answer 7

Each individual muscle fibers (myofibril) within a fascicle is wrapped by endomysium.

Question 8

Muscle Anatomy: Sarcolemma

Answer 8

The plasma membrane that encases individual muscle fibers (myofibrils) w/i a fascicle.

Question 9

Muscle Anatomy: Myofibrils

Answer 9

Each individual muscle fiber is made of cylindrical myofibrils, which is composed of overlapping myofilaments.

Question 10

Muscle Anatomy: Cellular components

Answer 10

Sarcoplasm containing:

Glycogen (stored glucose)
Myoglobin (molecule that carries O2)
Mitochondria (powerhouse)

Question 11

Muscle Anatomy: Myofilaments

Answer 11

The contractile components of muscle tissue, composed of:

Actin: Thin, stringlike filament

Myosin: Thick filament

Question 12

Muscle Anatomy: Sarcomere

Answer 12

The functional unit of muscle system where muscle contraction occurs. A section of repeating Actin & Myosin.

Question 13

Muscle Anatomy: Z-line

Answer 13

The ends of a each single sarcomere, where the next sarcomere meets.

Question 14

Muscle Anatomy: Sketch a Sarcomere

Answer 14

Include:

Actin
Myosin
Z-line

Question 15

Muscle Anatomy: Sketch a Myofibril

Answer 15

Include overlapping myofilament

Question 16

Muscle Anatomy: Flowchart

Answer 16

Fascia: Surrounds & connects muscle sys

Muscle: Bundle of fascicles surrounded by deep fascia EPIMYSIUM connectv. tiss

Fascicle: Bundle of muscle fibers surrounded by PERIMYSIUM connect tiss

Muscle Fiber: Bundle of myofibrils surrounded by ENDOMYSIUM conect tis

Myofibril: A cylindrical shape of repeating Sarcomeres containing the Myofilaments, Actin & Myosin.

Question 17

Muscle Anatomy: Tropomyosin

Answer 17

A protein structure located on the Actin filament that is responsible for myosin-binding sites along the Actin filament to prevent muscle contraction when muscle is in a relaxed state.

Question 18

Muscle Anatomy: Troponin

Answer 18

A protein structure located on the Actin filament that provides binding site for tropomysin and calcium when a muscle needs to contract.

Question 19

Neural Activation

Answer 19

The communication link between the Nervous System and the Muscular System.

Question 20

Neuromuscular Junction

Answer 20

The communication site between Nervous & Muscular Systems. It is a synapse between the motor neuron and the muscle cell.

Question 21

Motor Unit

Answer 21

One motor neuron and the muscle cell it innervates with.

Question 22

Action Potential

Answer 22

A nerve impulse from the CNS that travels thru the PNS and across the neuromuscular junction into the muscle.

Question 23

Neurotransmitter

Answer 23

Chemical messengers that cross the synapse between neuron & muscle and assist w/ nerve transmission. They are a translation of the nervous system’s electrical impulse that muscle cells can understand & act on.

Question 24

Acetylcholine (ACh)

Answer 24

A neurotransmitter that helps the action potential cross the synapse into the muscle, which initiates the steps in muscle contraction.

Question 25

Sliding Filament Theory

Answer 25

The act of the myofilaments Actin & Myosin sliding past one another to produce a muscle contraction, shortening the entire length of the sarcomere.

Question 26

Excitation-Contraction Coupling: definition & flowchart

Answer 26

The steps in muscle contraction: An Action Potential is released by CNS The AP travels down the motor neuron, which is facilitated by sodium & potassium electrolytes, to the NM junct. Acetylcholine (ACh) is released into the NM junction, which helps the AP cross the synapse into the muscle. The AP travels into the muscle infrastr. stimulating the Sarcoplasmic Reticulum to release the electrolyte calcium. Calcium is then released into the muscle, stimulating a chain of events resulting in Myosin heads binding to Actin. The Myosin heads pull the Actin closer to the Sarcomere center, which slides the overlapping filaments past eachother, thus shortening the entire Sarcomere, known as the Power Stroke.

Question 27

Power Stroke

Answer 27

Contraction of the muscles, in the myofilament Myosin uses ATP to bond with Actin.

Question 28

Type 1 Muscle

Answer 28

Small motor units that innervate small muscle fibers and are fatigue resistant. Comprised of smaller muscles used to stabilize the body in slow long term contractions. Able to do this b/c: More mitochondria, capillaries & myoglobin. Increased o2 delivery. Known as “red fibers” b/c o2.

Question 29

Type 2 Muscles

Answer 29

Large motor units that innervate large muscle fibers and fatigue more quickly. They generate force quicker than Type 1. Comprised of larger muscles responsible for moving the body. Fast Twitch. Fatigues quick due to less mitochondria, myoglobin & capillaries. “White fibers”

Question 30

All or Nothing Principle

Answer 30

Motor units cannot vary the amount of force they generate; they either contract maximally or not at all. Hence, the overall strength of a muscle contraction will depend on the motor unit being recruited (whether the motor unit is small or large & the overall number of motor units that are activated at a given time).

Question 31

Characteristics of muscles involved in fine motor skills vs. those involved in large powerful movements.

Answer 31

Fine motor skills: Each motor unit is assigned fewer muscle fibers to control. Gross motor power: Each motor unit is assigned a larger amount of muscle fibers to control.

Question 32

Type 2a & Type 2x

Answer 32

Type 2x: Truly “fast twitch” Fatigues quickest of all due to low oxidative capacity. Type 2a: Fatigues less faster than Type 2x but still not as resistant as Type 1. Therefore, known as “Intermediate fast-twitch fiber”

Question 33

Muscle Fiber Hierarchy

Answer 33

Type I: Most fatigue resistant b/c more energy related cellular organelles. Type 2: Less resistant due to fewer energy related cellular organelles. Separated into Type 2a & 2x. Since 2x fibers are the least fatigue resistant of all the fibers, 2a is described as “intermediate fast-twitch”

Question 34

Muscle System life course

Answer 34

Peaks between 20 to 30 years old. Stable from 30 to 50. After age 50, mass is lost 1-2% per year. Strength is lost 1.5 to 5% per year.

Question 35

Muscle Anatomy Chart

Answer 35

TBD