muscular system

what are the functions of the muscular system?

movement of the body

maintaining posture

generating body heat

plays a role in other body systems

what were Tom’s symptoms?

he didn’t crawl until eighteen months and he fell a lot

what is gower’s sign?

difficulty standing, taking several steps to do so (putting hands on knees to hoist oneself up)

what is a muscle that is composed of many muscle fibers arranged in bundles called?

fascicles

what are the fibers found within muscle cells called?

myofibrils

what do individual muscles that are separated by the fascia form?

tendons

what is fascia?

a dense layer of collagen fibers

what layer surrounds the entire muscle

epimysium

what surrounds the fascicles

perimysium

what surrounds each individual muscle fiber

endomysium

what is the membrane that surrounds the entire muscle fiber?

sarcolemma

what is the inner material surrounding the muscle fibers?

sarcoplasm

what is utilized for transport within a muscle fiber

the sarcoplasmic reticulum

what are parallel muscle fibers within the sarcoplasm called?

myofibrils

what is another way of saying muscle fiber?

muscle cell

which two prefixes are used when something is related to muscles?

myo- and sarco-

what are myofibrils made up of?

myofilaments

what are the two types of myofilaments?

myosin and actin

which is the dark and thick myofilament?

myosin

what type of bands are myosin?

A bands

which is the light, thin myofilament?

actin

what type of bands is actin?

I bands

what is the primary source of energy for muscle cells?

creatine phosphate

what is dystrophin and where is it found in the muscle cell?

a protein

between the sarcolemma and the myofilaments

what was tom’s diagnosis?

duchenne muscular dystrophy (DMD)

how did Tom get his disease?

through a gene mutation

what was tom’s prognosis?

DMD is fatal - muscle weakness eventually affects the heart and diaphragm

what is EXODYS51?

gene therapy that repairs the gene that makes dystrophin for those with a specific mutation (exo 51st)

what is the pectoralis major skeletal muscle’s size and location?

large

in the chest

what is the deltoid skeletal muscle’s shape?

a triangle

what is the extensor digitorum skeletal muscle’s function?

extending digits (fingers and toes)

what is the bisceps brachii skeletal muscle’s number of attachments and location?

two

found in the arm

what does the sternocleidomastoid skeletal muscle attach to?

sternum, clavicle, and mastoid process

what is the external oblique skeletal muscle’s location and direction of fibers?

near the outside of the body

slanted/diagonal

what is the sarcomere?

the region between two z lines

what is the h zone?

the gap between the thin filaments

what is the neuromuscular junction?

where a nerve and muscle fiber come together?

motor end plate

folded area where the muscle and neuron communicate (a synapse but specifically between a neuron and skeletal muscle)

synapse

gap between the neuron and the motor end plate (another word for it is synaptic cleft)

what are synaptic vesicles?

where neurotransmitters are stores before being released

how does the neuron tell the muscle to contract?

by releasing neurotransmitters

what is the neurotransmitter that is primarily used for muscle function?

acetylcholine

which enzyme breaks down acetylcholine?

cholinesterase

what are the steps of muscle contraction?

1) the brain sends a signal to a motor neuron

2) the signal travels down the motor neuron, creating an action potential, which releases acetylcholine

3) the release of acetylcholine causes a depolarization, which allows calcium channels to open up and release calcium

4) calcium binds to the troponin, causing it to change shape and expose the active sites on the actin

5) an ATP molecule binds to the myosin head, and the myosin hydrolyzes it, and the energy of that reaction allows the myosin to change shape and bind onto the actin, forming a cross bridge

6) the ADP and Pi left on the myosin detach, causing a “power stroke” and the myosin slides to the left, shortening the actin

7) an ATP molecule binds onto the myosin, allowing it to detach from the actin and the cycle begins again

what increases the regeneration of ATP?

creatine phosphate

what is the energy that is not used in metabolic processes released as?

heat

what is elevated in people who have suffered heart attacks or have DMD?

creatine kinase

what is a biomarker?

substances that can indicate damage to tissues

what are biomarkers commonly used to detect?

DMD or having a heart attack

what is muscle fatigue?

when the muscle loses the ability to contract after prolonged use

what is a muscle cramp?

a sustained involuntary contraction due to temporary lack of ATP

what does oxygen debt mean and what does it cause?

means a lack of oxygen, which causes lactic acid to accumulate in the muscles, causing soreness

what is hypertrophy?

muscles enlarge

what is atrophy?

muscles become small and weak due to disuse

what is rigor mortis and what causes it?

the stiffening of joins of the body; when an organism cannot produce ATP anymore, the myosin stays attached to the actin and keeps it contracted

what are type 1 muscle fibers?

slow fibers

do type 1 muscle fibers show slow or fast contraction?

slow

what color are type 1 muscle fibers? why?

red; because of myoglobin

do type 1 muscle fibers have a lot of mitochondria or not?

they are rich in mitochondria as they carry out prolonged, slower actions

are type 1 muscle fibers easily fatigued?

no, they are resistant to fatigue

what are type 2 muscle fibers?

fast fibers

do type 2 muscle fibers show a slow or fast contraction?

fast

what color are type 2 muscle fibers? why?

white/pale; because they are rich in glycogen or phosphorylase

do type 2 muscle fibers have a lot of mitochondria or not?

no, they are poor in mitochondria

are type 2 muscle fibers easily fatigued?

yes since they carry out short bursts of activity

what is tetanus caused by?

exposure to the bacteria clostridium tetani

what does tetanus do to the muscular system?

causes cholinesterase to not break down acetylcholine, causing the muscles to repeatedly contract, never relaxing

what is myasthenia gravis?

an autoimmune disease that damages acetylcholine receptors; symptoms include droopy eyes and slurred speech

what is ALS?

disease that causes motor nerves to degenerate and stop sending messages to the muscles, causing atrophy

what is muscular dystrophy?

weakness of muscles; many forms

what is botulinum and what is it produced by?

a poison to the muscular system that is produced by bacteria

what is strychnine and what does it do?

a poison for the muscular system that lowers the threshold for an action potential, making it more likely that muscles will contract

what is curare and what does it do?

a poison of the muscular system that causes flaccidity in skeletal muscle (muscles get paralyzed) by competing with acetylcholine (blocks receptor sites)