Muscular System diseases

Carpal Tunnel Syndrome

Due to a build up of fluid (inflammation) of the tendon from use. Pressure on the median nerve is what causes pain.

Muscular Dystrophy

X-linked disease (from mom) causing a mutation with the gene that makes dystrophin

Resulting in decrease of or no dystrophin, therefore cells are no contracting.

Rigor Mortis

The stiffening of muscle past death due to the lack of ATP to relax the muscle and release the myosin head from the actin.

Myasthenia Gravis

autoimmune disorder resulting in Flaccid paralysis due to Y-shaped antibodies that attach to Ach receptors

Pesticides

Acetylcholinesterase inhibitors. Resulting in Spastic paralysis

Curare

poison on arrow/dart used by indigenous peoples Block Ach receptors resulting Flaccid paralysis

Botulism

bacteria in honey, and when given to babies blocks ACh from being released at the neuromuscular junction. Results in Flaccid paralysis

Tetanus

Toxins from bacteria in rusted metal that suppress the mechanism inhibiting motor neuron activity.

Polio

destroys (LMN) motor neurons in only in the anterior horn of the spinal cord. Resulting in Flaccid paralysis where sensation is intact.

Atrophy

muscle wasting due to little muscle use or malnutrition

Avulsion

muscle tears from tendon OR Tendon tears from bone

Muscle Spasm

Involuntary contraction of skeletal muscle “muscle cramp” often due to overexercise

Sprain

over stretching of a ligament

Strain

over stretching of a tendon/muscle.

non-medical treatment is RICE (rest, ice, compression, elevation)

Contracture

group of muscles stimulated involuntarily into a tetanic contraction by motor neurons.

Ex: epilepsy, seizures

Dupuytren’s Contracture

4th and 5th digit are in a fixed flexion.

Bursitis

inflammation of the bursa

Fasciitis

inflammation of fascia

Tendonitis

inflammation of tendon

Plantar fasciitis

inflammation of fascia on the plantar region commonly due to running

Shin splits

inflammation of tendon on the flexor muscle of the leg, anterior tibia. Commonly due to excess running on uneven surfaces

Myosin

What is the main protein that makes up the thick filament of the sarcomere?

Actin

What is the main protein that makes up the thin filament of the sarcomere?

Dark Myosin

The A band is the ____ band?

a) Light Actin

b) Dark Myosin

Actin

The I band is the entire length of one ____?

a) Actin

b) Myosin

c) Both

It blocks the active sites on actin and prevents myosin heads from binding

What is the function of tropomyosin?

it binds to troponin which opens the myosin binding sites on the actin

What does Ca do tropomyosin?

Contraction

High Ca concentration would indicate _____.

Relaxation

Low Ca concentration would indicate _____.

Actin, ATP

The myosin head has 2 binding sites for ____ and _____.

Actin, tropomyosin

At rest the myosin binding site on ____ is blocked by _____.

Cross-bridge

What is the connection between a myosin head and the active site on a thin filament called?

Myosin heads bind and form a cross-bridge with actin molecules. The myosin heads then pull on the actin molecules causing them to slide along the myosin filaments. Thus, sarcomeres shorten.

How do sarcomeres shorten?

Myosin head releases ADP and Phosphate

what causes the power stoke?

ATP

What causes the myosin head to detach from the actin?

hydrolysis of ATP turning it into ADP and Phosphate

What cocks the myosin head back in place to the initial pre-bonded position?

Dystrophin

Transfers forces of muscle contraction to the CT around the muscle fiber. Links actin to proteins that link it to the endomysium.

Duchenne muscular dystrophy

genetic disorder that causes progressive muscle weakness, primarily affecting boys. It's characterized by the absence of the protein, dystrophin.

commonly exhibits Gower's sign

Gower's sign

a characteristic seen in patients with weakness of the proximal lower extremities, particularly the hip and thigh muscles. It's described as a patient needing to "walk" or "climb" up their legs using their hands to stand up from a squatting position.

Triad

Terminal Cisterna + T-tubules + Terminal Cisterna (portions of the sarcolemma)

Sarcoplasmic reticulum

storage organ for Ca

somatic motor neuron

carries signal that stimulate skeletal muscle

Visceral motor neuron

carries signal that stimulate smooth muscle or gland

-70mV

What charge is resting membrane potential?

-55mV

What is the threshold for the Na gates to open and trigger an AP?

+35mV

What charge does the Na gate shut and the K gates open?

-70mV

At what change do the K gates start to close?

K gates close slowly due to leaky channels

What is the cause of hyperpolarization?

Na⁺K⁺ATPase pump

What restores the ionic balance?

Na 3 out : K 2 inside

What is the ratio the Na⁺K⁺ATPase pump?

ACh

_____ is the neurotransmitter released at presynaptic membrane.

Choline

What is recycled in the neuromuscular junction?

Yes, but it would need be with a strong enough stimulus to get the charge to the threshold. Since the cell is in a relative refractory period.

In the scenario where an action potential has been fired and a cell reached a charge that is less than or equal to -70mV can an action potential occur?

no since the cell is in absolute refractory period.

In the scenario where an action potential has been fired and a cell reached a charge to+15mV can an action potential occur?

no since AP is a all or nothing principal. Unless it reached a charge of -55mV no AP will occur. However the cell is more excitable at -50mV

In the scenario where an a cell reach’s a max charge of -50 mV will an action potential occur?