Muscles Wk 7 A&P

What factors regulate muscle tension generation?

Frequency, stretching, and other factors.

What are the two types of muscle contraction?

Isotonic and isometric contractions.

What protects muscles from being overstretched or over contracted?

Muscle spindles and Golgi tendon apparatus.

What is the primary function of skeletal muscle?

To assist with locomotion and movement.

How are upper motor neurons involved in muscle control?

They send signals from the brain to activate motor neurons in the spinal cord.

What is the difference between small and large motor units?

Small motor units provide fine control; large motor units generate a lot of force.

What role does ATP play in muscle contraction?

ATP is necessary for contraction and for separating thick and thin filaments.

What is rigor mortis?

A condition where muscle stiffens after death due to lack of ATP.

What causes a muscle twitch?

An increase in tension reaching a peak followed by relaxation.

What happens during the latent period of a muscle twitch?

Electrical activity passes into the muscle to depolarize the membrane.

What determines the relaxation period of a muscle twitch?

The rate at which calcium is removed from the cytoplasmic space.

What is summation in muscle contraction?

Increased muscle tension when subsequent twitches occur before complete relaxation.

What is tetanus in muscle contraction?

A state of sustained contraction where the muscle does not relax between stimuli.

What is the significance of Lorentz's threshold for muscle stimulation?

It's the minimum voltage required to generate a response in muscle fibers.

What is the Q10 law?

An increase in enzymatic activity or metabolic rate for every 10 degrees Celsius rise in temperature.

Define isotonic contraction.

Muscle generates the same tension while shortening.

Define isometric contraction.

Muscle generates tension without changing length.

How does warming up affect muscle function?

Reduces stiffness and prepares muscles for effective contraction.

What are muscle spindles?

Sensory receptors within muscles that detect stretch.

What are Golgi tendon organs?

Sensory receptors that respond to muscle tension and protect against over contraction.

What is the Westphal sign?

A reflex that assesses peripheral nerve damage by tapping the patella.

What type of muscle fibers are most trainable?

Type 2A fibers.

What is hypertrophy?

Increase in muscle size due to growth processes.

What are satellite cells?

Quiescent stem cells that aid in muscle repair and regeneration.

What is the difference between hypertrophy and hyperplasia?

Hypertrophy is an increase in the size of muscle fibers; hyperplasia is an increase in the number of muscle fibers.

What hormonal factor is known to stimulate muscle growth?

Insulin-like growth factor (IGF).

What are the risks associated with long-term steroid use?

Enhanced muscle growth but potential for negative health impacts such as heart disease.

Why is muscle mass important for metabolism?

Muscle is metabolically active and helps regulate energy expenditure.

What happens to metabolic rate as people age?

It generally declines due to loss of muscle mass.

What is sarcopenia?

Age-related loss of muscle mass and strength.

What are motor units?

Groups of muscle fibers innervated by a single motor neuron.

How does aging affect muscle repair?

Decreased efficacy and speed of satellite cell response to injury.

What is the relationship between muscle and obesity?

Muscle loss accelerates with obesity, increasing health risks.

Why is muscle often referred to as a metabolic organ?

It plays a crucial role in energy metabolism and glucose uptake.

How does exercise influence muscle and aging?

Regular exercise can slow muscle loss and improve strength in aging individuals.

What happens to motor neurons with age?

There is a loss of motor neurons, leading to larger but fewer motor units.

What happens to muscle fiber cross-sectional area with hypertrophy?

It increases, generating more force through added sarcomeres in parallel.

What is the role of calcium in muscle contraction?

Calcium binds to troponin, enabling actin-myosin interaction.

What is the peak period of muscle mass gain typically during life?

Around ages 20-30.

What happens to muscle fibers over time due to aging?

They decrease in size and number, leading to decreased strength.

What impact does exercise have on muscle fibers during recovery?

Promotes the activation and proliferation of satellite cells for repair.

What do muscle spindles detect?

The degree of stretch in muscles.

What is rigor mortis caused by?

Lack of ATP preventing muscle relaxation after death.

What is the phenomenon of muscle fatigue largely associated with?

Exhaustion of ATP and accumulation of lactic acid.

What is the primary function of satellite cells in skeletal muscle?

To repair and regenerate muscle tissue.

What leads to an increase in muscle mass following training?

Stimulus from mechanical activity, hormonal signals, and protein intake.

What is one major difference between cardiac muscle and skeletal muscle?

Cardiac muscle fibers are not under voluntary control, whereas skeletal muscle fibers are.

What is meant by the term 'muscle atrophy'?

A decrease in muscle size and strength due to disuse or aging.

What happens to muscle tissue during mechanical stress?

It can lead to hypertrophy where muscle fibers increase in size.

What are the main components affecting the force generation of muscle?

Frequency of stimulation, strength of stimulation, and degree of muscle stretch.

What happens to muscle mass as we age?

Muscle mass generally decreases with age, starting from around age 25, leading to potential physical disabilities.

What is sarcopenia?

Sarcopenia is the age-related loss of muscle mass and strength, characterized by smaller and fewer muscle fibers.

How does exercise impact muscle mass decline in older adults?

Regular exercise can slow the rate of muscle mass decline and help maintain a higher starting muscle mass.

What role do satellite cells play in muscle repair?

Satellite cells help repair muscle after injury, but their ability to sense damage and proliferate decreases with age.

How does aging affect basal metabolic rate?

Basal metabolic rate declines by about 2% every decade after age 25, impacting energy expenditure and fat accumulation.

What is the relationship between muscle mass and obesity?

Increased muscle mass can enhance metabolic rate and reduce the risk of obesity, while obesity accelerates muscle loss.

What caloric deficit is associated with a 2% decline in metabolic rate per decade?

A 2% decline represents roughly 50 calories per day for men and 40 calories for women, equivalent to about 4 pounds of fat per year.

Why is maintaining muscle mass important for glucose metabolism?

Muscle plays a crucial role in glucose uptake; loss of muscle mass can lead to glucose resistance and diabetes.

What impact does being overweight have on aging muscle mass?

Being overweight or obese accelerates the loss of muscle mass with aging, leading to increased frailty and health risks.

How does aging impact motor unit control and muscle function?

As we age, there is a decline in the number of motor units, making them larger and resulting in less control and finesse over muscle function.

What happens to the extensor digitorum muscle as one ages?

The extensor digitorum muscle in the foot tends to degenerate with age, affecting performance in sports like basketball.

What is the significance of motor unit heterogeneity among individuals?

At any age, individuals show great variation in motor unit numbers; those who exercise regularly often maintain higher motor unit counts.

What is the difference between muscle fiber atrophy and loss of muscle fibers with age?

Muscle fiber atrophy refers to the shrinking of existing fibers, which can be slowed by exercise, while the loss of muscle fibers is much harder to replace.

What are the consequences of fewer motor neurons with age?

The loss of motor neurons leads to reinnervation into existing motor units, resulting in larger motor units with decreased control.

What injury risks increase as we age during exercise?

Aging increases the likelihood of muscle injuries, prolonged healing times, and severe, often irreversible muscle damage.

How do satellite cells respond to muscle injury as one ages?

Satellite cells show decreased ability to sense damage, migrate slower to injury sites, and have impaired dividing ability, which affects muscle repair.

How does the aging process affect exercise performance in sports?

Sports requiring finesse, like basketball, are negatively impacted by age due to reduced motor control resulting from motor unit changes.

Why is maintaining muscle mass critical for older adults?

Maintaining muscle mass is vital to prevent physical disability, falls, and the associated health risks that come with aging.

What is the effect of exercise on the aging process of muscle mass?

Regular exercise can significantly slow the decline of muscle mass and improve overall muscle function as one ages.