musclesun

Which types of muscle can contract without nervous system stimulation?

Smooth and cardiac muscle.

What is the state following death where the body becomes stiff?

Rigor mortis.

Which muscle type is responsible for blood leaving the heart?

Cardiac muscle.

Which muscle type is responsible for raising eyebrows?

Skeletal muscle.

Which muscle type is responsible for blinking eyelids and smiling?

Skeletal muscle.

Which muscle type is responsible for deep inspiration?

Skeletal muscle (as it's a voluntary action).

Which muscle type is responsible for causing goosebumps?

Smooth muscle.

True or False: Chickens need fast twitch fibers to fly long distances.

False. Chickens do not fly long distances.

Describe the characteristics of smooth muscle cells.

Spindle-shaped cells with one centrally located nucleus (wider than tapered ends). They perform peristalsis.

Define peristalsis.

The rhythmic, wave-like contractions of smooth muscle that propel substances through tubular organs, such as the digestive tract.

What is plasticity in the context of smooth muscle?

The ability of smooth muscle to stretch significantly (distend) and then return to its original tension and shape without becoming flabby (e.g., the urinary bladder).

Which type of muscle tissue contains the largest mitochondria?

Cardiac muscle.

Are intercalated discs electrical connectors? Do they unify all muscle cells?

Yes, they are electrical connectors. No, they unify only cardiac muscle cells, not all muscle cells.

Where are intercalated discs found?

Only in cardiac muscle cells (the heart).

What is the primary function of intercalated discs in cardiac muscle?

They connect two cardiac muscle cells together, allowing for synchronized contraction.

Do intercalated discs contain gap junctions?

Yes.

What is the role of gap junctions within intercalated discs?

To facilitate rapid communication and electrical signal transmission between cardiac cells, acting like tunnels.

What term describes a loss of muscle mass, where the muscle size gets smaller?

Atrophy.

What is the physiological reason for breathing heavily after intense exercise?

To repay the oxygen debt (also known as EPOC: Excess Post-exercise Oxygen Consumption), which is needed for tissue recovery and metabolic restoration.

Explain isometric contraction.

A type of muscle contraction where the muscle generates tension but does not change in length, resulting in no movement (e.g., holding a heavy object still).

What is the concentric phase of muscle contraction?

The shortening of a muscle while maintaining tension, a phase of isotonic contraction (e.g., lifting a weight during a bicep curl).

What is the eccentric phase of muscle contraction?

The lengthening of a muscle while maintaining tension, a phase of isotonic contraction (e.g., slowly lowering a weight).

What is the defining characteristic of isotonic contraction?

The muscle changes in length (shortening or lengthening) while maintaining tension, resulting in movement.

Among the following, who would likely have the most mitochondria in their skeletal muscle: a person in hospice, a newborn baby, a sedentary computer programmer, or a 22-year-old soccer player?

A 22-year-old soccer player, due to the continuous energy demands of athletic training.

Which enzyme is responsible for transferring a phosphate group from creatine phosphate (CP) to ADP (adenosine diphosphate) to generate ATP (adenosine triphosphate)?

Creatine Kinase.

What physiological event occurs when calcium dissociates from troponin and is not replaced?

Muscle relaxation, as troponin re-covers the active sites on actin, preventing myosin heads from binding.

What mechanisms cause a relaxed muscle to return to its original length?

1. Gravity. 2. Contraction of opposing muscles (antagonists).

Do actin and myosin 'push' during muscle contraction?

No, actin and myosin only 'pull' on each other during muscle contraction; they do not push.

Which ATP production pathway for skeletal muscle contraction requires a continuous supply of oxygen?

Aerobic respiration.

What phenomenon occurs when a muscle fiber receives subsequent nerve stimuli before it has fully relaxed from a previous twitch, leading to increased contraction strength?

Incomplete tetanus (also known as temporal summation or wave summation).

According to the length-tension relationship, how is maximum tension achieved in sarcomeres?

Maximum tension is achieved when there is an optimal range of overlap between actin and myosin filaments, allowing for the greatest number of cross-bridges to form.