BMS Muscle

Study Notes

Muscle comprises 40% of an individual's body weight.
Defined as a band of fibrous tissue capable of contraction, enabling movement or maintaining body positions.

Muscle cells consist of myofibrils, which are the contractile threads within muscle tissue.
Myofibrils span the entire length of a muscle fiber.
The sarcomere is the basic structural unit of muscle, formed by fibrous proteins that create alternating dark and light bands visible under a microscope.

Muscle contractions rely on Adenosine Triphosphate (ATP), a chemical energy source.
ATP is generated from the metabolism of food, which is converted into chemical energy.

Lever systems coordinate bones and muscles to produce movement.
Two primary functions of lever systems:
- Generate muscular effort to overcome loads.
- Increase the speed of movements.

Maintaining a stable body temperature is essential for healthy survival, facilitated by heat production from muscles.

Cardiac Muscle:
- Exclusively located in the heart.
- Contracts synchronously to pump blood throughout the circulatory system.
Skeletal Muscle:
- Connected to bones, facilitating voluntary movements controlled by the somatic nervous system.
Smooth Muscle:
- Present in organs like the stomach, intestines, and blood vessels.
- Functions automatically under involuntary control without conscious effort.

Movement:
- Muscles contract and relax to facilitate voluntary and involuntary movements.
- During contraction, muscles shorten forcefully while lengthening passively.
Posture:
- Muscles stabilize bones, helping maintain body posture and balance.
- Tonic contractions provide muscle tone, keeping the head and body upright.
Temperature Regulation:
- Muscles contribute to thermoregulation, maintaining the body’s temperature.
Energy Utilization:
- Convert chemical energy into mechanical energy.
- Store essential nutrients, including carbohydrates and amino acids.
Blood Circulation:
- Cardiac muscles are responsible for pumping blood, vital for oxygenating cells.
Digestion:
- Smooth muscles contract to propel food and waste through the digestive tract.
Blood Pressure Regulation:
- Smooth muscles in arteries and veins assist in regulating blood pressure.
Vision:
- Eye muscles, a combination of skeletal and smooth muscles, work together to support vision.
Urination:
- Muscles coordinate with nerves to control the retention and release of urine from the bladder.

Extensibility:
- The capacity of a muscle to be stretched without damage.
Excitability:
- The ability of a muscle to respond to a stimulus, leading to contraction.
Contractility:
- Muscles can produce forceful contractions, shortening in response to stimuli.
Elasticity:
- Muscles can return to their original length after being stretched, like an elastic band.