Phys M7 Muscular + Skeletal Systems

3 Muscle Types:

Skeletal, smooth, cardiac

What are the major functions of skeletal muscles?

• Movement Production: Pull on bones via tendons to produce voluntary movements and fine motor skills.

• Posture Maintenance: Continuously contract to maintain body position and support the spine.

• Support of Soft Tissues: Protect and cushion internal organs and help maintain body shape.

• Guarding Entrances and Exits: Sphincter muscles regulate the passage of food, urine, and feces.

• Thermoregulation (Heat Production): Muscle contractions generate heat; shivering helps warm the body.

• Energy Storage: Store glycogen, which serves as an energy reserve during exercise.

• Venous Return: Muscle contractions act as a muscle pump, helping return blood to the heart and preventing blood pooling.

How do skeletal muscles contribute to overall health and bodily processes?

Skeletal muscles are essential for movement, posture, organ protection, regulation of body openings, heat production, energy storage, and maintaining circulation, making them crucial for both everyday activities and vital physiological functions.

What are the major functions of smooth muscle?

Smooth muscle performs involuntary movements and regulates many internal body functions, including:

• Regulation of blood vessel diameter: Controls vasoconstriction and vasodilation, affecting blood pressure and blood flow.

• Movement of food through the digestive tract: Performs peristalsis to move food and aid digestion.

• Control of airway diameter: Regulates airflow in the lungs through constriction and dilation.

• Uterine contractions: Produces contractions during childbirth (parturition).

• Urine flow control: Propels urine through the ureters and helps regulate bladder emptying via the internal sphincter.

• Regulation of pupil size: Controls miosis (constriction) and mydriasis (dilation) in response to light.

• Goosebumps: Arrector pili muscles contract to raise hairs in response to cold or emotions.

• Movement of reproductive tract contents: Helps transport eggs through the fallopian tubes and contributes to ejaculation in males.

What are the major functions of cardiac muscle?

Cardiac muscle is found only in the heart and is responsible for:

• Pumping blood throughout the body to deliver oxygen and remove wastes.

• Rhythmic and involuntary contractions controlled by the heart's pacemaker cells.

• Maintaining the heartbeat through coordinated diastole (relaxation) and systole (contraction).

• Adapting to increased demands via the Frank-Starling mechanism, producing stronger contractions when the heart fills with more blood.

• Endurance and resistance to fatigue due to its rich blood supply and abundant mitochondria.

• Self-excitability and automaticity, generating its own electrical impulses through the SA node, with the AV node, bundle of His, and Purkinje fibers coordinating contraction.

• Ensuring blood circulation and oxygen delivery to tissues.

• Protection against overstretching through intercalated discs, which contain gap junctions and desmosomes that allow cardiac muscle cells to contract as a unit.

What makes cardiac muscle unique?

Cardiac muscle is unique because it performs continuous, rhythmic, involuntary contractions, possesses automaticity (self-generated electrical impulses), is highly resistant to fatigue, and uses intercalated discs to coordinate contractions and resist overstretching, ensuring constant blood circulation necessary for life.