MUSCULAR SYSTEM

·  The muscular system is a network of tissue in the human body responsible for movement, posture support & heart generation.

·  The muscular system is complex and vital part of human body.

·   Muscular system play an vital role in body

·   Muscle are composed of smaller unit called myofibrils

·   The muscular system depend on the circulatory system to provide oxygen, nutrients & remove waste product.

NOTE: 

• Sarcomeres- smaller unit of myofibrils

• It allow the interaction between actin & myosin proteins allows for muscle contraction.

TYPES OF MUSCLES

1. Skeletal muscle:

· Skeletal muscle attached to bones that enable voluntary movement.

· Structure- it is composed of long cylindrical muscle fibers bundled together & connect the bone via tendons

· Function- generate force for action like walking, running, & lifting object.

2. Smooth muscle:

·  Muscle found in the wall of hallow organs blood vessels and certain body system

·  Structure- smooth in appearance

·  Function- involuntary contraction to regulate movement within organ such as digestion and blood flow.

3. Cardiac muscle:

· They are involuntary muscle that form the wall of the heart chambers.

· Structure- striated appearance like skeletal muscles, interconnected by intercalated disc

·  Function- involuntary contraction to pump blood efficiency

BLOOD SUPPLY

1. Arterial blood supply:

·   Oxygen-rich blood is pumped from the heart through large arteries.

·   Branching off from these large arteries are smaller arterioles, which further divide into a dense network of capillaries within muscle tissue.

2.     Capillary:

·   Capillaries are tiny thin-walled blood vessels that penetrate deep into muscle tissue.

·   They have a large surface area and are in close proximity to muscle cells.

·    As blood flows through the capillaries oxygen & nutrients diffuse from the blood into the interstitial fluid surrounding muscle cells.

·   Simultaneously, waste products such as carbon dioxide & metabolic by-products diffuse from the interstitial fluid into the bloodstream.

3.     Oxygen and nutrient delivery:

·  Oxygen diffuses from the capillaries into muscle cells, where it is used in cellular respiration to produce energy (ATP) for muscle contraction.

·  Nutrients such as glucose, amino acids, and fatty acids are also transported from the capillaries into muscle cells to support energy production and repair.

4.     Waste removal:

·  Carbon dioxide diffuses from muscle cells into the bloodstream through capillary walls.

·  Other waste products generated during muscle activity, such as lactic acid & urea, are also removed from muscle tissue through capillary exchange.

5.     Venous return

·  Deoxygenated blood now laden with waste products is collected by venules, which merge to form larger veins.

·  Veins transport this deoxygenated blood back to the heart and lungs for re-oxygenation and removal of waste products.

·  The cycle repeats as oxygenated blood is pumped out from the heart to supply muscles during ongoing activity.

6.     Regulation:

·  Blood flow to muscles is regulated by various factors, including neural signals, local metabolic demands, and hormonal influences.

MUSCLE CONTROL AND COORDINATION

·  Nerve & motor neuron that control muscle contraction

·  Transmit electrical signals from the brain & spinal cord to the muscle

Interaction with circulatory system

·  Muscle rely on the circulatory system for oxygen, nutrients & waste removal.

FUNCTION

The muscular system perform several essential function in human body.

1. Movement:

·  It enable movement

2. Posture support:

·  Muscle play a crucial role in maintain posture & stability

·  Muscle provide strength & tension to keep the body aligned & prevent stouching or collapsing.

3. Heat generation:

·  Muscle contraction generate heat contributing to the regulation of body temperature

·  When muscle contract energy is produced & some of it is converted into heat.

4. Joint stability:

·  Joint provide support & stability to prevent dislocation & ensure proper joint alignment

·  Strong & well conditioned muscle play a crucial role in joint stability & stability & preventing injury

5. Protection:

·  Muscle especially in abdominal & pelvic regions help protect internal organ & external impact or injury.

6. Circulation assistance:

·  Smooth muscle found in blood vessels assist in regulating blood flow & maintaing blood pressure.

WASTING AND DEGENRATING OF MUSCLE

·  Wasting & degeneration of muscle refers to the loss of muscle mass & strength

·  These condition can due to various factor & can have significant implication for indivisual mobility strength & overall health.

Muscle wasting (muscle atrophy)

·  Muscle wasting also called muscle atrophy

·  It refers to the shrinking or reduction in the size of muscle tissue

·  These condition arise when there is decrease in muscle protein synthesis or an increase in muscle protein decrease

·  Muscle atrophy is classified into two types

a. Muscle atrophy-  It occur when muscle are not regularly used or subjected to prolonged immobilization during inactivity extended bed rest or limb immobilization due to injury.

b. Neurogenic atrophy- It is caused by damage or impairment of the nerve that control muscle function.

·  Neurological condition such as spinal cord injury, peripheral neuropathy or motor neuron disease.

Degeneration of muscle

·  It refers to the deterioration or breakdown of muscle tissue

·  This condition occur with certain disease genetic disorder etc.

a. Muscular dystrophy- It is a group of genetic disorder characterized by progressive muscle degeneration & weakness.

• Duchenne muscular dystrophy (DMD) is one of the most common type

b. Sarcopenia- It refer to the age related loss of muscle mass strength & function.

• It influenced by factor such as hormonal changes decreased physical activity inadequate nutrition & chronic disease.

c. Cachexia- It is a severe form of muscle wasting that occur in the advanced stages of certain chronic illness, such as cancer, HIV/AIDS or congestive heart failure.