Aging of the Skeletal System

Aging of the Skeletal System

• Skeletal system comprises 206 bones, accounting for ~50% of body weight.
• The bone matrix is composed of calcium phosphate (non-living).
• Bone tissue itself is living.
• A primary concern with aging is bone brittleness.

Functions of Bone

• Provides a framework for the body
• Offers attachment points for muscles
• Protects vital organs (skull, spinal cord, rib cage)
• Stores calcium, sodium, phosphorus, and potassium
• Bone marrow is the site of blood cell formation.

Bone Modification Throughout Life

• Bones undergo continuous remodeling throughout life.
• Cartilage is replaced by bone tissue through ossification during growth.
• Ossification centers form which leads to the development of bone.
• Osteoblasts are responsible for bone formation.
• Osteoclasts are responsible for bone resorption.

Osteoporosis

• Osteoporosis is characterized by porous bone.
• Bone mass decreases with age, particularly after menopause in women.
• Increased bone resorption rates lead to a loss of calcium and other minerals.
• Estrogen plays a role in osteoblast function, impacting bone density.

Evolution & Osteoporosis

• Human skeletons have become lighter over time.
• Chimp bones have spongy bone structures, while human bones do not.
• Studies suggest that less physical activity, rather than evolution, may be a factor in reduced bone density.

Osteoporosis (Disease of Elderly Women)

• Osteoporosis is significant in elderly women, affecting 65% of women older than 65 years.
• Hip fractures are a significant concern due to high mortality rates following them (25% die in the year following the fracture)
• 80% of elderly women suffering from osteoporosis experience severe mobility issues due to fragility.
• It's a disease marked by reduced bone density and increased risk of fractures.

Older Americans & Falling

• Falls among older Americans (age 65 and older) are a significant concern, as they often result in emergency room visits.
• Older adults are disproportionately affected by falls.

Osteoporosis Prevention & Treatment

• Prevention of osteoporosis can be achieved through diet and exercises like Milk, Ca tablets, and 12 minutes of yoga daily
• Treatment options may include Estrogen Replacement Therapy (ERT)
• Calcium and vitamin D intake should be a concern.

Hip Replacement

• Hip replacement surgery is a major procedure frequently performed on people suffering from severe arthritis.
• Recovery from hip replacement is often challenging.
• Advancements in medical technology have improved hip replacement outcomes, with higher success rates and less pain in the 10-20 years following the procedure.

Arthritis

• Arthritis is an inflammation in joints.
• Different types of Arthritis exist; however some of the most common types include OA (Osteoarthritis) and RA (Rheumatoid Arthritis).
• Osteoarthritis is characterized by the degeneration of articular cartilage, leading to bony spur formation.
• Rheumatoid arthritis is an autoimmune disease affecting the synovial membrane of joints.

Arthritis Treatment

• Non-steroidal anti-inflammatory drugs (NSAIDS) like aspirin and ibuprofen are used to treat inflammation.
• Steroids like prednisone also reduce inflammation.
• Biologic anti-inflammatory drugs target certain inflammatory pathways.
• Surgery is also a treatment option for some cases.

Reduced Mobility with Aging

• Mobility is often reduced with aging due to factors such as musculoskeletal changes and coordination issues.
• Exercises are important to maintain mobility as you age.
• This section generally focuses on the link between age and the inability to move as easily as when younger.

Aging of Muscle

• Muscle composition changes significantly with age resulting in a substantial amount of muscle loss.

Muscle Types

• Skeletal muscles are responsible for voluntary movements and mobility.
• Smooth muscles operate involuntarily; for example, within the digestive system and blood vessels.
• Cardiac muscles form part of the heart and are responsible for the heart's rhythmic pumping.

Muscular System

• The muscular system is made up of 700 skeletal muscles.
• Loss of tone, coordination, and decreased muscle mass are common concerns with aging.
• This section generally focuses on the changes within the muscular system due to aging.

Muscle Cells & Myocytes

• Myocytes, often referred to as muscle fibers, are the fundamental units of muscle tissue.
• Myofibrils within myocytes are the contractile units responsible for muscle movement.
• Myofilaments such as actin and myosin contribute to the overall mechanical function of the muscle.

Skeletal Muscle Contraction

• The neuromuscular junction is the point of contact between nerve and muscle cells, and signals muscle contraction.
• Acetylcholine is the primary neurotransmitter for skeletal muscle contraction.
• The sliding filament theory describes the mechanisms involved in muscle contractions.

Types of Muscle Cells

• Skeletal muscles are composed of slow-twitch, intermediate-twitch and fast-twitch muscle cells.
• These differ in their contraction speeds and fatigue resistance.
• Genetic and exercise factors may impact the percentage of each type of muscle cell.

Skeletal Muscle Problems

• Sarcopenia is a condition marked by age-related loss of skeletal muscle and function.
• Both muscle cross-sectional area and total muscle fibers decrease with age.

Smooth Muscle Features

• Smooth muscles are responsible for involuntary movements (digestion, circulation).
• They lack striations and are less organized than skeletal muscles.
• Examples include the esophagus, stomach, intestine, and blood vessels.

Smooth Muscle Problems

• Diverticulitis and hernias are common smooth muscle-related issues.

Cardiac Muscle Features

• Cardiac muscles are essential for the cardiovascular system.
• These muscles are responsible for the rhythmic contractions that help pump blood.
• They work involuntarily, and intercalated discs help coordinate the function of the different cells.

Cardiac Muscle & Aging

• Heart diseases like coronary artery disease and myocardial infarction become more prevalent with age.
• Left ventricular hypertrophy is a thickening of the left ventricle of the heart due to age and health issues.

Age-Related Changes in Skeletal Muscle

• The strength, endurance, coordination, and reaction time of skeletal muscles decline with age.

How Much Exercise is Enough?

• Daily aerobic exercise with sustained maximum heart rate helps maintain skeletal muscle health and fitness.
• Varying exercises to include aerobic activities such as walking, swimming, or biking are important to engage different muscle groups.

Age-Associated Muscle Disorder (Parkinson's)

• Parkinson's is a disorder resulting from dopamine deficiency, affecting muscle coordination.
• It's characterized by tremors, stiffness, and slow movements/slowness.