Anatomy & Physiology Study Guide: Skeletal, Muscular, Cardiovascular, and Blood Systems

Chapter 6: The Skeletal System

Osteoporosis: Causes and Prevention

Osteoporosis is a condition characterized by decreased bone mass and increased risk of fractures. It is especially common in postmenopausal women due to hormonal changes.

• Causes: Decreased estrogen (especially after menopause), inadequate calcium/vitamin D intake, sedentary lifestyle, genetics.

• Preventative Measures: Weight-bearing exercise, adequate calcium and vitamin D, medications (e.g., bisphosphonates), hormone replacement therapy (in some cases).

• Example: Postmenopausal women are at higher risk due to reduced estrogen levels.

Epiphyseal Plate and Hormonal Regulation

The epiphyseal plate (growth plate) is a region of cartilage in growing bones where lengthening occurs. Hormones regulate its activity.

• Growth Hormone (GH): Stimulates general growth, including at the epiphyseal plate.

• Thyroid Hormone: Modulates growth hormone activity and ensures proper skeletal development.

• Sex Hormones (Estrogen & Testosterone): Promote growth during puberty, then cause closure of the plate, ending growth.

Functions of the Skeletal System

• Support: Provides structural framework for the body.

• Protection: Shields vital organs (e.g., skull protects brain).

• Movement: Acts as levers for muscles.

• Mineral Storage: Reservoir for calcium and phosphorus.

• Blood Cell Production: Hematopoiesis in red bone marrow.

• Triglyceride Storage: In yellow bone marrow.

Bone Cells: Osteoblasts vs. Osteoclasts

• Osteoblasts: Bone-forming cells; synthesize bone matrix.

• Osteoclasts: Bone-resorbing cells; break down bone matrix, releasing calcium.

• Comparison: Osteoblasts build bone, osteoclasts break it down.

Hormonal Regulation of Blood Calcium

• Parathyroid Hormone (PTH): Increases blood calcium by stimulating osteoclasts, increasing intestinal absorption, and reducing renal excretion.

• Calcitonin: Lowers blood calcium by inhibiting osteoclasts and promoting calcium deposition in bone.

Spongy vs. Compact Bone

• Spongy Bone: Contains trabeculae (lattice-like structures), found at ends of long bones and inside flat bones.

• Compact Bone: Dense, forms outer layer of bones, provides strength.

• Example: The femur's epiphysis contains spongy bone; its diaphysis is mostly compact bone.

Chapter 9: Joints (Articulations)

Classification of Joints

Joints are classified both structurally and functionally.

• Structural Classification: Based on material binding bones and presence of joint cavity:

  • Fibrous (e.g., sutures)

  • Cartilaginous (e.g., intervertebral discs)

  • Synovial (e.g., knee, shoulder)

• Functional Classification: Based on movement:

  • Synarthrosis (immovable)

  • Amphiarthrosis (slightly movable)

  • Diarthrosis (freely movable)

Joint Anatomical Terms

• Examples: Articular cartilage, joint capsule, synovial membrane, ligaments, bursae.

• Application: Understanding these terms is essential for describing joint structure and function.

Stability vs. Mobility in Joints

• Multiaxial Joints: Allow movement in multiple planes (e.g., shoulder, hip).

• Trade-off: Increased mobility leads to decreased stability, making these joints more prone to injury.

• Example: The shoulder joint is highly mobile but easily dislocated.

Chapter 10: Muscle Tissue

Connective Tissue Wrappings

• Endomysium: Surrounds individual muscle fibers.

• Perimysium: Surrounds bundles of fibers (fascicles).

• Epimysium: Surrounds the entire muscle.

• Fascicle: Bundle of muscle fibers within a muscle.

Rigor Mortis

• Definition: Stiffening of muscles after death due to lack of ATP, which prevents detachment of myosin from actin.

Sarcoplasmic Reticulum (SR)

• Function: Stores and releases calcium ions, which are essential for muscle contraction.

Functional Units of Skeletal Muscle

• Sarcomere: The basic contractile unit, defined by Z-disks; contains actin and myosin filaments.

T Tubules

• Function: Invaginations of the sarcolemma that transmit action potentials into the muscle fiber, ensuring coordinated contraction.

Properties of Muscle Tissue

• Excitability: Ability to respond to stimuli.

• Contractility: Ability to shorten forcibly.

• Extensibility: Ability to be stretched.

• Elasticity: Ability to return to original length after stretching.

Sarcomere Structure

• Z disk: Defines boundaries of a sarcomere.

• A band: Dark region; length of thick filaments.

• I band: Light region; thin filaments only.

• H zone: Central region of A band; thick filaments only.

Chapter 18: Blood and Hematology

White Blood Cell (WBC) Types and Functions

• Neutrophils: Phagocytize bacteria.

• Lymphocytes: Immune response (B and T cells).

• Monocytes: Become macrophages; phagocytosis.

• Eosinophils: Combat parasites, modulate allergic responses.

• Basophils: Release histamine; involved in inflammation.

Erythropoietin

• Function: Hormone produced by kidneys that stimulates red blood cell production in bone marrow.

Centrifugation and Hematocrit

• Definition: Centrifugation separates blood components by density to determine hematocrit (percentage of RBCs in blood).

Erythrocyte Properties

• Biconcave Shape: Increases surface area for gas exchange.

• Lack of Organelles: Maximizes space for hemoglobin.

• Anaerobic Metabolism: Erythrocytes generate ATP without using oxygen, preserving oxygen for delivery.

Anemias: Causes and Types

• Sickle Cell Anemia: Abnormal hemoglobin causes RBCs to sickle, leading to blockages and hemolysis.

• Pernicious Anemia: Vitamin B12 deficiency impairs RBC production.

• Other Types: Iron-deficiency, aplastic, hemolytic anemias.

Hemoglobin Structure and Oxygen Transport

• Structure: Four polypeptide chains, each with a heme group containing iron.

• Oxygen Binding: Each hemoglobin molecule can carry up to four oxygen molecules.

Diapedesis

• Definition: The process by which WBCs move out of blood vessels into tissues ("foot" refers to the cell's movement).

Clotting Factors and Disorders

• Hemophilia: Lack of specific clotting factors leads to excessive bleeding.

• Result: Inability to form stable blood clots.

Chapter 19: The Heart and Circulation

Ventricular Wall Thickness

• Left Ventricle: Thicker wall to pump blood throughout the systemic circulation (higher pressure).

• Right Ventricle: Thinner wall; pumps blood to the lungs (lower pressure).

Pulmonary Circulation and Blood Flow

• Pulmonary Arteries: Carry deoxygenated blood from right ventricle to lungs.

• Pulmonary Veins: Carry oxygenated blood from lungs to left atrium.

• Blood Flow Pathway: Right atrium → right ventricle → pulmonary arteries → lungs → pulmonary veins → left atrium → left ventricle → aorta → body.

Heart Location and Pericardium

• Mediastinum: Central compartment of thoracic cavity where the heart is located.

• Pericardial Cavity: Space between the parietal and visceral layers of the pericardium, containing lubricating fluid.

Foramen Ovale

• Definition: Fetal opening between right and left atria; closes after birth to become the fossa ovalis.

Oxygenation of Blood in the Heart

• Deoxygenated Blood: Right side of heart, pulmonary arteries.

• Oxygenated Blood: Left side of heart, pulmonary veins, systemic arteries.

Coronary Circulation

• Coronary Arteries: Supply oxygenated blood to the myocardium (heart muscle).