Anatomy

Introduction to Anatomy and Physiology

• Anatomy vs. Physiology

  • Anatomy: Study of the structure of body parts and their relationships to one another.

  • Physiology: Study of the functions of the body's systems and mechanisms.

Levels of Organization in the Human Body

1. Chemical Level: Atoms combine to form molecules.

2. Cellular Level: Cells are made up of molecules.

3. Tissue Level: Groups of similar cells that have a common function.

4. Organ Level: Contains two or more types of tissues.

5. Organ System Level: Organs that work closely together.

6. Organism Level: The human organism is made up of many organ systems.

Body Systems and Their Functions

• Acronym to remember the 11 body systems:

  • Integumentary

  • Skeletal

  • Muscular

  • Nervous

  • Endocrine

  • Cardiovascular

  • Lymphatic

  • Respiratory

  • Digestive

  • Urinary

  • Reproductive

Anatomical Position and Directional Terms

• Anatomical Position: Standard position of the body used as a reference point.

  • Body standing upright, facing forward, arms at the side, palms facing forward.

• Key Directional Terms:

  • Superior: Above.

  • Inferior: Below.

  • Anterior (ventral): Front.

  • Posterior (dorsal): Back.

  • Medial: Closer to the midline.

  • Lateral: Further from the midline.

  • Proximal: Closer to the trunk of the body.

  • Distal: Further from the trunk.

Body Planes

• Three Body Planes:

  • Sagittal Plane: Divides the body into left and right.

  • Frontal (Coronal) Plane: Divides the body into anterior and posterior.

  • Transverse Plane: Divides the body into superior and inferior.

Major Body Cavities

1. Dorsal Cavity: Protects the nervous system. Includes cranial and spinal cavities.

2. Ventral Cavity: Houses the internal organs. Divided into thoracic cavity and abdominopelvic cavity.

Skeletal System

• Five Types of Bones:

  1. Long Bones: Longer than they are wide (e.g., femur).

  2. Short Bones: Nearly equal in length and width (e.g., carpals).

  3. Flat Bones: Thin and flat (e.g., sternum).

  4. Irregular Bones: Complex shapes (e.g., vertebrae).

  5. Sesamoid Bones: Formed within tendons (e.g., patella).

• Anatomical Features of a Long Bone:

  • Epiphysis: Ends of a long bone (proximal and distal).

  • Diaphysis: Main shaft of the bone.

  • Medullary Cavity: Hollow center of the diaphysis containing bone marrow.

  • Epiphyseal Plate: Growth plate for lengthening the bone.

  • Articular Cartilage: Covers the ends of the bones.

  • Red Bone Marrow: Site of blood cell production.

  • Yellow Bone Marrow: Fat storage area.

  • Periosteum: Tough outer covering of the bone.

  • Spongy Bone: Cancellous bone, lighter and less dense.

  • Compact Bone: Dense outer layer of bone.

Bone Cell Types

1. Osteoblasts: Bone-forming cells.

2. Osteoclasts: Bone-resorbing cells.

3. Osteocytes: Mature bone cells involved in regulating bone maintenance.

Bone Growth

• Length Growth: Occurs at the epiphyseal plates during childhood and adolescence.

• Appositional Growth: Increase in bone thickness by adding new layers of bone at the surface.

Calcium Regulation and Hormones

• Parathyroid Hormone (PTH): Regulates low blood calcium levels by stimulating osteoclasts, increasing bone resorption and releasing calcium into the bloodstream.

• Calcitonin: Hormone that helps lower high blood calcium levels by inhibiting osteoclast activity and promoting calcium deposition in bones.

Ossification and Hemopoiesis

• Ossification: The process of bone formation, particularly during fetal development and growth.

• Hemopoiesis: The formation of blood cells in the bone marrow.

Bone Repair

• Steps in Bone Repair:

  1. Hematoma formation (blood clot).

  2. Fibrocartilaginous callus formation (soft callus).

  3. Bony callus formation (hard callus).

  4. Bone remodeling (restoring original shape).

Joint Types

• Three Types of Joints:

  1. Fibrous Joints: Immovable (e.g., sutures in skull).

  2. Cartilaginous Joints: Slightly movable (e.g., intervertebral discs).

  3. Synovial Joints: Freely movable joints with a synovial cavity (e.g., knee).

Synovial Joints

• Six Types of Synovial Joints:

  1. Hinge Joints: Elbow, knee.

  2. Ball-and-Socket Joints: Shoulder, hip.

  3. Pivot Joints: Atlantoaxial joint (neck).

  4. Condyloid Joints: Wrist joint.

  5. Saddle Joints: Thumb joint.

  6. Plane Joints: Intercarpal joints.

Muscular System

• Three Types of Muscle Tissue:

  1. Skeletal Muscle: Voluntary, striated muscles attached to bones.

  2. Cardiac Muscle: Involuntary, striated muscles found in the heart.

  3. Smooth Muscle: Involuntary, non-striated muscles found in hollow organs.

Muscle Anatomy

• Key Muscle Anatomy Terms:

  • Fascicle: Bundle of muscle fibers.

  • Epimysium: Connective tissue surrounding the entire muscle.

  • Perimysium: Connective tissue surrounding each fascicle.

  • Endomysium: Connective tissue surrounding each muscle fiber.

• Myofilament Diagram:

  • Actin: Thin filament.

  • Myosin: Thick filament.

  • Sarcomere: Contractile unit of muscle fiber.

Muscle Function

• Origin vs. Insertion:

  • Origin: Attachment to the stationary bone.

  • Insertion: Attachment to the movable bone.

• Muscle Roles in Movement:

  • Prime Mover: Muscle primarily responsible for movement.

  • Antagonist: Muscle that opposes the prime mover.

Rigor Mortis

• Rigor Mortis Explanation:

  • Occurs after death; muscles remain contracted.

  • Cause: Lack of ATP production, leading to sustained cross-bridging between actin and myosin filaments.

  • Muscles remain contracted until tissue breakdown allows them to release.

Nervous System Organization

• Chart Organization of the Nervous System:

  • Central Nervous System (CNS): Brain and spinal cord.

  • Peripheral Nervous System (PNS): All nerves not in the brain or spinal cord.

• Neuroglia in the CNS: Functions include:

  • Astrocytes: Support and maintain the blood-brain barrier.

  • Microglia: Immune defense in the CNS.

  • Oligodendrocytes: Produce myelin in the CNS.

  • Ependymal cells: Line cavities in the CNS.

• Neuroglia in the PNS: Functions include:

  • Schwann cells: Produce myelin around peripheral nerves.

  • Satellite cells: Support neuronal cell bodies in the PNS.

Neuron Anatomy

• Labeling of Neuron Parts:

  • Dendrites: Receive signals from other neurons.

  • Myelin Sheath: Insulates axons to increase conduction speed of impulses.

  • Cell Body: Contains nucleus and organelles.

  • Axon: Transmits impulses away from the cell body.

  • Nodes of Ranvier: Gaps in the myelin sheath that facilitate the rapid conduction of impulses.

  • Axon Terminals: Release neurotransmitters into the synapse.

Nerve Impulse Transmission

• Steps of Nerve Impulse Transmission:

  1. Resting Potential: No signal; neuron is polarized.

  2. Depolarization: Sodium channels open, Na+ enters rapidly; the neuron's membrane potential becomes positive.

  3. Repolarization: Potassium channels open; K+ exits, restoring the negative charge inside the neuron.

  4. Sodium-Potassium Pump: Restores resting potential by pumping Na+ out and K+ in.

Brain Structure and Function

• Three Major Layers of the Brain:

  1. Dura Mater: Tough outer layer.

  2. Arachnoid Mater: Web-like middle layer.

  3. Pia Mater: Delicate inner layer that clings to the brain's surface.

• Four Lobes of the Brain and Their Functions:

  1. Frontal Lobe: Responsible for reasoning, planning, parts of speech, movement, emotions, and problem-solving.

  2. Parietal Lobe: Processes sensory information such as touch, temperature, and pain.

  3. Temporal Lobe: Involved in perception and recognition of auditory stimuli, memory, and speech.

  4. Occipital Lobe: Responsible for visual processing.

Chronic Traumatic Encephalopathy (CTE)

• Molecular Level Changes in CTE:

  • Caused by repeated head injuries. Leads to tau protein accumulation.

  • Effects on Brain Matter: Tau protein forms tangles that disrupt normal brain function.

  • Cell Type Involved: Neurons.

  • Behavioral Changes: Can lead to memory loss, confusion, depression, and other cognitive impairments.