Anatomy and Physiology: Structural Organization

• Anatomy is the study of the body's structure.
• Physiology is the study of how the body functions.
• These two scientific fields are often studied in conjunction because structure and function are closely related.

Levels of Structural Organization

• The human body exhibits several levels of structural organization.
• These levels are: chemical, cellular, tissue, organ, system, and organismal.
• The chemical level consists of atoms and molecules.
• Cells, the basic structural and functional units of an organism, comprise the cellular level.
• The tissue level is made up of groups of similar cells performing specific functions.
• The organ level is composed of two or more different tissues with a specific function.
• The system level is composed of related organs with a common function.
• The organismal level is the complete living organism.

Basic Life Processes

• Several basic life processes differentiate living organisms from nonliving matter.
• These processes are metabolism, responsiveness, movement, growth, differentiation, and reproduction.
• Metabolism includes all the chemical reactions that occur in the body.
• Responsiveness is the ability to detect and respond to environmental changes.
• Movement includes motion of the whole body, individual organs, single cells, and organelles inside cells.
• Growth is an increase in body size.
• Differentiation is the process where unspecialized cells become specialized.
• Reproduction is the formation of new cells or new organisms.

Homeostasis

• Homeostasis: maintaining relatively stable conditions in the body's internal environment.
• This ensures efficient functioning of the body's cells.
• Regulatory systems, especially feedback systems, maintain homeostasis.
• A feedback system's components: receptor, control center, and effector.
• The receptor monitors changes in a controlled condition, sending information to the control center.
• The control center sets the range of acceptable values for a controlled condition, evaluates receptor input, and generates commands.
• The effector, a body structure, receives directives from the control center and produces a response that changes the controlled condition.

Integumentary System

• The integumentary system includes the skin, hair, nails, and associated glands.
• This system protects the body, regulates temperature and detects sensations.

Skeletal System

• The skeletal system consists of bones, cartilage, and joints.
• Functions: support, protection, assists in movement, stores minerals, and produces blood cells.

Muscular System

• The muscular system consists of skeletal muscles.
• Functions: body movements, posture maintenance, and heat production.

Nervous System

• The nervous system includes the brain, spinal cord, nerves, and sensory receptors.
• Functions: controls body, detects sensations, and initiates responses.

Endocrine System

• The endocrine system contains hormone-secreting glands.
• This system regulates diverse body functions.

Cardiovascular System

• The cardiovascular system includes the heart, blood vessels, and blood.
• Functions: transports oxygen, carbon dioxide, nutrients, and wastes; regulates acid-base balance, temperature, and water content of body fluids; defends against disease; and repairs damaged blood vessels.

Lymphatic System and Immunity

• The lymphatic system consists of lymphatic vessels, lymph nodes, and lymphatic tissues.
• Functions: returns proteins and fluid to the blood; carries lipids from the gastrointestinal tract to the blood; and contains sites for B cell and T cell maturation and proliferation to protect against disease.

Respiratory System

• The respiratory system includes the lungs and air passageways.
• It exchanges oxygen and carbon dioxide between air and blood.

Digestive System

• The digestive system includes the gastrointestinal tract and accessory organs.
• Functions: physical and chemical breakdown of food, nutrient absorption, and waste elimination.

Urinary System

• The urinary system consists of the kidneys, ureters, urinary bladder, and urethra.
• Functions: eliminates wastes, regulates blood volume and composition, and helps regulate acid-base balance.

Reproductive Systems

• The reproductive systems consist of the gonads and associated organs.
• Functions: produce gametes, release hormones, and are responsible for reproduction
• In females, it also supports a developing embryo and produces milk.

Cells

• Cells are the basic structural and functional units of the body.
• All living organisms are composed of cells.
• Cells vary widely in size, shape, and function.
• Most human cells range in size from 1 to 100 micrometers in diameter.
• A typical cell has three main parts: the plasma membrane, the cytoplasm, and the nucleus.
• The plasma membrane forms the cell's outer boundary, separating the cell's internal and external environments.
• The cytoplasm is the cellular content between the plasma membrane and the nucleus.
• The nucleus is a large organelle containing the cell's DNA.

Tissues

• Tissues are groups of similar cells performing specific functions.
• The four basic tissue types: epithelial, connective, muscle, and nervous.
• Epithelial tissue covers surfaces, lines cavities and ducts, and forms glands.
• Connective tissue: protection and support, binds organs, stores energy, and provides immunity.
• Muscle tissue is responsible for movement.
• Nervous tissue detects environmental changes and generates electrical signals, activating muscle contractions and gland secretions.

Muscle Tissue

• Muscle tissue is specialized for contraction.
• The three types of muscle tissue: skeletal, cardiac, and smooth.
• Skeletal muscle is attached to bones and is responsible for voluntary movements.
• Cardiac muscle forms the heart and is responsible for pumping blood.
• Smooth muscle is found in the walls of internal organs and is responsible for involuntary movements.

Skeletal Muscle Tissue

• Skeletal muscle tissue consists of long, cylindrical cells called muscle fibers.
• Muscle fibers are multinucleated and have striations.
• Skeletal muscle is responsible for voluntary movements of the body.

Cardiac Muscle Tissue

• Cardiac muscle tissue is exclusively in the heart.
• Cardiac muscle cells are branched and have striations.
• Intercalated discs connect cardiac muscle cells, enabling rapid electrical signal spread.
• Cardiac muscle is responsible for pumping blood.

Smooth Muscle Tissue

• Smooth muscle tissue is in the walls of internal organs, such as the stomach, intestines, and blood vessels.
• Smooth muscle cells are spindle-shaped and lack striations.
• Smooth muscle is responsible for involuntary movements, such as peristalsis and vasoconstriction.

Anatomical Terminology

• Anatomical terminology provides a standardized way of describing body structures and their locations.
• Anatomical position is a standard reference point.
• Anatomical position: body erect, feet flat on the floor, arms at the sides, and palms facing forward.
• Directional terms describe the location of one body part relative to another.
• Superior: toward the head.
• Inferior: away from the head.
• Anterior: toward the front.
• Posterior: toward the back.
• Medial: toward the midline.
• Lateral: away from the midline.
• Intermediate: between two structures.
• Ipsilateral: on the same side of the body.
• Contralateral: on the opposite side of the body.
• Proximal: nearer to the point of attachment.
• Distal: farther from the point of attachment.
• Superficial: toward the surface.
• Deep: away from the surface.

Body Planes and Sections

• Body planes are imaginary flat surfaces passing through the body.
• A sagittal plane divides the body into right and left sides.
• A midsagittal plane divides the body into equal right and left sides.
• A parasagittal plane divides the body into unequal right and left sides.
• A frontal plane divides the body into anterior and posterior portions.
• A transverse plane divides the body into superior and inferior portions.
• An oblique plane passes through the body at an angle.
• Sections are cuts made along a body plane.
• Sagittal sections are cuts made along a sagittal plane.
• Frontal sections are cuts made along a frontal plane.
• Transverse sections are cuts made along a transverse plane.

Body Cavities

• Body cavities: spaces within the body containing internal organs.
• The dorsal body cavity is located near the posterior surface of the body.
• It has two subdivisions: the cranial cavity and the vertebral canal.
• The cranial cavity contains the brain.
• The vertebral canal contains the spinal cord.
• The ventral body cavity is located near the anterior surface of the body.
• It has two subdivisions: the thoracic cavity and the abdominopelvic cavity.
• The thoracic cavity contains the heart, lungs, esophagus, trachea, and major blood vessels.
• The abdominopelvic cavity contains the stomach, intestines, liver, gallbladder, pancreas, spleen, kidneys, urinary bladder, and reproductive organs.

Explore the interconnected fields of anatomy and physiology, focusing on the structural organization of the human body. Learn about the different levels of organization, from chemical to organismal, and their roles. The content describes cells, tissues, organs, and systems.