Introduction to Human Anatomy

• Human anatomy is the scientific study of the structure of the human body.
• It examines the body's parts, their locations, and their relationships to each other.
• Anatomy provides a foundation for understanding how the body functions in health and disease.
• Anatomy is broadly divided into macroscopic (gross) anatomy and microscopic (histology) anatomy.

Macroscopic Anatomy

• Macroscopic anatomy, also known as gross anatomy, is the study of anatomical structures that can be seen with the naked eye.
• Approaches to gross anatomy include systemic and regional approaches.
• Systemic anatomy studies the body by organ systems (e.g., skeletal, muscular, nervous, cardiovascular).
• Regional anatomy studies the body by regions (e.g., head, neck, thorax, abdomen).
• Surface anatomy studies internal structures as they relate to the skin surface.
• Clinical anatomy focuses on anatomical features that are important for medical practice.

Microscopic Anatomy

• Microscopic anatomy, also known as histology, examines structures that cannot be seen without magnification.
• It involves the use of microscopes to study tissues and cells.
• Histology is essential for understanding the microscopic organization of organs and tissues.
• Cytology is the study of cells, including their structure, function, and pathology.

Anatomical Terminology

• Anatomical terminology provides a standardized language for describing the human body.
• It ensures clarity and precision in communication among healthcare professionals and scientists.
• Anatomical position is a standard reference point: body erect, feet slightly apart, palms facing forward.
• Directional terms describe the location of structures relative to each other.
• Superior (cranial): toward the head end or upper part of a structure or the body; above.
• Inferior (caudal): away from the head end or toward the lower part of a structure or the body; below.
• Anterior (ventral): toward or at the front of the body; in front of.
• Posterior (dorsal): toward or at the back of the body; behind.
• Medial: toward or at the midline of the body; on the inner side of.
• Lateral: away from the midline of the body; on the outer side of.
• Intermediate: between a more medial and a more lateral structure.
• Proximal: closer to the origin of the body part or the point of attachment of a limb to the body trunk.
• Distal: farther from the origin of a body part or the point of attachment of a limb to the body trunk.

Body Planes

• Sagittal plane: divides the body into right and left parts.
• Midsagittal (median) plane: sagittal plane that lies exactly in the midline.
• Frontal (coronal) plane: divides the body into anterior and posterior parts.
• Transverse (horizontal) plane: divides the body into superior and inferior parts.
• Oblique section: cuts made diagonally.

Body Cavities

• Body cavities are spaces within the body that house internal organs.
• They protect organs and allow for movement and expansion.
• The dorsal body cavity includes cranial cavity (brain) and vertebral cavity (spinal cord).
• The ventral body cavity includes thoracic cavity (heart and lungs) and abdominopelvic cavity (abdominal and pelvic organs).
• The thoracic cavity is separated from the abdominopelvic cavity by the diaphragm.
• Serous membranes line the ventral body cavity and cover its organs.
• Parietal serosa lines the cavity walls.
• Visceral serosa covers the organs.

Skeletal System

• The skeletal system provides support, protection, and movement.
• It consists of bones, cartilage, joints, and ligaments.
• Bones are living organs made of bone tissue, cartilage, and connective tissue.
• Functions of the skeletal system include support, protection, movement, mineral storage, blood cell formation (hematopoiesis), and energy storage.
• Bones are classified by shape: long, short, flat, and irregular.
• Long bones have a shaft (diaphysis) and two ends (epiphyses).
• Short bones are cube-shaped.
• Flat bones are thin, flat, and often curved.
• Irregular bones have complex shapes.
• Bone markings include projections, depressions, and openings.
• Examples include condyles, facets, heads, processes (projections), fossae, and foramina.

Muscular System

• The muscular system is responsible for movement, posture, and heat production.
• It consists of skeletal muscles, smooth muscles, and cardiac muscle.
• Skeletal muscles attach to bones and produce voluntary movements.
• Smooth muscles line the walls of internal organs and produce involuntary movements.
• Cardiac muscle forms the heart wall and pumps blood.
• Functions of the muscular system include movement, maintaining posture, stabilizing joints, and generating heat.
• Skeletal muscles are composed of muscle fibers, connective tissue, blood vessels, and nerves.
• Muscles attach to bones directly or indirectly via tendons or aponeuroses.
• Muscles produce movement by contracting, which pulls on bones.
• Muscle actions include prime movers (agonists), antagonists, synergists, and fixators.

Nervous System

• The nervous system controls and coordinates bodily functions.
• It consists of the brain, spinal cord, nerves, and sensory receptors.
• The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS).
• The CNS consists of the brain and spinal cord.
• The PNS consists of nerves that extend from the brain and spinal cord.
• Functions of the nervous system include sensory input, integration, and motor output.
• Sensory input: gathering information from sensory receptors.
• Integration: processing and interpreting sensory input.
• Motor output: effecting a response by activating muscles or glands.
• Nervous tissue consists of neurons (nerve cells) and neuroglia (supporting cells).
• Neurons transmit electrical signals.

Endocrine System

• The endocrine system regulates bodily functions through hormones.
• It consists of glands that secrete hormones into the bloodstream.
• Hormones travel through the blood to target cells, where they exert their effects.
• Major endocrine glands include the pituitary gland, thyroid gland, adrenal glands, pancreas, and gonads.
• Functions of the endocrine system include regulating growth, metabolism, reproduction, and stress responses.
• Hormones are classified as amino acid-based hormones or steroids.

Cardiovascular System

• The cardiovascular system transports blood, nutrients, oxygen, and carbon dioxide.
• It consists of the heart, blood vessels, and blood.
• The heart pumps blood through the blood vessels.
• Blood vessels include arteries, veins, and capillaries.
• Arteries carry blood away from the heart.
• Veins carry blood toward the heart.
• Capillaries are the smallest blood vessels, where exchange of nutrients and gases occurs.
• Functions of the cardiovascular system include transport of oxygen, carbon dioxide, nutrients, hormones, and waste products; regulation of body temperature; and protection against disease.

Lymphatic System

• The lymphatic system returns fluids leaked from blood vessels back to the bloodstream.
• It consists of lymphatic vessels, lymph nodes, and lymphoid organs.
• Lymphatic vessels collect excess tissue fluid (lymph) and return it to the blood.
• Lymph nodes filter lymph and house immune cells.
• Lymphoid organs include the spleen, thymus, tonsils, and Peyer's patches.
• Functions of the lymphatic system include fluid recovery, immunity, and lipid absorption.

Respiratory System

• The respiratory system exchanges gases between the body and the environment.
• It consists of the nose, pharynx, larynx, trachea, bronchi, and lungs.
• Functions of the respiratory system include gas exchange (oxygen and carbon dioxide), voice production, and regulation of blood pH.
• Air enters the respiratory system through the nose and mouth.
• Air passes through the pharynx, larynx, and trachea.
• The trachea divides into two main bronchi, which enter the lungs.
• Within the lungs, the bronchi branch into smaller and smaller airways (bronchioles) that terminate into alveoli.
• Alveoli are the sites of gas exchange.

Digestive System

• The digestive system breaks down food into absorbable nutrients.
• It consists of the oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus.
• Accessory digestive organs include the salivary glands, liver, gallbladder, and pancreas.
• Functions of the digestive system include ingestion, digestion, absorption, and elimination.
• Digestion involves mechanical and chemical breakdown of food.
• Absorption is the process by which nutrients pass from the digestive tract into the blood or lymph.
• Elimination is the removal of undigested waste products.

Urinary System

• The urinary system removes waste products from the blood and regulates fluid and electrolyte balance.
• It consists of the kidneys, ureters, urinary bladder, and urethra.
• The kidneys filter blood and produce urine.
• The ureters transport urine from the kidneys to the urinary bladder.
• The urinary bladder stores urine.
• The urethra transports urine from the urinary bladder to the outside of the body.
• Functions of the urinary system include excretion of metabolic wastes, regulation of blood volume and blood pressure, regulation of electrolyte balance, and regulation of blood pH.

Reproductive System

• The reproductive system enables reproduction.
• It consists of the gonads (testes in males, ovaries in females) and accessory reproductive organs.
• The male reproductive system produces sperm and delivers them to the female reproductive tract.
• The female reproductive system produces eggs, provides a site for fertilization, and supports the developing fetus.
• Functions of the reproductive system include production of gametes (sperm and eggs), secretion of sex hormones, and reproduction.