Anatomy: Macroscopic and Microscopic Studies

• Anatomy studies the structure of living organisms.
• It investigates the body's components, their appearance, location, and organization.
• Understanding anatomy is vital for grasping physiology and pathology.
• Macroscopic anatomy (gross anatomy) examines structures visible without aid.
• Microscopic anatomy studies structures at the cellular level using microscopes.

Macroscopic Anatomy (Gross Anatomy)

• Regional anatomy examines all structures within specific body regions like the head, thorax, or abdomen.
• Systemic anatomy studies organ systems, like the nervous, skeletal, or cardiovascular systems.
• Surface anatomy studies internal structures as they relate to the skin surface, such as locating muscles by observing their effect on the skin.

Microscopic Anatomy

• Cytology is the study of cells, focusing on their structure and function.
• Histology studies tissues, which are groups of similar cells performing specific functions.

Anatomical Terminology

• Anatomical position is the standard reference: body erect, feet slightly apart, palms forward, thumbs point away.
• Directional terms describe the location of structures relative to each other; examples include superior/inferior, anterior/posterior, medial/lateral, and proximal/distal.
• Superior (cranial): Situated toward the head or upper part of a structure or the body; above.
• Inferior (caudal): Situated away from the head end or toward the lower part of a structure or the body; below.
• Anterior (ventral): Situated toward or at the front of the body; in front.
• Posterior (dorsal): Situated toward or at the back of the body; behind.
• Medial: Situated toward or at the midline of the body; on the inner side.
• Lateral: Situated away from the midline of the body; on the outer side.
• Intermediate: Situated between a more medial and a more lateral structure.
• Proximal: Situated closer to the origin of the body part or the point of attachment of a limb to the body trunk.
• Distal: Situated farther from the origin of a body part or the point of attachment of a limb to the body trunk.
• Superficial (external): Situated toward or at the body surface.
• Deep (internal): Situated away from the body surface; more internal.
• Ipsilateral: Situated on the same side.
• Contralateral: Situated on opposite sides.

Body Planes

• Sagittal plane: Divides the body into right and left parts.
• Midsagittal (median) plane: A sagittal plane that lies exactly in the midline.
• Parasagittal plane: A sagittal plane offset from the midline.
• Frontal (coronal) plane: Divides the body into anterior and posterior parts.
• Transverse (horizontal) plane: Divides the body into superior and inferior parts.

Body Cavities

• Dorsal body cavity: Protects nervous system organs, with cranial and vertebral subdivisions.
• Cranial cavity: Encasing the brain.
• Vertebral cavity (spinal cavity): Enclosing the spinal cord.
• Ventral body cavity: Anterior and larger, housing internal organs (viscera), divided into thoracic and abdominopelvic cavities.
• Thoracic cavity: Superior subdivision, surrounded by ribs and chest muscles.
• Pleural cavities: Each enveloping a lung.
• Mediastinum: Containing the pericardial cavity.
• Pericardial cavity: Encloses the heart and surrounds remaining thoracic organs like the esophagus and trachea.
• Abdominopelvic cavity: Inferior to the thoracic cavity.
• Abdominal cavity: Superior, containing the stomach, intestines, spleen, liver, and other organs.
• Pelvic cavity: Inferior, within the pelvis, containing the urinary bladder, reproductive organs, and rectum.

Serous Membranes

• Serous membrane (or serosa): A thin, double-layered membrane.
• Parietal serosa: Lines the cavity walls.
• Visceral serosa: Covers the organs in the cavity.
• Serous fluid: Separates the serous membranes.
• Pleura: Lines the thoracic wall and covers the lungs.
• Pericardium: Encloses the heart.
• Peritoneum: Encloses the abdominopelvic organs.

The Skeletal System

• Function: Support, protection, movement, mineral storage, and blood cell formation.
• Bones: Provide body framework, support, and protect organs.
• Cartilages: Cushion joints, provide support and flexibility.
• Joints: Where bones meet, allowing movement.
• Ligaments: Connect bones, stabilizing joints.
• Axial skeleton: Skull, vertebral column, and rib cage.
• Appendicular skeleton: Limb bones, shoulder, and pelvic girdles.
• Bones are classified by shape: long, short, flat, irregular.

The Muscular System

• Function: Movement, posture, and heat production.
• Skeletal muscles: Attached to bones, responsible for voluntary movement.
• Smooth muscles: In internal organ walls, responsible for involuntary movement (e.g., digestion).
• Cardiac muscle: In the heart, responsible for pumping blood.
• Muscles produce movement by contracting and pulling on bones.

The Nervous System

• Function: Control, communication, and sensation.
• Brain: The body's control center.
• Spinal cord: Connects the brain to the peripheral nervous system.
• Nerves: Transmit signals throughout the body.
• Central nervous system (CNS): Brain and spinal cord.
• Peripheral nervous system (PNS): Nerves outside the brain and spinal cord.
• Neurons: Specialized cells that transmit electrical signals.

The Endocrine System

• Function: Hormone secretion and regulation of body functions.
• Glands: Produce and secrete hormones, such as the pituitary, thyroid, and adrenal glands.
• Hormones: Chemical messengers that travel through the bloodstream.
• It regulates processes such as growth, metabolism, and reproduction.

The Cardiovascular System

• Function: Transport of blood, oxygen, nutrients, and waste.
• Heart: Pumps blood throughout the body.
• Blood vessels: Arteries, veins, and capillaries.
• Blood: Carries oxygen, nutrients, and waste.
• Arteries: Carry blood away from the heart.
• Veins: Carry blood back to the heart.
• Capillaries: Tiny blood vessels for nutrient and waste exchange.

The Lymphatic System

• Function: Immunity and fluid balance.
• Lymph vessels: Collect excess fluid (lymph) from tissues.
• Lymph nodes: Filter lymph and contain immune cells.
• Spleen: Filters blood and stores immune cells.
• Thymus: Involved in immune cell maturation.

The Respiratory System

• Function: Gas exchange (oxygen and carbon dioxide).
• Lungs: Site of gas exchange.
• Trachea: Windpipe.
• Bronchi: Branches of the trachea leading to the lungs.
• Alveoli: Tiny air sacs in the lungs for gas exchange.

The Digestive System

• Function: Breaking down food, absorbing nutrients, and eliminating waste.
• Mouth: Where digestion begins.
• Esophagus: Carries food to the stomach.
• Stomach: Mixes food with gastric juices.
• Small intestine: Site of most nutrient absorption.
• Large intestine: Absorbs water and eliminates waste.
• Liver, pancreas, and gallbladder: Accessory organs aiding digestion.

The Urinary System

• Function: Filters blood, eliminates waste, and regulates fluid balance.
• Kidneys: Filter blood and produce urine.
• Ureters: Carry urine from kidneys to the bladder.
• Bladder: Stores urine.
• Urethra: Carries urine from the bladder to the outside of the body.

The Reproductive System

• Function: Reproduction.
• Male reproductive system: Testes, ducts, glands, and penis.
• Female reproductive system: Ovaries, uterine tubes, uterus, and vagina.
• It produces hormones that regulate sexual development and function.