Anatomy and Physiology Introduction

Introduction to Anatomy and Physiology

• Anatomy is the earliest form of medical science, dating back to 1600 B.C.
• Anatomy describes the body's structures, including their composition, location, and associated structures.
• Physiology studies the functions of anatomical structures, both individually and cooperatively.

Anatomy

• Gross anatomy, also known as macroscopic anatomy, examines large, visible structures.
• Microscopic anatomy examines cells and molecules.

Physiology

• Cell physiology studies processes at work within cells and between cells.
• Special physiology focuses on the function of specific organs.
• Systemic physiology studies the functions of an organ system.
• Pathological physiology studies the effects of diseases.

Levels of Organization

• The chemical level involves atoms, which are the smallest chemical units.
• Molecules are groups of atoms working together.
• The cellular level comprises cells, which are groups of atoms, molecules, and organelles working together.
• The tissue level consists of tissues, which are groups of similar cells working together.
• The organ level consists of organs, which are groups of different tissues working together.
• The organ system level refers to organ systems, which are groups of organs working together.
• Humans have 11 organ systems.
• The organism level is a complete human being.

Anatomical Terminology

• Anatomical position involves the body standing with hands at the sides and palms facing forward.
• Supine refers to lying down with the face up.
• Prone refers to lying down with the face down.
• Anatomical landmarks reference palpable structures.
• Anatomical regions include body regions, abdominopelvic quadrants, and abdominopelvic regions.
• Anatomical directions involve reference terms based on the subject's body.

Anatomical Landmarks

• Cephalon refers to the head or cephalic region.
• Cervicis refers to the neck or cervical region.
• Thoracis refers to the chest or thoracic region.
• Brachium refers to the arm or brachial region.
• Antebrachium refers to the forearm or antebrachial region.
• Carpus refers to the wrist or carpal region.
• Manus refers to the hand or manual region.
• Abdomen refers to the abdominal region.
• Lumbus refers to the loin or lumbar region.
• Gluteus refers to the buttock or gluteal region.
• Pelvis refers to the pelvic region.
• Pubis refers to the anterior pelvis or pubic region.
• Inguen refers to the groin or inguinal region.
• Femur refers to the thigh or femoral region.
• Crus refers to the anterior leg or crural region.
• Sura refers to the calf or sural region.
• Tarsus refers to the ankle or tarsal region.
• Pes refers to the foot or pedal region.
• Planta refers to the sole or plantar region.

Abdominopelvic Quadrants

• RUQ: Right Upper Quadrant
• LUQ: Left Upper Quadrant
• RLQ: Right Lower Quadrant
• LLQ: Left Lower Quadrant

Abdominopelvic Regions

• Right and Left Hypochondriac Regions
• Epigastric Region
• Right and Left Lumbar Regions
• Umbilical Region
• Right and Left Inguinal Regions
• Hypogastric (Pubic) Region

Anatomical Relationships

• The abdominopelvic regions contain a number of organs including the liver, gallbladder, large and small intestines, appendix, stomach, spleen, and urinary bladder.

Sectional Anatomy

• Plane: A three-dimensional axis.
• Section: A slice parallel to a plane.
• Sectional anatomy is used to visualize internal organization and structure.
• Important radiological techniques include MRI, PET and CT scans.

Terms Indicating Sectional Planes

• Transverse sections separate superior and inferior portions of the body.
• Sagittal sections separate right and left portions.
• Midsagittal or median sections divide the body into equal right and left sides.
• Parasagittal sections separate the body into unequal right and left portions.
• Frontal sections separate anterior and posterior portions of the body.

Body Cavities

• Body cavities protect organs from accidental shocks and permit changes in the size and shape of internal organs.
• The ventral body cavity is divided by the diaphragm into the thoracic and abdominopelvic cavities.
• Serous membranes line body cavities and cover organs.
• The parietal layer lines the cavity.
• The visceral layer covers the organ.

Thoracic Cavity

• Separated into right and left pleural cavities containing the right and left lungs respectively.
• The mediastinum has an upper portion filled with blood vessels, the trachea, esophagus, and thymus.
• The lower portion of the mediastinum contains the pericardial cavity.
• The heart is located within the pericardial cavity.

Abdominopelvic Cavity

• The peritoneal cavity is a chamber within the abdominopelvic cavity.
• The parietal peritoneum lines the internal body wall.
• The visceral peritoneum covers the organs,
• The abdominal cavity is the superior portion, extending from the diaphragm to the top of the pelvic bones, and contains digestive organs.
• The retroperitoneal space is posterior to the peritoneum and anterior to the muscular body wall, containing the pancreas, kidneys, ureters, and parts of the digestive tract.
• The pelvic cavity is the inferior portion, within the pelvic bones, and contains reproductive organs, the rectum, and the bladder.

Membranes

• Membranes are thin sheets of tissue that cover surfaces, serve as dividers, line hollow organs or body cavities, anchor organs, and secrete lubricants to ease the movement of organs.
• There are two main categories of membranes: epithelial and connective tissue membranes.

Membranes - Epithelial

• Epithelial tissue contains cells of different shapes arranged in single or multiple layers, depending on the function and location in the body.
• Simple epithelium is a single layer of cells.
• Stratified epithelium is multiple layers of cells.
• Pseudostratified epithelium appears to be multiple layers due to cell size variation, but is only a single layer.
• Squamous epithelium is flat and sheet-like.
• Cuboidal epithelium is cube-like, having equal width, height, and depth.
• Columnar epithelium is column-like, being taller than wide.

Epithelial Membranes - Types Based on Function

• Serous membranes line body cavities and cover internal organs.
• Mucous membranes line tubes and ducts that open to the outside of the body.
• Cutaneous membranes are commonly known as skin.

Serous Membranes

• Serous membranes line body cavities and cover internal organs, not connecting to the outside.
• Serous membranes secrete serous fluid as lubricant.
• Pleura consists of a parietal layer lining the thoracic cavity and a visceral layer covering the lungs.
• Serous pericardium has a parietal layer lining the pericardial sac and a visceral layer covering the heart.
• Peritoneum has a parietal layer lining the abdominal cavity and a visceral layer covering abdominal organs.

Mucous Membranes

• Mucous membranes line tubes and ducts open to the body's exterior.
• Mucous membranes vary in structure and function.
• Mucous membranes trap and remove foreign particles.
• Mucous membranes protect deeper tissue.
• Mucous membranes absorb food materials.

Connective Tissue Membranes

• Connective tissue membranes support and bind other tissues and organs, without epithelium.
• Synovial membranes line joint cavities and secrete synovial fluid to lubricate the joints.
• Meninges cover the brain and spinal cord.
• Fascia has a superficial layer underneath the skin insulates the body.
• Deep fascia covers, separates, and protects skeletal muscles.
• Periosteum surrounds bone.
• Perichondrium surrounds cartilage.

Homeostasis

• Homeostasis is all body systems working together to maintain a stable internal environment.
• Systems respond to external and internal changes and function within a normal range (body temperature, fluid balance).

Mechanisms of Homeostatic Regulation

• Autoregulation (intrinsic) is an automatic response in a cell, tissue, or organ to an environmental change.
• Extrinsic regulation involves responses controlled by the nervous and endocrine systems.
• A receptor receives the stimulus.
• The control center processes the signal and sends instructions.
• The effector carries out instructions.

Feedback Mechanisms

• With negative feedback, the effector negates the stimulus and the body is brought back into homeostasis, achieving normal range.
• With positive feedback, the effector increases the change of the stimulus and body is moved away from homeostasis, with the normal range being lost, and is used to speed up processes.

Systems Integration

• Systems integration is the process of systems working together to maintain homeostasis.
• Homeostasis is a state of equilibrium with opposing forces in balance.
• Physiological systems work to restore balance.
• Failure of systems integration results in disease or death.