Introduction to Human Anatomy & Physiology: Body Systems, Organization, and Terminology

Anatomy and Physiology: Foundations

Definitions and Scope

Anatomy is the study of the structure of body parts and their relationships to one another. Physiology is the study of the function of body parts and how they work to sustain life.

• Anatomy: Focuses on what something is made of (structure).

• Physiology: Focuses on what the body does (function).

Levels of Organization

• Chemical level: Atoms and molecules.

• Cellular level: Cells and their organelles.

• Tissue level: Groups of similar cells.

• Organ level: Structures composed of two or more tissue types.

• Organ system level: Organs working together.

• Organismal level: The human body as a whole.

Body Systems Overview

Integumentary System

The integumentary system forms the outer protective covering of the body.

• Includes: skin, hair, nails, sweat glands.

• Skin: First line of defense against infection; major organ of the system.

• Functions: Protection, temperature regulation, sensation.

• Diagnostic technique: Inspection (noninvasive).

Muscular System

The muscular system enables movement through muscle contractions.

• Includes: Skeletal muscles attached to bones.

• Functions: Movement, posture, heat production.

• Examples: Quadriceps, hamstrings, heart, stomach, brain.

Skeletal System

The skeletal system provides structural support and protection for the body.

• Includes: Bones, cartilage, ligaments.

• Functions: Support, protection, movement, mineral storage, blood cell formation.

• Vital for life-sustaining functions and as sites of muscle attachment.

Nervous System

The nervous system coordinates body activities through electrical signals.

• Includes: Brain, spinal cord, nerves.

• Central nervous system (CNS): Brain and spinal cord.

• Peripheral nervous system (PNS): Nerves outside the CNS.

• Functions: Communication, control, sensation.

• Key distinction: Nerves are different from the spinal cord and neurons.

Endocrine System

The endocrine system regulates body functions through hormones.

• Includes: Glands such as pituitary, thyroid, adrenal.

• Functions: Hormone secretion, regulation of growth, metabolism, reproduction.

Cardiovascular System

The cardiovascular system transports blood, nutrients, and waste products.

• Includes: Heart, blood vessels.

• Functions: Circulation, nutrient delivery, waste removal.

• Cardio: Heart; Vascular: Vessels; Auscultation: Listening (with stethoscope).

Lymphatic System

The lymphatic system defends against infection and maintains fluid balance.

• Includes: Lymph nodes, tonsils, spleen.

• Functions: Immune response, transport of lymph.

Respiratory System

The respiratory system enables gas exchange between the body and environment.

• Includes: Lungs, airways.

• Functions: Oxygen intake, carbon dioxide removal.

• Diagnostic techniques: CT (computed tomography), noninvasive imaging.

Digestive System

The digestive system processes food for nutrient absorption and waste elimination.

• Includes: Mouth, esophagus, stomach, intestines, pancreas, liver.

• Functions: Digestion, absorption, waste production.

• Diagnostic techniques: Endoscopy (invasive), percussion (noninvasive).

• Pancreas: Functions in both digestive and endocrine systems.

Urinary System

The urinary system removes waste products and regulates blood composition.

• Includes: Kidneys, ureters, urinary bladder, urethra.

• Functions: Waste removal, blood volume and composition regulation.

• Diagnostic technique: Ultrasound.

Reproductive System

The reproductive system enables production of offspring.

• Includes: Gonads (testes, ovaries), reproductive organs.

• Functions: Gamete production, fertilization, hormone secretion.

Types of Anatomy

• Systemic anatomy: Study of organ systems.

• Regional anatomy: Study of body regions (e.g., head, neck, back).

• Surface anatomy: Study of external body features.

• Gross anatomy: Structures visible to the naked eye.

• Microscopic anatomy: Structures requiring a microscope.

• Histology: Study of tissues.

• Cytology: Study of cells.

Body Cavities and Membranes

Major Body Cavities

• Vertebral cavity: Contains the spinal cord; protects the nervous system.

• Thoracic cavity: Contains lungs (within pleural cavity), heart (within pericardial cavity), rib cage, muscles, sternum, thoracic column, diaphragm.

• Abdominopelvic cavity: Below the diaphragm; contains the peritoneal cavity.

Serous Membranes

• Outer membrane (parietal): Lines the cavity wall.

• Inner membrane (visceral): Covers the organs.

• Example: The lungs are wrapped by the visceral pleural membrane, which is then wrapped by the parietal pleural membrane.

Body Regions and Anatomical Position

Body Regions

• Axial region: Head, neck, trunk.

• Appendicular region: Upper and lower limbs.

Anatomical Position

• Body standing upright, feet shoulder-width apart, palms facing forward.

Directional Terms

• Anterior: Front

• Posterior: Back

• Superior: Toward the head

• Inferior: Away from the head

• Proximal: Closer to attachment

• Distal: Farther from attachment

• Medial: Close to midline

• Lateral: Far from midline

• Superficial: Closer to the surface

• Deep: Farther below surface

Planes of the Body

• Sagittal plane: Divides the body from left to right.

• Midsagittal plane: Divides the body into equal right and left halves.

• Parasagittal plane: Divides the body into unequal right and left planes.

• Frontal (coronal) plane: Divides the body into anterior and posterior sections.

• Transverse (horizontal) plane: Divides the body into superior and inferior parts; also divides appendicular region into proximal and distal parts.

Body Regions Table

The following table summarizes major body regions and their corresponding anatomical terms:

Region of the Trunk	Pertaining To
Thoracic	Chest
Abdominal	Abdomen
Pelvic	Pelvis
Dorsal	Back
Vertebral	Spinal column
Scapular	Shoulder blade
Gluteal	Buttock
Inguinal	Groin

Region of the Head	Pertaining To
Cranial	Skull
Facial	Face
Orbital	Eye
Oral	Mouth
Buccal	Cheek
Mental	Chin
Nasal	Nose
Otic	Ear

Region of the Upper Limb	Pertaining To
Brachial	Arm
Antebrachial	Forearm
Carpal	Wrist
Manual	Hand
Digital	Fingers

Region of the Lower Limb	Pertaining To
Femoral	Thigh
Crural	Leg
Tarsal	Ankle
Pedal	Foot
Digital	Toes

Homeostasis and Feedback Mechanisms

Homeostasis

Homeostasis is the maintenance of a stable internal environment despite changes in external conditions.

• Dynamic: Balance fluctuates up and down.

• ICF: Inside cells.

• ECF: Outside cells.

Feedback Loops

• Feedback: Cycle of events that regulate internal conditions.

• Controlled condition: Variable regulated.

• Stimulus: Any disruption in controlled condition.

• Receptor: Delivers signal to control center; effector is called into action.

Types of Feedback

• Negative feedback: Most common; inhibits changes in regulated variables and returns system to balance.

• Positive feedback: Enhances changes; less common. Examples: Labor contractions, blood clotting.

• Feedforward feedback: Anticipates changes; uncommon. Example: Cephalic phase of digestion.

Clinical Terminology

• Disorder: Any abnormality.

• Symptom: Subjective experience reported by patient.

• Sign: Objective evidence observed by clinician.

Word Roots and Terminology

• Cardi-: Heart

• Encephal-: Brain

• My-: Muscle

• An-: Without

• -le: Condition of

Additional Info

• Imaging procedures: Noninvasive (inspection, auscultation, percussion, ultrasound, CT), invasive (endoscopy).

• Abdominal quadrants: Used for describing site of pain or abnormality; defined by sagittal and transverse lines at the belly button or umbilicus.

• Subcostal line: Below ribs.

• Transtubercular line: One side of pelvis to other side.

• Midclavicular lines: Vertical through collar bones.