Anatomy and Physiology Overview

Anatomy

• Anatomy is the study of the structure and shape of the body and its parts
• Observation is used to determine the sizes and relationships of body parts
• Anatomy can be studied as "gross" anatomy or "microscopic" anatomy

Physiology

• Physiology studies how the body and its parts function
• Body structure determines the functions that can occur
• For example, lungs' air sacs have thin walls to facilitate gas exchange and oxygen delivery

Levels of Structural Organization

• There are six levels of structural organization in the body
  • Atoms
  • Cells
  • Tissues
  • Organs
  • Organ systems
  • Organisms

Organ System Overview (Integumentary System)

• The integumentary system forms the external covering of the body (including skin, hair, and fingernails)
• It waterproofs the body and cushions/protects underlying tissues
• It produces Vitamin D through sunlight exposure
• It excretes salts through perspiration
• It helps regulate body temperature
• Cutaneous nerve receptors are located in this system

Organ System Overview (Skeletal System)

• The skeletal system consists of bones, cartilages, ligaments, and joints
• It provides attachment points for muscle movement
• It protects vital organs
• It produces blood cells
• It stores minerals

Organ System Overview (Muscular System)

• The muscular system includes skeletal muscles enabling body movement
• Skeletal muscles contract (shorten) to produce body movements

Organ System Overview (Nervous System)

• The nervous system is a fast-acting control system containing the brain, spinal cord, nerves, and sensory receptors
• The nervous system responds to external and internal stimuli
• Sensory receptors detect changes and send messages to the central nervous system
• The central nervous system processes and responds to information by activating muscles and glands

Organ System Overview (Endocrine System)

• The endocrine system secretes hormones into the blood
• Hormones regulate body functions including growth, reproduction, and nutrient use
• Endocrine glands include the pituitary, thyroid and parathyroids, adrenal, thymus, pancreas, pineal, ovaries (females), and testes (males)
• Glands secrete hormones that regulate body functions, including growth, reproduction, and nutrient use by body cells

Organ System Overview (Cardiovascular System)

• The cardiovascular system includes the heart and blood vessels
• The heart pumps blood, and blood vessels transport blood to tissues
• Blood transports oxygen, carbon dioxide, nutrients, and hormones
• Blood also contains immune cells to protect against foreign invaders

Organ System Overview (Lymphatic System)

• The lymphatic system includes lymphatic vessels, lymph nodes, and lymphoid organs
• It complements the cardiovascular system by returning leaked fluids to the bloodstream
• Lymph nodes and organs cleanse the blood and provide immunity

Organ System Overview (Respiratory System)

• The respiratory system includes the nasal passages, pharynx, larynx, trachea, bronchi, and lungs
• It facilitates gas exchange in the lungs, providing oxygen and removing carbon dioxide to the blood

Organ System Overview (Digestive System)

• The digestive system includes the oral cavity, esophagus, stomach, small and large intestines, rectum, and accessory organs
• It breaks down food into absorbable nutrients that the blood then absorbs
• It eliminates indigestible food as feces

Organ System Overview (Urinary System)

• The urinary system includes the kidneys, ureters, urinary bladder, and urethra
• It eliminates waste products
• It maintains acid-base balance
• It regulates water and electrolyte balance and helps regulate blood pressure

Organ System Overview (Reproductive System)

• The reproductive system enables reproduction
• In males, it includes the testes, scrotum, penis, accessory glands, and duct system; testes produce sperm
• In females, it includes the ovaries, uterine tubes, uterus, and vagina; ovaries produce eggs, and the uterus develops the fetus

The Language of Anatomy

• Exact terminology is used to prevent misunderstandings
• Exact terms are used for position, direction, regions, and structures

Anatomical Position

• Standard body position to avoid confusion
• Terminology uses this position even when the body is not in this position
• Stand erect, feet parallel, arms hanging at sides, palms facing forward

Directional Terms

• Directional terms explain the location of one body structure in relation to another
  • Superior/inferior, anterior/posterior, medial/lateral, proximal/distal, superficial/deep

Regional Terms

• Anterior (ventral) body landmarks (e.g. upper/lower limbs, thorax, abdomen etc.)
• Posterior (dorsal) body landmarks (e.g. back, spinal column, head region etc.)

Body Planes and Sections

• Sections are cuts along imaginary lines known as planes
• Three planes (sagittal, median/midsagittal, frontal/coronal, transverse/cross) exist at right angles to one another

Body Cavities

• Two internal body cavities exist (dorsal and ventral)
  • Dorsal: Cranial, spinal
  • Ventral: Thoracic, abdominopelvic
• Other body cavities include oral and digestive, nasal, orbital, and middle ear cavities

Homeostasis

• Homeostasis refers to the maintenance of stable internal conditions
  • Dynamic process of equilibrium important for body functions
• Main controlling systems are nervous and endocrine systems
• Homeostatic imbalance can lead to disease

Maintaining Homeostasis

• Homeostatic control mechanisms have three components: receptor, control center, and effector

Feedback Mechanisms

• Negative feedback is the most common type, reducing the initial stimulus
  • Ex: body thermostat
• Positive feedback increases the stimulus
  • Ex: blood clotting and childbirth