Introduction to the Human Body Anatomy

Introduction to the Human Body

• Anatomy is the scientific study of the body's structures or form.
• Physiology is the study of the chemistry and physics of the body's functions.

Chapter Objectives

• Students will be able to differentiate between anatomy and physiology, and identify different branches of each.
• Students will be able to describe the body's structure from simplest to complex, using the six levels of organization.
• Students will be able to define homeostasis and explain its significance to normal human functioning.
• Students will be able to use anatomical terminology to identify key body structures, body regions, and directions.

Anatomy

• Anatomy is the study of the internal and external structures of the body and their physical relationships.
• It can be categorized as gross anatomy, or microscopic anatomy.
  • Gross anatomy is the examination of large structures that can be seen with the naked eye.
    • Approaches include surface anatomy, regional anatomy, and systemic anatomy.
  • Microscopic anatomy is the examination of structures that require magnification.
    • It can be subdivided into cytology (study of cells) and histology (study of tissues).

Physiology

• Physiology is the study of the chemistry and physics of how body structures function together to support life.
• It is more complex and difficult to study than anatomy.
• It can be divided into the study of individual organs or organ systems, and is closely related to anatomy.

Structural Organization of the Human Body

• The human body is organized in six levels: chemical, cellular, tissue, organ, organ system, and organism.

Systems of the Body

• Integumentary System: Organs—skin, hair, nails; Functions—external support, protection, temperature regulation, barrier for immune function.
• Skeletal System: Organs—bones, cartilage, joints; Functions—internal support, protection of organs, flexible framework for movement, forms blood cells, and mineral storage.
• Muscular System: Organs—skeletal muscles, tendons; Functions—locomotion, support, and body heat production.
• Nervous System: Organs—brain, spinal cord, peripheral nerves; Functions—detects and processes sensory information, directs responses to stimuli, coordinates activities of other organ systems.
• Endocrine System: Organs—hormone-secreting glands (thyroid, pituitary, adrenal, pineal, pancreas, testes, ovaries); Functions—secretion of hormones, which act as signals, regulating body processes.
• Cardiovascular System: Organs—heart, blood and blood vessels; Functions—transport of nutrients to cells and waste products from cells, homeostasis of body temperature
• Lymphatic and Immune System: Organs—lymph nodes, lymphatic vessels, spleen, thymus gland, bone marrow, tonsils; Functions—returning extracellular fluid to the blood, houses immune cells, protection against infection, and transports lymph.
• Respiratory System: Organs—lungs, trachea, larynx, nasal passages; Functions—gas exchange (O2 and CO2) between air and circulating blood.
• Digestive System: Organs—salivary glands, esophagus, stomach, small intestine, large intestine, liver, and gallbladder; Functions—intake, breakdown, and absorption of food to obtain nutrients, minerals, and vitamins.
• Urinary System: Organs—kidneys, ureters, urinary bladder, and urethra; Functions—controls water balance in the body, filters blood to eliminate nitrogenous wastes and excess water and electrolytes, controls pH.
• Reproductive System (Male): Organs—testes, scrotum, prostate gland, seminal vesicles, epididymis, and penis; Functions—production and delivery of sperm and production of sex hormones.
• Reproductive System (Female): Organs—ovaries, uterus, vagina, and mammary glands; Functions—production of egg (gamete), secretion of sex hormones, copulation, and support of fetus/infant.

Homeostasis

• Homeostasis is the maintenance of a stable internal environment within a specific range.
• Three components:
  • Receptor
  • Control center
  • Effector
• Two types of homeostatic systems:
  • Negative feedback: Change goes in the opposite direction of the stimulus.
  • Positive feedback: Change goes in the same direction as the stimulus.

Anatomical Terminology

• Anatomical position: Standard body position (standing upright, feet parallel, upper limbs at the sides, palms facing forward).
• Directional terms (superior/inferior, cranial/caudal, posterior/anterior, dorsal/ventral, right/left, lateral/medial, proximal/distal, deep/superficial).
• Body regions
• Body planes (sagittal, frontal/coronal, transverse)

Body Cavities

• The body has specific internal spaces (cranial, vertebral, thoracic, abdominal, pelvic, and the abdominopelvic)

Serous Membranes

• Serous membranes line body cavities and surround organs, comprised of a parietal layer and visceral layer, and a fluid filled space.