Introduction to the Body Systems Structures and Functions

Human Body Systems n The levels of organization in a multicellular organism include cells, tissues, organs and organ systems.

Levels of Organization - Cells n Cells – basic unit of structure and function in living things q q Individual cells tend to be specialized Specialized cells perform a particular function

Levels of Organization - Tissue n n A group of cells that perform a single function 4 basic types of tissue q Epithelial tissue – glands and tissues that cover the interior and exterior body surfaces q Connective tissue – provides support for the body and connects its parts q Nervous tissue – transmits nerve impulse throughout the body q Muscle tissue- along with bones enables the body to move

11 Human Organ Systems

The Nervous System n Structures: q Brain q Spinal cord q Peripheral nerves n Function: q Gathers and interprets information q Coordinates responses to changes in internal and external environment q Regulates body activities

Integumentary System n Structures: q q q n Skin Hair Nails Function: q q q Covers body Protection against infection and injury Helps regulate body temperature Removes wastes Protects against UV radiation Produces vitamin D

Respiratory System n Structure: q q n Nose Pharynx Trachea Alveoli Bronchioles Lungs Function: q q Takes in oxygen needed for cellular respiration Removes carbon dioxide from the body

Digestive System n Structures: q q q n Mouth Pharynx Esophagus Stomach Salivary glands Intestines Liver Pancreas Rectum Gall bladder Function: q q q Take in and break down food Absorb nutrients Remove indigestible material

Excretory System n Structure: q q n Kidneys Ureters Lungs Urethra Urinary Bladder Skin Function: q q Filters blood and removes waste products from cellular metabolism (urea, water, carbon dioxide) Helps the body maintain homeostasis

Skeletal System n Structure: q q n Bones Cartilage Ligaments Tendons Function: q q q Provides shape and support for the body Protects the internal organs Allows for movement Stores minerals Produces blood cells

Muscular System n Structure q q q n Skeletal muscle Smooth muscle Cardiac muscle Function q q q Moves the body Moves blood through blood vessels Moves food through the digestive tract

Circulatory System n Structure: q q q Heart Veins Blood Arteries Capillaries Function: q Brings oxygen, nutrients, and hormones to cells q Fights infection q Removes cell wastes q Helps to regulate body temperature

Endocrine System n Structure: q Glands n Hypothalamus Pituitary Thyroid n Thymus Adrenal Pancreas n Ovaries Testes q Hormones n Insulin, Glucagon, Thyroxin, Adrenalin, Estrogen, Testosterone, Human Growth Hormone, etc. n Function: q Controls growth, development and metabolism q Helps maintain homeostasis

Reproductive System n Structure: q Males n n n Testes Epididymis Vas deferens Penis Females Ovaries Fallopian tubes Uterus Vagina Function: q q Produces reproductive cells In females – nurtures and protects the developing embryo

Immune System n Structure: q White blood cells n n n q q n T cells B cells Phagocytes Thymus Skin Function: q Fight off foreign invaders in the body

Lymphatic System n Structure: q q q n Lymph nodes Lymph vessels Spleen Function: q q q Collects fluid lost from blood vessels Returns fluid to the circulatory system Kills foreign organisms

Maintaining Homeostasis n n Homeostasis – means “keeping things in balance” Homeostasis is the process by which organisms keep internal conditions relatively constant despite changes in external environments. q q Non- living example – Heating system of a house Feedback inhibition (negative feedback) – process in which a stimulus produces a response that opposes the original stimulus

Regulation and Hormones n Some of the properties kept in check by homeostasis are: q q Body temperature Blood glucose Water potential Oxygen and carbon dioxide concentrations