Structures and Functions Introduction to the Body Systems Structures and Functions

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

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

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

11 Human Organ Systems

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

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

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

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

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

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

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

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

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

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

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

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

Maintaining Homeostasis Homeostasis – means “keeping things in balance” Homeostasis is the process by which organisms keep internal conditions relatively constant despite changes in external environments. 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 Some of the properties kept in check by homeostasis are: Body temperature Blood glucose Water potential Oxygen and carbon dioxide concentrations