Human Body Systems 35-1 BIO 1004 Flora

Review – Levels of Organization Cells – tissues – organs – organ systems – organism Tissue – group of cells that are so similar that they are able to work together to function 11 organ systems make up the human body and maintain homeostasis

Organ Systems Nervous Integumentary Respiratory Digestive Excretory Skeletal Muscular Circulatory Endocrine Reproductive Lymphatic/Immune

Organization of the Body Cells – basic unit of life Specialized cells – able to perform specific functions Tissues – 4 basic types Epithelial – includes glands and tissues that cover interior and exterior body surfaces Connective – provides support for the body and connects its parts Nervous – transmits nerve impulses throughout the body Muscle – along with bones, enables the body to move

Organization of Body Cont. Organ – group of different types of tissue that work together to perform a single function Ex: eye – consists of epithelial, nervous, muscle, and connective tissue. Organ System – group of organs that perform closely related functions to maintain homeostasis.

Maintaining Homeostasis Homeostasis – process by which organisms keep internal conditions relatively constant despite changes in external environments. Feedback inhibition – process by which a stimulus produces a response that opposes the original stimulus

Ex: Feedback inhibition Ex: heating system Ex: Maintaining body temp Hypothalamus of brain regulates body temperature Nerve cells at surface and organ cores monitor temperatures If temp. drops below 37 degrees C, the hypothalamus releases a chemical that speeds up cell activities

Cont. Example Shivering is a direct result of the hypothalamus releasing chemicals that causes your muscles to contract involuntarily. Above 37? Hypothalamus releases chemicals to slow cellular activities This is why you feel sluggish on a hot day Body also releases sweat to help with cooling.