1. Human Body Systems 35-1
BIO 1004
Flora

2. 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

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

4. 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

5. 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.

6. 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

7. 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

8. 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.