Unit 9-Anatomy and PhysiologyChapter 30-Digestive and Excretory

Systems

Chapter 30.1:Organization of the Human Body

Levels of Organization in the Body- Cells

- Are the basic unit of structure and function in an organism

- Tissues- Are a group of cells that perform a single

function

Levels of Organization in the Body

- Four types of tissues:1) Epithelial

- Lines interior and exterior body surfaces

2) Connective- Supports and connects body parts

3) Nervous- Transmits nerve impulses

4) Muscle- Moves body parts

Levels of Organization in the Body- Organs

- Are groups of different tissue types that work together to perform a single function or several related functions

- Organ Systems- Are groups of organs that perform closely

related functions

Homeostasis- Is the relatively constant internal physical and chemical

conditions that organisms maintain despite changes in internal and external environments

Homeostasis- Is maintained through feedback

inhibition- Also called negative feedback

- A stimulus produces a response that opposes the original stimulus

- A thermostat is a good example- Room gets cooler- Heater turns on- Room gets warmer

Examples of Homeostasis- Body Temperature

- Hypothalamus acts like a thermostat

- Triggers the body to shiver when cold, and to sweat when hot

- Blood Sugar- Blood sugar (glucose) rises after a meal

- Too much blood sugar can damage organs

- Body cells absorb glucose, and the liver stores glucose as glycogen

- Blood sugar drops to a safe level