Organ systems

Chapter 20

Structural Hierarchy

Animal tissue types

• What is a tissue?• A cooperative unit of many very similar

cells that perform a specific function.• Examples

– Epithelial– Connective– Muscle– Nervous

Tissues to organs

• An organ is composed of several tissue types

• Ex. stomach

Organ systems

• Groups of several organs that work together to perform vital body functions

• 12 major organ systems

Digestive system

• Ingests food, breaks it down into small units, absorbs the units, eliminates unused parts.

Respiratory system

• Lungs and breathing tubes exchange gases with the environment.

Cardiovascular system

• The heart and blood vessels supply nutrients and oxygen to the body and carry away wastes and carbon dioxide.

Lymphatic and immune systems

• Supplements the cardiovascular system

• A diffuse system of cells and processes that protect the body from foreign invasion

• Makes up the circulatory system along with the cardiovascular system

Excretory system

• Kidneys, bladder, and urethra remove nitrogen containing wastes from the blood and maintain osmotic balance.

Endocrine system

• Endocrine glands secrete hormones into the blood that regulate most other activities.

Reproductive system

• Different in males andfemales

• Ovaries and testes produce female and male gametes, and help in fertilization and embryo development.

Nervous system

• The brain, spinal cord, nerves, and sense organs work together with the endocrine system to sense the outside environment, affect responses, and coordinate body activities.

Muscular system

• All skeletal muscles provide movement as they work with the skeletal system

Skeletal system• Bones and cartilage

provide support and protection, and work with the muscular system to provide movement.

Integumentary system• Skin, hair and nails

protect the internal body parts from injury, infection, temperature extremes, and drying out.

Exchanges with the external environment

• Organisms cannot survive unless they exchange materials with their environment

• Organ systems function to make the exchange of nutrients and wastes with the external environment possible in larger animals

• Examples: Hydra vs Whale

Exchanges with the external environment

• Hydra– Small, 2 cell layers, each in contact with the environment– Exchange is easy

Exchanges with the external environment

• More complex animal– large, many cell

layers, few in contact with the external environment

– Exchange is achieved by organ systems and with the interstitial fluid.

– Fine branches in each system circ, resp, dig.

Regulation of the internal environment

• Homeostasis -”a steady state”

• Claude Bernard• Control systems

regulate large external fluctuations in external environment into small fluctuation s in the internal environment.

Homeostasis and negative feedback

• Homeostasis works through negative feedback• Set point = “temperature”• Error signal =“wire”• Effector =“heater”• Response =“heat”• Stimulus =“temperature of room”

Homeostasis and negative feedback

Example