The Skeletal System

1. The Skeletal System

2. The Nervous System • Nervous System – group of nerves and organs that controls all of our actions and thoughts • Nerves – made up of axons • Neurons– single nerve cell (basic unit of the nervous system) • The neuron has 3 main parts: • Cell body – houses the nucleus(DNA) • Axon– tail that the message travels along • Dendrite– the “fingers” on the body of the cell that receive the message from another cell **Synapse – the gap between neurons over which messages must jump

3. Types of neurons • 3 types of neurons – • Sensory neurons – sense changes in the environment inside and outside the body; they carry impulses from the sense organs, the skin, the muscles, and the internal organs (touch a stove – neurons sense hot and send it to your brain) • Interneurons – receive sensory messages and send responses – found only in the brain and spinal cord (touch stove – realize your hand is burning – move hand) • Motor neurons – carry a response from interneurons to the muscles, glands, and internal organs – controls every body movement

4. The Nervous System • The nervous system is like the boss of the body – it tells all of the other systems what to do! • Its organs include: • The brain (like the main computer) • The spinal cord (like the main telephone line) • Nerves (like radar detectors and small telephone lines)

5. The Brain can be divided into 3 main parts… • Cerebrum • Cerebellum • Brain stem (medulla oblongata)

6. Cerebrum • The Cerebrum controls functions such as memory, thought, decision making, feelings, and the five senses.

7. Cerebellum • The cerebellum controls functions such as coordination, balance, and posture • What are some things you couldn’t do if your cerebellum was not functioning properly?

8. Brainstem – add this to your notes! • Connects the brain to the spinal cord • Controls heart rate, breathing, digestion, and circulation • Also controls involuntary movements • Examples of involuntary movement???

9. Spinal Cord • Spinal cord extends from the medulla to the ribs – it’s about 18 inches long and the diameter of a finger • The spinal cord is the main highway that links the brain to nerves and nerves to the brain and also regulates blood pressure and pulse • This highway sends and receives messages (electrical impulses) • It is protected by the spine (vertebra) – if it’s damaged you may not be able to feel or move from the point of damage

10. Tonight’s Homework • What are the five functions of the skeletal system? • How many bones are in an adult skeleton? • How are bones classified? • What are the five internal and external characteristics of bone? • What are the two classifications of joints? Describe them.