Chapter 21

1. Chapter 21 Nervous System

2. Your body responds to changes in the environment. Any internal or external change that brings about a response is called a ________________. stimulus

3. Give an example of an external stimulus and an internal stimulus. External stimulus Loud noise, smell of food Internal Stimulus hormones

4. Your nervous system is one of several control systems used by your body to maintain homeostasis. Explain what maintaining homeostasis means. Regulation of steady, life-maintaining conditions inside an organism despite changes in its environment. Examples: body temperature, blood glucose levels, proper levels of water in the body

5. The basic functioning units of the nervous system are nerve cells or ________________. neurons

6. Identify the three major parts of a neuron and describe the function of each. Dendrites Receive impulses from other neurons and send them to the cell body Cell Body Factory of the neuron; contains a nucleus and other organelles Axon Carry impulses away from the cell body

7. Distinguish between sensory neurons, interneurons, and motor neurons. • Sensory neurons Receive information and send it to the brain or spinal cord • Interneurons Relay impulses between the sensory and motor neurons • Motor neurons Conduct impulses from brain or spinal cord to muscles or glands throughout the body

8. Neurons do not touch each other. To move from one neuron to another, an impulse crosses a small space between neurons called a _____________________. synapse

9. Explain how an impulse crosses the space between neurons. The axon releases a chemical that flows across the synapse and stimulates the impulse in the dendrite of the next neuron.

10. Distinguish between the central nervous system and the peripheral nervous system. Central nervous system Made up of brain and spinal cord Peripheral nervous system Consists of all nerves outside the central nervous system. 12 pairs of cranial nerves, 31 pairs of spinal nerves

11. Identify the three major parts of the brain and the function of each. Cerebrum Largest part of brain; where thinking occurs, memory is stored, and senses are interpreted Cerebellum Maintains muscle tone, balance Brain Stem Controls involuntary actions such as breathing and heartbeat; connects brain to spinal cord; consists of the midbrain, pons, and medulla

12. Identify the largest part of the brain. cerebrum

13. Define cortex. Outer layer of the cerebrum; marked by many ridges and grooves ; theses ridges and grooves increase surface area, allowing for more complex thought.

14. Identify the part of the brain that controls the following: • Breathing brain stem • Coughing brain stem • Tasting cerebrum • Stores memory Cerebrum • Balance cerebellum

15. Identify the part of the brain that controls the following: Vision Cerebrum Heartbeat brain stem Blood pressure Brain stem Muscle tone Cerebellum Interprets senses cerebrum

16. Your spinal cord is an extension of your ___________________. Brain stem

17. Your brain and spinal cord are connected to the rest of your body by the ________ _________ _______. Peripheral Nervous System

18. The peripheral nervous system has two divisions. Identify them and describe the function of each. Somatic system Controls voluntary movements Autonomic system Controls involuntary movements

19. The peripheral nervous system is made up of 12 pairs of nerves from your brain called _______ and 31 pairs of nerves from your spinal cord called______________. Cranial Nerves Spinal Nerves

20. Identify three major causes of head and spinal cord injury. Automobile accidents Bicycle accidents Motorcycle accidents Sports injuries

21. What can an individual do to prevent head injury? Wear appropriate safety gear, such as helmets.

22. A ________ is an involuntary, automatic response to a stimulus. reflex

23. Identify three examples of reflexes. Touching something hot and jerking your hand away Stepping on something hot and lifting your foot Production of insulin by the pancreas when blood glucose levels become too high.

24. You cannot control reflexes because they occur before you know what happened. A reflex involves a simple nerve pathway called a _______ _________. Reflex arc

25. Explain how a reflex impulse moves through a reflex arc. • Sensory receptors send an impulse to the spinal cord • The impulse passes to an interneuron in the spinal cord. • The interneuron relays the impulse to the motor neurons. • Motor neurons transmit the impulse to muscles or glands throughout the body

26. Reflexes are controlled by the ________________, not your brain. Your brain reacts after the reflex to help you figure out what to do . Spinal Cord

27. Contrast stimulants and depressants. Stimulants Drugs that speeds up the activity of the central nervous system, causing restlessness, increased heart rate, and insomnia Depressants Drugs that slow down the activity of the central nervous system, impairing concentration, memory, muscle control, and judgment

28. Give an example of a stimulant and a depressant. Stimulants cocaine, crack , amphetamines Caffeine in soft drinks, tea, coffee Depressants Alcohol, marijuana, heroine, codeine, morphine

29. Explain why you might have trouble going to sleep after several cups of hot coffee. Coffee contains caffeine ,which is a stimulant. The caffeine in the coffee can make you restless and cause insomnia.

30. Label the parts of a neuron

31. Study for the test!!!!! : )