1. The Human Body The Nervous System
Textbook Chapter 14
Review Book Topic 1

2. Neuron Structure
Specialized cells that help you gather information about your environment, interpret the information, and react to it
Make up the communication network of your body known as the nervous system

3. Three major parts Dendrites Cell body Axon
Receive signals (impulses) from other neurons
Conducts impulses to cell body
Single neuron has many dendrites
Cell body
Contains nucleus and other cell organelles
Axon
Carries nerve impulse from cell body to other neurons and muscles

5. Types of neurons Sensory neurons
Send impulses from receptors in skin and sense organs to the brain and spinal cord
Signal interneurons

6. Interneurons Motor neurons Found in spinal cord and brain
Carry impulse to motor neurons
Motor neurons
Carries impulses away from brain and spinal cord to a gland or muscle
Results in a response

7. Reflex Arc
Nerve pathway that consists of a sensory neuron, an interneuron, and a motor neuron
Reflex ~ quick response to a change in the environment
Brain is NOT involved (doesn’t require conscious thought)
Involuntary
Basic structure of the nervous system

9. Nerve Impulse
Nerve impulse is an electrical charge traveling the length of a neuron
Impulses result from a stimulus
A neuron at rest is not conducting an impulse
A stimulus causes nerve impulse, opening channels within the cell membrane, moving charge particles (ions) across the membrane (creating a concentration gradient)

10. Charge is passed along the length of the axon
Can be slow or fast
Axons can be covered with a myelin sheath (lipid) which insulate the nodes of the axon
With myelin ~ carry impulses associated with sharp pain (faster)
Without myelin ~ carry impulses associated with dull, throbbing pain (slower)
How quickly the charge goes from node to node determines the reaction time

12. A small gap exists between the axon of one neuron and the dendrites of another
Known as a synapse
Vesicles move the chemical signal across this gap to continue the pathway of the impulse

13. Neurotransmitter
Chemical that diffuses across a synapse and binds to receptors on the dendrite of a neighboring neuron
25 known types
Can be broken down by enzymes or recycled
Neuron BrainPop

14. Organization of the Nervous System
Two divisions
Central nervous system (CNS)
Brain and spinal cord
Peripheral nervous system (PNS)
Sensory and motor neurons
Carries information to and
from CNS

15. Central Nervous System
Mostly interneurons
Coordinates all of the body’s activities
Relays messages, processes information, and analyzes responses

16. Sensory neurons carry information about the environment to the spinal cord
Interneurons in the spinal cord might respond via a reflex arc or they might relay information to the brain
Brain sends messages by way of spinal cord to motor neurons and body responds or brain stores information to be recalled later

17. Brain
100 billion neurons found here
Maintains homeostasis
Involved with almost all of the body’s activities
Control center of the body

19. Parts
Cerebrum
Largest part of the brain
Divided into two halves called hemispheres
Not independent of each other
Connected to each other by a bundle of nerves

20. Carries out thought processes involved with learning, memory, language, speech, voluntary body movement, and sensory perception
Higher thought processes occur near the surface of the brain
Folds and grooves on the surface increase the surface area and allows for more complicated processes

21. Cerebellum Controls balance, posture and coordination
Located in the back of the brain
Controls smooth and coordinated movement of skeletal muscles
Involved with motor skills

22. Brain stem connects the brain to the spinal cord and is made of two regions
Medulla oblongata
Relays signals between the brain and spinal cord
Helps control breathing rate, heart rate, and blood pressure
Contains interneurons that form a reflex arc for swallowing, vomiting, coughing, and sneezing

23. Pons
Relays signals between the cerebrum and cerebellum
Helps control the rate of breathing

24. Hypothalamus Located between brain stem and cerebrum
Essential for maintaining homeostasis
Regulates body temperature, thirst, appetite, and water balance
Partially regulates blood pressure, sleep, aggression, fear, and sexual behavior
Size of a fingernail
Performs more function that any other brain structure of its size

25. Spinal cord Nerve column that extends from the brain to the lower back
Protected by vertebrate
Spinal nerves extend from spinal cord to parts of the body and connect them to the CNS
Reflexes are processed here

26. Peripheral Nervous System
Nerves are made up of bundles of axons made from sensory and motor neurons
12 Cranial nerve that lead to and from the brain
31 spinal nerves (and their branches) that lead to and from the spinal cord

27. Two classifications
Somatic nervous system
Autonomic nervous system
Nerves relay information from external sensory receptors to the CNS
Motor neurons relay information from CNS to skeletal muscles
Voluntary
Reflexes mostly go to the spinal cord and not to the brain

28. Autonomic nervous system
Carries impulses from the CNS to the heart and other internal organs
Involuntary
Not under conscious control
“Fight-or-flight” response or
“rests-and-digests”

29.     Nervous System Central Nervous System
Peripheral nervous System  
Somatic Nervous System
(voluntary)
Relays info to and from skin and skeletal muscles
Autonomic Nervous System
(involuntary)
Relays info to internal organs
Nervous System BrainPop