Nervous System

Weekly Standards: S7L2, S7CS10 Weekly Elements: Explain that cells are organized into tissues, tissues into organs, organs

into systems, and systems into organisms. Explain that tissues, organs, and organ systems serve the needs cells

have for oxygen, food, and waste removal. These fall under the categories of metabolism.

Identify that similarities and differences in structures exist among kingdoms of living organisms

Explain that the function of many systems within an organism involve supporting life by ensuring the organism maintains homeostasis.

build vocabulary knowledge demonstrate an understanding of conceptual vocabulary in various

subjects use context vocabulary in writing and speaking explore understanding of new words found in subject area texts

Enduring Understandings1. Each organ system has structures (organs) that

support each other in carrying out the functions of that organ system, while collectively working together with other organ systems to meet the survival needs of the organism.

2. Organ systems are interdependent. Every action taken by one organ system has an effect on the rest of the organ systems even though we may not be aware of what that effect is.

3. There are similar structures and organ systems in almost all multi-cellular organisms in the same kingdom that provide similar functions for those organisms.

Essential QuestionsLevel OneWhat are the major structures of the nervous system?What are the various functions of the nervous system?What are the body’s five sense organs?How do nerve impulses travel to and from the brain?What is the function of a reflex response and how is a

reflex response different from a normal motor impulse?Level Two1. How does the nervous system of humans differ from

other organisms in the same phylum?2. How does the nervous system work collectively with

other systems to help the organism sustain life?

The brain works like a computer that answers questions and sends messages (called impulses or signals) all over the body.  

It has the appearance of a wrinkled walnut shell. An adult brain weighs between two and three pounds. It is very fragile and soft and therefore, needs protection. This protection is provided by the skull which is a very hard bone. 

The brain contains long lines of nerve cells called neurons which function like little telephone lines that send messages all over the body. Some of these messages (impulses) go to other parts of the body through the spinal cord. Messages from the brain move very quickly through the body. 

The brain keeps the heart beating and the lungs breathing. It enables the body to move. It facilitates thinking and remembering.

One of the most important jobs of the brain is to make sure all systems in the body are functioning the way they are supposed to be and within certain limits. These limits might include the amount of sugar or salt in the blood; body temperature; or the amount of water in the body. This attempt to keep the body operating within normal limits is known as homeostasis.

CUE BrainPop Nervous System http://www.brainpop.com/health/bodysystems/nervoussystem/

Introduction

The human nervous system consists of the brain, spinal cord, and peripheral nerves of the body.

•Central Nervous System- brain and spinal cord.

Cue BrainPop:

Brain- http://www.brainpop.com/health/bodysystems/brain/

Spinal Cord- http://www.brainpop.com/health/bodysystems/spinalcord/

•Peripheral Nervous System- the nerves that extend into our appendages.

The nervous system controls all functions of the body and allows us to perceive the world through our senses, process an incredible amount of information, and respond to things in our world. But it is far more than that. Our brain provides humans with an ability to “think” far beyond any other animal.

Nervous System

The brain is connected to the rest of our body by millions of special nerve cells called neurons. Nerve cells, or neurons, carry messages to and from the brain at very fast speeds! (Go to How Fast Are Your Neurons Link http://www.nsta.org/publications/interactive/nerves/basics/how_fast.html.)

Nerve cells are one-way only. Each neuron either carries a message to the brain or away from it depending upon whether they are motor or sensory neurons.

Neurons are similar to other cells in the body in that they have the full host of organelles: cell membranes, a nucleus (more than one), mitochondria, cytoplasm, etc.

But the shape of neurons is very different. Neurons have specialized extensions called dendrites and axons. Dendrites bring information to the cell body and axons take information away from the cell body.

Let’s talk through how a nerve impulse passes along.

Cue BrainPop

Neurons-http://www.brainpop.com/health/bodysystems/neurons/

Neurons communicate with each other through a series of lightening fast electrochemical reactions.

The axons and dendrites are separated from other neurons by a small space known as a synapse. As messages pass from one neuron to another on the way to or from the brain, the messages are carried across the synapse by chemicals known as neurotransmitters.

I. Nerve Cells (neurons): Messages travel to and from our brain on special nerve cells called neurons

A. Motor neurons- send messages (impulses) from the brain to the rest of the body.

1. Voluntary impulses- messages to our body for movements we control (walking, throwing, etc)

2. Involuntary impulses- messages to our body for actions we do not control. Examples of involuntary actions a. Our heart beating, the muscles of our stomach and intestines contracting during digestion.

b. Blinking and breathing (which is controlled by an organ called the diaphragm) are examples of involuntary movements that can also be controlled voluntarily.

c. These different organs function on their own, and are therefore considered involuntary. These motor messages make up our autonomic part of our nervous system.

B. Sensory neurons- send messages (impulses) from the senses to the brain. The sensory organs are

1. Eyes (sight)2. Nasal passages (smell)3. Tongue (taste)4. Ears (hearing)5. Skin (touch)

Reflexes are lightning fast commands that fire out from our brain to help us escape a potentially dangerous or harmful situation. We jump at a loud sound, quickly pull our hand away from a hot surface, or instantaneously throw our hands up in front of our faces when something comes flying toward us. These are all examples of reflexes.

How can our reflexes operate so quickly? Most sensory impulses (including pain) must be processed by the brain which then responds in some way to the signal. The motor signals involved in an impulse response do not get processed in the brain first. Our nervous system has a way to bypass the brain in emergencies. Our body is designed to react immediately to potential danger. Even the fraction of second it might take to think about the lion jumping out of the tall grass at you might be too long and result in severe injury or death.

Reflexes

Nervous System Foldable Outside

Nervou

s System

Nervous System Foldable Inside

Nervous System I. Function-

Controls all actions of the body. Stores information. Allows us to think and understand our world. II. Structures- A. Central Nervous System- consists of brain and spinal cord. B. Peripheral Nervous System- consists of all the nerves that extend from our spinal column into our appendages. C. Neurons- nerve cells that carry messages (impulses) to and from our brain. 1. Motor neurons carry commands from our brain to the body. These commands are either voluntary (we control them) or involuntary (they take place without our knowledge like our heart beating.) 2. Sensory neurons carry impulses from our sense organs to our brain.

neurons

1. Identify which part of the nervous system makes up the central nervous system.The brain and the spinal cord.

2. Explain the function of a neuron.Neurons carry messages/signals (impulses) to or from the brain.

3. Which of these is an example of a reflex?-catching a Frisbee-kicking a soccer ball-jerking your hand back when a dog you are petting snaps at it

4. List two organs that function involuntarily (in other words, are part of our autonomic nervous system.)• The muscles lining your digestive system organs (stomach, small intestine,

large intestine.)• Your diaphragm (breathing muscle) though you are able to control it to a

degree.• Heart.• Most glands that produce hormones.

Bell Ringer and Closing Questions