C-Notes: Nervous SystemStnd: 9b

05/13/2014

Objective: SWBAT Identify the components of the nervous system and how it mediates communication between different parts of the body.

Nervous System

• The master controlling and communicating system of the body

• Functions– Sensory input – monitoring stimuli – Integration – interpretation of sensory input– Motor output – response to stimuli

Nervous System

Figure 11.1

The Nervous System has TWO Major Divisions.

• The Central Nervous System (CNS)– Brain and spinal cord– Integration and command center

• The Peripheral Nervous System (PNS)– Paired spinal and cranial nerves– Carries messages to and from the spinal cord and

brain

The Central Nervous System (CNS)

• The Central Nervous System (CNS) consist of the Brain and the Spinal Cord. – The spinal cord carries messages from the

body to the brain, where they are analyzed and interpreted. 

– Response messages are then passed from the brain through the spinal cord and to the rest of the body.

– Both the brain and the spinal cord are enclosed with bone.

Brain

• One of the most active organs of the human body

• The brain receives 20% of the blood that is pumped from the heart

• Brain and spinal cord float in a fluid known as cerebrospinal fluid. – This fluid cushions against shock.

• Major parts of the Brain: – Cerebrum (Cerebral Cortex)– Cerebellum– Medulla Oblongata

• Thalamus – message center between Brain and spinal cord

• Hypothalamus – controls body temperature, blood pressure, and emotions

0

100

1stQtr

4thQtr

E

W

N

Cerebral cortex

• 3 major Functions– Sensory areas that receive impulses from sense

receptors (Eyes, ears, taste, nose, pain, pressure, heat/cold, touch)

– Motor areas that start impulses that are responsible for all voluntary movement

– Associative areas of the brain are responsible for memory, learning and thought

• The cerebral cortex has many folds called convolutions

• Convolutions – are folds on the brain that increase surface area

The Cerebellum

• Controls all voluntary movements and some involuntary

• The cerebellum helps with balance, rate of muscle contraction, and the muscles position in relation to gravity

• Allows for smooth orderly movement

• Also plays a roll in sensory perception to maintain balance (inner ear)

Medulla Oblongata

• Connect the spinal cord to all other parts of the brain

• Control involuntary activities – Breathing– Heartbeat– Blood flow– coughing

Memory

• Scientist do not know exactly how memories are created

• 3 types of memory – Momentary – lasts a few min– Short-term – Several hours – Long-term – Weeks to years and longer

• How memories change from short-term to long-term is unknown

THE SPINAL CORD • 2 Important Functions

– Connects the nerves of the peripheral nervous system with the brain

– Controls certain reflexes which are automatic responses

• The spinal cord is continuous with the brain and emerges from an opening at the base of the skull.

The Peripheral Nervous System (PNS)

• The Peripheral Nervous System (PNS) consists of the neurons NOT Included in the brain and spinal cord.  – AFFERENT (Sensory) NEURONS -

Peripheral Neurons collect information from the skin, skeletal muscles, and joints from the body and transmit it TOWARD the CNS

– EFFERENT (motor) NEURONS. - Peripheral Neurons transmit information (impulses) AWAY from the CNS to effector organs

Divisions of the Peripheral Nervous System

• Somatic Nervous System – This system is responsible for body movements over which the individual has some conscious awareness or voluntary control of skeletal muscles

• Autonomic Nervous System – This system is responsible for involuntary activities and regulates smooth muscles, cardiac muscle, and glands– 2 divisions

• Sympathetic • Parasympathetic

THE SOMATIC NERVOUS SYSTEM

• Regulates activities that ARE UNDER CONSCIOUS CONTROL, movement of skeletal muscles. – Every time you lift your finger or wiggle your

toes, you are using the motor neurons of the Somatic Nervous System.

• Many nerves within this system are part of reflexes and can act automatically.

THE AUTONOMIC NERVOUS SYSTEM

• Regulates ACTIVITIES THAT ARE AUTOMATIC, OR INVOLUNTARY.

• The nerves of the Autonomic Nervous System control functions of the body that are NOT UNDER CONSCIOUS CONTROL.

• MAINTAINING HOMEOSTASIS IN THE FUNCTIONING OF MANY ORGANS OF THE BODY. – Examples:  heart rate, breathing rate, digestion

salivation ect. . . .

THE AUTONOMIC NERVOUS SYSTEM IS SUBDIVIDED INTO TWO PARTS:

Sympathetic “Fight or Flight” Nervous System

• The sympathetic nervous system prepares the body for sudden stress– For example if you see a robbery taking place.

• When something frightening happens, the sympathetic nervous system takes over – makes the heart beat faster – diverts blood to your muscles and chest – makes the pupils dilate – causes the adrenal glands at the top of the kidneys to release

adrenaline, to give extra power to the muscles for a quick getaway.

• This process is known as the body's "fight or flight" response.• http://www.youtube.com/watch?v=LjX88mkzU4g&safety_mod

e=true&persist_safety_mode=1

Parasympathetic “Sit and Digest” nervous system

• It prepares the body for rest.

• Slows heart rate

• It also helps the digestive tract move along so our bodies can efficiently take in nutrients from the food we eat.

• Opposite of the sympathetic

REFLEXES

• A reflex is an involuntary response to a STIMULUS.

• Reflexes are very fast, and Most Reflexes Never Reach the Brain.

• The reflex arc is an automatic, involuntary reaction to a stimulus. When the doctor taps your knee with the rubber hammer, she/he is testing your reflex (or knee-jerk).

25

Special senses

• Smell• Taste• Sight• Hearing• “Touch” = temperature + pressure + pain of

skin, muscles, & joints• Equilibrium (in the ear)

Sensory Receptors• Large complex organs (eyes, ears)• Localized clusters of receptors (taste buds,

olfactory epithelium)

Vision Tests

Are the squares inside the blue and yellow squares all the same color?

Bezold effect

The smaller squares inside the blue and yellow squares are all the same color.

They seem different (magenta and orange) because a color is perceived differently depending on its relation to adjacent colors (here blue or yellow depending on the outer square).

Are the horizontal lines straight or crooked?

Café Wall Illusion

The horizontal lines are straight, even though they do not seem straight. In this illusion, the vertical zigzag patterns disrupt our horizontal perception.

Does Lincoln’s face look normal?

Some neurons in the brain seem specialized in processing faces. Faces are usually seen upright. When presented upside down, the brain no longer recognizes a picture of a face as a face but rather as an object. Neurons processing objects are different from those processing faces and not as specialized. As a consequence these neurons do not respond to face distortions as well. This explains why we miss the weird eyes when the face is inverted.

Can you see a baby?

Illusory ContourThe baby’s head is on the left, the baby’s feet are

against the trunk of the tree on the right.Illusory Contour: a form of visual illusion where

contours are perceived without a luminance or color change across the contour

How quickly can you say the color of the words below?

EXIT Slip (Nervous System)1. What is the difference between peripheral

and central nervous systems?2. Explain the difference between somatic and

autonomic nervous system?3. What are the two divisions of the PNS?4. What is the name of the nerve (neuron) that

sends a message to the brain?5. What is the name of the nerve (neuron) that

sends back the response message from the brain to the body?