AP Biology 2003-2004 The Nervous System. Regents Biology 2003-2004 Overview ▪ The Nervous System controls and coordinates all the functions of the body.

AP Biology 2003-2004

The Nervous System

Regents Biology 2003-2004

Overview▪ The Nervous System controls and

coordinates all the functions of the body.

▪ The Nervous System consists of two main sub-divisions:▪ Central Nervous System

(CNS)▪ Peripheral Nervous System

(PNS)▪ The Peripheral Nervous System is

divided into two sub-divisions:▪ Somatic- voluntary▪ Autonomic- involuntary

Regents Biology 2003-2004 http://inside.salve.edu/walsh/cns_pns.jpg

http://inside.salve.edu/walsh/cns_pns.jpg


Structure and Function of the Neuron▪Neuron is the scientific name for a Nerve Cell.

▪Neurons consist of 3 basic structures:▪ Cyton, or cell body.▪ Dendrites- receive messages,

impulses, and send them to the cell body.

▪ Axons- send messages away from the cell body.

▪Nerve impulses travel from one neuron to another across synapses, or spaces in between the cells.

▪ The “jumping across” the synapse is facilitated (helped) by chemicals called Neurotransmitters.


Parts of the Neuron▪ Dendrites – Branched

parts of a neuron that receive impulses from other neurons.

▪ Cyton- Contains cytoplasm and the nucleus. Impulses pass through here to the axon.

▪ Axon- Single long fiber that carries impulses away from the cell body.

▪ A Neuron



Synapse

synapse

Junction between nerve cells◆ 1st cell releases chemical to trigger

next cell◆ where drugs affect nervous system


Types of NeuronsNeurons can also be classified by the

direction that they send information:･ Sensory (or afferent) neurons: send

information from sensory receptors (e.g., in skin, eyes, nose, tongue, ears) TOWARD the central nervous system.

･Motor (or efferent) neurons: send information AWAY from the central nervous system to muscles or glands.

･ Interneurons: send information BETWEEN sensory neurons and motor neurons. Most interneurons are located in the central nervous system.


Reflexes▪Stimulus- a

change in the environment.

▪Response/Reaction- how the body reacts to a stimulus.

▪Reflex Arc- the pathway that an impulse follows to illicit a response to a stimulus.


Parts of the Central Nervous System

▪ Brain

▪ Spinal cord


The Brain

▪ Coordinates body activities ▪ Made up of approximately 100 billion neurons▪ Uses 20% of bodies oxygen and energy ▪ Divided into three major parts-

◆ the Cerebrum◆ the Cerebellum◆ the Brain Stem (Medulla Oblongata, Pons)


Cerebrum▪ Largest part of the brain

▪ Thinking

▪ Memory is stored

▪ Movements are controlled

▪ Impulses from the senses are interpreted.


signaldirection

myelin coating

Myelin Sheath▪ Axon coated with insulation

made of myelin cells (Fatty, protein substance)◆ speeds signal◆ 330 mph vs. 11 mph

Multiple Sclerosis▪ immune system (T cells) attacks myelin coating ▪ loss of signal

Regents Biology

Gray Matter vs. White Matter

▪ Gray Matter – Absence of myelin in masses of neurons accounts for the gray matter of the brain – Cerebral Cortex

▪ White Matter - Myelinated neurons gives neurons a white appearance – inner layer of cerebrum


Cerebrum specialization

frontal

temporal

▪ Regions specialized for different functions▪ Lobes

◆ frontal▪ speech,

control of emotions◆ temporal

▪ smell, hearing◆ occipital

▪ vision◆ parietal

▪ speech, tastereading

occipital

parietal


Cerebellum▪ Responsible for the

coordination of muscles and is the center of balance



Medulla▪ Center of heart beat,

respiration, and other involuntary actions

Regents Biology

Other Structures inside the Brain

▪ Thalamus – receives messages from sensory receptors; relays information to proper regions of cerebrum

▪ Hypothalamus - Regulates hunger, thirst, fatigue, anger, etc… ◆ Control of pituitary for endocrine function


The Spinal Cord▪ Extension of the brain stem

▪ Bundles of neurons that carry impulses from all parts of the body to the brain and from the brain to all parts of your body


Research Visit the Glencoe Science Web site at tx.science.glencoe.com for more information about the nervous system. Make a brochure outlining recent medical advances.

The Peripheral Nervous System Your brain and spinal cord are connected to the rest of your body by the peripheral nervous system. The PNS is made up of 12 pairs of nerves from your brain called cranial nerves, and 31 pairs from your spinal cord called spinal nerves. Spinal nerves are made up of bundles of sensory and motor neurons bound together by connective tissue. For this reason, a single spinal nerve can have impulses going to and from the brain at the same time. Some nerves contain only sensory neurons, and some contain only motor neurons, but most nerves contain both types of neurons.

Somatic and Autonomic Systems The peripheral nervous system has two major divisions. The somatic system controls voluntary actions. It is made up of the cranial and spinal nerves that go from the central nervous system to your skeletal muscles. The autonomic system controls involuntary actions-those not under conscious control-such as your heart rate, breathing, digestion, and glandular functions. These two divisions, along with the central nervous system, make up your body's nervous system.

http://tx.science.glencoe.com/



AP Biology 2003-2004 The Nervous System. Regents Biology 2003-2004 Overview ▪ The Nervous System controls and coordinates all the functions of the body.

Documents

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neuron slide

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