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1
NERVOUS SYSTEMBRAIN
SPINAL CORD
Nerve Cell
Nervous System:What it is & what it does.
• The control and communication network
of the body.
• 3 functions of the nervous system:
1. Detects internal & external stimuli
2. Controls responses to stimuli
3. Integrates activities of organ systems.
Neurons & Nerves• Neuron: a nerve cell that
carries information from one place to another.
• Nerve: a bundle of neuronstogether
• Types of Neurons:1. Sensory Neurons: get
information from the environment through the senses and relays the message to the brain.
2. Motor Neurons: carry information from the brain to the muscle and glands to cause action.
Parts of A Nerve Cell• Dentrites carry impulses
from the environment or other neurons toward the cell body.
• Axons carry impulses away from the cell body.
• The area where one nerve cell transfers an impulse to another is called a synapse
• Myelin Sheath insulates the axons and helps nerve cells send impulses
NeuronDendrites
Axon
Nucleus
Cell Body
Schwann Cell
Mylenated
Sheath
Two Main parts of the Nervous System
• Central Nervous System:
composed of the brain and the spinal cord.
– The brain has different parts that perform specific tasks.
– The spinal cord runs up and down the back and is surrounded by
vertebrae which provides protection. The spinal cord transmits sensory and motor information between the
body and the brain.
2
Figure 48.24 Structure and functional areas of the cerebrum
Two Main parts of the Nervous System
• Peripheral Nervous System: consists of all other parts of the nervous system. It carries
nerve impulses from the brain and spinal cord to the body and transmits sensory input from the body to the brain.
• It is broken into two parts:
1. Autonomic system: controls the involuntarysystems such as glands and smooth muscles.
2. Somatic system: controls the voluntary systems like the skeletal muscles.
Figure 48.16 The nervous system of a vertebrate
Central Nervous System:
Brain & Spinal Cord
-evolved from the
embryonic dorsal nerve
cord
Peripheral Nervous System:
Cranial Nerves, Spinal
Nerves, Ganglia
Figure 48.1 Overview of a vertebrate nervous system
Senses
• Senses are the ability for us to detect what
is happening in our environment and are used for protection.
• 5 senses: smell, sight, touch, hearing, taste
5 senses
• Taste: can be used for protection, a bad taste can indicate poison or rotten food.
• Smell: assists in taste and associates memory with odor.
• Sight: allows us to see to obtain food and avoid danger.
• Touch: protects us from harming our selves physically.
• Hearing: allows us to detect danger and obtain food, the ears also maintain balance.
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Other info.
• Simpler animals have simpler system.
– Cnidarians have nerve nets that conduct
impulses from the body and cause the cells to contract.
– Flatworms have a small brain called a
ganglion. The ganglion sends messages down 2 nerve cords that run the length of
the body.
– Insects have well developed nervous systems including brains that allow the
organisms to respond to their environment.