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Nervous Systems. Structure of a Vertebrate Neuron. Diversity of Nervous Systems. Simple, slow moving animals like hydra have neurons arranged in a network of bipolar neurons called a nerve net. Basic Tasks of the Nervous System.
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Diversity of Nervous Systems Simple, slow moving animals like hydra have neurons arranged in a network of bipolar neurons called a nerve net.
Basic Tasks of the Nervous System Sensory Input: Monitor both external and internal environments. Integration: Process the information and often integrate it with stored information. Motor output: If necessary, signal effector organs to make an appropriate response.
The brain The spinal cord The nerves The senses Nervous System A system that controls all of the activities of the body. The nervous system is made of:
The nervous system also allows you to react to a stimulus. Stimulus A stimulus is a change in the environment. Example: A hot stove Or… tripping over a rock
Your reactions are automatic. Automatic Automatic means that you do not have to think about your reactions. Example: If a bug flies by your eye, you will blink.
Brain An organ that controls your emotions, your thoughts, and every movement you make.
Central Nervous System The Central Nervous System is made of the brain and the spinal cord. The Central Nervous System controls everything in the body.
Nerves Sense organs Outer Nervous System The Outer Nervous System (Peripheral Nervous System)is made of the nerves and the sense organs.
Nerve Impulse Messages carried throughout the body by nerves.
You have a nerve along your whole arm. "Funny Bone" The “funny bone” is the only place on the arm where the nerve is not protected. The “funny bone” is on the elbow.
Anatomy of a Neuron • Cell body: functional portion • Dendrites: short extensions that receive signals • Axon: long extension that transmits impulses away
Nerve Impulse - The Action Potential Threshold potential will trigger an action potential or nerve impulse The action potential is an all-or-none response
Many vertebrate peripheral neurons have an insulating sheath around the axon called myelin which is formed by Schwann cells. Myelinated Neurons • Myelin sheathing allows these neurons to conduct nerve impulses faster than in non-myelinated neurons.
Saltatory Conduction in Myelinated Axons Myelin sheathing has bare patches of axon called nodes of Ranvier Action potentials jump from node to node Fig. 48.11
How does a signal move from one neuron to another? • A synape divides 2 neurons • The action potential will not move across the synape • Neuro transmitters • Released by the signal cell to the receiver cell • Move by diffusion
Types of chemical synapse • Acetylcholine: neuromuscular junctions, glands, brain and spinal cord • Norepinepherine: affects brain regions concerned with emotions, dreaming
The Nervous System The Central Nervous System
The Central Nervous System 1. The brain 2. The spinal cord * The Central Nervous System controls all of the body’s activities. * The Central Nervous System is made of two main organs.
The Spinal Cord * The spinal cord sends messages to the brain. * The spinal cord is the part of the nervous system that connects the brain to the rest of the nervous system.
The Brain * The brain controls everything in the body. * The brain is made of more than 10 billion nerves! * The brain is divided into three parts and is protected by the skull.
The Three Parts of the Brain * The Brain has three main parts… 1. The Cerebrum 2. The Cerebellum 3. The Brain Stem
The Cerebrum * The Cerebrum is the largest part of the brain. 1. The cerebrum controls your thinking. 2. The cerebrum controls your memory. 3. The cerebrum controls your speaking. 4. The cerebrum controls your movement and identifies the information gathered by your sense organs.
The Cerebellum 1. The cerebellum controls you balance. 2. The cerebellum controls your posture. * The cerebellum is below and to the back of the cerebrum.
The Brain Stem * The Brain Stem connects the brain to the spinal cord. * The nerves in the brain stem control your heartbeat, breathing, and blood pressure.
The Vertebrae * The vertebrae are the many bones that protect the nerves in the spinal cord.
Outer Nervous System * The outer nervous system carries messages between the central nervous system and the rest of the body. * The Outer Nervous System’s job is to connect the Central Nervous System to the rest of the body.
Nerves Eye Skin Ear Tongue Outer Nervous System * The outer nervous system is made of the nerves and the sense organs.
Reflex * An automatic reaction that happens without thinking about it. * A reflex happens quickly in less than a second.
controls Automatic Nervous System * The outer nervous system controls the body’s activities that you don’t think about. * The outer nervous system controls activities in your small intestine, your breathing, and your heartbeat.
Sense Organs Sense organs carry messages about the environment to the central nervous system.
Sense Organs The eyes, ears, nose, tongue, and skin are examples of sense organs. The sense organs gather information (light, sound, heat, and pressure) from the environment.
Environment The environment is everything outside the body. The sense organs gather information from outside the body, then send the messages to the brain.
Vision is your ability to see. Vision Vision involves the eye and the brain.
Parts of the Eye Detectors on the Fovea • Rods • light intensity and motion sensitive • Cones • color sensitive The blind spot for the eye is cause by the optic nerve.
Myopia (Near-Sightedness) People with near-sightedness cannot see clearly at distance.
Hyperopia (Farsightedness) People with far-sightedness cannot see clearly up close
