The Nervous System

Functions of the Nervous System Control center for all body activitiesControl center for all body activities Responds and adapts to changes that occur both inside and outside the bodyResponds and adapts to changes that occur both inside and outside the body (Ex: pain, temperature, pregnancy) (Ex: pain, temperature, pregnancy)

Neurons Neurons :microscopic nerve cells that make up the brain, spinal cord, and nerves (30,000 neurons can fit on a pinhead)

Anatomy of a Neuron Each neuron contains: Cell body with nucleusCell body with nucleus Dendrites : fibers that receive messages from other neuronsDendrites : fibers that receive messages from other neurons Axons : fibers that send messages to other neuronsAxons : fibers that send messages to other neurons

Anatomy of a Neuron Neurons do NOT touch; there is a gap between them called a synapseNeurons do NOT touch; there is a gap between them called a synapse Messages are sent across the synapses by special chemicals called neurotransmittersMessages are sent across the synapses by special chemicals called neurotransmitters

Communication Between Neurons The use of neurotransmitters causes an electrical currentThe use of neurotransmitters causes an electrical current There is enough electrical current in the brain to power a flashlightThere is enough electrical current in the brain to power a flashlight

Two Major Divisions of the Nervous System

Central Nervous System Consists of the brain and spinal cord.Consists of the brain and spinal cord. Largest part of the nervous systemLargest part of the nervous system Integrates & coordinates all of the information that it receives from all of the parts of the bodyIntegrates & coordinates all of the information that it receives from all of the parts of the body

Central Nervous System The BRAIN The BRAIN A mass of 100 billion neurons located inside the skullA mass of 100 billion neurons located inside the skull The mass of an adult human brain is approximately 2.87 to 3.1 poundsThe mass of an adult human brain is approximately 2.87 to 3.1 pounds A newborn human brain is about 0.77 to 0.88 poundsA newborn human brain is about 0.77 to 0.88 pounds The average Male's brain weighs 3 poundsThe average Male's brain weighs 3 pounds The average Female's brain weighs 2.8 poundsThe average Female's brain weighs 2.8 pounds Learning occurs as more and stronger connections are made between neuronsLearning occurs as more and stronger connections are made between neurons

Anatomy of the Brain Cerebrum Cerebrum largest part of human brainlargest part of human brain responsible for: responsible for: - Thought - Thought - Language - Language - Senses - Senses - Memory - Memory - Voluntary movement - Voluntary movement

Anatomy of the Brain Cerebrum Cerebrum divided in to two hemispheres; the right and leftdivided in to two hemispheres; the right and left the dividing point is a deep grove called the longitudal cerebral fissurethe dividing point is a deep grove called the longitudal cerebral fissure the different sides of the cerebrum do different things for the opposite sides of the body. The right side of the cerebrum controls things such as imagination and 3-D forms. The left side, controls numbering skills, posture, and reasoning.the different sides of the cerebrum do different things for the opposite sides of the body. The right side of the cerebrum controls things such as imagination and 3-D forms. The left side, controls numbering skills, posture, and reasoning. the hemispheres also consist of many other parts such as the lobes.the hemispheres also consist of many other parts such as the lobes.

Retrieval of a Memory A memory is not a snapshot stored in the brain – it must be put together from information stored in various parts of the brain

Anatomy of the Brain Cerebellum located at base of brain responsible for: - Muscle coordination - Balance - Posture

Anatomy of the Brain Cerebellum accounts for only 10% of the brain's total weight maintains muscle tone about the size of an orange in size and consists of two hemispherical lobes injury to the cerebellum usually results in disruption of eye movements, balance, or muscle tone.

Anatomy of the Brain Brain Stem Brain Stem connects brain to spinal cordconnects brain to spinal cord responsible for:responsible for: - Breathing - Breathing - Swallowing - Swallowing - Heartbeat - Heartbeat - Blood pressure - Blood pressure

Anatomy of the Brain Brain Stem Brain Stem upper segment of the brain stem, the pons, contains nerve fibers that connect the two halves of the cerebellumupper segment of the brain stem, the pons, contains nerve fibers that connect the two halves of the cerebellum

Anatomy of the Brain Brain Stem Brain Stem below the pons and continuous with the spinal cord is the medulla, which controls many involuntary muscular and glandular activities, including breathing, heart contraction, artery dilation, salivation, vomiting, and probably laughingbelow the pons and continuous with the spinal cord is the medulla, which controls many involuntary muscular and glandular activities, including breathing, heart contraction, artery dilation, salivation, vomiting, and probably laughing

Central Nervous System Spinal Cord Spinal Cord column of nerves from brain to coccyx – protected by the vertebrae of spinecolumn of nerves from brain to coccyx – protected by the vertebrae of spine responsible for conducting impulses between the brain and the rest of the bodyresponsible for conducting impulses between the brain and the rest of the body * Impulses may travel as fast at 268 miles/hr

Peripheral Nervous System Nerves (Neurons) Nerves (Neurons) visible bundles of axons and dendrites that extend from the brain and spinal cord to all other parts of the body visible bundles of axons and dendrites that extend from the brain and spinal cord to all other parts of the body

Peripheral Nervous System Sensory neurons Sensory neurons carry messages from the body and its environment to the brain… including pain, pressure, and temperature (stimuli) carry messages from the body and its environment to the brain… including pain, pressure, and temperature (stimuli)

Peripheral Nervous System Motor neurons Motor neurons carry messages from the brain to body. The muscles respond to these messages