Nervous System
What is the Function of the Nervous System? Controls all body functions through: Controlling muscles Coordinating activity of the organs Enables senses to work properly The Nervous System can be divided into 2 parts: Central Nervous System (CNS) Peripheral Nervous System (PNS)
Central Nervous System (CNS) Made up of the brain and spinal cord Brain = receive nerve impluses from spinal cord Spinal cord = contains nerves that carry messages from the brain to the body.
Peripheral Nervous System (PNS) Contains only nerves These nerves connect the body to the spinal cord There are two major subdivisions of the PNS: Somatic Nervous System Autonomic Nervous System
Somatic Nervous System Controls voluntary body movements – or conscious movement For example: Action of skeletal muscle Receiving external stimuli, which helps with sight, hearing, smell, etc.
Autonomic Nervous System Controls involuntary body movements – or unconscious movement (body functions that you don’t have to think about) Regulates functions such as: Stomach, intestines, bladder Heart rate Breathing Blood vessels Muscles in the eyes
Autonomic Nervous System continued…. Can be divided into 2 systems: Sympathetic Nervous System - involved in the fight or flight response; causes an “adrenaline rush” Parasympathetic Nervous System - involved in relaxation. It is responsible for “rest and digest”. Each of these subsystems operates in the opposite of the other (see picture on next slide)
That was a lot of information. Let’s review: The nervous system can be divided into 2 systems. What are the names of these systems? The ____________ is the brain and the spinal cord. The ___________ is the other nerves. The PNS can be further broken down into: Which of these systems controls voluntary movement? And involuntary movement? The autonomic nervous system can be divided into which 2 parts? What is the key function of each of these parts?
Organizational Chart of the Nervous System Central Nervous System (CNS) Autonomic Nervous System Peripheral Nervous System (PNS) Somatic Nervous System Parasympathetic Nervous System Sympathetic Nervous System
Structure of the Nervous System The neuron is the functional unit of the nervous system. Humans have about 100 billion neurons in their brain alone! All neurons have three parts: the dendrite, cell body, and the axon.
The Structure of the Neuron Dendrites - receive information from another cell and transmit the message to the cell body. Cell body - contains the nucleus, mitochondria and other organelles typical of eukaryotic cells. Axon - conducts messages away from the cell body.
3 Types of Neurons 1. Sensory neurons - carry messages from sensory receptors to the central nervous system. 2. Motor neurons - transmit messages from the central nervous system to the muscles (or to glands). 3. Interneurons - are found only in the central nervous system where they connect neuron to neuron. See picture on next slide
How do Neurons work? Synapse - the junction between a nerve cell and another cell Messages travel within the neuron as an electrical impulse. Neurotransmitters are exchanged between neurons and the receiving cells Neurotransmitters carry the “message” to the other cell.
A final review: What type of neuron connects neuron to neuron and is only found in the CNS? Interneuron Neurotransmitter Motor neuron Sensory Neuron What is the junction between a nerve cell and another cell called? Synapse Hormone Dendrite
Review continued… What are the 3 parts of a neuron? What is the function of each part? What substance is responsible for carrying the message from the neuron to the receiving cell? Synapse Neurotransmitter Neuron Mitochondria