Neural and Hormonal Systems Will Explain Why We FEEL……
It all Starts with the Neuron
Neuron Structure Neurons do NOT touch each other- the space in between is call the synapse.
Types of Neurons Sensory Neurons Motor Neurons Inter Neurons
Sensory Neurons (Afferent Neurons) Take information from the senses to the brain.
Inter Neurons Take messages from Sensory Neurons to other parts of the brain or to Motor Neurons.
Motor Neurons (Efferent Neurons) Take information from brain to the rest of the body.
How a Neuron Fires It is an electrochemical process Electrical inside the neuron Chemical outside the neuron (in the synapse in the form of a neurotransmitter). The firing is called Action Potential.
The All-or None Response The idea that either the neuron fires or it does not- no part way firing. Like a gun
Action Potential
How Neurons Communicate
Neurotransmitters Chemical messengers released by terminal buttons through the synapse. We should know at least 4 types and what they do.
Acetylcholine Its function is motor movement and maybe memory. To much and you will…. Not enough and you will…. Lack of ACH has been linked to Alzheimer’s disease.
Dopamine Its function is motor movement and alertness. Lack of dopamine is associated with Parkinson’s disease. Overabundance is associated with schizophrenia.
Serotonin Function deals with mood control. Lack of serotonin has been linked to depression.
Endorphins Function deals with pain control. We become addicted to endorphin causing feelings.
Agonists and Antagonists
Divisions of the Nervous System
Human Nervous System Central Nervous System Brain + Spinal Cord Peripheral Nervous System Nerves (extensions from the CNS) Provides Basis For Conscious Experience
Peripheral Nervous System Afferent Efferent Skeletal - controls voluntary movements of skeletal muscles Autonomic - self-regulating, controls glands & muscles of internal organs (e.g., heart) Sympathetic (arousing) Parasympathetic (calming)
Organization of the Nervous System Central Nervous System Peripheral Nervous System Brain Spinal Cord Somatic Autonomic
Skeletal/Somatic Nervous System Nerves that connect to voluntary skeletal muscles and to sensory receptors Afferent Nerve Fibers Axons that carry info away from the periphery to the CNS Efferent Nerve Fibers Axons that carry info from the CNS outward to the periphery
Autonomic Nervous System Nerves that connect to the heart, blood vessels, smooth muscles and glands Sympathetic Division Mobilizes the body’s resources for emergencies (e.g., stim adrenal gland) Fight or Flight Response Cannon (1932) Parasympathetic Division Generally conserves bodily resources (e.g., slows heart rate)
Central Nervous System (billions of neurons & trillions of connections) Spinal Cord Conduit between peripheral nervous system and the brain Organize certain behaviors without the brain Conduit Function - Ascending tract carries sensory info to brain - Descending tract carries info from brain to muscles Organization Function - Governs reflexive actions of muscles
A Simple Reflex
A Simplified Neural Network Neurons that learn to work together as a team.
The Endocrine System A system of glands that secrete hormones. Similar to nervous system, except hormones work a lot slower than neurotransmitters. Hormones Neurotransmitters
The Major Endocrine Glands