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The Nervous System
Human Regulation
• In humans and animals regulation is done by the nervous and endocrine system – There are some
differences and some similarities between the two systems
Similarities between the Endocrine and Nervous system
• Both secret chemical messages – Nervous system
secretes – neurotransmitters
– Endocrine – secretes hormones
• BOTH PLAY A MAJOR ROLE IN HOMEOSTASIS
Differences between the Endocrine and Nervous system
• Nervous system response is much much faster
• Nerve response is shorter in duration than endocrine
Human Nervous system
• What is a neuron?– A neuron is the basic
cell of the nervous system
There are three types of neurons.
• Sensory Neurons – Transmit ( sends
messages) from receptors to the central nervous system ( fire is hot)
– They are located near the sensory organs such as
• Eyes
• Ears
• Nose
• Tongue
• Skin
Interneuron
• Another type of neurons
• Located mainly in the central nervous system – It’s job is to interpret
and relay the information from the sensory neurons to the motor neurons
Motor Neurons
• Transmit impulses from the central nervous system to the effectors – Effectors are glands
and muscles
• These messages cause the effectors to respond– ( fire is hot pull hand
back)
So what are nerves?
• Nerves are groups of neurons or parts of neurons specialized for high speed and long distances impulse transmission
• They can be – motor neurons – Sensory neurons – Or mixed
Nerves
• Most nerves have a fatty sheath– This is for
• Protection • Make sure not touching
other nerves or tissues
• A neuron is a long cell that consists of three regions: a cell body, dendrites, and an axon.
Nerves continued
• Dendrites- receive impulses and carry them toward the cell body
• Axon- carries impulses away from the cell body and toward other neurons, muscles, or glands.
• Cell body- contains the nucleus
How does it work
• Resting - no impulse, cell is polarized ( + on outside & - on inside)– Sodium/Potassium pump in axon using ATP
maintains this polarity
• 2.Impulse: stimulus excites neuron– Na+ gates open– Na+ goes inside, therefore inside becomes more +– Depolarization occurs ~ a nerve impulse– Impulse moves in one direction
Connection between Neurons
• Synapse: gap between neurons or neurons and effectors
• Neurotransmitter: chemical, such as acetylcholine, which, when secreted aid in the transmission of of an impulse across a synapse.
There are two parts to the Nervous System
-Central Nervous system
-Peripheral Nervous system
Central Nervous System (CNS)
• There are two main parts to the CNS – Brain – Spinal Cord
Brain
• Is a large mass of neurons located in the head – Responsible for controlling and coordinating most
activities of the body • Cerebrum:
– Conscious activities– Intelligence– Memory– Language– Voluntary activity
• Cerebellum:– Coordinates motor activity– Balance
• Medulla Oblongata:– involuntary activities such as breathing, & heart rate
Spinal Cord
• Lies within the vertebrae – Bones of the spinal column
• Spinal cord is connected to the Medulla
• It is the center for reflex activities – Does not require activity
from the brain to give off a response
• Reflex actions – are inborn reflexes – Ex blinking
Peripheral Nervous system
• Is located outside the CNS – It contains nerves that
extend throughout the body
– There are two parts to the PNS
• Somatic nervous system
• Autonomic nervous system
Somatic Nervous system
• These neurons deal with voluntary actions – Ex
• run • Play• Swing • Hit •
Autonomic nervous system
• Generally deal with involuntary acts – Breathing glands
Malfunctions of the nervous system
• Listed are some of the malfunctions of the nervous system – Cerebral Palsy – Meningitis – Stroke – Polio
Cerebral Palsy (CP)
• A group of diseases you are born with which disturb the motor functions
• Person still has normal mental capacity but – Speach and motor
function are distorted
Meningitis
• Inflammation of the membrane that surrounds the spinal cord and brain
Stroke
• Caused by a cerebral Hemorrhage ( burst of blood vessels) or a blood clot in the brain – May cause brain
damage or death
Polio
• Viral disease in the CNS may cause paralysis
• Can be prevented through immunization Shots