Anatomy And Physiology[1]
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NERVOUS SYSTEM The nervous System is composed of : Central Nervous System (CNS) Peripheral Nervous System (PNS)
A discussion of the different cell types that makes up the nervous system. The nervous system is made out of two types of cells and they are neurons and neuroglia.
neurons • There are 3 types of neurons and they are sensory neurons, motor neurons, and interneurons. • Sensory neurons are used to gather information about the internal and external environment of the body. • There are approximately 10 million sensory neurons in the human body.
Motor neurons • Motor neurons are used to carry instruction from the brain to other organs in the body. • There are approximately half a million motor neurons in the body. • The motor neurons are also divided into somatic motor neurons which innervates skeletal muscle and visceral motor neurons which innervates cardiac muscles, smooth muscles, and glands.
interneurons • Interneurons are used to connect all the other neurons • There are about 20 billion interneurons in the body • All neurons are made out of a soma (cell body), dendrites, axon and synaptic terminals.
neuroglia • There are 4 types of neuroglia and they are astrocytes, oligodendrocytes, microglia, and ependymal cells. • The astrocytes job is it is use to maintain the blood-brain barrier by making chemicals and it is used to repair damaged neural tissues.
neuroglia • The oligodendrocytes job is to wrap other nerve cells axon with myelin that helps improve the speed of impulse on the cell and myelin is a lipid. • Microglia are the rarest neuroglia and they are phagocytic cells in the brain that helps to protect it by acting almost like white blood cell. • The ependymal cells job is to line the spinal cord’s central canal and the chamber of the brain with ependyma.
How does a neuron transfer information around? • A neuron receives information because of action potentials. Action potentials happen when something cause a nerve cell to depolarize to threshold which is -70 to -60mv and it continues to stay like that till repolarization because as long as the nerve cell stays depolarized, it can't respond normally to further stimulation. So the action potential is move around by the nerve cell and pass on to another nerve cell when they touch and create the chemical neurotransmitter till the body reacts.
PNS Peripheral Nervous System • • • • • •
General Overview Structure Composition-Division Relations to the CNS Relations to the rest of the Organs Bibliography
General Overview The PNS is one of the two components of the Nervous System.
STRUCTURE • The PNS is mainly composed of axons. They are wrapped in connective tissue, form peripheral nerves, or simply nerves. A nerve might be sensory, motor or mixed. The PNS is structured as sensory and motor axons packed together into nerves and clusters of cell bodies or ganglia (sing. Ganglion.) All the sensory information and motor command are carried by the axons.
COMPOSITION • • • • •
The PNS includes: Cranial Nerves Spinal Nerves Somatic Autonomic
Cranial Nerves • The cranial Nerves are composed of (12) Twelve pairs of nerves that are joined to the brain. Here are two phrases to help memorize the 12 pairs of nerves: On Old Olympic Towering Tops A Finn And German Viewed Some Hops. or Oh, Once One Takes The Anatomy Final, Very Good Vacations Are Heavenly. Each first letter represent a cranial nerve.
Spinal Nerves There are (31) pairs of nerves that are connected to the spinal cord.
CORDINATION BETWEEN PNS and CNS The CNS and PNS work together in order to achieve the demands of the rest of the organ. One of these is reflex. Reflex is an automatic motor response triggered by a specific stimulus. It includes: receptor, sensory neuron, motor neuron, and receptor. There are two types of reflex: Simple and complex. This is due to the synapses.
Pathways Pathways are used to connect the PNS, the CNS and the rest of the organs. There are of two types: Sensory Motor.
A discussion of the different cell types that makes up the nervous system. The nervous system is made out of two types of cells and they are neurons and neuroglia.
neurons • There are 3 types of neurons and they are sensory neurons, motor neurons, and interneurons. • Sensory neurons are used to gather information about the internal and external environment of the body. • There are approximately 10 million sensory neurons in the human body.
Motor neurons • Motor neurons are used to carry instruction from the brain to other organs in the body. • There are approximately half a million motor neurons in the body. • The motor neurons are also divided into somatic motor neurons which innervates skeletal muscle and visceral motor neurons which innervates cardiac muscles, smooth muscles, and glands.
interneurons • Interneurons are used to connect all the other neurons • There are about 20 billion interneurons in the body • All neurons are made out of a soma (cell body), dendrites, axon and synaptic terminals.
neuroglia • There are 4 types of neuroglia and they are astrocytes, oligodendrocytes, microglia, and ependymal cells. • The astrocytes job is it is use to maintain the blood-brain barrier by making chemicals and it is used to repair damaged neural tissues.
neuroglia • The oligodendrocytes job is to wrap other nerve cells axon with myelin that helps improve the speed of impulse on the cell and myelin is a lipid. • Microglia are the rarest neuroglia and they are phagocytic cells in the brain that helps to protect it by acting almost like white blood cell. • The ependymal cells job is to line the spinal cord’s central canal and the chamber of the brain with ependyma.
How does a neuron transfer information around? • A neuron receives information because of action potentials. Action potentials happen when something cause a nerve cell to depolarize to threshold which is -70 to -60mv and it continues to stay like that till repolarization because as long as the nerve cell stays depolarized, it can't respond normally to further stimulation. So the action potential is move around by the nerve cell and pass on to another nerve cell when they touch and create the chemical neurotransmitter till the body reacts.
PNS Peripheral Nervous System • • • • • •
General Overview Structure Composition-Division Relations to the CNS Relations to the rest of the Organs Bibliography
General Overview The PNS is one of the two components of the Nervous System.
STRUCTURE • The PNS is mainly composed of axons. They are wrapped in connective tissue, form peripheral nerves, or simply nerves. A nerve might be sensory, motor or mixed. The PNS is structured as sensory and motor axons packed together into nerves and clusters of cell bodies or ganglia (sing. Ganglion.) All the sensory information and motor command are carried by the axons.
COMPOSITION • • • • •
The PNS includes: Cranial Nerves Spinal Nerves Somatic Autonomic
Cranial Nerves • The cranial Nerves are composed of (12) Twelve pairs of nerves that are joined to the brain. Here are two phrases to help memorize the 12 pairs of nerves: On Old Olympic Towering Tops A Finn And German Viewed Some Hops. or Oh, Once One Takes The Anatomy Final, Very Good Vacations Are Heavenly. Each first letter represent a cranial nerve.
Spinal Nerves There are (31) pairs of nerves that are connected to the spinal cord.
CORDINATION BETWEEN PNS and CNS The CNS and PNS work together in order to achieve the demands of the rest of the organ. One of these is reflex. Reflex is an automatic motor response triggered by a specific stimulus. It includes: receptor, sensory neuron, motor neuron, and receptor. There are two types of reflex: Simple and complex. This is due to the synapses.
Pathways Pathways are used to connect the PNS, the CNS and the rest of the organs. There are of two types: Sensory Motor.
