Chapter 13
Nervous system has two major divisions
Central nervous system contains the brain and spinal cord
Peripheral nervous system contains nerves. The nerves lie outside of the central nervous system.
The nervous system has three specific functions
nervous system receives sensory input
the CNS performs integration
the CNS generates motor output.
Nervous tissue contains two types of cell neurons which are cells that transmit nerve impulses between parts of the nervous system. The second type is Neuroglia that support and nourish neurons.
Neuron structure there is 3 different types
Sensory neuron takes messages from sensory preceptor to the central nervous system.
Interneuron lie entirely with the CNS they can input from sensory neurons along with other interneuron in the CNS.
Motor neuron takes impulses away from the CNS to muscle fibers or glands.
Nerve impulses have information within the nervous system. It is studied by using excised axons and voltmeter to measure voltage.
A terminal that lies very close to a dendrite or the cell body of another neuron. The region of close space is called a synapse. At this space there is a small gap called a synaptic clerk that separates the sending from the receiving neurons.
The central nervous system
The brain and the spinal cord make up the central nervous system. It is where sensory information is received and motor control is initiated. Both the spinal cord and the brain are protected by bone, the brain is enclosed by the skull and the spinal cord is surrounded by vertebrae. Along with bone they are also protected by membranes known as meninges. Then the spaces between the meninges is filled with fluid called cerebrospinal fluid which cushions and protects the central nervous system.
The spinal cord extends from the base of the brain through a large opening in the skull and into the vertebral canal formed by openings in the vertebrae.
The functions of the spinal cord
It is a mean of communication between the brain and the peripheral nerves that leave the cord. When someone touches you sensory receptors generate nerve impulses that pass through sensory fibers to the spinal cord and up ascending tracts to the brain.
The brain
The goal of modern neuroscience is to better understand the structures and functions of the working brain. This will help in preventing or correcting the thousands of mental disorders that affect many people. There are many parts in the brain that have different functions that help it.
The peripheral nervous system your eyes send messages by way of a cranial nerve to the brain, allowing you to read a page and your brain is directing the muscles in your fingers to turn the page by way of the spinal cord and a spinal nerve.
Humans have 12 points of cranial nerves attached to the brain cranial nerves are largely concerned with the head, neck, and facial regions of the body.
The nerves in the somatic system serve the skin, skeletal muscles and tendons and it contains nerves that take sensory information from external sensory receptors to the CNS and motor commands away from the CNS to the skeletal muscles.
Autonomic system regulates the activity of cardiac and smooth muscles and glands. The system is divided into the sympathetic and parasympathetic divisions. Activation of these two systems causes opposite response.
Drug abuse has an affect on the nervous system and can affect your mood and or emotional state. These drugs have two affects such as on the limbic systems, and they promote or decrease the action of a particular neurotransmitter.
Stimulants are drugs that increase the likelihood of neuron excitation and depressants decrease the likelihood of excitation. Some of the names of these drugs that affect the body in different ways are alcohol, nicotine, cocaine, methamphetamine, heroin and marijuana.
Chapter 14
Sensory receptors are dendrites that detect a certain type of stimuli
Exteroceptors are sensory receptors that detect stimuli from outside the body, such as those that result in taste, smell, vision, hearing and equilibrium
Interceptors receive stimuli from inside the body
Different types of sensory receptors
Chemoreceptor’s respond to chemical substances
Pain receptors are types of chemoreceptor’s they are naked dendrites that respond to chemical released by drainage tissues
Pain receptors alert us to possible danger.
Photoreceptors respond to light energy. Our eyes have photo rectors that are sensitive to light rays and provide us with a sense of vision. Stimulation to photoreceptors also known as rod cells affect black and white vision and stimulation of the photoreceptors known as cone cells results in color vision.
Mechanoreceptors are stimulated by mechanical forces which have to do with some kind of pressure. When we hear airborne sound waves are changed into fluid borne pressure waves that are detected by mechanoreceptors in the inner ear.
Sensory receptors respond to environmental stimuli by having nerve impulses. When they reach the cerebral cortex of the brain, sensation which is conscious perception of stimuli occurs. All sensory receptors require nerve impulses and the sensation that results depends on the part of the brain receiving the nerve impulses.
Proprioceptors and cutaneous receptors
Proprioceptors are mechanoreceptors that affect reflex action that maintain muscle tone and thereby the body’s equilibrium and posture. This helps us know the position of our limbs in space by detecting the degree of muscle relaxation, the stretch of tendons and fine movement of ligaments.
Cutaneous receptors
The two layers of the skin are the Epidermis and the Dermis. Epidermis is stratified squanmous epithelium in which cells become keratinized as they raise to the surface. Dermis is a thick connective tissue layer. The dermis contains cutaneous receptors that make the skin sensitive to touch, pressure, pain, and temperature. These types of cutaneous are sensitive to fine touch. Two types are sensitive to pressure.
Sense of taste and smell
Sense of taste in adults happens by the 3,000 taste buds that are located mostly on the tongue. There are four types of taste: sweet, sour, salty, and bitter. Then a fifth taste bud might exist which is called umami. This is for certain flavors of cheese, beef broth, and some seafood. Taste buds are located in certain places for certain tastes. The tip of the tongue is most sensitive to sweet tastes making it especially pleasurable to lick ice cream cones. The margins of the tongue are most sensitive to salty and sour taste and the rear of the tongue to bitter tastes. The brain receives taste by messages.
Sense of smell
80% - 90% of what we taste actually is due to the sense of smell. Our sense of smell depends on between 10 and 20 million olfactory cells located high in the roof of the nasal cavity. How the brain receives odor information. Every odor contains odor molecules this activates a characteristic combination of receptor proteins. An odor signature is figured by which neurons are stimulated. Once the neurons have communicated this information to the olfactory tract then it is sent to the olfactory areas of the cerebral cortex. That’s how we know that we have smelled.
Sense of vision
A lot of processing of stimuli occurs in the eyes before nerve impulses are transferred to the brain. Researchers believe that about a third of the cerebral cortex takes part on processing visual information. There are three different layers that contain many things within the eyes.
Sense of hearing has two functions: hearing and balance. The functions for both of these are found in the inner ear and each consists of hair cells. These hair cells are sensitive to mechanical stimulation.
These are three divisions of the ear: the outer that has the exterior flap called the pinna and the auditory canal where the opening is lined with fine hairs and sweat glands. Located in the upper wall of the canal are modified sweat glands that secrete earwax.
The middle ear begins at the tympanic membrane but ends at the bony wall that has two small openings covered by membrane. An auditory tube permits equalization of air pressure. As this happens we sometimes hear our ears pop. The outer and middle ear has air while the inner has fluid.
The vestibular nerve takes nerve impulses to the brain stem and cerebellum. As it communicates with the brain, the vestibular nerve helps us achieve equilibrium also other structures of the body are involved. Proprioceptors are necessary in maintaining equilibrium and vision provides helpful imput the brain can act upon.
Nervous system has two major divisions
Central nervous system contains the brain and spinal cord
Peripheral nervous system contains nerves. The nerves lie outside of the central nervous system.
The nervous system has three specific functions
nervous system receives sensory input
the CNS performs integration
the CNS generates motor output.
Nervous tissue contains two types of cell neurons which are cells that transmit nerve impulses between parts of the nervous system. The second type is Neuroglia that support and nourish neurons.
Neuron structure there is 3 different types
Sensory neuron takes messages from sensory preceptor to the central nervous system.
Interneuron lie entirely with the CNS they can input from sensory neurons along with other interneuron in the CNS.
Motor neuron takes impulses away from the CNS to muscle fibers or glands.
Nerve impulses have information within the nervous system. It is studied by using excised axons and voltmeter to measure voltage.
A terminal that lies very close to a dendrite or the cell body of another neuron. The region of close space is called a synapse. At this space there is a small gap called a synaptic clerk that separates the sending from the receiving neurons.
The central nervous system
The brain and the spinal cord make up the central nervous system. It is where sensory information is received and motor control is initiated. Both the spinal cord and the brain are protected by bone, the brain is enclosed by the skull and the spinal cord is surrounded by vertebrae. Along with bone they are also protected by membranes known as meninges. Then the spaces between the meninges is filled with fluid called cerebrospinal fluid which cushions and protects the central nervous system.
The spinal cord extends from the base of the brain through a large opening in the skull and into the vertebral canal formed by openings in the vertebrae.
The functions of the spinal cord
It is a mean of communication between the brain and the peripheral nerves that leave the cord. When someone touches you sensory receptors generate nerve impulses that pass through sensory fibers to the spinal cord and up ascending tracts to the brain.
The brain
The goal of modern neuroscience is to better understand the structures and functions of the working brain. This will help in preventing or correcting the thousands of mental disorders that affect many people. There are many parts in the brain that have different functions that help it.
The peripheral nervous system your eyes send messages by way of a cranial nerve to the brain, allowing you to read a page and your brain is directing the muscles in your fingers to turn the page by way of the spinal cord and a spinal nerve.
Humans have 12 points of cranial nerves attached to the brain cranial nerves are largely concerned with the head, neck, and facial regions of the body.
The nerves in the somatic system serve the skin, skeletal muscles and tendons and it contains nerves that take sensory information from external sensory receptors to the CNS and motor commands away from the CNS to the skeletal muscles.
Autonomic system regulates the activity of cardiac and smooth muscles and glands. The system is divided into the sympathetic and parasympathetic divisions. Activation of these two systems causes opposite response.
Drug abuse has an affect on the nervous system and can affect your mood and or emotional state. These drugs have two affects such as on the limbic systems, and they promote or decrease the action of a particular neurotransmitter.
Stimulants are drugs that increase the likelihood of neuron excitation and depressants decrease the likelihood of excitation. Some of the names of these drugs that affect the body in different ways are alcohol, nicotine, cocaine, methamphetamine, heroin and marijuana.
Chapter 14
Sensory receptors are dendrites that detect a certain type of stimuli
Exteroceptors are sensory receptors that detect stimuli from outside the body, such as those that result in taste, smell, vision, hearing and equilibrium
Interceptors receive stimuli from inside the body
Different types of sensory receptors
Chemoreceptor’s respond to chemical substances
Pain receptors are types of chemoreceptor’s they are naked dendrites that respond to chemical released by drainage tissues
Pain receptors alert us to possible danger.
Photoreceptors respond to light energy. Our eyes have photo rectors that are sensitive to light rays and provide us with a sense of vision. Stimulation to photoreceptors also known as rod cells affect black and white vision and stimulation of the photoreceptors known as cone cells results in color vision.
Mechanoreceptors are stimulated by mechanical forces which have to do with some kind of pressure. When we hear airborne sound waves are changed into fluid borne pressure waves that are detected by mechanoreceptors in the inner ear.
Sensory receptors respond to environmental stimuli by having nerve impulses. When they reach the cerebral cortex of the brain, sensation which is conscious perception of stimuli occurs. All sensory receptors require nerve impulses and the sensation that results depends on the part of the brain receiving the nerve impulses.
Proprioceptors and cutaneous receptors
Proprioceptors are mechanoreceptors that affect reflex action that maintain muscle tone and thereby the body’s equilibrium and posture. This helps us know the position of our limbs in space by detecting the degree of muscle relaxation, the stretch of tendons and fine movement of ligaments.
Cutaneous receptors
The two layers of the skin are the Epidermis and the Dermis. Epidermis is stratified squanmous epithelium in which cells become keratinized as they raise to the surface. Dermis is a thick connective tissue layer. The dermis contains cutaneous receptors that make the skin sensitive to touch, pressure, pain, and temperature. These types of cutaneous are sensitive to fine touch. Two types are sensitive to pressure.
Sense of taste and smell
Sense of taste in adults happens by the 3,000 taste buds that are located mostly on the tongue. There are four types of taste: sweet, sour, salty, and bitter. Then a fifth taste bud might exist which is called umami. This is for certain flavors of cheese, beef broth, and some seafood. Taste buds are located in certain places for certain tastes. The tip of the tongue is most sensitive to sweet tastes making it especially pleasurable to lick ice cream cones. The margins of the tongue are most sensitive to salty and sour taste and the rear of the tongue to bitter tastes. The brain receives taste by messages.
Sense of smell
80% - 90% of what we taste actually is due to the sense of smell. Our sense of smell depends on between 10 and 20 million olfactory cells located high in the roof of the nasal cavity. How the brain receives odor information. Every odor contains odor molecules this activates a characteristic combination of receptor proteins. An odor signature is figured by which neurons are stimulated. Once the neurons have communicated this information to the olfactory tract then it is sent to the olfactory areas of the cerebral cortex. That’s how we know that we have smelled.
Sense of vision
A lot of processing of stimuli occurs in the eyes before nerve impulses are transferred to the brain. Researchers believe that about a third of the cerebral cortex takes part on processing visual information. There are three different layers that contain many things within the eyes.
Sense of hearing has two functions: hearing and balance. The functions for both of these are found in the inner ear and each consists of hair cells. These hair cells are sensitive to mechanical stimulation.
These are three divisions of the ear: the outer that has the exterior flap called the pinna and the auditory canal where the opening is lined with fine hairs and sweat glands. Located in the upper wall of the canal are modified sweat glands that secrete earwax.
The middle ear begins at the tympanic membrane but ends at the bony wall that has two small openings covered by membrane. An auditory tube permits equalization of air pressure. As this happens we sometimes hear our ears pop. The outer and middle ear has air while the inner has fluid.
The vestibular nerve takes nerve impulses to the brain stem and cerebellum. As it communicates with the brain, the vestibular nerve helps us achieve equilibrium also other structures of the body are involved. Proprioceptors are necessary in maintaining equilibrium and vision provides helpful imput the brain can act upon.
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