The Nervous System Flashcards
Nervous System consists of
[Central Nervous system (CNS) controls brain & spinal cord] & [Peripheral Nervous System (PNS) peripheral nerves extending from the spinal cord working to control function and movement of the body. cranial nerve, spinal nerve and plexuses]
nerve
It is made out of bundles of neurons (nerve cells) that will connect the brain and spinal cord with other parts of the body.
tract
Bundle of nerve fibers actually within the brain and spinal cord.
ascending nerve tract
It carries nerve impulses toward the brain
descending nerve tracts
carry nerve impulses away from the brain
Neurons
It is protected by endoneurium—>perineurium—>epineurium
Neurons are individual cells that conduct electrical impulses, sending them in response to millions of stimuli you receive each day
Neurons do not have any capability to divide (mitosis), which is what enables other cells in the body to reproduce. Thus, the neuron is irreplaceable.
Ganglion
Nerve center made up of cluster of nerve cells outside the CNS.
Plexus
A network of intersecting spinal nerves
Innervation
Supply of nerves to a specific body part
Receptors
Sites in sensory organs that receive external stimulation. The receptors receive the electrical stimulus and transmit signal to brain for interpretation.
stimulus
anything that excites or activates a nerve and causes the electrical impulse to move along the nerve
reflux
automatic, involuntary response to some change, either inside or outside of the body
Neuron cell body
main part of the neuron that hold the nucleus, mitochondrion, and other cell structure.
Dendrites
processes that receive impulses and conduct them toward the cell body
It brings information to the cell. These branch-like projections literally “catch” the electrical impulse sent from the previous cell’s axon across the synaptic gap, which is also known as synaptic cleft. Typically short; a number of them project from the cell body, allowing the neuron to catch as much information as possible.
axon
Message from dendrites passes through the cell body and down the axon. Although the number of dendrites can vary, there is always only one axon coming from the cell body. Message is sent down the axon to its terminal ends. Neuros do not directly communicate, messages must “leap” across the synaptic cleft with the help of chemical messengers called neurotransmitters
myelion sheath
Many axons are protected by a myelin sheath made of schwann cells. There are periodic breaks in the myelin sheath called nodes of Ranvier. These allow the electrical impulse to move faster along the fiber.
The Central Nervous System (CNS)
It is made up of the brain and spinal cord. They are protected by meninges (system of membranes) There are 3 layers of meninges: dura mater, arachnoid membrane, pia mater
Dura Mater
Dura mater: The thick, tough, outermost membrane. It lines the inside of the cranium (skull) and vertebral column. Space between bone and dura mater is called the epidural space.
Arachnoid Membrane
Arachnoid membrane: Middle layer that looks like a spider web. It is loosely attached to other meninges and allows fluid to flow between layers. Under the arachnoid membrane is the subarachnoid space.
Pia Mater
Pia mater: Innermost layer of meninges. It contains a rich supply of blood vessels nourishing membranes and nerve issues.
Cerebral Spinal Fluid
Cerebral Spinal Fluid: CS is produced by capillaries in the brain. It is clear, colorless, and watery and flows throughout the brain and around the spinal cord. It functions to cushion structures. Also provides nourishment to brain and spinal cord
Brain ? Cerebrum ? Cerebral Cortex ? Cerebral hemispheres ?
Brain controls the functions of the body. Different areas in brain controls specific set functions for the body
Cerebrum: Largest portion of brain. It is responsible for controlling and integrating voluntary motor functions and sensory functions in the body. Also responsible for the highest level of thought, judgment, memory, critical thinking, and emotions.
Cerebral cortex: Made up of gray matter. Outer layer of the cerebrum and is made up of elevated fold (gyri) and deep fissure (sulci), or cracks.
Cerebral hemispheres: Brain is divided into the right and left cerebral hemispheres. Left hemisphere mainly controls the functions of the right side of the body while the right cerebral hemisphere controls the left side of the body.
Lobes of the brain ? Frontal lobe ? Parietal Lobe? Occipital lobe? Temporal lobe? thalamus ? Hypothalamus? brainstem?
Lobes of the brain: Each cerebral hemisphere subdivided into lobes and is named for the bone directly underneath the brain area.
Frontal lobe: Controls skilled motor functions, memory, and behavior.
Parietal lobe: Receives and interprets nerve impulses to form sensory receptors in tongue, skin, and muscles.
Occipital lobe: Control eyesight Temporal lobe: Controls hearing and smell as well as ability to create, store, and access new information.
Thalamus: Located below the cerebrum. It relays sensory stimuli from the spinal cord and midbrain to the cerebral cortex.
Hypothalamus: Located below the thalamus. It performs many regulatory functions of the body.
Brainstem: Stalk-like structure that connects the cerebral hemispheres with the spinal cord. Made up of the midbrain, pons, and medulla oblongata.
Spinal Cord
The Spinal Cord
It is a long, tube-like structure beginning at the brainstem in the brain and ending at the bottom of the spinal column. It contains all the nerves that control the limbs and lower part of the body. Spinal cord is protected by the meninges and vertebral column of the skeletal system.
The Peripheral Nervous System ? What are the 3 nerves ?
The Peripheral Nervous System
The systems consist of 12 pairs of cranial nerves and 31 pairs of spinal nerves extending from the spinal cord. These nerves control the functions of body parts and muscles away from the spinal column and brain. There are three types of specialized peripheral nerves that transmit signals to and from CNS.
1. Peripheral spinal nerves: These are grouped together and named based on the region of the body they innervate. Within each region, the nerves are referred to by number.
2. Sympathetic nerves: It prepares the body for emergencies and stress. It increases the respiratory rate, heart rate, and blood flow to muscles.
3. Parasympathetic nerves: It returns the body to normal after the stress response.
Autonomic Nerve Fiber
Autonomic nerve fibers: These carry instructions to the organs and glands from the autonomic nervous system.
Sensory Nerve Fibers
It receives external stimuli for feelings and then transmits information to the brain. Brain interprets the information to make meaning.
Somatic nerve fibers
These are the motor nerve fibers that convey information controlling the body’s voluntary muscular movements.
Autonomic nervous system
Organized into two divisions.ANS controls our involuntary functions. The ANS is made up of two branches: sympathetic & parasympathetic. The sympathetic division of the ANS is known as being “antagonistic” to the body’s organs because it often works in opposition to their normal functioning. It is also responsible for releasing adrenaline into the bloodstream and inhibiting digestion. Also known as “fight or flight” response, when the body prepares for a sustained high level of activity.
When crisis is over, the parasympathetic branch kicks in and returns the body to “normal”
Nerve Physiology
Nerve impulse is initiated and moves across the neuron from the dendrite end toward the cell body and then out the axons. At the end of the axon are axon terminals. Here neurotransmitters are secreted into the synaptic cleft (space between the axon terminal of one neuron and the dendrite of another neuron)
Neurotransmitters
Neurotransmitters are chemical substances that make it possible for messages to be transmitted from one neuron to another and to target receptors. There are 200-300 neurotransmitters at work in the body.
Neurotransmitters travel across the synaptic cleft and land in a receptor site on the opposite side. A chemical reaction keeps the impulse moving from one neuron to another.
Acetylcholine
Acetylcholine: (Learning) Released at some synapses in the spinal cord & neuromuscular junctions. It is involved in the impulse of muscle action. Associated with attention and awakening. Involved in thoughts, learning, and memory.
Dopamine
Dopamine: (Pleasure) Released in the brain. Too much or too little can lead to serious disorders. Feeling of pleasure, also addiction, movement, and motivation. People repeat behavior that leads to dopamine release.
Epinephrine
Epinephrine: (Adrenal/ fight or flight) Released in the brain and in adrenal glands. Produced in stressful situations. Increased heart rate and blood flow, leading to physical boost and heightened awareness.
Norepinephrine
Norepinephrine: (Concentration) It impacts arousal and alertness by increasing blood pressure, heart rate, and respiration. It is also produced by adrenal glands. It affects attention and responding actions in the brain. Contracts blood vessels, increasing blood flow.
Serotonin
Serotonin: (Mood) Released in the brain and impacts hunger, pleasure, and sleep. It contributes to wellbeing and happiness. Helps sleep cycle and digestive system regulation. Affected by exercise and light exposure.
Gaba
Gaba: (calming) Calms firing nerves in the central nervous systems. High levels improve focus, low levels cause anxiety. Also contributes to motor control and vision.
Glutamate
Glutamate: (memory) Most common neurotransmitter that is involved in learning and memory, regulates development and creation of nerve contacts.
Function of Cranial Nerve
There are 12 pairs of cranial nerves that originate from under the surface of the brain. There are 2 nerves of each pair that do the same thing on each side of the body. Cranial nerves are identified by Roman numerals.
