Kaplan Prep - Nervous System Flashcards
The function of the nervous system is to integrate and control the other body systems. Explain how the nervous system does this.
The nervous system receives and processes information and sends out signals to the muscles and glands to elicit an appropriate response. In this way, the nervous system integrates and controls the other systems of the body.
What are the 2 parts of the central nervous system?
the brain & the spinal cord
What are the two ways that the two parts of the central nervous system are protected?
The skull protects the brain & the vertebrae protect the spinal cord
How do the central nervous system and the peripheral nervous system interact?
The central nervous system can SEND signals or impulses TO and RECEIVE impulses FROM the peripheral nervous system
What is included in the peripheral nervous system?
The peripheral nervous system includes all nerves not in the brain or spinal cord which are the cranial nerves that connect directly to the brain and the spinal nerves which project from either side of the spinal cord.
What are the 2 divisions of the peripheral nervous system?
The peripheral nervous system can be divided into a sensory or afferent division and a motor or efferent division.
Describe the movement of nerve impulses in the peripheral nervous system.
The peripheral nervous system receives impulses from the sensory organs via the afferent division and then relays signals or impulses from the central nervous system to muscles and glands via the motor or efferent division.
What are the 2 divisions of the efferent division of the peripheral nervous system?
The efferent division can be further divided into the somatic system and the autonomic system.
What three things are controlled by the somatic nervous system?
The somatic system nerves control:skeletal, muscles, skin, joints
What two things are controlled by the autonomic nervous system?
The autonomic system nerves control:the glands smooth muscles of the internal organs (they are not generally under conscious control)
What are the 2 divisions of the autonomic nervous system?
The 2 divisions of the autonomic nervous system are the sympathetic and parasympathetic nervous systems.
What is the function of the sympathetic nervous system?
The sympathetic nervous system: activates and prepares the body for vigorous muscular activity, stress, and emergencies.
What is the function of the parasympathetic nervous system?
The parasympathetic system: lowers activity operates during normal situations, permits digestion, conserves energy
Identify the parts of the neuron shown in the diagram.
a = dendrite b = cell body c = nucleus d = axon e = myelin sheath f = Schwann cell g = Node of Ranvier h = axon terminal
What are three unusual characteristics of neurons?
- Neurons do not undergo mitosis (cell division) 2. Neurons require enormous amounts of fuel being able to survive just minutes without oxygen 3.Neurons can last an entire human lifetime.
What are the three parts of a neuron?
1.the dendrites 2.the cell body 3.the axon
What is the function of the neuron cell body?
The neuron cell body synthesizes all nerve cell products.
What are three aspects of the structure of the neuron cell body?
1.Consists of a large nucleus 2.the nucleus is surrounded by cytoplasm 3.it contains the normal organelles
Describe the structure and function of the dendrite.
The dendrites are numerous short extensions that emanate from the cell body which receive information from other neurons conducting those nerve impulses toward the cell body.
Describe the axon, including the number in each neuron, function, structure and organelles.
The single axon conducts nerve impulses away from the cell body to its axon terminals where it is emitted across a synapse to the dendrite of another neuron. Axons can vary in length being as long as three feet. Axons are composed of cells like the cell body but lack rough endoplasmic reticulum.
Describe the composition and function of Schwann cells.
The axon is coated in short sections called Schwann cells mainly composed of a white fatty layer called the myelin sheath rolled around the axon which insulates the nerve fiber from others and increases the speed of nerve impulses.
Describe the location and function of the Nodes of Ranvier.
The Schwann cell insulating sections are not continuous, having gaps between them called Nodes of Ranvier. At these exposed nodes, the nerve impulse is forced to jump to the next node in a manner called salutatory conduction, greatly increasing the nerve impulse transmission along the axon.
What important organelle is absent from the neuron cell body and what does the absence of this organelle indicate about activity of the cell body?
The cell body lacks centrioles making it incapable of mitosis.
Describe the function and site of synthesis and storage of neurotransmitters.
One of the main functions of the cell body is to manufacture neurotransmitters, which are chemicals stored in secretory vesicles at the end of axon terminals. When neurotransmitters are released by the axon terminal vesicles, they participate in the transmission of the nerve impulse from one neuron to another.
List the four types of support neuroglial cells and a function of each.
ependymal cells which circulate cerebrospinal fluid and allow fluid exchange between brain, spinal cord and CSF) oligodendrocytes which insulate the central nervous system axons (similar to Schwann cells in the PNS). astrocytes which (control chemical environment of neurons). microglial cells (protect CNS by scavenging dead cells and infectious microoganisms).
List the 3 STRUCTURAL classes of neurons, and describe the structure and an example of each.
Multipolar neurons have three or more extensions, one axon and many dendrites and are found as motor neurons or interneurons within the CNS. Bipolar neurons have two extensions, one axon and one dendrite and are found as receptors cells in the visual and olfactory systems. Unipolar neurons have one extension which branches into two, one central process running to the CNS and another peripheral process running to the sensory receptor and are found as sensory neurons in the peripheral nervous system.
Are sensory neurons are unipolar, bipolar or multipolar?
unipolar
What are the most common type of neurons in the body?
multipolar nuerons
List the 3 FUNCTIONAL classes of neurons, and describe the structure and an example of each.
Sensory neurons are unipolar and carry impulses from receptors in the skin or internal organs toward the CNS. Motor neurons are multipolar and carry impulses from the central nervous system to muscle fibers or glands. Interneurons are usually multipolar and found within the central nervous system only and they transmit impulses between sensory and motors neurons conveying messages between various parts of the central nervous system, such as from one side of the brain or spinal cord to the other, or from the brain to the spinal cord, and vice versa.
What is the technical term used to describe a nerve impulse and what causes the impulse?
A nerve impulse is called an action potential and is caused by the movement of unequally distributed ions on either side of an axon’s plasma membrane.
An axon’s membrane is polarized with a resting potential of -70 mV. Explain what this means and what maintains this resting potential.
The axon plasma membrane is polarized, meaning that one side has a different charge than the other side. This difference called a resting potential means that the charge on the inside of the axon’s cell membrane is 70 millivolts less than the outside of the membrane. A sodium- potassium pump using active transport carries ions across the plasma membrane and because three Na+ ions are pumped out as two K+ ions are pumped in a relative positive charge develops and is maintained on the outside of the membrane.
Label each numbered section (1-4) of the diagram which describes an action potential.
1 = resting state 2 = depolarization 3 = repolarization 4 = afterpolarization.
Describe what happens to the charges on the axon cell membrane during depolarization and what causes this to happen.
During the resting phase both sodium and potassium gates that control the relative charges on sides of the membrane are closed. During depolarization the sodium gates open and sodium rushes into the axon and the inside becomes more positive than the outside causing the membrane potential to become more positive.
Describe what happens to the charges on the axon cell membrane during repolarization and what causes this to happen?
During repolarization the sodium gates close and potassium gates open allowing potassium to rush out of the axon. This returns a negative charge to the inside of the axon re-establishing the negative potential.
What happens during afterpolarization?
The potassium gates that open during repolarization are slow to close and there is generally an afterpolarization undershoot of the potential.
What causes the difference in intensity of a sensation?
The difference in intensity of a sensation is due to the number of neurons stimulated and the frequency with which they are activated.
How is an impulse passed from one nerve cell to another?
There is a minute fluid-filled space, called a synapse, between the axon terminal of the sending neuron and the dendrite of the receiving neuron. When a nerve impulse reaches the end of an axon, neurotransmitters are released into the synapse. These bind with a receptor on the next neuron, opening Na+ gates in the receiving dendrite which causes depolarization and the impulse is carried.
What prevents continuous stimulation of a nerve synapse and how is this accomplished?
The short existence of neurotransmitters in the synapse prevents continuous stimulation. Some synapses contain enzymes that rapidly inactivate neurotransmitters and other synapses rapidly absorb the neurotransmitter.
What is the mnemonic to remember which cranial nerves are sensory or motor or both
Some say marry money but my brother says big brains matter more
What is the mnemonic to remember the cranial nerves?
On old Olympus’ towering top a Finn and German viewed some hops
For each cranial nerve, state the number, the name, whether sensory or motor, and what it controls
1st - Olfactory - Sensory - Sense of smell. 2nd - Optic - Sensory - Sense of sight. 3rd - Oculomotor - Motor - Eye movement. 4th -Trochlear - Motor - Eye movement. 5th - Trigeminal - Motor and Sensory - Chewing and sensation of face, nose, and mouth. 6th - Abducens - Motor - Eye movement. 7th - Facial - Motor and sensory - Facial expressions and sensation of tongue. 8th - Vestibulocochlear - Sensory - Hearing and balance. 9th - Glossopharyngeal - Motor and sensory - Swallowing and taste. 10th - Vagus - Motor and sensory - Digestion, regulation of heart rate, sensation of digestive tract. 11th - Accessory - Motor - Rotation of the head and shrugging of the shoulders. 12th - Hypoglossal - Motor - Tongue movements.
List the 5 types of human spinal nerves and how many of each there are.
Humans have eight pairs of cervical (cranial) nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves.
Describe in detail the structure of spinal nerves within the vertebral column.
Each spinal nerve emerges from the spinal cord by two short roots, the dorsal root which contains the axons of afferent sensory neurons, which conduct impulses to the cord and the ventral root which contains the axons of efferent motor neurons, which conduct impulses away from the cord. These two roots join just before a spinal nerve leaves the vertebral column.
