What are the two major divisions of the nervous system?
The central nervous system (CNS) and the peripheral nervous system (PNS)
What are the three general functions of the nervous system?
Sensory, integrative, and motor
How is the peripheral nervous system divided up?
It is divided into the somatic and autonomous nervous system
What is the function of neuroglia?
They fill spaces, provide structural frameworks, produce the components of myelin, and carry out phagocytosis
What are the types of neuroglia in the central nervous system?
- microglial cells
- ependymal cells
What are microglial cells?
A type of neuroglia in the CNS that support neurons and phagocytise bacterial cells, and form scars in areas of damage.
What are oligodendrocytes?
A type of neuroglia in the CNS that align along nerve fibers. They provide a myelin sheath around axons within the brain and spinal cord.
What are astrocytes?
A type of neuroglia in the CNS that provide structural support, join parts by their abundant cellular processes, and help regulate the concentration of nutrients and ions within the tissue. Form scar tissue that fills spaces following CNS injury.
What are ependymal cells?
A type of neuroglia in the CNS that form an epithelial-like membrane that covers specialised brain parts and form inner linings that enclose spaces in the brain and spinal cord.
What structure in the brain do astrocytes help form?
The blood-brain barrier
What are the neuroglia in the peripheral nervous system?
What is chromatophilic substance? (also know as Nissl bodies)
A large granular body found in neurons. These granules are rough endoplasmic reticulum (RER) with rosettes of free ribosomes, and are the site of protein synthesis
What is neurilemma?
The outermost layer of Schwann cells that surrounds the axon of the neuron. It forms the outermost layer of the nerve fiber in the peripheral nervous system.
When peripheral nerves are damaged, their _____ can regenerate. The ___________ plays an important role in this process. In contrast, the ___ axons are myelinated by oligodendrocytes which do not provide a __________. Consequently, damaged CNS neurons usually do not regenerate.
When peripheral nerves are damaged, their axons can regenerate. The neurilemma plays an important role in this process. In contrast, the CNS axons are myelinated by oligodendrocytes which do not provide a neurilemma. Consequently, damaged CNS neurons usually do not regenerate.
What are the three groups that neurons are classified into?
- Multipolar neurons
- Bipolar neurons
- Unipolar neurons
What are the main features of multipolar neurons?
- many processes arising from cell bodies
- only one process of each neuron is an axon, the rest are dendrites
What are the main features of bipolar neurons?
- have two processes, one arising from each end of the cell body
- one process of an axon, the other is a dendrite
What are the main features of unipolar neurons?
- have a single process extending from cell body
- the process divides into two branches which function as a single axon
- there is a peripheral process and a central process
The cell bodies of some _________ neurons aggregate in specialised masses of nervous tissue called _____ which are located outside the _____ and ______ _____.
The cell bodies of some unipolar neurons aggregate in specialised masses of nervous tissue called ganglia which are located outside the brain and spinal cord.
What are the types of neuron based on their function?
- sensory neurons
- motor neurons
What do sensory (afferent) neurons do?
Transmit nerve impulses from peripheral body parts to the brain or spinal cord. They either have special receptor ends or are closely associated with receptor cells in the skin or in sensory organs.
What do interneurons do?
They transmit impulses from one part of the brain or spinal cord to another
What is an aggregation of the bodies of interneurons called?
A nucleus (plural nuclei). They are similar to ganglia, but in the CNS.
What do motor (efferent) neurons do?
Transmit impulses out of the brain or spinal cord to effectors.
What is a synapse?
A junction between any two communicating neurons
Neurons are seperated by a gap called a _______ _____.
What are the chemicals that transmit impulses?
Define resting potential
The difference in charge between the inside and outside of a resting nerve cell
What is the resting potential of a neuron? (mV)
What is the threshold potential? (mV)
What are the main steps in an action potential being generated?
Action potentials are normally initiated at a low threshold "_______ ____" that is more excitable than any other part of the dendrites. This _______ _____ is located at the axon initial segment, the _______ _______.
Action potentials are normally initiated at a low threshold "trigger zone" that is more excitable than any other part of the soma or dendrites. This trigger zone is located at the axon initial segment, the axon hillock.
What are sensory fibers?
Neuron processes that bring sensory information into the CNS
What are motor fibers?
Neuron processes that carry impulses from the CNS to effectors
Like neurons, nerves that conduct impulses to the brain of spinal cord are called _________ _______, and those that carry impulses to muscles or glands are termed ______ ______. Most nerves include both of these and are called _______ ______.
Like neurons, nerves that conduct impulses to the brain of spinal cord are called sensory nerves, and those that carry impulses to muscles or glands are termed motor nerves. Most nerves include both of these and are called mixed nerves.
What is a named example of a reflex?
What muscle does the patellar reflex stimulate?
The quadriceps femoris muscle group
The brain lies in the ________ ________ of the skull, and the spinal cord occupies the ________ ______ in the vertebral column.
The brain lies in the cranial canal of the skull, and the spinal cord occupies the vertebral canal in the vertebral column.
What are the three layers in meninges?
The dura mater, arachnoid mater, and the pia mater.
Describe dura mater
Outermost layer of the meninges. It is composed primarily of tough, white, fibrous connective tissue and contains many blood vessels and nerves.
Dura mater continues into the vertebral canal as a strong, tubular sheath that surrounds the spinal cord. It terminates as a blind sac below the end of the cord.
Describe arachnoid mater
A thin, weblike membrane without blood vessels that lies between the dura and pia maters.
What is between the arachnoid and pia mater?
Subarachnoid space that contains cerebrospinal fluid (CSF)
Describe pia mater
A thin membrane that contains many nerves and blood vessels that nourish underlying cells of the brain and spinal cord. This layer hugs the surfaces of these organs and follows their irregular contours.
Define spinal cord
A slender nerve column that passes downward from the brain into the vertebral canal
How many segments are in the spinal cord?
What does each spinal segment give rise to?
A pair of spinal nerves
In the neck region, a thickening in the spinal cord, called the _______ _________, supplies nerves to the upper limbs. A similar thickening in the lower back, the ______ _________, gives off nerves to the lower limbs.
In the neck region, a thickening in the spinal cord, called the cervical enlargement, supplies nerves to the upper limbs. A similar thickening in the lower back, the lumbar enlargement, gives off nerves to the lower limbs.
What are the two types of tracts in the spinal cord?
Ascending and descending
How many pairs of spinal nerves are there?
Each spinal nerve is associated with the vertebra _____ it. The _______ spinal nerves are an exception, because spinal nerve __ passes superior to the vertebra __. Thus, although there are seven _______ vertebrae, there are _____ pairs of _______ nerves.
Each spinal nerve is associated with the vertebra above it. The cervical spinal nerves are an exception, because spinal nerve C1 passes superior to the vertebra C1. Thus, although there are seven cervical vertebrae, there are eight pairs of cervical nerves.
How many pairs of thoracic nerves are there?
How many pairs of cervical nerves are there?
How many pairs of lumbar nerves are there?
How many pairs of sacral nerves are there?
How many pairs of coccygeal nerves are there?
The lumbar, saccral and coccygeal nerves descend beyond the spinal cord, forming a structure called the ______ _______.
The lumbar, saccral and coccygeal nerves descend beyond the spinal cord, forming a structure called the cauda equina.
The dorsal root contains the cell bodies of what type of neurons?
The ventral root contains the axons of which type of neuron?
A branching network of vessles or nerves
What is the cervical plexus?
A plexus that lies deep within the neck and form from the branches of the first four cervical nerves.
Supplies the muscles and skin of the neck.
What do the phrenic nerves control? What nerves does it include?
Made up from C3, C4, and C5. They conduct motor impulses to the muscle fibers of the diaphragm.
What is the brachial plexus? What nerves is it made up from?
Supplies the muscles and the skin of the arm, forearm, and hand. Contains the lower four cervical nerves and the first thoracic nerve.
What nerves are in the brachial plexus?
What is the lumbosacral plexus?
A plexus that extends out from the lumbard region and has axons from T12 to Co extending from it.
Motor and sensory axons associated with the muscles and skin of the lower abdominal wall, external genitalia, buttocks, thighs, legs, and feet.
What nerves are in the lumbosacral plexus?
What are the intercostal nerves?
The nerves associated with breathing, T2-T11